title: Reduced cytosolic protein synthesis suppresses mitochondrial degeneration.
abstract: Mitochondrial function degenerates with ageing and in ageing-related neuromuscular degenerative diseases, causing physiological decline of the cell. Factors that can delay the degenerative process are actively sought after. Here, we show that reduced cytosolic protein synthesis is a robust cellular strategy that suppresses ageing-related mitochondrial degeneration. We modelled autosomal dominant progressive external ophthalmoplegia (adPEO), an adult- or later-onset degenerative disease, by introducing the A128P mutation into the adenine nucleotide translocase Aac2p of Saccharomyces cerevisiae. The aac2(A128P) allele dominantly induces ageing-dependent mitochondrial degeneration and phenotypically tractable degenerative cell death, independently of its ADP/ATP exchange activity. Mitochondrial degeneration was suppressed by lifespan-extending nutritional interventions and by eight longevity mutations, which are all known to reduce cytosolic protein synthesis. These longevity interventions also independently suppressed ageing-related mitochondrial degeneration in the pro-ageing prohibitin mutants. The aac2(A128P) mutant has reduced mitochondrial membrane potential (delta psi(m)) and is synthetically lethal to low delta psi(m) conditions, including the loss of prohibitin. Mitochondrial degeneration was accelerated by defects in protein turnover on the inner membrane and was suppressed by cycloheximide, a specific inhibitor of cytosolic ribosomes. Reduced cytosolic protein synthesis suppressed membrane depolarization and defects in mitochondrial gene expression in aac(A128P) cells. Our finding thus establishes a link between protein homeostasis (proteostasis), cellular bioenergetics and mitochondrial maintenance during ageing.
authors.affiliation: Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, New York 13210, USA.
authors.forename: Xiaowen
authors.initials: X
authors.lastname: Wang
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Zuo
authors.forename: Blanka
authors.initials: B
authors.lastname: Kucejova
authors.forename: Xin Jie
authors.initials: XJ
authors.lastname: Chen
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000483:Alleles; D003600:Cytosol / Q000378:metabolism*; D004272:DNA, Mitochondrial / Q000378:metabolism; D050296:Microbial Viability; D008928:Mitochondria / Q000378:metabolism / Q000473:pathology*; D000226:Mitochondrial ADP, ATP Translocases / Q000737:chemistry / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D000091402:Prohibitins; D014176:Protein Biosynthesis; D017433:Protein Structure, Secondary; D012097:Repressor Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000166:cytology; D029701:Saccharomyces cerevisiae Proteins / Q000096:biosynthesis* / Q000737:chemistry / Q000378:metabolism; D013997:Time Factors
chemical_list: D004272:DNA, Mitochondrial; D024101:Mitochondrial Proteins; C112225:PET9 protein, S cerevisiae; D000091402:Prohibitins; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D000226:Mitochondrial ADP, ATP Translocases