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Mitochondrial cardiolipin involved in outer-membrane protein biogenesis: implications for Barth syndrome.

ABSTRACT: The biogenesis of mitochondria requires the import of a large number of proteins from the cytosol [1, 2]. Although numerous studies have defined the proteinaceous machineries that mediate mitochondrial protein sorting, little is known about the role of lipids in mitochondrial protein import. Cardiolipin, the signature phospholipid of the mitochondrial inner membrane [3-5], affects the stability of many inner-membrane protein complexes [6-12]. Perturbation of cardiolipin metabolism leads to the X-linked cardioskeletal myopathy Barth syndrome [13-18]. We report that cardiolipin affects the preprotein translocases of the mitochondrial outer membrane. Cardiolipin mutants genetically interact with mutants of outer-membrane translocases. Mitochondria from cardiolipin yeast mutants, as well as Barth syndrome patients, are impaired in the biogenesis of outer-membrane proteins. Our findings reveal a new role for cardiolipin in protein sorting at the mitochondrial outer membrane and bear implications for the pathogenesis of Barth syndrome.

SUBMITTER: Gebert N

PROVIDER: S-EPMC4329980 | biostudies-literature | 2009 Dec

REPOSITORIES: biostudies-literature

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Mitochondrial cardiolipin involved in outer-membrane protein biogenesis: implications for Barth syndrome.

Gebert Natalia N Joshi Amit S AS Kutik Stephan S Becker Thomas T McKenzie Matthew M Guan Xue Li XL Mooga Ved P VP Stroud David A DA Kulkarni Gnanada G Wenk Markus R MR Rehling Peter P Meisinger Chris C Ryan Michael T MT Wiedemann Nils N Greenberg Miriam L ML Pfanner Nikolaus N

Current biology : CB 20091203 24

The biogenesis of mitochondria requires the import of a large number of proteins from the cytosol [1, 2]. Although numerous studies have defined the proteinaceous machineries that mediate mitochondrial protein sorting, little is known about the role of lipids in mitochondrial protein import. Cardiolipin, the signature phospholipid of the mitochondrial inner membrane [3-5], affects the stability of many inner-membrane protein complexes [6-12]. Perturbation of cardiolipin metabolism leads to the X ...[more]

PMID: 19962311

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Project description:BackgroundCardiomyopathy is a major clinical feature in Barth syndrome (BTHS), an X-linked mitochondrial lipid disorder caused by mutations in Tafazzin (TAZ), encoding a mitochondrial acyltransferase required for cardiolipin remodeling. Despite recent description of a mouse model of BTHS cardiomyopathy, an in-depth analysis of specific lipid abnormalities and mitochondrial form and function in an in vivo BTHS cardiomyopathy model is lacking.MethodsWe performed in-depth assessment of cardiac function, cardiolipin species profiles, and mitochondrial structure and function in our newly generated Taz cardiomyocyte-specific knockout mice and Cre-negative control mice (n≥3 per group).ResultsTaz cardiomyocyte-specific knockout mice recapitulate typical features of BTHS and mitochondrial cardiomyopathy. Fewer than 5% of cardiomyocyte-specific knockout mice exhibited lethality before 2 months of age, with significantly enlarged hearts. More than 80% of cardiomyocyte-specific knockout displayed ventricular dilation at 16 weeks of age and survived until 50 weeks of age. Full parameter analysis of cardiac cardiolipin profiles demonstrated lower total cardiolipin concentration, abnormal cardiolipin fatty acyl composition, and elevated monolysocardiolipin to cardiolipin ratios in Taz cardiomyocyte-specific knockout, relative to controls. Mitochondrial contact site and cristae organizing system and F1F0-ATP synthase complexes, required for cristae morphogenesis, were abnormal, resulting in onion-shaped mitochondria. Organization of high molecular weight respiratory chain supercomplexes was also impaired. In keeping with observed mitochondrial abnormalities, seahorse experiments demonstrated impaired mitochondrial respiration capacity.ConclusionsOur mouse model mirrors multiple physiological and biochemical aspects of BTHS cardiomyopathy. Our results give important insights into the underlying cause of BTHS cardiomyopathy and provide a framework for testing therapeutic approaches to BTHS cardiomyopathy, or other mitochondrial-related cardiomyopathies.

Dataset Information

Mitochondrial cardiolipin involved in outer-membrane protein biogenesis: implications for Barth syndrome.

Publications

Mitochondrial cardiolipin involved in outer-membrane protein biogenesis: implications for Barth syndrome.

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