The role of autophagy in mitochondria maintenance: characterization of mitochondrial functions in autophagy-deficient S. cerevisiae strains.
Autophagy is a lysosome-dependent cellular degradation process. Organisms bearing deletions of the essential autophagy genes exhibit various pathological conditions, including cancer in mammals and shortened life span in C. elegans. The direct cause forthese phenotypes is not clear. Here we used yeast as a model system to characterize the cellular consequence of ATG (autophagy-related) gene deletions. We found that the atgmutant strains, atg1delta, atg6delta, atg8delta and atg12delta, showed defects related to mitochondrial biology. These strains were unable to degrade mitochondria in stationary culture. In non-fermentable medium, which requires mitochondrial oxidative phosphorylation for survival, these atg strains showed a growth defect with an increased cell population at the G(1) phase of the cell cycle. The cells had lower oxygen consumption rates and reduced mitochondrial electron transport chain activities. Under these growth conditions, the atg strains had lower mitochondrial membrane potential. In addition, these mutants generated higher levels of reactive oxygen species (ROS) and they were prone to accumulate dysfunctional mitochondria. This study clearly indicates that an autophagy defect has a functional impact on various aspects of mitochondrial functions and suggests a critical role of autophagy in mitochondria maintenance.
Zhang
Yong
Y
Pharmacology Department and the Cancer Institute of New Jersey, University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School, Piscataway, New Jersey 08854, USA.
Qi
Haiyan
H
Taylor
Robert
R
Xu
Weihong
W
Liu
Leroy F
LF
Jin
Shengkan
S
D001343:Autophagy / Q000502:physiology*; D017353:Gene Deletion; D015966:Gene Expression Regulation, Fungal; D050259:Genes, Mitochondrial; D008928:Mitochondria / Q000235:genetics* / Q000378:metabolism / Q000502:physiology* / Q000648:ultrastructure; D010085:Oxidative Phosphorylation; D010101:Oxygen Consumption / Q000502:physiology; D017382:Reactive Oxygen Species / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism
D017382:Reactive Oxygen Species