FIGURE 3.

An overview of autophagy. Autophagy is classified into three modalities, namely macro-autophagy, micro-autophagy, and chaperone-mediated autophagy. Macro-autophagy requires autophagosome formation, which can selectively engulf and sequester part of the cellular contents, such as lipid droplets, protein aggregates, and organelles. Then, the autophagosome is fused with the lysosome, where these cellular contents are degraded. Micro-autophagy refers to the direct engulfment and subsequent degradation of cellular constituents by the lysosome. Chaperone-mediated autophagy is specialized in degrading the proteins containing the KFERQ-like motif, which combine with HSPA8, and then bind to LAMP2A receptor on the lysosome and be further translocated to the lysosome where these proteins are degraded.