207 replies to this topic

[Kevnzworld]

Should this study regarding mitochondrial antioxidants ( MitoQ ) be of concern for those of us taking what we presume is another mitochondrial targeted antioxidant C60?
" mtDNA Mutagenesis Disrupts Pluripotent Stem Cell Function by Altering Redox Signaling "
http://www.cell.com/...1247(15)00521-5

[niner]

Should this study regarding mitochondrial antioxidants ( MitoQ ) be of concern for those of us taking what we presume is another mitochondrial targeted antioxidant C60?
" mtDNA Mutagenesis Disrupts Pluripotent Stem Cell Function by Altering Redox Signaling "
http://www.cell.com/...1247(15)00521-5

This looks like the main problem:

 

 

Clonal capacity, i.e., ability of a single stem cell to generate a new stem cell clone, is considered a measure of stemness. The clonality of mutator iPSCs was decreased to one-fourth of WTs. This self-renewal defect was partially rescued by NAC (100 μM) and low concentration of MitoQ (10 nM). NAC treatment had no significant effect on WT cells (Figures 1D and 1E). However, 100 nM MitoQ—the concentration successfully used during MEF reprogramming—instead of improving mutators, had a detrimental effect on WT clonality (Figures 1D and 1E), whereas NAC even in 10-fold concentration (1 mM) improved self-renewal of mutator iPSCs and showed no adverse effects on WTs (Figures 1D and 1E). These results indicate that MitoQ has a narrow therapeutic window and can be harmful to stem cells at higher concentrations.

 

Skulachev's SkQ1 is MitoQ with a plastoquinone instead of ubiquinone.  Supposedly this resulted in a wider concentration range in which it acted as an antioxidant, as compared to MitoQ.  Skulachev says that MitoQ becomes pro-oxidant at a relatively low concentration.  (Caveat:  Skulachev is an economic competitor to MitoQ)  Is that what we're seeing here, or is this a general effect where if the antioxidant effect gets too effective it causes signaling problems?  I don't know.  It would have been nice if they pushed the NAC concentration up by another order of magnitude to see if they could get it to show the negative effect on clonality.   At this point, I think you have to look at this as at least an indication that just because some is good, that doesn't mean more is better, which is a pretty good general rule.  It is well known that different compounds have different ranges of concentration in which good outweighs bad. In pharmaceutics, the "therapeutic index" or sometimes "therapeutic window" is the ratio of the concentration needed to cause toxicity versus the therapeutic concentration.  Bigger is better.  Generally speaking, this is an argument against megadosing of poorly-characterized compounds.  It may well be the case that c60oo has a large therapeutic index, but I don't think we have the data to say that we know that.  What we've seen so far from the c60oo user community is a few reports that could be explained by c60oo having a positive effect on stem cell differentiation.  If megadoses (or any dose) were having a negative effect, that seems like something that would take a long time to show up.

[Kalliste]

Science is always such a mess. This is one of the risks. I still suspect the benefits will outweigh the costs for C60.

 

In conclusion, we demonstrate that mtDNA mutations can reduce reprogramming efficiency of somatic cells and lead to stemness defects via ROS-mediated signaling. Antioxidants can cure these defects, and mitochondrial-targeted MitoQ was very effective in rescue but also showed toxic effects. Antioxidants are common dietary supplements worldwide. Little is, however, known of their cell-type-specific effects. Our data indicate that a therapeutic dose may vary considerably between cell types: a dose that may rescue pathology in one tissue may severely challenge function in another. An effect on NSC pool may remain undetected for years. Our data implicate the need of dose-effect studies of antioxidants on SSC pools to establish their safety as nutritional supplements or therapeutic agents—especially in the case of antioxidants accumulating into mitochondria.

 

 

[HighDesertWizard]

As someone who has experienced C60 Rejuvenation Effects, I certainly am interested in understanding the Mechanism of Action. And it seems to me that a big question is this...

 

Are there multiple Biological Rejuvenation Mechanisms within us or is there some Primary Mechanism that can be triggered, initially, by various means, with C60 being among those means?

 

I believe the latter is true and our challenge is to uncover the science of that Primary Biological Mechanism. NF-kB blockade has demonstrated rejuvenation effects, as has increased Telomerase Expression. And, in fact...

• NF-kB Transcription Inhibition has been shown to lengthen Human Lifespans via its surrogate marker, Heart Rate Variability.
• it appears, increasingly, that NF-kB Inhibition and Telomerase Expression are two processes within a larger, Systemic, Primary Mechanism.

Is there someone here willing to try to make the case that there is some specific biological MoA for rejuvenation that is distinct to the C60-OO technique, independent of these biological processes already demonstrated as having rejuvenation effects? It would be entertaining to read and mock that kind of thing... :-)

 

The focus on an explanation that is unique to C60 effects itself then, without focus, too, to ensure that The C60 Rejuvenation Explanation makes sense in light of those other experiments demonstrating rejuvenation effects, virtually guarantees that the single technique explanation will turn out to be profoundly missing key elements...

 

[bixbyte]

  Generally speaking, this is an argument against megadosing of poorly-characterized compounds.  It may well be the case that c60oo has a large therapeutic index, but I don't think we have the data to say that we know that.  What we've seen so far from the c60oo user community is a few reports that could be explained by c60oo having a positive effect on stem cell differentiation.  If megadoses (or any dose) were having a negative effect, that seems like something that would take a long time to show up.

 

 

Only way such a possible stem cell differentiation could be proved would be by a mouse or rat study.

I wonder if anyone could figure out how to model such a study?

My interest is from the stem cell view as the starting of cancer mutations.

Can C60 prevent the very start of mutagens?  

 

[aribadabar]

 

Can C60 prevent the very start of mutagens?  

 

 

In a circuitous way, yes - by neutralizing the ROS generated in the ETC (mitochondria) and other exogenous factors (UV light, inflammation, radiation etc) and therefore minimizing their detrimental effect on DNA stability.

Un- or less harmed DNA is less likely to mutate and turn cancerogenic.

 

 

  

[aribadabar]

 

Is there someone here willing to try to make the case that there is some specific biological MoA for rejuvenation that is distinct to the C60-OO technique, independent of these biological processes already demonstrated as having rejuvenation effects? 

 

The distinct feature of C60-oo perhaps is its bimodal action - 1) as a super antioxidant (neutralizing ROS by acting as an electron donor/acceptor "sponge" while maintaing charge stability) and 2) as a stem cell activator (upregulating tissue remodelling and rejuvenation).

 

And if I can add my question - are there any other compounds that can mediate these 2 extremely important processes simultaneously? 

[niner]

 

 

Is there someone here willing to try to make the case that there is some specific biological MoA for rejuvenation that is distinct to the C60-OO technique, independent of these biological processes already demonstrated as having rejuvenation effects? 

 

The distinct feature of C60-oo perhaps is its bimodal action - 1) as a super antioxidant (neutralizing ROS by acting as an electron donor/acceptor "sponge" while maintaing charge stability) and 2) as a stem cell activator (upregulating tissue remodelling and rejuvenation).

 

And if I can add my question - are there any other compounds that can mediate these 2 extremely important processes simultaneously? 

 

It's not really bimodal, in that the stem cell effects are mediated through antioxidant action.  There are other antioxidants that will do this; primarily mitochondrial antioxidants like SkQ1, MitoQ, or SS-31, but also a sufficiently potent / sufficiently hydrophobic antioxidant like NAC.

[Kalliste]

I wonder if this could be balanced by introducing exogenous sources of ROS. Maybe this is the reason that stuff like Curcumin seems to have a positive effect on brain health. It's acting as a pro oxidant in the right stage. So if we find out that C60 or MitoQ has some negative effects under some circumstances maybe that could be balanced by the right supplementation with, for example, curcumin to maintain the ROS load in the right tissue. This is probably not correct but the thought came to me in my dreams.

