Axon degeneration: Linking axonal bioenergetics to myelin

The mechanisms by which axonal degeneration occurs, even in the presence of apparently normal myelin sheaths, remain unknown. In this issue, Yin et al. (2016. J. Cell Biol. https ://doi .org /10 .1083 /jcb .201607099) study mutant mice in which proteolipid protein is replaced by the peripheral myelin protein P₀ and describe a number of early axonal abnormalities, which together suggest that aberrant mitochondrial energy metabolism precedes axonal degeneration.