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World J Biol Chem. Jan 26, 2012; 3(1): 1-6
Published online Jan 26, 2012. doi: 10.4331/wjbc.v3.i1.1
Autophagy in mammalian cells
Kadija Abounit, Tiziano M Scarabelli, Roy B McCauley
Kadija Abounit, Tiziano M Scarabelli, Roy B McCauley, Department of Pharmacology, School of Medicine, Wayne State University, Detroit , MI 48201, United States
Tiziano M Scarabelli, Wayne State University School of Medicine and St. John’s Hospital, Detroit, MI 48201, United States
Author contributions: McCauley RB wrote this manuscript with the contributions of Abounit K and Scarabelli TM. Abounit K designed and executed the experiments performed in our laboratory.
Correspondence to: Roy B McCauley, PhD, Department of Pharmacology, School of Medicine, Wayne State University, Detroit , MI 48201, United States.
Telephone: +1-313-5776737 Fax: +1-313-5776739
Received: July 7, 2011
Revised: August 22, 2011
Accepted: August 29, 2011
Published online: January 26, 2012

Autophagy is a regulated process for the degradation of cellular components that has been well conserved in eukaryotic cells. The discovery of autophagy-regulating proteins in yeast has been important in understanding this process. Although many parallels exist between fungi and mammals in the regulation and execution of autophagy, there are some important differences. The pre-autophagosomal structure found in yeast has not been identified in mammals, and it seems that there may be multiple origins for autophagosomes, including endoplasmic reticulum, plasma membrane and mitochondrial outer membrane. The maturation of the phagophore is largely dependent on 5’-AMP activated protein kinase and other factors that lead to the dephosphorylation of mammalian target of rapamycin. Once the process is initiated, the mammalian phagophore elongates and matures into an autophagosome by processes that are similar to those in yeast. Cargo selection is dependent on the ubiquitin conjugation of protein aggregates and organelles and recognition of these conjugates by autophagosomal receptors. Lysosomal degradation of cargo produces metabolites that can be recycled during stress. Autophagy is an important cellular safeguard during starvation in all eukaryotes; however, it may have more complicated, tissue specific roles in mammals. With certain exceptions, autophagy seems to be cytoprotective, and defects in the process have been associated with human disease.

Keywords: Autophagy, Phagophore, Autophagosome, Atg proteins, Cell survival