Targeted siRNA Screens Identify ER-to-Mitochondrial Calcium Exchange in Autophagy and Mitophagy Responses in RPE1 CellsReportar como inadecuado




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Cell Biology Laboratories, School of Biochemistry, University of Bristol, Bristol BS81TD, UK



These authors contributed equally to this work.





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Academic Editor: Jeremy C. Simpson

Abstract Autophagy is an important stress response pathway responsible for the removal and recycling of damaged or redundant cytosolic constituents. Mitochondrial damage triggers selective mitochondrial autophagy mitophagy, mediated by a variety of response factors including the Pink1-Parkin system. Using human retinal pigment epithelial cells stably expressing autophagy and mitophagy reporters, we have conducted parallel screens of regulators of endoplasmic reticulum ER and mitochondrial morphology and function contributing to starvation-induced autophagy and damage-induced mitophagy. These screens identified the ER chaperone and Ca2+ flux modulator, sigma non-opioid intracellular receptor 1 SIGMAR1, as a regulator of autophagosome expansion during starvation. Screens also identified phosphatidyl ethanolamine methyl transferase PEMT and the IP3-receptors IP3Rs as mediators of Parkin-induced mitophagy. Further experiments suggested that IP3R-mediated transfer of Ca2+ from the ER lumen to the mitochondrial matrix via the mitochondrial Ca2+ uniporter MCU primes mitochondria for mitophagy. Importantly, recruitment of Parkin to damaged mitochondria did not require IP3R-mediated ER-to-mitochondrial Ca2+ transfer, but mitochondrial clustering downstream of Parkin recruitment was impaired, suggesting involvement of regulators of mitochondrial dynamics and-or transport. Our data suggest that Ca2+ flux between ER and mitochondria at presumed ER-mitochondrial contact sites is needed both for starvation-induced autophagy and for Parkin-mediated mitophagy, further highlighting the importance of inter-organellar communication for effective cellular homeostasis. View Full-Text

Keywords: autophagy; mitophagy; Parkin; SIGMAR1; IP3Rs; ATG5; LC3; calcium autophagy; mitophagy; Parkin; SIGMAR1; IP3Rs; ATG5; LC3; calcium





Autor: Thomas D. B. MacVicar †, Lilith V. J. C. Mannack †, Robert M. Lees and Jon D. Lane *

Fuente: http://mdpi.com/



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