Isolation of a Chinese Hamster Ovary (CHO) cDNA Encoding Phosphatidylglycerophosphate (PGP) Synthase, Expression of Which Corrects the Mitochondrial Abnormalities of a PGP Synthase-defective Mutant of CHO-K1 Cells

Kawasaki, Kiyoshi; Kuge, Osamu; Chang, Shao Chun; Heacock, Philip; Rho, Minseok; Suzuki, Kenji; Nishijima, Masahiro; Dowhan, William

doi:10.1074/jbc.274.3.1828

Cited by 89 publications

(78 citation statements)

References 45 publications

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“…Mitochondria in cells lacking phosphatidylglycerophosphate synthase are characterized by reductions in both PG and CL and appear swollen with missing or disorganized cristae; 26,27 however, mitochondria in yeast lacking only CL exhibit normal morphology. 3 We accordingly examined the ultrastructural morphology of mitochondria in hCLS-RNAi cells, and found that the mitochondria in hCLS-RNAi #2 cells exhibited increased electron density and disorganized cristae (Figure 4a), suggesting that CL undertakes a role in maintaining mitochondrial morphology that requires the presence of more than 25% but less than 54% of the endogenous levels.…”

Section: Resultsmentioning

confidence: 99%

Cardiolipin deficiency releases cytochrome c from the inner mitochondrial membrane and accelerates stimuli-elicited apoptosis

et al. 2006

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Cardiolipin (CL) is a mitochondria-specific phospholipid synthesized by CL synthase (CLS). We describe here a human gene for CLS and its analysis via RNAi knockdown on apoptotic progression. Although mitochondrial membrane potential is unchanged in cells containing only 25% of the normal amount of CL, free cytochrome c (cyt. c) is detected in the intermembrane space and the mitochondria exhibit signs of reorganized cristae. However, the release of cyt. c from the mitochondria still requires apoptotic stimulation. Increased sensitivity to apoptotic signals and accelerated rates of apoptosis are observed in CL-deficient cells, followed by elevated levels of secondary necrosis. Apoptosis is thought to progress via binding of truncated Bid (tBid) to mitochondrial CL, followed by CL oxidation which results in cyt. c release. The exaggerated and accelerated apoptosis observed in CL-deficient cells is matched by an accelerated reduction in membrane potential and increased cyt. c release, but not by decreased tBid binding. This study suggests that the CL/cyt. c relationship is important in apoptotic progression and that regulating CL oxidation or/and deacylation could represent a possible therapeutic target.

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Section: Resultsmentioning

confidence: 99%

Cardiolipin deficiency releases cytochrome c from the inner mitochondrial membrane and accelerates stimuli-elicited apoptosis

et al. 2006

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“…CL plays a key role in mitochondrial bioenergetics (Jiang et al, 2000; Greenberg, 2000, 2002;Schlame et al, 2000;Pfeiffer et al, 2003) and is also involved in mitochondrial biogenesis (Kawasaki et al, 1999;Jiang et al, 2000). Defective remodeling of CL is associated with Barth syndrome, a severe genetic disorder characterized by cardiomyopathy, neutropenia, skeletal myopathy, and respiratory chain defects (Vreken et al, 2000).…”

Section: Introductionmentioning

confidence: 99%

Loss of Function ofKRE5Suppresses Temperature Sensitivity of Mutants Lacking Mitochondrial Anionic Lipids

Zhong

Gvozdenović-Jeremić

Webster

et al. 2005

MBoC

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Disruption of PGS1, which encodes the enzyme that catalyzes the committed step of cardiolipin (CL) synthesis, results in loss of the mitochondrial anionic phospholipids phosphatidylglycerol (PG) and CL. The pgs1⌬ mutant exhibits severe growth defects at 37°C. To understand the essential functions of mitochondrial anionic lipids at elevated temperatures, we isolated suppressors of pgs1⌬ that grew at 37°C. One of the suppressors has a loss of function mutation in KRE5, which is involved in cell wall biogenesis. The cell wall of pgs1⌬ contained markedly reduced ␤-1,3-glucan, which was restored in the suppressor. Stabilization of the cell wall with osmotic support alleviated the cell wall defects of pgs1⌬ and suppressed the temperature sensitivity of all CL-deficient mutants. Evidence is presented suggesting that the previously reported inability of pgs1⌬ to grow in the presence of ethidium bromide was due to defective cell wall integrity, not from "petite lethality." These findings demonstrated that mitochondrial anionic lipids are required for cellular functions that are essential in cell wall biogenesis, the maintenance of cell integrity, and survival at elevated temperature. INTRODUCTIONCardiolipin (CL), a unique anionic phospholipid with dimeric structure, is ubiquitous in eukaryotes and primarily found in the mitochondrial inner membrane . CL plays a key role in mitochondrial bioenergetics (Jiang et al., 2000; Greenberg, 2000, 2002;Schlame et al., 2000;Pfeiffer et al., 2003) and is also involved in mitochondrial biogenesis (Kawasaki et al., 1999;Jiang et al., 2000). Defective remodeling of CL is associated with Barth syndrome, a severe genetic disorder characterized by cardiomyopathy, neutropenia, skeletal myopathy, and respiratory chain defects (Vreken et al., 2000). The phenotype of Barth syndrome is dependent upon multiple factors that are not well understood (Barth et al., 1983(Barth et al., , 1996. Elucidation of the functions of CL will help to clarify the abnormalities associated with this disorder.The biosynthesis of CL is conserved in eukaryotic organisms. It occurs via three enzymatic reactions , including formation of phosphatidylglycerolphosphate (PGP) from CDP-DAG and glycerol-3-P, dephosphorylation of PGP to phosphatidylglycerol (PG), and condensation of CDP-DAG and PG to form CL. Disruption of PGS1, the structural gene encoding PGP synthase, results in the complete loss of both PG and CL (Janitor et al., 1996;Chang et al., 1998a). The crd1⌬ mutant, which lacks CL synthase, has no detectable CL but accumulates PG (Jiang et al., 1997;Chang et al., 1998b;Tuller et al., 1998;Jiang et al., 2000;Pfeiffer et al., 2003;Zhong et al., 2004). The human taffazin gene (TAZ1), which is associated with Barth syndrome, encodes a transacylase that may be involved in the remodeling of CL (Xu et al., 2003). Deletion of the yeast homolog of this gene, TAZ1, leads to decreased CL, aberrant CL acyl species, and accumulation of monolysocardiolipin . Mutants deficient in CL biosynthesis exhibit growth defects at elevat...

