Regulation of JMY's actin nucleation activity by TTC5/STRAP and LC3 during autophagy.

Actin plays indispensable roles in autophagosome biogenesis. Branched actin networks assembled within phagophore membranes are required for generating the autophagosome membrane shape and movement. The ARP2/3 complex and its regulators, such as JMY (junction mediating and regulatory protein, p53 cofactor), translocate to phagophore membranes to promote local actin filament formation during autophagy. Hu et al., recently showed that during autophagy LC3 recruits JMY to the phagophore and promotes its actin nucleation activity. They also characterized TTC5/STRAP (tetratricopeptide repeat domain 5) as a negative autophagy regulator via binding to JMY and antagonizing its activation. Moreover, an in vitro reconstitution system was developed to demonstrate that membrane-bound LC3 is sufficient to recruit JMY and stimulate JMY-mediated actin filament assembly.