[Turnbuckle]

 

 

 

Is there someone here willing to try to make the case that there is some specific biological MoA for rejuvenation that is distinct to the C60-OO technique, independent of these biological processes already demonstrated as having rejuvenation effects? 

 

The distinct feature of C60-oo perhaps is its bimodal action - 1) as a super antioxidant (neutralizing ROS by acting as an electron donor/acceptor "sponge" while maintaing charge stability) and 2) as a stem cell activator (upregulating tissue remodelling and rejuvenation).

 

And if I can add my question - are there any other compounds that can mediate these 2 extremely important processes simultaneously? 

 

It's not really bimodal, in that the stem cell effects are mediated through antioxidant action.  There are other antioxidants that will do this; primarily mitochondrial antioxidants like SkQ1, MitoQ, or SS-31, but also a sufficiently potent / sufficiently hydrophobic antioxidant like NAC.

 

 

 

Do you have evidence that these other antioxidants stimulate stem cells?

[bixbyte]

Here is an interesting new study about C60 Fullerenes and Carboxylic Acid Derivatives that suggest they in combination can turn on microglial cells your first line of immune defense in protecting your Central Nervous System........The more I continue to read about using C60 adjunctively Maybe they (C60) are actually doing all the work?

 

 

 Nanoscale Res Lett. 2015 Dec;10(1):953. doi: 10.1186/s11671-015-0953-9. Epub 2015 May 30.

Carboxylic Acid Fullerene (C60) Derivatives Attenuated Neuroinflammatory Responses by Modulating Mitochondrial Dynamics.

Ye S1, Zhou T, Cheng K, Chen M, Wang Y, Jiang Y, Yang P.

Author information

 

Abstract

Fullerene (C60) derivatives, a unique class of compounds with potent antioxidant properties, have been reported to exert a wide variety of biological activities including neuroprotective properties. Mitochondrial dynamics are an important constituent of cellular quality control and function, and an imbalance of the dynamics eventually leads to mitochondria disruption and cell dysfunctions. This study aimed to assess the effects of carboxylic acid C60 derivatives (C60-COOH) on mitochondrial dynamics and elucidate its associated mechanisms in lipopolysaccharide (LPS)-stimulated BV-2 microglial cell model. Using a cell-based functional screening system labeled with DsRed2-mito in BV-2 cells, we showed that LPS stimulation led to excessive mitochondrial fission, increased mitochondrial localization of dynamin-related protein 1 (Drp1), both of which were markedly suppressed by C60-COOH pretreatment. LPS-induced mitochondria reactive oxygen species (ROS) generation and collapse of mitochondrial membrane potential (ΔΨm) were also significantly inhibited by C60-COOH. Moreover, we also found that C60-COOH pretreatment resulted in the attenuation of LPS-mediated activation of nuclear factor (NF)-κB and mitogen-activated protein kinase (MAPK) signaling, as well as the production of pro-inflammatory mediators. Taken together, these findings demonstrated that carboxylic acid C60 derivatives may exert neuroprotective effects through regulating mitochondrial dynamics and functions in microglial cells, thus providing novel insights into the mechanisms of the neuroprotective properties of carboxylic acid C60 derivatives.

PMID:   26058514   [PubMed]    Free full text

 

 

http://www.sigmaaldrich.com/content/dam/sigma-aldrich/structure6/112/mfcd00213323.eps/_jcr_content/renditions/mfcd00213323-large.png

 

Edited by bixbyte, 14 June 2015 - 06:43 PM.

[Kalliste]

I have been trying to wrap my head around the issue of stem cells and oxidation, here are some articles which approach the subject, none of them very encompassing.  

 

Fullerene Nanoparticles Selectively Enter Oxidation-Damaged Cerebral Microvessel Endothelial Cells and Inhibit JNK-Related Apoptosis

Fang Lao ‡†, Long Chen ‡†, Wei Li §†, Cuicui Ge §†, Ying Qu ‡†, Quanmei Sun ‡†, Yuliang Zhao §†, Dong Han ‡†* and Chunying Chen ‡†*

^† CAS Key Lab for Biological Effects of Nanomaterials and Nanosafety (NCNST-IHEP)

^‡ National Center for Nanoscience and Technology (NCNST), Beijing 100190, China

^§ Institute of High Energy Physics (IHEP), Chinese Academy of Sciences, Beijing 100049, China

ACS Nano, 2009, 3 (11), pp 3358–3368

DOI: 10.1021/nn900912n

Publication Date (Web): October 19, 2009

Copyright © 2009 American Chemical Society

* Address correspondence to chenchy@nanoctr.cn, dhan@nanoctr.cn.

Abstract

There is a dearth in fundamental cellular-level understanding of how nanoparticles interact with the cells of the blood brain barrier (BBB), particularly under the oxidative environment. The apoptosis of cerebral microvessel endothelial cells (CMECs) induced by oxidative stress injury plays a key role in the dysfunction of BBB. By use of CMECs as an in vitro BBB model, we show for the first time that C₆₀(C(COOH)₂)₂ nanoparticles can selectively enter oxidized CMECs rather than normal cells, and maintain CMECs integrity by attenuating H₂O₂-induced F-actin depolymerization via the observation of several state-of-the art microscopic techniques. Additionally, we have found that C₆₀(C(COOH)₂)₂ nanoparticles greatly inhibit the apoptosis of CMECs induced by H₂O₂, which is related to their modulation of the JNK pathway. C₆₀(C(COOH)₂)₂ nanoparticles can regulate several downstream signaling events related to the JNK pathway, including reduction of JNK phosphorylation, activation of activator protein 1 (AP-1) and caspase-3, and inhibition of polyADP-ribose polymerase (PARP) cleavage and mitochondrial cytochrome c release. Our results indicate that C₆₀(C(COOH)₂)₂ nanoparticles possess a novel ability of selectively entering oxidation-damaged cerebral endothelial cells rather than normal endothelial cells and then protecting them from apoptosis.

 

 

 

 

Significant effort has focused on using synthetic small molecules to control stem cell development¹⁵, but endogenous (that is, naturally occurring) molecules have not been extensively examined. Our untargeted metabolomics analysis has revealed a unique metabolic signature in ESCs characterized by the presence of highly unsaturated endogenous molecules. The high degree of unsaturation makes these metabolites reactive and susceptible to oxygenation and hydrogenation reactions, conferring them with what may be interpreted as 'chemical plasticity'. Examples of such metabolites include polyunsaturated fatty acids such as AA, EPA and DHA, which are rapidly released by cell membranes in response to stress or altered homeostasis, making them available for oxidative metabolism by COX, LOX and P450 enzymes.

Our findings suggest that the redox status of ESCs is regulated during the process of differentiation, as revealed by measurements of GSH/GSSG ratios and ascorbic acid levels. The inverse relationship between the GSH/GSSG ratio and the ascorbic acid level may indicate that ascorbic acid compensates for the accumulation of GSSG to maintain homeostasis during ESC differentiation. This is consistent with the closely linked antioxidant actions of glutathione and ascorbic acid previously observed in the liver of adult mice¹⁶, where induction of glutathione deficiency is accompanied by a rapid increase in ascorbic acid (in contrast to other adult tissues or liver in newborn rats). Previous studies have revealed the importance of ascorbic acid in promoting differentiation when it is present during the early stages of stem cell differentiation^{17, 18}.

