[초청강연] Intracellular degradation by autophagy-dependent and independent pathways

Organelle degradation by autophagy-dependent and independent pathways
Noboru Mizushima
Department of Biochemistry and Molecular Biology, Graduate School of Medicine, The
University of Tokyo
Autophagy is a major degradation system in the cell and is important for various cellular
processes such as starvation adaptation and intracellular quality control. Intracellular
components including organelles are sequestered by autophagosomes and then degraded
upon fusion with lysosomes. However, we recently found that organelles can be degraded
in a manner that is independent of autophagy. In eye lenses, cells undergo massive
degradation of all organelles during terminal differentiation even in autophagy-deficient
mice. Using zebrafish and mice, we revealed that PLAAT (phospholipase A and
acyltransferase) family phospholipases, which are highly expressed in the lens, are
essential for the degradation of lens organelles such as the ER, mitochondria, and
lysosomes. PLAATs translocate from the cytosol to these organelles to degrade them. This
new type of organelle degradation is essential for achieving optimal transparency and
refractive function of the lens. These findings expand our understanding of intracellular
organelle degradation.