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Expression of monolysocardiolipin acyltransferase activity is regulated in concert with the level of cardiolipin and cardiolipin biosynthesis in the mammalian heart.

Taylor WA, Xu FY, Ma BJ, Mutter TC, Dolinsky VW, Hatch GM - BMC Biochem. (2002)

Bottom Line: Rat heart mitochondrial MLCL AT activity was determined under conditions in which the levels of cardiac cardiolipin and cardiolipin synthase activity were either reduced or unaltered using four different disease models in the rat.In all models, phospholipase A2 activities were unaltered compared with controls.We propose a general model in which the expression of MLCL AT activity is regulated in concert with the biosynthesis and level of cardiolipin in the heart.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Pharmacology, Centre on Aging, University of Manitoba, Winnipeg, Canada. taylorw@ms.umanitoba.ca

ABSTRACT

Background: Monolysocardiolipin acyltransferase (MLCL AT) catalyzes the acylation of monolysocardiolipin to cardiolipin in mammalian tissues. We previously reported that cardiac cardiolipin levels, MLCL AT and cardiolipin synthase activities were all elevated in rats made hyperthyroid by thyroxine treatment. In this study, we examined if cardiac mitochondrial MLCL AT activity was dependent upon the biosynthesis and level of cardiolipin in the heart. Rat heart mitochondrial MLCL AT activity was determined under conditions in which the levels of cardiac cardiolipin and cardiolipin synthase activity were either reduced or unaltered using four different disease models in the rat. In addition, these parameters were examined in a murine model of cardiac cell differentiation.

Results: In rats made hypothyroid by treatment with 6-n-propyl-2-thiouracil in the drinking water for 34 days, cardiac cardiolipin content was decreased 29% (p < 0.025) and this was associated with a 32% decrease (p < 0.025) in cardiolipin synthase and a 35% reduction (p < 0.025) in MLCL AT activities. Streptozotocin-induced diabetes or hyperinsulinemia in rats did not affect cardiac cardiolipin content nor MLCL AT and cardiolipin synthase activities. Finally, cardiolipin content, MLCL AT and cardiolipin synthase activities were unaltered during murine P19 teratocarcinoma cell differentiation into cardiac myocytes. In all models, phospholipase A2 activities were unaltered compared with controls.

Conclusion: We propose a general model in which the expression of MLCL AT activity is regulated in concert with the biosynthesis and level of cardiolipin in the heart.

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Expression of genes during differentiation of P19 cells into cardiac myocytes. P19 cells were incubated with 1% DMSO for up to 8 days. At various times, 0–8 days post DMSO addition, cells were harvested and mRNA levels of GATA-4, BNP, α MHC, β MHC, troponin C and tubulin were determined by quantitative RT-PCR analysis.
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Figure 1: Expression of genes during differentiation of P19 cells into cardiac myocytes. P19 cells were incubated with 1% DMSO for up to 8 days. At various times, 0–8 days post DMSO addition, cells were harvested and mRNA levels of GATA-4, BNP, α MHC, β MHC, troponin C and tubulin were determined by quantitative RT-PCR analysis.

Mentions: As a distinct model, we examined if CL synthase activity was altered in murine P19 teratocarcinoma cells induced to undergo differentiation into cardiac myocytes. We chose this model since differentiation of murine P19 cells into cardiac myocytes results in an increase in phosphatidylethanolamine biosynthesis, phosphatidylethanolamine mass and lysophosphatidylethanolamine acyltransferase activities [17,25]. The cells were harvested at various times, 0–8 days post DMSO addition, and MRNA analysis of markers of cardiac cell differentiation performed on cell lysates. GATA-4 is a member of the GATA family of zinc finger transcription factors and is an early marker of cardiac cell differentiation. As seen in Figure 1, GATA-4 was expressed at 4 days post DMSO addition relative to the constitutive expression of tubulin. As expected GATA-4 expression preceded the expression of other cardiac genes including B-natriuretic peptide (BNP), alpha myosin heavy chain (αMHC), beta myosin heavy chain (βMHC) and Troponin C relative to the constitutive expression of tubulin. Thus, the P19 cells used in this study differentiated into cardiac myocytes. As previously shown CL content, MLCL AT and PLA2 activities were unaltered during P19 cell differentiation into cardiac myocytes [17,25]. CL synthase activity was 2.7 ± 0.5 pmol/min·mg protein in undifferentiated and unaltered (2.8 ± 0.3 pmol/min·mg protein) in differentiated P19 cells. Together, the above five models using hyper- and hypothyroid, diabetic and hyperinsulinemic rats and murine P19 cell differentiation into cardiac myocytes all indicate that expression of mammalian cardiac mitochondrial MLCL AT activity appears to be regulated in concert with the biosynthesis and content of CL in the heart.