We show that inhibition of 5Δ and 6Δ desaturases by curcumin and sesamin delays differentiation. These desaturases are key enzymes involved in the synthesis of 'plastic' ω-3 and ω-6 polyunsaturated fatty acids. Notably, curcumin is also known to act as an antioxidant¹⁹. Therefore, we cannot exclude the possibility that the increased levels of Nanog and Oct4 caused by curcumin are partially due to its regulation of the redox status.

Our experimental results also show that supplementation of ESC media with essential, naturally occurring metabolites associated with oxidative metabolism in the mitochondria²⁰, such as saturated fatty acids and acyl-carnitines in β-oxidation, leads to a substantial increase in neuronal and cardiac differentiation. This is consistent with previous observations that increased production of mitochondrial proteins is associated with neurogenesis^{21, 22, 23}. Activation of oxidative enzymes such as NADPH oxidase, and subsequent ROS generation, is also a prerequisite for cardiovascular differentiation of ESCs^{24, 25}.

Overall, our results suggest that the activation of oxidation is a metabolic signature of stem-cell differentiation. Indeed, several independent lines of evidence have demonstrated that stem cells contain lower levels of ROS than their more mature progeny^{23, 26, 27} and that ROS accumulation and signaling is required for differentiation²³. This is consistent with previous observations that the intracellular oxidation state regulates the balance between self-renewal and differentiation²⁸. Specifically, signaling molecules that promote pluripotency make stem cells more reduced, whereas those that promote differentiation make cells more oxidized. In addition, it is well known that hypoxia maintains the pluripotent and undifferentiated phenotype of stem or precursor cells both in vitro and in vivo^{29, 30}. We speculate that redox regulation, together with hypoxic conditions, allows stem cells to differentiate in vivo in response to oxidative processes such as inflammation.

Finally, our results raise the noteworthy possibility that specific endogenous inflammatory mediators might regulate the regenerative properties of stem cells. We found that inhibition of PLA₂, COX and LOX promotes the pluripotent, undifferentiated state of ESCs. In support of our results, a high-throughput screening assay has shown that anti-inflammatory drugs promote self-renewal in human ESCs³¹. For the first time, to our knowledge, we show that neuroprotectin D1 (ref. 32), a DHA-derived lipid mediator that activates inflammation resolution³³, accelerates neuronal differentiation. Pro-inflammatory lipid mediators such as leukotriene B4 and C4, in contrast, have no substantial effect on mESC differentiation. Previous studies have also revealed that stem cell fate is influenced by specific eicosanoids, such as prostaglandin E2 (ref. 34) and lipoxin A4 (ref. 35). These data suggest that specific molecular responses to injury and inflammation may regulate the proliferation and differentiation of stem cells; this may lead to the exploration of new avenues in understanding properties associated with regeneration. Further investigation will determine the mechanisms by which pro-inflammatory and pro-resolving endogenous metabolites activate proliferation and differentiation of quiescent stem or progenitor cells in response to tissue repair or wound healing.

http://www.nature.co...hembio.364.html

 

 

Curcumin is a natural phenolic component of yellow curry spice, which is used in some cultures for the treatment of diseases associated with oxidative stress and inflammation. Curcumin has been reported to be capable of preventing the death of neurons in animal models of neurodegenerative disorders, but its possible effects on developmental and adult neuroplasticity are unknown. In the present study, we investigated the effects of curcumin on mouse multi-potent neural progenitor cells (NPC) and adult hippocampal neurogenesis. Curcumin exerted biphasic effects on cultured NPC; low concentrations stimulated cell proliferation, whereas high concentrations were cytotoxic. Curcumin activated extracellular signal-regulated kinases (ERKs) and p38 kinases, cellular signal transduction pathways known to be involved in the regulation of neuronal plasticity and stress responses. Inhibitors of ERKs and p38 kinases effectively blocked the mitogenic effect of curcumin in NPC. Administration of curcumin to adult mice resulted in a significant increase in the number of newly generated cells in the dentate gyrus of hippocampus, indicating that curcumin enhances adult hippocampal neurogenesis. Our findings suggest that curcumin can stimulate developmental and adult hippocampal neurogenesis, and a biological activity that may enhance neural plasticity and repair.

http://www.jbc.org/c.../21/14497.short

 

 

[HighDesertWizard]

I found this patent application in my study abstract travels while trying to get a handle on Activated Charcoal effects. I was surprised to find most of the graphic figures related to Survival, Dosing, and Inflammatory Cytokine Expression. That is, the same kind of information found in the NF-kB Inhibition effects literature of Kevin Tracey. (See, especially, figures 9 and 16 from the patent application and compare to Tracey's complete 2012 literature review, and especially figure 4.)

 

Lo and behold... Kevin Tracey is a co-applicant for the patent... :-)

 

Use of charcoal for treating inflammatory conditions

 

I've spent some time looking at this. I'll have more to say about this in a bit, but I thought I'd provide an early heads up that the discussion is about to get more interesting...

[Aurel]

You can have a patent on supplementing with charcoal?

[Turnbuckle]

You can have a patent on supplementing with charcoal?

 

 

You can file a patent application on anything as long as the format is right and you pay the fees. Getting it issued is the rub.

 

In any case, charcoal is seriously off topic.

Edited by Turnbuckle, 15 June 2015 - 08:41 PM.

[niner]

 

 

The distinct feature of C60-oo perhaps is its bimodal action - 1) as a super antioxidant (neutralizing ROS by acting as an electron donor/acceptor "sponge" while maintaing charge stability) and 2) as a stem cell activator (upregulating tissue remodelling and rejuvenation).

 

And if I can add my question - are there any other compounds that can mediate these 2 extremely important processes simultaneously? 

 

It's not really bimodal, in that the stem cell effects are mediated through antioxidant action.  There are other antioxidants that will do this; primarily mitochondrial antioxidants like SkQ1, MitoQ, or SS-31, but also a sufficiently potent / sufficiently hydrophobic antioxidant like NAC.

 

Do you have evidence that these other antioxidants stimulate stem cells?

 

All I know of are in vitro systems that might be a bit artificial, but examples would be the Hamalainen Cell Rep. paper  that Kevinzworld linked above, or perhaps more illuminating, this 2014 paper by Kim.  Hamalainen warned people about mitochondrial antioxidants in general, of which those three are examples, but only looked at MitoQ and NAC.  I thought I'd seen something on SS-31 but couldn't find it.  Kim also looked at NAC.   Here's a paper looking at embryo development, finding that antioxidants result in improved embryo development when starting with eggs from both old and young mice.  (NAC, ALA, tocopherol)  I don't know if I could call any of this stimulating stem cells as much as keeping them from failing.

[Turnbuckle]

 

 

 

The distinct feature of C60-oo perhaps is its bimodal action - 1) as a super antioxidant (neutralizing ROS by acting as an electron donor/acceptor "sponge" while maintaing charge stability) and 2) as a stem cell activator (upregulating tissue remodelling and rejuvenation).

 

And if I can add my question - are there any other compounds that can mediate these 2 extremely important processes simultaneously? 

 

It's not really bimodal, in that the stem cell effects are mediated through antioxidant action.  There are other antioxidants that will do this; primarily mitochondrial antioxidants like SkQ1, MitoQ, or SS-31, but also a sufficiently potent / sufficiently hydrophobic antioxidant like NAC.

 

Do you have evidence that these other antioxidants stimulate stem cells?

 

All I know of are in vitro systems that might be a bit artificial, but examples would be the Hamalainen Cell Rep. paper  that Kevinzworld linked above, or perhaps more illuminating, this 2014 paper by Kim.  Hamalainen warned people about mitochondrial antioxidants in general, of which those three are examples, but only looked at MitoQ and NAC.  I thought I'd seen something on SS-31 but couldn't find it.  Kim also looked at NAC.   Here's a paper looking at embryo development, finding that antioxidants result in improved embryo development when starting with eggs from both old and young mice.  (NAC, ALA, tocopherol)  I don't know if I could call any of this stimulating stem cells as much as keeping them from failing.

