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Down-regulation of cardiac lineage protein (CLP-1) expression in CLP-1 +/- mice affords.

Mascareno E, Manukyan I, Das DK, Siddiqui MA - J. Cell. Mol. Med. (2009)

Bottom Line: There was a decrease in Cdk7 and Cdk9 kinase activity and consequently in phosphorylation of serine-5 and serine-2 of Pol II CTD in CLP-1 +/- hearts.However, the levels of mitochondrial proteins, PGC-1alpha and HIF-1alpha, which enhance mitochondrial activity and are implicated in cell survival, were increased in CLP-1 +/- hearts subjected to ischaemic stress compared to that in wild-type CLP-1 +/- hearts treated identically.Taken together, our data suggest that regulation of the CLP-1 levels is critical to cellular adaptation of the survival program that protects cardiomyocytes against stress due collectively to a decrease in RNA Pol II phosphorylation but an increase in expression of target proteins that regulate mitochondrial function and metabolic adaptation to stress.

View Article: PubMed Central - PubMed

Affiliation: Center for Cardiovascular and Muscle Research, Department of Anatomy and Cell Biology, State University of New York Downstate Medical Center, Brooklyn, NY 112031, USA.

ABSTRACT
In order to understand the transcriptional mechanism that underlies cell protection to stress, we evaluated the role of CLP-1, a known inhibitor of the transcription elongation complex (pTEFb), in CLP-1 +/- mice hearts. Using the isolated heart model, we observed that the CLP-1 +/- hearts, when subjected to ischaemic stress and evaluated by haemodynamic measurements, exhibit significant cardioprotection. CLP-1 remains associated with the pTEFb complex in the heterozygous hearts, where as it is released in the wild-type hearts suggesting the involvement of pTEFb regulation in cell protection. There was a decrease in Cdk7 and Cdk9 kinase activity and consequently in phosphorylation of serine-5 and serine-2 of Pol II CTD in CLP-1 +/- hearts. However, the levels of mitochondrial proteins, PGC-1alpha and HIF-1alpha, which enhance mitochondrial activity and are implicated in cell survival, were increased in CLP-1 +/- hearts subjected to ischaemic stress compared to that in wild-type CLP-1 +/- hearts treated identically. There was also an increase in the expression of pyruvate dehydrogenase kinase (PDK-1), which facilitates cell adaptation to hypoxic stress. Taken together, our data suggest that regulation of the CLP-1 levels is critical to cellular adaptation of the survival program that protects cardiomyocytes against stress due collectively to a decrease in RNA Pol II phosphorylation but an increase in expression of target proteins that regulate mitochondrial function and metabolic adaptation to stress.

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CLP‐1 +/− mice hearts exhibit a decreased infarct size. Infarct size was measured as described in Materials and Methods. Infarct size is significantly reduced in CLP‐1 +/− heart mice during ischemia/reperfusion without preconditioning. Results are shown as mean ± S.E.M. of six mice per group. *P < 0.05 versus control, **P < 0.01 versus control.
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f3: CLP‐1 +/− mice hearts exhibit a decreased infarct size. Infarct size was measured as described in Materials and Methods. Infarct size is significantly reduced in CLP‐1 +/− heart mice during ischemia/reperfusion without preconditioning. Results are shown as mean ± S.E.M. of six mice per group. *P < 0.05 versus control, **P < 0.01 versus control.

Mentions: Isolated hearts from CLP‐1+/+ and CLP‐1 +/− mice were subjected to the experimental stress protocol of ischemia/reper fusion, as shown in Figure 1 and described in ‘Materials and Methods’. Functional haemodynamic measurements such ascoronary flow and LVdp/dt were made as before [22]. After reperfusion, the control hearts of CLP‐1+/+ showed a decrease in the absolute values of aortic flow, developed pressure, and the first derivative of developed pressure (dP/dt max). As expected, preconditioned CLP‐1+/+ hearts display a recovery following ischemia/reperfusion (see Fig. 2A, D and E). However, following reperfusion, the hearts of the CLP‐1+/− mice showed haemodynamic values of developed pressure, the first derivative of developed pressure (dP/dt max) and aortic flow similar to hearts from wild‐type CLP‐1 subjected to PC, suggesting that the CLP‐1+/− hearts harbour an intrinsic cardioprotective program. Indeed, when CLP‐1 +/− mice hearts were subjected to PC followed by I/R, the degree of cardioprotection was similar to CLP‐1 +/+ subjected to PC, i.e. no further protection was observed. Coronary flow and heart rate did not exhibit significant changes between genotypes (Fig. 2B and C). Cardioprotection was also evident when the infarct sizes were measured. In the wild‐type hearts, the infarct size was reduced upon PC, whereas in the CLP‐1+/− mice the infarct size was the same with or without PC (Fig. 3).


