Autophagy A Cellular Mechanism: A Review

Autophagy is a basically survival mechanism of body in which cell digests its own content to maintain cellular homeostasis in multiple stress conditions and starvation. The term ‘autophagy’ was first described in 1963 by Christian de Duve, a Japanese cell biologist to describe presence of double-membrane vesicles containing cytoplasmic constituents within the cell. These vesicles that encapsulate cytoplasm, organelles and proteins, are known as autophagosomes. After formation of autophagosome it fuses with endosomes and travels via cytoplasm to fuse with lysosomes for degradation. In lysosomes internal content material of autophagosome is degraded with the action of acid hydrolases. Autophagy is very important for regulation of diverse cellular functions i.e., growth, differentiation, response to nutrient deficit and oxidative stress, cell death and macromolecule and organelle turnover. Nutrient starvation is most typical trigger of autophagy. Depending on the mechanism by which intracellular materials are delivered into lysosome for degradation, there are four types- Macroautophagy, Microautophagy, Chaperon mediated autophagy and Crinophagy. Autophagy is important in normal development and it responds to changing environmental stimuli. It plays role in cancer and numerous important diseases such as bacterial and viral infections, liver and kidney diseases, Diabetes mellitus, inflammatory bowel diseases, neurodegenerative disorders, several myopathies and cardiovascular diseases.