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Mol Biol Cell. 2008 May;19(5):2179-92. doi: 10.1091/mbc.E07-11-1155. Epub 2008 Mar 12.

Constitutive activation of chaperone-mediated autophagy in cells with impaired macroautophagy.

Author information

1
Departments of Anatomy and Structural Biology and Developmental and Molecular Biology, Marion Bessin Liver Research Center and Institute for Aging Research, Albert Einstein College of Medicine, Bronx, NY 10461, USA.

Abstract

Three different types of autophagy-macroautophagy, microautophagy, and chaperone-mediated autophagy (CMA)-contribute to degradation of intracellular components in lysosomes in mammalian cells. Although some level of basal macroautophagy and CMA activities has been described in different cell types and tissues, these two pathways are maximally activated under stress conditions. Activation of these two pathways is often sequential, suggesting the existence of some level of cross-talk between both stress-related autophagic pathways. In this work, we analyze the consequences of blockage of macroautophagy on CMA activity. Using mouse embryonic fibroblasts deficient in Atg5, an autophagy-related protein required for autophagosome formation, we have found that blockage of macroautophagy leads to up-regulation of CMA, even under basal conditions. Interestingly, different mechanisms contribute to the observed changes in CMA-related proteins and the consequent activation of CMA during basal and stress conditions in these macroautophagy-deficient cells. This work supports a direct cross-talk between these two forms of autophagy, and it identifies changes in the lysosomal compartment that underlie the basis for the communication between both autophagic pathways.

PMID:
18337468
PMCID:
PMC2366850
DOI:
10.1091/mbc.e07-11-1155
[Indexed for MEDLINE]
Free PMC Article

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