1 how much time does it take for a stem cell to devide?
2 can the same stem cell start deviding again right after if we raise nad what about the newly made one?
3 how much time from when we raise nad+ do stem cells start to devide and does nad+ level have to be mentained
Higher NAD+ levels may improve stem cell functionality, but don't appear to trigger stem cell proliferation. The disappearance (or blocking) of mitochondrial UCP pores does that. The time required is dependent of the type of stem cell it is. Crypt cells in the epithelium are the fastest, taking 9-10 hours for a complete cycle. Other stem cells take a lot longer, with most of the time in a resting phase. Presumably you could push them to cycle faster with C60--
Here, we show that hPSCs [human pluripotent stem cells] have functional respiratory complexes that are able to consume O(2) at maximal capacity. Despite this, ATP generation in hPSCs is mainly by glycolysis and ATP is consumed by the F(1)F(0) ATP synthase to partially maintain hPSC mitochondrial membrane potential and cell viability. Uncoupling protein 2 (UCP2) plays a regulating role in hPSC energy metabolism by preventing mitochondrial glucose oxidation and facilitating glycolysis via a substrate shunting mechanism. With early differentiation, hPSC proliferation slows, energy metabolism decreases, and UCP2 is repressed, resulting in decreased glycolysis and maintained or increased mitochondrial glucose oxidation. Ectopic UCP2 expression perturbs this metabolic transition and impairs hPSC differentiation. Overall, hPSCs contain active mitochondria and require UCP2 repression for full differentiation potential.
https://www.ncbi.nlm...pubmed/22085932
Progression of mammalian cells through the G1 and S phases of the cell cycle is driven by the D-type and E-type cyclins. According to the current models, at least one of these cyclin families must be present to allow cell proliferation. Here, we show that several cell types can proliferate in the absence of all G1 cyclins. However, following ablation of G1 cyclins, embryonic stem (ES) cells attenuated their pluripotent characteristics, with the majority of cells acquiring the trophectodermal cell fate. We established that G1 cyclins, together with their associated cyclin-dependent kinases (CDKs), phosphorylate and stabilize the core pluripotency factors Nanog, Sox2 and Oct4.
https://www.nature.c...ticles/ncb3474