Autophagy pathway machinery

The autophagy pathway machinery refers to the highly conserved network of proteins and signaling cascades responsible for macroautophagy, a fundamental process for the degradation and recycling of cytoplasmic components (Mizushima & Komatsu, 2011). This machinery is orchestrated by autophagy-related (ATG) proteins that form functional complexes to manage the initiation, nucleation, elongation, and lysosomal fusion stages of autophagosome development (Galluzzi et al., 2017). Under physiological conditions, this system maintains cellular homeostasis by removing damaged organelles and protein aggregates, but its dysregulation is a hallmark of various diseases (Levine & Kroemer, 2019). In neurodegenerative disorders, the machinery is often insufficient to clear toxic protein aggregates, whereas in cancer, it can act as a tumor suppressor in early stages or a survival mechanism for established tumors under metabolic stress (Levine & Kroemer, 2019). Therapeutic strategies target specific nodes of this machinery, such as using mTOR inhibitors to induce autophagy for neuroprotection or lysosomotropic agents to inhibit it in oncology (Klionsky et al., 2021). Monitoring the efficacy of these interventions typically involves assessing the conversion of LC3-I to LC3-II or the accumulation of the cargo adapter p62 (Klionsky et al., 2021).

Other names

Macroautophagy pathwayAutophagic machineryAutophagy-related protein systemATG system

Modulation of the autophagy pathway machinery occurs through several distinct mechanisms: mTORC1 inhibitors (e.g., Rapamycin) relieve the suppression of the ULK1 initiation complex to induce autophagosome formation (Mizushima & Komatsu, 2011); class III PI3K inhibitors (e.g., SAR405) prevent the nucleation of the phagophore by blocking VPS34 activity (Galluzzi et al., 2017); and lysosomotropic agents (e.g., Hydroxychloroquine) inhibit the final stage of the pathway by increasing lysosomal pH, which prevents the fusion of autophagosomes with lysosomes and the subsequent degradation of cargo (Klionsky et al., 2021).