title: Tubular network formation protects mitochondria from autophagosomal degradation during nutrient starvation.
abstract: Mitochondria are highly dynamic organelles that mediate essential cell functions such as apoptosis and cell-cycle control in addition to their role as efficient ATP generators. Mitochondrial morphology changes are tightly regulated, and their shape can shift between small, fragmented units and larger networks of elongated mitochondria. We demonstrate that mitochondrial elements become significantly elongated and interconnected shortly after nutrient depletion. This mitochondrial morphological shift depends on the type of starvation, with an additive effect observed when multiple nutrients are depleted simultaneously. We further show that starvation-induced mitochondrial elongation is mediated by down-regulation of dynamin-related protein 1 (Drp1) through modulation of two Drp1 phosphorylation sites, leading to unopposed mitochondrial fusion. Finally, we establish that mitochondrial tubulation upon nutrient deprivation protects mitochondria from autophagosomal degradation, which could permit mitochondria to maximize energy production and supply autophagosomal membranes during starvation.
authors.affiliation: The Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Angelika S
authors.initials: AS
authors.lastname: Rambold
authors.forename: Brenda
authors.initials: B
authors.lastname: Kostelecky
authors.forename: Natalie
authors.initials: N
authors.lastname: Elia
authors.forename: Jennifer
authors.initials: J
authors.lastname: Lippincott-Schwartz
mesh_terms: D000818:Animals; D001343:Autophagy / Q000502:physiology*; D002478:Cells, Cultured; D034281:Dynamins / Q000235:genetics / Q000378:metabolism; D005347:Fibroblasts / Q000166:cytology; D020558:GTP Phosphohydrolases / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism; D008928:Mitochondria / Q000378:metabolism* / Q000648:ultrastructure; D024101:Mitochondrial Proteins / Q000378:metabolism; D010588:Phagosomes / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D013217:Starvation / Q000378:metabolism*
chemical_list: D008869:Microtubule-Associated Proteins; D024101:Mitochondrial Proteins; D020558:GTP Phosphohydrolases; C488750:Mfn1 protein, mouse; C498809:Opa1 protein, mouse; C486391:Dnm1l protein, mouse; D034281:Dynamins