 

 

 

 

None of these references support the claim that anti-oxidants stimulate stem cells in the way that is apparently happening with C60. In particular, it seems to be just the opposite. Antioxidants keep stem cells as stem cells. According to the Kim paper you referenced--

 

...rapid loss of stemness can occur due to spontaneous ROS overload, leading to their active commitment into neurons; however, stemness is restored by the addition of an antioxidant...

 

 

A couple of years ago someone here made the suggestion that UCP might be involved, and this seems more and more likely true. Stem cells are loaded with UCP pores that decouple ATP production and thus depress ROS formation. If the round C60 molecules acted like a cork to the cylindrical UCP pore, it could shut it off, thereby forcing stem cells from glycolysis (like cancer cells) to oxidative phosphorylation (like somatic cells) and thus forcing stem cells to differentiate.

 

Mitochondrial Regulation in Pluripotent Stem Cells

 

 

 these findings demonstrate an important role of UCP2 in PSC differentiation and show that UCP2-mediated suppression of OXPHOS is required for the maintenance of pluripotency.  

 

 

It also might explain why some C60 effects fade with continuous use. UCP proteins are important to regulating somatic cells as well as stem cells, and thus feedback loops must exist. If the cells begin producing a good deal more ATP continuously, then you might expect cells to produce more UCP proteins to compensate. And if you combine this with C60's known antioxidant properties, you get a dual mode of action that can explain the spectrum of effects users here have seen. In particular, the effect on stem cells might be somewhat unpredictable, as the antioxidant properties are working at cross purposes with the effect on boosting oxidative phosphorylation. So too much C60 might eliminate any stem cell effects altogether.

 

The UCP hypothesis also suggests that other nano-particles might have a similar effect on stem cells, as they could also block mitochondrial pores. Like gold and silica particles, for instance--

 

 

Development of gold nanoparticles that control osteogenic differentiation of stem cells

 

It has been reported that nanosized gold particles promote the differentiation of human mesenchymal stem cells into osteoblasts.

 

Edited by Turnbuckle, 16 June 2015 - 11:06 AM.

[Kalliste]

Heres another paper from 2011 on stem cells and ROS. Sufficive to say the issue is not very straightforward, I'm too stupid to understand most of it but the issue warrants attention.

Proliferative Neural Stem Cells Have High Endogenous ROS Levels that Regulate Self-Renewal and Neurogenesis in a PI3K/Akt-Dependant Manner

http://www.sciencedi...934590910006508

 

 

Discussion Reactive Oxygen Species Regulate Neural Stem Cell Function

In the current manuscript we have demonstrated that both exogenous and endogenous ROS can have a significant impact on neural stem and progenitor cell proliferation, self-renewal, and neurogenesis. Our observations of the effects of ROS on these cells are surprising for the fact that the neural stem cell compartment appears to be disproportionately dependent on ROS-mediated signaling in the brain. This is not inconsistent with observations by others that embryonic and neural stem cells have enhanced antioxidant capacity compared to more differentiated progeny (Madhavan et al., 2006) because this activity may be a protective mechanism in stem cell populations with active oxidant-mediated signaling to prevent excessive or toxic levels of ROS from being generated. Stem cell populations have been observed to possess an enhanced resistance to oxidative stress-mediated cell death (Madhavan et al., 2006, Madhavan et al., 2008 and Romanko et al., 2004). One such mechanism important for cellular redox regulation could be FOXO proteins. When FOXO genes are deleted from neural stem and progenitor cells, antioxidant defenses are significantly depleted and endogenous ROS levels undergo large increases ( Renault et al., 2009 and Paik et al., 2009). As a result of this elevated cellular ROS, there is an initial hyperproliferation of NSCs leading to brain overgrowth on par with what has been observed with PTEN deletion in the developing brain. However, toxic levels of ROS build up over time, leading to a premature senescence in the cells, suggesting that control of endogenous ROS levels may play a significant role in the regulation of self-renewal and proliferation in neural stem and progenitor cells. Accordingly, Yoneyama et al. (2010) have recently observed that NOX inhibition and antioxidant treatments significantly inhibit hippocampal progenitor proliferation. On the other hand, another recent study has identified a novel ROS-regulating gene, Prdm16, which results in brain undergrowth when deleted ( Chuikov et al., 2010). Prdm16 was identified by the authors as a result of BMI-1 inhibition, which has also been shown to regulate cellular ROS levels in hematopoetic stem cells by specifically altering mitochondrial ROS and not NADPH oxidase-generated ROS ( Liu et al., 2009). Thus, the contradictory inhibitory effects of Prdm16-mediated ROS regulation on NSCs may be related to the endogenous source of the ROS and the cellular compartment in which they act.

Previous studies have disagreed on whether stem cells generally have lower or higher endogenous ROS levels than their differentiated progeny (Madhavan et al., 2006, Tsatmali et al., 2005, Limoli et al., 2004, Jang and Sharkis, 2007 and Diehn et al., 2009). Definitive NSCs might be expected to have a lower endogenous ROS status than that of the highly proliferative, transit-amplifying progenitors because the adult neural stem cell in vivo is thought to be a relatively quiescent cell under normal circumstances (Doetsch et al., 1997). Thus, the higher ROS status of the SVZ that we observed may play a role in maintaining the proliferation of progenitor cells within this neurogenic niche. However, in order for the stem cell population to maintain a more quiescent state in this environment, it would necessitate that they are able to maintain a lower endogenous ROS level when not dividing, suggesting a robust antioxidant regulation in a subset of specialized cells in vivo. Our ex vivo and in vitro data are consistent with high endogenous ROS levels in neural stem cells but could be reflective of an “activated” state in the cells as a result of removal from their normal in vivo environment. In vivo we observed significantly reduced SVZ proliferation and neurogenesis when endogenous ROS levels are reduced in the NOX2 mutants and APO-treated mice. This suggests that in order to maintain normal levels of neurogenesis, the neural stem cells must need to be able to increase ROS levels when required for cell division but does not rule out the possibility that NSCs maintain a low ROS state in vivo when they are in a quiescent state.

The Effects of ROS on NSC Function Are Dependent on PI3k/Akt Signaling

The most often cited mechanism by which ROS contribute to cellular signaling is by modifying the actions of proteins through the reversible oxidation of essential cysteine residues (Ross et al., 2007, Leslie et al., 2003 and Kwon et al., 2004), although other mechanisms have been proposed such as cell cycle targets (cyclin D1 and forkhead proteins) (Abid et al., 2004, Burch and Heintz, 2005 and Blanchetot and Boonstra, 2008). Our data are consistent with a model of posttranslational oxidative inactivation of the tumor suppressor PTEN, a negative regulator of PI3K signaling. Although the involvement of other pathways such as MAPK signaling has not been ruled out, our data suggest a critical role for the PI3K/Akt pathway and are similar to the phenotype observed after genetic deletion of PTEN ( Groszer et al., 2001, Groszer et al., 2006 and Gregorian et al., 2009).

Perhaps more surprising than the stimulatory effects of exogenous ROS, we have found that the inhibition of normal endogenous ROS production by NOX inhibition or mutation negatively regulated the PI3K/Akt pathway and NSC function. Thus, the high ROS status of NSCs appears to be required to maintain their self-renewal and neurogenesis by maintaining adequate levels of PI3K signaling.