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“…It plays a key role in mitochondrial bioenergetics by optimizing the activities of enzymes in the oxidative phosphorylation pathway (1), stabilizing the supercomplexes of Saccharomyces cerevisiae respiratory chain complexes III and IV (2), preventing rate-dependent uncoupling, and providing osmotic stability in yeast mitochondria (3). CL is also involved in mitochondrial biogenesis, possibly via assisting protein import into mitochondria (4) and maintaining optimal mitochondrial internal structure (5). Defective remodeling of CL is associated with Barth syndrome, a severe genetic disorder characterized by cardiomyopathy, neutropenia, skeletal myopathy, and respiratory chain defects (6).…”

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confidence: 99%

Absence of Cardiolipin Results in Temperature Sensitivity, Respiratory Defects, and Mitochondrial DNA Instability Independent of pet56

Zhong¹,

Gohil²,

Ma³

et al. 2004

Journal of Biological Chemistry

101

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Cardiolipin (CL) is a dimeric phospholipid localized primarily in the mitochondrial membrane. Previous studies have shown that yeast cells containing a disruption of CRD1, the structural gene encoding CL synthase, exhibit temperature-sensitive colony formation and multiple mitochondrial defects. A recent report (Zhang, M., Su, X., Mileykovskaya, E., Amoscato, A. A., and Dowhan, W. (2003) J. Biol. Chem. 278, 35204 -35210) suggested that defects associated with CL deficiency may result from the reduced expression of PET56 in crd1⌬ mutant backgrounds and should be reevaluated. In the current study, we present evidence that CL deficiency leads to mitochondrial DNA instability, loss of viability, and defects in oxidative phosphorylation at elevated temperatures. The observed mutant phenotypes are characteristic of crd1⌬ mutant cells of both PET56 and pet56 backgrounds and are complemented by an episomal copy of CRD1 but not by expression of the PET56 gene. Phosphatidylglycerol is elevated in crd1⌬ mutant cells when grown in the presence of fermentable and non-fermentable carbon sources, although the extent of the increase is higher in nonfermentable medium. An increase in the ratio of phosphatidylethanolamine to phosphatidylcholine was also apparent in the mutant. These findings demonstrate that CRD1, independent of PET56, is required for optimal mitochondrial function and for an essential cellular function at elevated temperatures.Cardiolipin (CL), 1 a unique phospholipid with dimeric structure, is ubiquitous in eukaryotes and is primarily found in the mitochondrial inner membrane (1). It plays a key role in mitochondrial bioenergetics by optimizing the activities of enzymes in the oxidative phosphorylation pathway (1), stabilizing the supercomplexes of Saccharomyces cerevisiae respiratory chain complexes III and IV (2), preventing rate-dependent uncoupling, and providing osmotic stability in yeast mitochondria (3). CL is also involved in mitochondrial biogenesis, possibly via assisting protein import into mitochondria (4) and maintaining optimal mitochondrial internal structure (5). Defective remodeling of CL is associated with Barth syndrome, a severe genetic disorder characterized by cardiomyopathy, neutropenia, skeletal myopathy, and respiratory chain defects (6). The phenotype of Barth syndrome is dependent upon multiple factors that are not well understood (7,8). Elucidation of the functions of CL will help to clarify the abnormalities associated with this disorder.We have observed that the yeast crd1⌬ mutant, which lacks CL synthase and has no detectable CL, loses cell viability during growth at elevated temperatures (4, 9). Crd1⌬ mutant cells cannot form colonies at 37°C from single cells seeded on YPD (1% yeast extract, 2% peptone, and 2% dextrose) plates (9). In addition, crd1⌬ mutant cells grown in fermentable or non-fermentable carbon sources also segregate large numbers of petites (respiratory incompetent cells) after prolonged culture at elevated temperatures (4). CL is, thus, essential for maintaining...

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Isolation of a Chinese Hamster Ovary (CHO) cDNA Encoding Phosphatidylglycerophosphate (PGP) Synthase, Expression of Which Corrects the Mitochondrial Abnormalities of a PGP Synthase-defective Mutant of CHO-K1 Cells

Cited by 89 publications

References 45 publications

Cardiolipin deficiency releases cytochrome c from the inner mitochondrial membrane and accelerates stimuli-elicited apoptosis

Cardiolipin deficiency releases cytochrome c from the inner mitochondrial membrane and accelerates stimuli-elicited apoptosis

Loss of Function ofKRE5Suppresses Temperature Sensitivity of Mutants Lacking Mitochondrial Anionic Lipids

Absence of Cardiolipin Results in Temperature Sensitivity, Respiratory Defects, and Mitochondrial DNA Instability Independent of pet56

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