Practice question

Induced pluripotent stem cells are adult somatic cells such as skin fibroblasts reprogrammed to embryonic stem-like state through forced ectopic expression of defined transcription factor cocktail Oct4, Sox2, Klf4, c-Myc, effectively overriding somatic epigenetic landscape and silencing fibroblast programs. Reprogramming involves sequential ordered events: mesenchymal to epithelial transition, stochastic activation of alkaline phosphatase, progressive demethylation of Oct4 distal enhancer, reactivation of endogenous pluripotency circuitry including Nanog and telomerase restoration. Resulting iPSCs do not exist naturally during normal ontogeny, but are laboratory constructs exhibiting unlimited self-renewal and tri-lineage differentiation offering isogenic disease models and potential autologous cell therapy platforms translationally.