The Effects of ROS-Mediated PI3K Pathway Signaling Are Context Dependent

Despite the broad influence of ROS-mediated signaling indicated by the stimulatory effects of exogenous ROS and the negative effects of NOX inhibition in neural stem cell-enriched populations, there are many cases in which cellular response to ROS is highly dependent on other factors such as cell phenotype, cell differentiation state, or other signaling cofactors. For example, conditional deletion of PTEN in nestin-expressing neural stem and progenitors in the developing brain and in GFAP-expressing stem cells in the SVZ of the adult brain leads to an enhanced and sustained neural stem cell self-renewal and neurogenesis, contributing to brain overgrowth ( Groszer et al., 2001, Groszer et al., 2006 and Gregorian et al., 2009). However, studies in the hematopoetic system indicate that although PTEN deletion results in a similar enhancement in self-renewal in hematopoietic stem cells (HSCs), it also results in a premature senescence in these cells ( Zhang et al., 2006, Yilmaz et al., 2006 and Chen et al., 2008). The effects of cellular ROS levels may also be similarly cell type dependent. For example, HSCs have been shown to have lower endogenous ROS levels than their more differentiated hematopoietic cell counterparts ( Jang and Sharkis, 2007).

Previous work has established that O2-A progenitor cells are modulated by changes in cellular redox status, namely that they maintain a low ROS status that promotes cell division and maintains an undifferentiated state (Li et al., 2007, Power et al., 2002 and Smith et al., 2000). Li et al. (2007) determined that one mechanism by which higher ROS inhibit O-2A progenitors is through c-Cbl-mediated receptor tyrosine kinase (RTK) ubiquitination and breakdown. On the other hand it has recently been shown in other cell types that PTEN deletion prevents c-Cbl-mediated RTK breakdown ( Vivanco et al., 2010). Therefore, NOX-mediated oxidative inactivation of PTEN should have similar RTK-stabilizing effects. Additionally, EGF signaling activates NOX and is required for aSVZ neurosphere cultures, whereas EGF is not utilized by O2-A progenitors ( Kondo and Raff, 2000). Thus phenotypic differences in cell NOX activity and EGF signaling could be important factors in the functional differences we have observed between NSCs and O-2A progenitors.

The effects of ROS are also dependent on the differentiation state of the cells. For example, the neurotrophic factor BDNF promotes differentiation of postmitotic neurons, but we found that in undifferentiated cells in the presence of growth factors, it will promote NSC self-renewal in a NOX- and ROS-dependent manner. Similarly, we found that the effects of exogenous ROS stimulation are dependent on the differentiation state of cells. ROS stimulation of undifferentiated cells in the presence of growth factors promotes both NSC self-renewal and neurogenic potential but, on the other hand, the same levels of ROS that were stimulatory to proliferative cells were found to be toxic to the same cells when present during differentiation after growth factor withdrawal. Consistently, the effect of PTEN deletion is also dependent on the differentiation state of the cells. For example, whereas PTEN deletion in undifferentiated, mitotic cells produced enhanced NSC proliferation and neurogenesis ( Groszer et al., 2001), PTEN deletion in postmitotic neurons does not influence cell phenotypes or cause cells to re-enter the cell cycle and divide ( Kwon et al., 2006). Rather, enhanced PI3K pathway signaling in differentiated neurons results in cellular hypertrophy, which can also contribute to a macrocephalic phenotype in vivo ( Zhou et al., 2009).

In conclusion, we have identified a redox-mediated regulatory mechanism of self-renewal and differentiation potential that is required for normal neural stem cell function and to support normal ontogeny. However, a large number of environmental factors and genetic mutations can potentially influence and deregulate ROS-mediated signaling, which may contribute to abnormal brain development or transformation and tumorigenesis. Thus, understanding how normal and transformed cells utilize ROS may play an important role in identifying new targets for anticancer treatments or points of vulnerability in brain development.

 

[Kalliste]

 

It is widely thought that accumulation of reactive oxygen species (ROS) causes injury to cells. In this study, we investigated the effect of endogenous ROS on the proliferation of neural stem/progenitor cells derived from the hippocampus of embryonic mice. The cells were treated with free radical-scavenging agents [3-methyl-1-phenyl-2-pyrazolin-5-one (edaravone) or 4-hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl (tempol)], an NADPH oxidase inhibitor (apocynin), catalase, a nitric oxide synthase inhibitor [N^ω-nitro-l-arginine methyl ester hydrochloride (L-NAME)] or a peroxynitrite generator (SIN-1) during the culture period. Edaravone and tempol had the ability to decrease endogenous ROS in the cells exposed for periods from 1 to 24 h, with attenuation of the proliferation activity of the cells during culture. Apocynin and L-NAME were also effective in attenuating cell proliferation but not cellular damage. Conversely, SIN-1 was capable of promoting the proliferation activity. However, catalase had no effect on the proliferation activity of the cells during culture. Furthermore, tempol significantly decreased the level of NFκB p65, phospho-cyclic AMP response element-binding protein, and β-catenin within the nucleus of the cells. These data suggest that endogenous ROS and nitric oxide are essential for the proliferation of embryonic neural stem/progenitor cells.

http://www.sciencedi...197018609003234

[niner]

 

 

 

 

The distinct feature of C60-oo perhaps is its bimodal action - 1) as a super antioxidant (neutralizing ROS by acting as an electron donor/acceptor "sponge" while maintaing charge stability) and 2) as a stem cell activator (upregulating tissue remodelling and rejuvenation).
 
And if I can add my question - are there any other compounds that can mediate these 2 extremely important processes simultaneously?

 
It's not really bimodal, in that the stem cell effects are mediated through antioxidant action.  There are other antioxidants that will do this; primarily mitochondrial antioxidants like SkQ1, MitoQ, or SS-31, but also a sufficiently potent / sufficiently hydrophobic antioxidant like NAC.

 
Do you have evidence that these other antioxidants stimulate stem cells?

 
All I know of are in vitro systems that might be a bit artificial, but examples would be the Hamalainen Cell Rep. paper  that Kevinzworld linked above, or perhaps more illuminating, this 2014 paper by Kim.  Hamalainen warned people about mitochondrial antioxidants in general, of which those three are examples, but only looked at MitoQ and NAC.  I thought I'd seen something on SS-31 but couldn't find it.  Kim also looked at NAC.   Here's a paper looking at embryo development, finding that antioxidants result in improved embryo development when starting with eggs from both old and young mice.  (NAC, ALA, tocopherol)  I don't know if I could call any of this stimulating stem cells as much as keeping them from failing.

 
None of these references support the claim that anti-oxidants stimulate stem cells in the way that is apparently happening with C60. In particular, it seems to be just the opposite. Antioxidants keep stem cells as stem cells. According to the Kim paper you referenced--
 

...rapid loss of stemness can occur due to spontaneous ROS overload, leading to their active commitment into neurons; however, stemness is restored by the addition of an antioxidant...

 
But doesn't loss of stemness mean that the stem cells have ceased to function as stem cells?  I think this might be a matter of magnitudes, where you need some ROS signaling for differentiation, but too much is bad. 
 

A couple of years ago someone here made the suggestion that UCP might be involved, and this seems more and more likely true. Stem cells are loaded with UCP pores that decouple ATP production and thus depress ROS formation. If the round C60 molecules acted like a cork to the cylindrical UCP pore, it could shut it off, thereby forcing stem cells from glycolysis (like cancer cells) to oxidative phosphorylation (like somatic cells) and thus forcing stem cells to differentiate.
 

Mitochondrial Regulation in Pluripotent Stem Cells
 
 these findings demonstrate an important role of UCP2 in PSC differentiation and show that UCP2-mediated suppression of OXPHOS is required for the maintenance of pluripotency.

