Rejuvenating nerve cells in adults

Like mammalian neurons, C. elegans neurons lose regeneration ability as they age, but it is not known why. C. elegans is a soil worm with its brain wiring diagram being mapped entirely - every connection between every nerve cell. Forty percent of genes identified in the worm genome have a counterpart in humans. Genes that allow neurons to connect with each other to form functional neuronal circuits and to regenerate themselves after injury are highly similar between worms and humans. Thus, what we learn in worms will likely be relevant to the development and regeneration of the human nervous system. The let-7 microRNA and its target, the LIN-41 tripartite motif protein, were recently shown to function as neuronal timers in worms to time the decline of the ability of neurons to regenerate as they age [1]. The progressive increase of let-7 and the progressive decrease of lin-41 in neurons provide intrinsic timing mechanism [1].