Down-regulation of cardiac lineage protein (CLP-1) expression in CLP-1 +/- mice affords.

Mascareno E, Manukyan I, Das DK, Siddiqui MA - J. Cell. Mol. Med. (2009)

CLP‐1 +/− mice hearts exhibit a decreased infarct size. Infarct size was measured as described in Materials and Methods. Infarct size is significantly reduced in CLP‐1 +/− heart mice during ischemia/reperfusion without preconditioning. Results are shown as mean ± S.E.M. of six mice per group. *P < 0.05 versus control, **P < 0.01 versus control.
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Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4940775&req=5

f3: CLP‐1 +/− mice hearts exhibit a decreased infarct size. Infarct size was measured as described in Materials and Methods. Infarct size is significantly reduced in CLP‐1 +/− heart mice during ischemia/reperfusion without preconditioning. Results are shown as mean ± S.E.M. of six mice per group. *P < 0.05 versus control, **P < 0.01 versus control.
Mentions: Isolated hearts from CLP‐1+/+ and CLP‐1 +/− mice were subjected to the experimental stress protocol of ischemia/reper fusion, as shown in Figure 1 and described in ‘Materials and Methods’. Functional haemodynamic measurements such ascoronary flow and LVdp/dt were made as before [22]. After reperfusion, the control hearts of CLP‐1+/+ showed a decrease in the absolute values of aortic flow, developed pressure, and the first derivative of developed pressure (dP/dt max). As expected, preconditioned CLP‐1+/+ hearts display a recovery following ischemia/reperfusion (see Fig. 2A, D and E). However, following reperfusion, the hearts of the CLP‐1+/− mice showed haemodynamic values of developed pressure, the first derivative of developed pressure (dP/dt max) and aortic flow similar to hearts from wild‐type CLP‐1 subjected to PC, suggesting that the CLP‐1+/− hearts harbour an intrinsic cardioprotective program. Indeed, when CLP‐1 +/− mice hearts were subjected to PC followed by I/R, the degree of cardioprotection was similar to CLP‐1 +/+ subjected to PC, i.e. no further protection was observed. Coronary flow and heart rate did not exhibit significant changes between genotypes (Fig. 2B and C). Cardioprotection was also evident when the infarct sizes were measured. In the wild‐type hearts, the infarct size was reduced upon PC, whereas in the CLP‐1+/− mice the infarct size was the same with or without PC (Fig. 3).

Bottom Line: There was a decrease in Cdk7 and Cdk9 kinase activity and consequently in phosphorylation of serine-5 and serine-2 of Pol II CTD in CLP-1 +/- hearts.However, the levels of mitochondrial proteins, PGC-1alpha and HIF-1alpha, which enhance mitochondrial activity and are implicated in cell survival, were increased in CLP-1 +/- hearts subjected to ischaemic stress compared to that in wild-type CLP-1 +/- hearts treated identically.Taken together, our data suggest that regulation of the CLP-1 levels is critical to cellular adaptation of the survival program that protects cardiomyocytes against stress due collectively to a decrease in RNA Pol II phosphorylation but an increase in expression of target proteins that regulate mitochondrial function and metabolic adaptation to stress.

View Article: PubMed Central - PubMed

Affiliation: Center for Cardiovascular and Muscle Research, Department of Anatomy and Cell Biology, State University of New York Downstate Medical Center, Brooklyn, NY 112031, USA.

ABSTRACT
In order to understand the transcriptional mechanism that underlies cell protection to stress, we evaluated the role of CLP-1, a known inhibitor of the transcription elongation complex (pTEFb), in CLP-1 +/- mice hearts. Using the isolated heart model, we observed that the CLP-1 +/- hearts, when subjected to ischaemic stress and evaluated by haemodynamic measurements, exhibit significant cardioprotection. CLP-1 remains associated with the pTEFb complex in the heterozygous hearts, where as it is released in the wild-type hearts suggesting the involvement of pTEFb regulation in cell protection. There was a decrease in Cdk7 and Cdk9 kinase activity and consequently in phosphorylation of serine-5 and serine-2 of Pol II CTD in CLP-1 +/- hearts. However, the levels of mitochondrial proteins, PGC-1alpha and HIF-1alpha, which enhance mitochondrial activity and are implicated in cell survival, were increased in CLP-1 +/- hearts subjected to ischaemic stress compared to that in wild-type CLP-1 +/- hearts treated identically. There was also an increase in the expression of pyruvate dehydrogenase kinase (PDK-1), which facilitates cell adaptation to hypoxic stress. Taken together, our data suggest that regulation of the CLP-1 levels is critical to cellular adaptation of the survival program that protects cardiomyocytes against stress due collectively to a decrease in RNA Pol II phosphorylation but an increase in expression of target proteins that regulate mitochondrial function and metabolic adaptation to stress.

Show MeSH
Related in: MedlinePlus