Regenerating neurons
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Fascinating (to me) stuff. Epigenetics is the new frontier.
Here we show that it is possible to safely reverse the age of a complex tissue and restore its biological function invivo. Using the eye as a model system, we present evidence that the ectopic expression of OSK transcription factors safely induces invivo epigenetic restora-tion of aged CNS neurons, without causinga loss of cell identity or pluripotency. Instead, OSK promotes a youthful epigenetic signature and gene-expression pattern that causes the neurons to function as though they were young again. The requirement for active demethyla-tion in this process supports the idea that changes in DNA methylation patterns are involved in the ageing process and its functional reversal (Extended Data Fig.10n). However, we do not wish to imply that DNA methylation is the only epigenetic mark involved in this process. It is likely to involve other transcription factors and epigenetic modifica-tions, such as the PRC2 complex and H3K27me3, both of which are involved in maintaining stem cell plasticity and are associated with DNA methylation clock sites4,49,50.Perhaps the most interesting question raised by these data is how cells encode and store youthful epigenetic information. Possibilities for information storage include covalent DNA modifications, DNA-binding proteins, RNA-guided chromatin modifying factors, and RNA–DNA hybrids that are established early in life. The role of these youth marks would be akin to the ‘observer’ in information theory, which preserves an original backup copy of information in case it is lost or obscured by noise11. We suggest that epigenetic reprogramming, either by gene therapy or other means, could promote tissue repair and the reversal of age-related decline in humans.
The important words here are "in vivo."