Expression of monolysocardiolipin acyltransferase activity is regulated in concert with the level of cardiolipin and cardiolipin biosynthesis in the mammalian heart.

Taylor WA, Xu FY, Ma BJ, Mutter TC, Dolinsky VW, Hatch GM - BMC Biochem. (2002)

Expression of genes during differentiation of P19 cells into cardiac myocytes. P19 cells were incubated with 1% DMSO for up to 8 days. At various times, 0–8 days post DMSO addition, cells were harvested and mRNA levels of GATA-4, BNP, α MHC, β MHC, troponin C and tubulin were determined by quantitative RT-PCR analysis.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC113744&req=5

Figure 1: Expression of genes during differentiation of P19 cells into cardiac myocytes. P19 cells were incubated with 1% DMSO for up to 8 days. At various times, 0–8 days post DMSO addition, cells were harvested and mRNA levels of GATA-4, BNP, α MHC, β MHC, troponin C and tubulin were determined by quantitative RT-PCR analysis.
Mentions: As a distinct model, we examined if CL synthase activity was altered in murine P19 teratocarcinoma cells induced to undergo differentiation into cardiac myocytes. We chose this model since differentiation of murine P19 cells into cardiac myocytes results in an increase in phosphatidylethanolamine biosynthesis, phosphatidylethanolamine mass and lysophosphatidylethanolamine acyltransferase activities [17,25]. The cells were harvested at various times, 0–8 days post DMSO addition, and MRNA analysis of markers of cardiac cell differentiation performed on cell lysates. GATA-4 is a member of the GATA family of zinc finger transcription factors and is an early marker of cardiac cell differentiation. As seen in Figure 1, GATA-4 was expressed at 4 days post DMSO addition relative to the constitutive expression of tubulin. As expected GATA-4 expression preceded the expression of other cardiac genes including B-natriuretic peptide (BNP), alpha myosin heavy chain (αMHC), beta myosin heavy chain (βMHC) and Troponin C relative to the constitutive expression of tubulin. Thus, the P19 cells used in this study differentiated into cardiac myocytes. As previously shown CL content, MLCL AT and PLA2 activities were unaltered during P19 cell differentiation into cardiac myocytes [17,25]. CL synthase activity was 2.7 ± 0.5 pmol/min·mg protein in undifferentiated and unaltered (2.8 ± 0.3 pmol/min·mg protein) in differentiated P19 cells. Together, the above five models using hyper- and hypothyroid, diabetic and hyperinsulinemic rats and murine P19 cell differentiation into cardiac myocytes all indicate that expression of mammalian cardiac mitochondrial MLCL AT activity appears to be regulated in concert with the biosynthesis and content of CL in the heart.

Bottom Line: Rat heart mitochondrial MLCL AT activity was determined under conditions in which the levels of cardiac cardiolipin and cardiolipin synthase activity were either reduced or unaltered using four different disease models in the rat.In all models, phospholipase A2 activities were unaltered compared with controls.We propose a general model in which the expression of MLCL AT activity is regulated in concert with the biosynthesis and level of cardiolipin in the heart.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Pharmacology, Centre on Aging, University of Manitoba, Winnipeg, Canada. taylorw@ms.umanitoba.ca

ABSTRACT

Background: Monolysocardiolipin acyltransferase (MLCL AT) catalyzes the acylation of monolysocardiolipin to cardiolipin in mammalian tissues. We previously reported that cardiac cardiolipin levels, MLCL AT and cardiolipin synthase activities were all elevated in rats made hyperthyroid by thyroxine treatment. In this study, we examined if cardiac mitochondrial MLCL AT activity was dependent upon the biosynthesis and level of cardiolipin in the heart. Rat heart mitochondrial MLCL AT activity was determined under conditions in which the levels of cardiac cardiolipin and cardiolipin synthase activity were either reduced or unaltered using four different disease models in the rat. In addition, these parameters were examined in a murine model of cardiac cell differentiation.

Results: In rats made hypothyroid by treatment with 6-n-propyl-2-thiouracil in the drinking water for 34 days, cardiac cardiolipin content was decreased 29% (p < 0.025) and this was associated with a 32% decrease (p < 0.025) in cardiolipin synthase and a 35% reduction (p < 0.025) in MLCL AT activities. Streptozotocin-induced diabetes or hyperinsulinemia in rats did not affect cardiac cardiolipin content nor MLCL AT and cardiolipin synthase activities. Finally, cardiolipin content, MLCL AT and cardiolipin synthase activities were unaltered during murine P19 teratocarcinoma cell differentiation into cardiac myocytes. In all models, phospholipase A2 activities were unaltered compared with controls.

Conclusion: We propose a general model in which the expression of MLCL AT activity is regulated in concert with the biosynthesis and level of cardiolipin in the heart.

Show MeSH
Related in: MedlinePlus