 
It also might explain why some C60 effects fade with continuous use. UCP proteins are important to regulating somatic cells as well as stem cells, and thus feedback loops must exist. If the cells begin producing a good deal more ATP continuously, then you might expect cells to produce more UCP proteins to compensate. And if you combine this with C60's known antioxidant properties, you get a dual mode of action that can explain the spectrum of effects users here have seen. In particular, the effect on stem cells might be somewhat unpredictable, as the antioxidant properties are working at cross purposes with the effect on boosting oxidative phosphorylation. So too much C60 might eliminate any stem cell effects altogether.
 
The UCP hypothesis also suggests that other nano-particles might have a similar effect on stem cells, as they could also block mitochondrial pores. Like gold and silica particles, for instance--
 

Development of gold nanoparticles that control osteogenic differentiation of stem cells
 
It has been reported that nanosized gold particles promote the differentiation of human mesenchymal stem cells into osteoblasts.

That's an attractive hypothesis.  I suspect that the nanoparticles are a lot bigger than c60, so a steric equivalence is hard to make, but they're clearly doing something.  The signature characteristic of c60oo is redox activity, and I think the case for mitochondrial location is pretty solid.  However, it's also very likely that it has receptor mediated effects, and docking in a protein cavity is not at all unlikely; There's been a ton of work on fullerene-based inhibitors of HIV protease, for example.  The UCP hypothesis makes sense from a stem cell stimulation point of view. 
 

[Turnbuckle]

 

That's an attractive hypothesis.  I suspect that the nanoparticles are a lot bigger than c60, so a steric equivalence is hard to make, but they're clearly doing something.  The signature characteristic of c60oo is redox activity, and I think the case for mitochondrial location is pretty solid.  However, it's also very likely that it has receptor mediated effects, and docking in a protein cavity is not at all unlikely; There's been a ton of work on fullerene-based inhibitors of HIV protease, for example.  The UCP hypothesis makes sense from a stem cell stimulation point of view. 
 

 

 

 

It's interesting that when you get gold nanoparticles down to twice the size of C60, they suddenly become very toxic due to the production of ROS, but when you coat them with antioxidants, the toxicity is much reduced. So this suggests that C60 might also be highly toxic if it wasn't itself an antioxidant.

 

 

Gold Nanoparticles of Diameter 1.4 nm Trigger Necrosis by Oxidative Stress and Mitochondrial Damage

 

Pretreatment of the nanoparticles with reducing agents/antioxidants N-acetylcysteine, glutathione, and TPPMS reduces the toxicity of Au1.4MS. AuNPs of similar size but capped with glutathione (Au1.1GSH) likewise do not induce oxidative stress

 

 

 

 

[aribadabar]

 

It's interesting that when you get gold nanoparticles down to twice the size of C60, they suddenly become very toxic due to the production of ROS, but when you coat them with antioxidants, the toxicity is much reduced. So this suggests that C60 might also be highly toxic if it wasn't itself an antioxidant.

 

 

Gold Nanoparticles of Diameter 1.4 nm Trigger Necrosis by Oxidative Stress and Mitochondrial Damage

 

Pretreatment of the nanoparticles with reducing agents/antioxidants N-acetylcysteine, glutathione, and TPPMS reduces the toxicity of Au1.4MS. AuNPs of similar size but capped with glutathione (Au1.1GSH) likewise do not induce oxidative stress

 

 

 

Interesting find. What is your assessment of the likes of MesoGold where the particle size is predonimantly in the 3.2 nm range, higher than 1.4nm, but still much smaller than 15nm that was claimed as harmful albeit less toxic in this paper? 

 

 

We showed that a diameter predominantly of 1.4 nm rendered AuNPs toxic in cell cultures.[24] Sizes above 15 nm as well as particles smaller than 1 nm with identical core–shell chemistry were less toxic.

 

Edited by aribadabar, 16 June 2015 - 03:48 PM.

[Turnbuckle]

 

 

It's interesting that when you get gold nanoparticles down to twice the size of C60, they suddenly become very toxic due to the production of ROS, but when you coat them with antioxidants, the toxicity is much reduced. So this suggests that C60 might also be highly toxic if it wasn't itself an antioxidant.

 

 

Gold Nanoparticles of Diameter 1.4 nm Trigger Necrosis by Oxidative Stress and Mitochondrial Damage

 

Pretreatment of the nanoparticles with reducing agents/antioxidants N-acetylcysteine, glutathione, and TPPMS reduces the toxicity of Au1.4MS. AuNPs of similar size but capped with glutathione (Au1.1GSH) likewise do not induce oxidative stress

 

 

 

Interesting find. What is your assessment of the likes of MesoGold where the particle size is predonimantly in the 3.2 nm range, higher than 1.4nm, but still much smaller than 15nm that was claimed as harmful albeit less toxic in this paper? 

 

 

We showed that a diameter predominantly of 1.4 nm rendered AuNPs toxic in cell cultures.[24] Sizes above 15 nm as well as particles smaller than 1 nm with identical core–shell chemistry were less toxic.

 

 

 

I've taken mesogold before with no apparent ill effects. See my postings from 2013 beginning here. At that time I'd been taking C60 for about a year, and was also taking Setria glutathione, both good antioxidants.

[Anthropositor]

Scientific idiom is often employed in ways as likely to obfuscate as to illuminate.  Studies and links often take us down tangential paths that go nowhere with jargon that obscures rather than illuminates.  We see lots of trees, branches, leaves and twigs.  The forest is not in evidence.  Subtle and simple mistakes or speculations are lost in the background noise.  

 

Someone above says the Fullerenes were "discovered," as if they existed in nature like graphite or diamond.  I suspect they were very carefully engineered and produced in a laboratory, after being imagined by a singularly exceptional genius, who might well have been trying to find a way to build a better building using macro-construction materials, something quite different.  Appreciation is in order for both the architectural innovator and the chemical theoretician(s) who adapted his notion in the molecular realm.   

 

Someone else complains that charcoal is off topic.  My logic alarm begins to vibrate gently.  I swat it and return to trying to get a look at a meaningful bigger picture.  While I haven't found a bigger picture here, I may have gotten a little inkling what I should be looking for.  The most interesting thing about these various nano-structures is that they are extremely small on cellular scales, and that they have symmetries that allow them to cage other substances which might be useful in some fashion if the substance (a chemopoision for example) and cage were delivered in some practical fashion to the interior of a rapidly metastasizing neoplasm without undo inconvenience to the larger organism.  A potentially useful notion.

 

I have little doubt that in the above communications, there were certainly other useful nuggets of wisdom to be found.  I fell short of finding them.  My bad. 

[Kalliste]

Some C60-news from pubmed.

 

 

Nanoscale Res Lett. 2015 Dec;10(1):953. doi: 10.1186/s11671-015-0953-9. Epub 2015 May 30.

Carboxylic Acid Fullerene (C60) Derivatives Attenuated Neuroinflammatory Responses by Modulating Mitochondrial Dynamics.

Ye S¹, Zhou T, Cheng K, Chen M, Wang Y, Jiang Y, Yang P.

Author information

• ¹Research Center of Biomedical Engineering, Department of Biomaterials, College of Materials, Xiamen University, Xiamen, 361005, People's Republic of China, yeshefang@xmu.edu.cn.

