Molecules and their functions in autophagy

Abstract

Autophagy is a self-degradation system of cellular components through an autophagosomal-lysosomal pathway. Over the last 15 yr, yeast genetic screens led to the identification of a number of genes involved in the autophagic pathway. Most of these autophagy genes are present in higher eukaryotes and regulate autophagy process for cell survival and homeostasis. Significant progress has recently been made to better understand the molecular mechanisms of the autophagy machinery. Especially, autophagy process, including the regulation of autophagy induction through mTOR and the nucleation and elongation in autophagosome formation through class III phosphatidylinositol 3-kinase complex and ubiquitin-like conjugation systems, became evident. While many unanswered questions remain to be answered, here, we summarize the recent process of autophagy with emphasis on molecules and their protein complexes along with advanced molecular mechanisms that regulate the autophagy machinery.

Figure 1

Molecular regulation of autophagosome formation in mammalian macroautophagy. Three major steps consisting of the initiation, nucleation and elongation in autophagosome formation are described. ER, endoplasmic reticulum; Mito, mitochondria; PM, plasma membrane; PE, phosphatidylethanolamine.

Figure 2

Ubiquitin-like protein conjugation systems in autophagy.