Autophagy is a cellular survival and death pathway that is based on degradation of cytoplasmic components such as damaged or long-lived organelles and proteins. How autophagy is regulated and executed at the molecular level have been made in yeast.30 different autophagy-related genes(ATG) has detected in that research. Autophagy is highly regulated by several pathways such as Mtorc, AMPK, and microRNAs.There are three different mechanisms of autophagy: macro-autophagy, micro-autophagy and chaperone-mediated autophagy that are all involved in degradation of the components at the lysosome.
Macroautophagy is the most important autophagy mechanism that leads to cell death by transportation of damaged organelles and protein aggregates to lysosome via autophagosomes. Autophagosome is a double-membrane vesicle that forms around cytoplasmic components, organelles and engulfs them to deliver to lysosome.Microautophagy is a cellular survival pathway to maintain homoeostasis by degradation of long-lived or damaged proteins under starvation.In microautophagy pathway, cytoplasmic materials are captured by lysosomal engulfment.Chaperone-mediated autophagy involves direct recognition of specific proteins by chaperone complex and directly delivering proteins to the lysosome.
The discovery of miRNAs is shown a new regulator of gene expression at post-transcriptional level. These RNA molecules are short non-coding molecules that regulate gene expression by digestion of mRNA or inhibiting translation on mRNA with P-bodies. Importantly, miRNAs play a key role on many biological processes, including differentiation, proliferation as well as cell death. Deregulation of miRNAs can function both tumor suppressor and oncogenes that lead to many human diseases including cancer or neurodegenerative diseases.It is proven that function and formation many proteins on autophagy process are regulated by miRNAs.