dSarm-ing Axon Degeneration

Plucked from the tree, a leaf withers. Such a loss of vitality upon removal from the whole appears so natural that one may take it for granted as a passive and unstoppable process. But is it? Although cell death was long thought to be a passive process, we now know that at least one form of cell death, apoptosis (from Greek “falling away”), is an active process that can be blocked by inhibiting a specific signaling pathway ( 1 ). On page 481 of this issue, Osterloh et al. ( 2 ) find that the death of a portion of a nerve cell, the axon, after it is severed from the cell body, can be dramatically slowed by the inactivation of just one gene. The discovery has important implications for understanding the molecular mechanisms of axon degeneration, as well as for developing drugs against neurodegenerative diseases.