Abstract

Fullerene (C60) derivatives, a unique class of compounds with potent antioxidant properties, have been reported to exert a wide variety of biological activities including neuroprotective properties. Mitochondrial dynamics are an important constituent of cellular quality control and function, and an imbalance of the dynamics eventually leads to mitochondria disruption and cell dysfunctions. This study aimed to assess the effects of carboxylic acid C60 derivatives (C60-COOH) on mitochondrial dynamics and elucidate its associated mechanisms in lipopolysaccharide (LPS)-stimulated BV-2 microglial cell model. Using a cell-based functional screening system labeled with DsRed2-mito in BV-2 cells, we showed that LPS stimulation led to excessive mitochondrial fission, increased mitochondrial localization of dynamin-related protein 1 (Drp1), both of which were markedly suppressed by C60-COOH pretreatment. LPS-induced mitochondria reactive oxygen species (ROS) generation and collapse of mitochondrial membrane potential (ΔΨm) were also significantly inhibited by C60-COOH. Moreover, we also found that C60-COOH pretreatment resulted in the attenuation of LPS-mediated activation of nuclear factor (NF)-κB and mitogen-activated protein kinase (MAPK) signaling, as well as the production of pro-inflammatory mediators. Taken together, these findings demonstrated that carboxylic acid C60 derivatives may exert neuroprotective effects through regulating mitochondrial dynamics and functions in microglial cells, thus providing novel insights into the mechanisms of the neuroprotective properties of carboxylic acid C60 derivatives.

 

 

 

Ukr Biochem J. 2015 Jan-Feb;87(1):91-8.

C60 fullerene prevents genotoxic effects of doxorubicin in human lymphocytes in vitro.

Afanasieva KS, Prylutska SV, Lozovik AV, Bogutska KI, Sivolob AV, Prylutskyy YI, Ritter U, Scharff P.

Abstract

The self-ordering of C60 fullerene, doxorubicin and their mixture precipitated from aqueous solutions was investigated using atomic-force microscopy. The results suggest the complexation between the two compounds. The genotoxicity of doxorubicin in complex with C60 fullerene (C 60+Dox) was evaluated in vitro with comet assay using human lymphocytes. The obtained results show that the C60 fullerene prevents the toxic effect of Dox in normal cells and, thus, C60+Dox complex might be proposed for biomedical application.

 

C70 produces a lot more singlet oxygen than C60.

 

 

Environ Sci Technol. 2015 May 19;49(10):5990-8. doi: 10.1021/acs.est.5b00100. Epub 2015 May 7.

Differential photoactivity of aqueous [c60] and [c70] fullerene aggregates.

Moor KJ, Snow SD¹, Kim JH¹.

Author information

• ¹‡School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States.

Abstract

Many past studies have focused on the aqueous photochemical properties of colloidal suspensions of C60 and various [C60] fullerene derivatives, yet few have investigated the photochemistry of other larger cage fullerene species (e.g., C70, C74, C84, etc.) in water. This is a critical knowledge gap because these larger fullerenes may exhibit different properties compared to C60, including increased visible light absorption, altered energy level structures, and variable cage geometries, which may greatly affect aggregate properties and resulting aqueous photoactivity. Herein, we take the first steps toward a detailed investigation of the aqueous photochemistry of larger cage fullerene species, by focusing on [C70] fullerene. We find that aqueous suspensions of C60 and C70, nC60 and nC70, respectively, exhibit many similar physicochemical properties, yet nC70 appears to be significantly more photoactive than nC60. Studies are conducted to elucidate the mechanism behind nC70's superior (1)O2 generation, including the measurement of (1)O2 production as a function of incident excitation wavelength, analysis of X-ray diffraction data to determine crystal packing arrangements, and the excited state dynamics of aggregate fullerene species via transient absorption spectroscopy.

 

[Kalliste]

Hmm I remember that Vince Guiliano speculated that C60 might have some effect on microtubules and the like. Maybe C60 is affecting a structure like this one.

 

 

Discovery of Nanotubes Offers New Clues About Cell-to-Cell Communication

Released: 29-Jun-2015 10:05 AM EDT
Embargo expired: 1-Jul-2015 1:00 PM EDT
Source Newsroom: University of Michigan

more news from this source

Contact Information

Available for logged-in reporters only

Citations Nature

Newswise — ANN ARBOR—When it comes to communicating with each other, some cells may be more "old school" than was previously thought.

Certain types of stem cells use microscopic, threadlike nanotubes to communicate with neighboring cells, like a landline phone connection, rather than sending a broadcast signal, researchers at University of Michigan Life Sciences Institute and University of Texas Southwestern Medical Center have discovered.

The findings, which are scheduled for online publication July 1 in Nature, offer new insights on how stem cells retain their identities when they divide to split off a new, specialized cell.

The fruit-fly research also suggests that short-range, cell-to-cell communication may rely on this type of direct connection more than was previously understood, said co-senior author Yukiko Yamashita, a U-M developmental biologist whose lab is located at the Life Sciences Institute.

"There are trillions of cells in the human body, but nowhere near that number of signaling pathways," she said. "There's a lot we don't know about how the right cells get just the right messages to the right recipients at the right time."

The nanotubes had actually been hiding in plain sight.

The investigation began when a postdoctoral researcher in Yamashita's lab, Mayu Inaba, approached her mentor with questions about tiny threads of connection she noticed in an image of fruit fly reproductive stem cells, which are also known as germ line cells. The projections linked individual stem cells back to a central hub in the stem cell "niche." Niches create a supportive environment for stem cells and help direct their activity.

Yamashita, a Howard Hughes Medical Institute investigator, MacArthur Fellow and an associate professor at the U-M Medical School, looked through her old image files and discovered that the connections appeared in numerous images.

"I had seen them, but I wasn't seeing them," Yamashita said. "They were like a little piece of dust on an otherwise normal picture. After we presented our findings at meetings, other scientists who work with the same cells would say, 'We see them now, too.'"

It's not surprising that the minute structures went overlooked for so long. Each one is about 3 micrometers long; by comparison, a piece of paper is 100 micrometers thick.

While the study looked specifically at reproductive cells in male Drosophila fruit flies, there have been indications of similar structures in other contexts, including mammalian cells, Yamashita said.

Fruit flies are an important model for this type of investigation, she added. If one was to start instead with human cells, one might find something, but the system's greater complexity would make it far more difficult to tease apart the underlying mechanisms.

The findings shed new light on a key attribute of stem cells: their ability to make new specialized cells while still retaining their identity as stem cells.

Germ line stem cells typically divide asymmetrically. In the male fruit fly, when a stem cell divides, one part stays attached to the hub and remains a stem cell. The other part moves away from the hub and begins differentiation into a fly sperm cell.

Until the discovery of the nanotubes, scientists had been puzzled as to how cellular signals guiding identity could act on one of the cells but not the other, said collaborator Michael Buszczak, an associate professor of molecular biology at UT Southwestern, who shares corresponding authorship of the paper and currently co-mentors Inaba with Yamashita.

The researchers conducted experiments that showed disruption of nanotube formation compromised the ability of the germ line stem cells to renew themselves.

The work was supported by the Howard Hughes Medical Institute and the MacArthur Foundation.

Yamashita lab

 

[bixbyte]

 

Hmm I remember that Vince Guiliano speculated that C60 might have some effect on microtubules and the like. Maybe C60 is affecting a structure like this one.

 

 

Discovery of Nanotubes Offers New Clues About Cell-to-Cell Communication

Released: 29-Jun-2015 10:05 AM EDT
Embargo expired: 1-Jul-2015 1:00 PM EDT
Source Newsroom: University of Michigan

more news from this source

Contact Information

Available for logged-in reporters only

Citations Nature

Newswise — ANN ARBOR—When it comes to communicating with each other, some cells may be more "old school" than was previously thought.

Certain types of stem cells use microscopic, threadlike nanotubes to communicate with neighboring cells, like a landline phone connection, rather than sending a broadcast signal, researchers at University of Michigan Life Sciences Institute and University of Texas Southwestern Medical Center have discovered.

