MARCH5-mediated quality control on acetylated Mfn1 facilitates mitochondrial homeostasis and cell survival

Abstract

Mitochondrial dynamics and quality control have a central role in the maintenance of cellular integrity. Mitochondrial ubiquitin ligase membrane-associated RING-CH (MARCH5) regulates mitochondrial dynamics. Here, we show that mitochondrial adaptation to stress is driven by MARCH5-dependent quality control on acetylated Mfn1. Under mitochondrial stress conditions, levels of Mfn1 were elevated twofold and depletion of Mfn1 sensitized these cells to apoptotic death. Interestingly, overexpression of Mfn1 also promoted cell death in these cells, indicating that a fine tuning of Mfn1 levels is necessary for cell survival. MARCH5 binds Mfn1 and the MARCH5-dependent Mfn1 ubiquitylation was significantly elevated under mitochondrial stress conditions along with an increase in acetylated Mfn1. The acetylation-deficient K491R mutant of Mfn1 showed weak interaction with MARCH5 as well as reduced ubiquitylation. Neither was observed in the acetylation mimetic K491Q mutant. In addition, MARCH5-knockout mouse embryonic fibroblast and MARCH5H43W-expressing HeLa cells lacking ubiquitin ligase activity experienced rapid cell death upon mitochondrial stress. Taken together, a fine balance of Mfn1 levels is maintained by MARCH5-mediated quality control on acetylated Mfn1, which is crucial for cell survival under mitochondria stress conditions.

Effect of Heme Oxygenase-1 on Mitofusin-1 protein in LPS-induced ALI/ARDS in rats

“…Furthermore, in Mfn1 knockout cells, more mitochondrial DNA (mtDNA) mutations were observed32. By contrast, overexpression of Mfn1 by transient transfection of cultured cells contributed to the formation of mitochondrial networks, whereas a point mutation in the Mfn1 gene resulted in dramatically attenuated mitochondrial fusion31. All these findings indicate that Mfn1 plays a key role in mitochondrial fusion machinery.…”

“…Previous studies suggested that Mfn1 was broadly expressed in different tissues and at high levels30. Lack of Mfn1 leads to fusion deficiency and results in severely fragmented mitochondria31. Furthermore, in Mfn1 knockout cells, more mitochondrial DNA (mtDNA) mutations were observed32.…”

Mitochondrial Metabolism in Aging Heart

“…195 In antimycin A-treated cells, the Mitofusin-1 level is markedly increased with augmented cell death. Antimycin-A is a complex III inhibitor that is used to increase ROS production from from the Qo site of complex III, 122 favoring ROS production in a similar manner to the age-related defect discussed above.…”

Regulators of mitochondrial dynamics in cancer

“…Assessing a potential link between March5 activity and mitochondrial morphology or function is complicated as experimental inactivation of March5 promotes conflicting phenotypes. For example, March5 knockdown [56] or expression of the March5 H43W -RING mutant results in elongated, hyperfused mitochondria [55*,57], which antagonizes mitochondrial stress-induced apoptosis [57,58]. By contrast, March5 knockout cells displays fragmented mitochondria [59,60*], and accordingly, are more sensitive to apoptotic insults [60*].…”