The findings, which are scheduled for online publication July 1 in Nature, offer new insights on how stem cells retain their identities when they divide to split off a new, specialized cell.

The fruit-fly research also suggests that short-range, cell-to-cell communication may rely on this type of direct connection more than was previously understood, said co-senior author Yukiko Yamashita, a U-M developmental biologist whose lab is located at the Life Sciences Institute.

"There are trillions of cells in the human body, but nowhere near that number of signaling pathways," she said. "There's a lot we don't know about how the right cells get just the right messages to the right recipients at the right time."

The nanotubes had actually been hiding in plain sight.

The investigation began when a postdoctoral researcher in Yamashita's lab, Mayu Inaba, approached her mentor with questions about tiny threads of connection she noticed in an image of fruit fly reproductive stem cells, which are also known as germ line cells. The projections linked individual stem cells back to a central hub in the stem cell "niche." Niches create a supportive environment for stem cells and help direct their activity.

Yamashita, a Howard Hughes Medical Institute investigator, MacArthur Fellow and an associate professor at the U-M Medical School, looked through her old image files and discovered that the connections appeared in numerous images.

"I had seen them, but I wasn't seeing them," Yamashita said. "They were like a little piece of dust on an otherwise normal picture. After we presented our findings at meetings, other scientists who work with the same cells would say, 'We see them now, too.'"

It's not surprising that the minute structures went overlooked for so long. Each one is about 3 micrometers long; by comparison, a piece of paper is 100 micrometers thick.

While the study looked specifically at reproductive cells in male Drosophila fruit flies, there have been indications of similar structures in other contexts, including mammalian cells, Yamashita said.

Fruit flies are an important model for this type of investigation, she added. If one was to start instead with human cells, one might find something, but the system's greater complexity would make it far more difficult to tease apart the underlying mechanisms.

The findings shed new light on a key attribute of stem cells: their ability to make new specialized cells while still retaining their identity as stem cells.

Germ line stem cells typically divide asymmetrically. In the male fruit fly, when a stem cell divides, one part stays attached to the hub and remains a stem cell. The other part moves away from the hub and begins differentiation into a fly sperm cell.

Until the discovery of the nanotubes, scientists had been puzzled as to how cellular signals guiding identity could act on one of the cells but not the other, said collaborator Michael Buszczak, an associate professor of molecular biology at UT Southwestern, who shares corresponding authorship of the paper and currently co-mentors Inaba with Yamashita.

The researchers conducted experiments that showed disruption of nanotube formation compromised the ability of the germ line stem cells to renew themselves.

The work was supported by the Howard Hughes Medical Institute and the MacArthur Foundation.

Yamashita lab

 

 

Abstract of Nanotubes mediate niche–stem-cell signalling in the Drosophila testis

Stem cell niches provide resident stem cells with signals that specify their identity. Niche signals act over a short range such that only stem cells but not their differentiating progeny receive the selfrenewing signals1. However, the cellular mechanisms that limit niche signalling to stem cells remain poorly understood. Here we show that the Drosophila male germline stem cells form previously unrecognized structures, microtubule-based nanotubes, which extend into the hub, a major niche component. Microtubule-based nanotubes are observed specifically within germline stem cell populations, and require intraflagellar transport proteins for their formation. The bone morphogenetic protein (BMP) receptor Tkv localizes to microtubule-based nanotubes. Perturbation of microtubule- based nanotubes compromises activation of Dpp signalling within germline stem cells, leading to germline stem cell loss. Moreover, Dpp ligand and Tkv receptor interaction is necessary and sufficient for microtubule-based nanotube formation. We propose that microtubule-based nanotubes provide a novel mechanism for selective receptor–ligand interaction, contributing to the short-range nature of niche–stem-cell signalling.

[Kalliste]

 

Abstract

The structures of transition states and activation parameters of radical addition of ^tBuOO^• and Ph(CH₃)₂COO^• to the C₆₀ and C₇₀ fullerenes have been found by density functional theory method PBE/3ζ. Calculated by Eyring equation, the rate constants of the ^tBuOO^• addition to C₆₀ and C₇₀, equal to 100 and 18.9 L mol⁻¹ s⁻¹, respectively; in the case of the Ph(CH₃)₂COO^• addition, these are 14.5 and 17.7 L mol⁻¹ s⁻¹ (all reactions are in gas phase). The estimated inhibitor capacity of C₆₀ equals to 3.7÷5.3. According to calculated rate constants, C₆₀ is more sensitive towards the structure of the peroxyls added. The calculated values agree with available experimental data on the reactions of these radicals with fullerenes. As follows from the calculated data, rate constants depend both on the nature of the fullerene and radical. The obtained data may be applied as reference values to the analysis of fullerene inhibition effect on the oxidation of organic compounds.

 

[Kalliste]

I re-read this paper the other day and came upon this quote. Would it be correct to say that C60 works in the same way? Does it squench electrophiles of every major specie or only truly oxygen based ROS?

 

 

Here, we test the OS hypothesis of aging by studying the
effects on life-span of an artificial hydroxylamine scavenger
(IAC). IAC reacts with most—if not all—carbon, nitrogen
and oxygen reactive species of biological interest (including
peroxyl radicals (ROO*) and superoxide radical-anion
[O2*-] and was recently found to attenuate oxidative
diseases where OS has a pathophysiological role (17–19).
Unlike conventional antioxidants, IAC has an additional
action: upon quenching ROS, it becomes super-activated,
turning from a hydroxylamine to a nitroxide—an even more
potent and catalytic antioxidant (20,21; Scheme 1).
Hence, its antioxidant behavior is modulated by redox
homeostasis.

http://biomedgeronto...na.glu160.short

http://biomedgeronto...0.full.pdf html

Edited by Cosmicalstorm, 10 July 2015 - 02:46 PM.

[Kalliste]

*Posting this here so people don't miss out on it.

 

 

Ichor Awarded $80,000 Grant for Oncology Research Ichor awarded $80,000 grant for oncology research by Methuselah Foundation

• 

LaFayette, NY (PRWEB) July 07, 2015

Ichor Therapeutics, Inc., a pre-clinical biotechnology company that develops technologies to target age-related pathology, announced today that it has received $79,775 in new grant funding from Methuselah Foundation, a 501©3 non-profit that funds regenerative medicine R&D.

This news comes in response to pilot studies completed at Ichor during winter 2014-2015 where c60oo administration doubled median lifespan in a mouse model of acute myeloid leukemia. Acute myeloid leukemia is a lethal blood cancer with only a 24% five-year survival rate.

"Like any preliminary study, we must be cautious not to jump too quickly at promising data," noted Ichor CEO Kelsey Moody. "This new grant will enable us to confirm our previous findings, and also begin to study biodistribution and pharmacokinetics within our model."

Such studies will include the distribution of c60oo into different organ tissues and half-life in blood plasma, in addition to assessing survival outcomes. Moody noted that success with this project could enable Ichor scientists to begin testing c60oo as an adjuvant for, and head-to-head with, traditional chemotherapy in mice in less than a year.

"Methuselah Foundation remains a prominent sponsor of research on aging and age-related disease," stated Moody. "They have supported this project since our initial crowd-funding campaign through Longecity.org, and we look forward to continuing to build upon our strong relationship in the future."

About Ichor Therapeutics, Inc.:

Ichor Therapeutics, Inc. (http://www.ichortherapeutics.com) is a privately held pre-clinical biotechnology company in LaFayette, NY. Founded in 2013 by then SUNY Upstate Medical University student Kelsey Moody, the company has raised over $1 million to support research in eye disease and oncology.