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Mitogen ‐ Activated Protein Kinase and Intracellular Polyamine Signaling Is Involved in TRPV1 Activation – Induced Cardiac Hypertrophy

View Article: PubMed Central - PubMed

ABSTRACT

Background: The transient receptor potential vanilloid type 1 (TRPV1) is expressed in the cardiovascular system, and increased TRPV1 expression has been associated with cardiac hypertrophy. Nevertheless, the role of TRPV1 in the pathogenesis of cardiac hypertrophy and the underlying molecular mechanisms remain unclear.

Methods and results: In cultured cardiomyocytes, activation of TRPV1 increased cell size and elevated expression of atrial natriuretic peptide mRNA and intracellular calcium level, which was reversed by TRPV1 antagonist capsazepine. Increased expression of phosphorylated calmodulin‐dependent protein kinase IIδ and mitogen‐activated protein kinases were found in TRPV1 agonist capsaicin‐treated cardiomyocytes. Selective inhibitor of calmodulin‐dependent protein kinase IIδ decreased phosphorylation of extracellular signal–regulated kinases and p38. Capsaicin induced an increase in expression of ornithine decarboxylase protein, which is the key enzyme in polyamine biosynthesis in cardiomyocytes. Nevertheless, there was no obvious change of ornithine decarboxylase expression in TRPV1 knockdown cells after capsaicin treatment, and specific inhibitors of calmodulin‐dependent protein kinase IIδ or p38 downregulated the capsaicin‐induced expression of ornithine decarboxylase. Capsazepine alleviated the increase in cross‐sectional area of cardiomyocytes and the ratio of heart weight to body weight and improved cardiac function, including left ventricular internal end‐diastolic and ‐systolic dimensions and ejection fraction and fractional shortening percentages, in mice treated with transverse aorta constriction. Capsazepine also reduced expression of ornithine decarboxylase and cardiac polyamine levels. Transverse aorta constriction induced increases in phosphorylated calmodulin‐dependent protein kinase IIδ and extracellular signal–regulated kinases, and p38 and Serca2a were attenuated by capsazepine treatment.

Conclusions: This study revealed that the mitogen‐activated protein kinase signaling pathway and intracellular polyamines are essential for TRPV1 activation–induced cardiac hypertrophy.

No MeSH data available.


Expression of CaMKIIδ‐dependent mitogen‐activated protein kinase signaling in TRPV1 siRNA–treated H9C2 cells. A, Morphologies of H9C2 cells were examined after CAP treatment on control or TRPV1 siRNA–treated groups for 48 hours. Scale bar=25 μm. B, Cardiomyocyte cross‐sectional area was measured after CAP treatment. C, Representative mRNA products of ANP in the CAP‐treated H9C2 cells (5 independent experiments per group) are shown. *P<0.05 versus control, #P<0.05 versus 2 μmol/L CAP. D, In scrambled siRNA– and TRPV1 siRNA–treated cells, 1 μmol/L CaMKIIδ inhibitor KN‐93, 2 μmol/L CAP, or 1 μmol/L KN‐93 plus 2 μmol/L CAP were added in culture media for 48 hours, and then cell extracts were analyzed by Western blotting for CaMKIIδ, ERKs, and p38 protein; β‐actin was used as internal control. Relative expression ratios of p‐CaMKIIδ to CaMKIIδ (E), p‐ERKs to ERKs (F), and p‐p38 to p38 (G) in cells with different treatment (5 independent experiments per group) are shown. **P<0.01, ***P<0.001. ANP indicates atrial natriuretic peptide; CaMKII, calmodulin‐dependent protein kinase II; CAP, capsaicin; ERK, extracellular signal–regulated kinase; p, phosphorylated; siRNA, small interfering RNA.
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jah31675-fig-0003: Expression of CaMKIIδ‐dependent mitogen‐activated protein kinase signaling in TRPV1 siRNA–treated H9C2 cells. A, Morphologies of H9C2 cells were examined after CAP treatment on control or TRPV1 siRNA–treated groups for 48 hours. Scale bar=25 μm. B, Cardiomyocyte cross‐sectional area was measured after CAP treatment. C, Representative mRNA products of ANP in the CAP‐treated H9C2 cells (5 independent experiments per group) are shown. *P<0.05 versus control, #P<0.05 versus 2 μmol/L CAP. D, In scrambled siRNA– and TRPV1 siRNA–treated cells, 1 μmol/L CaMKIIδ inhibitor KN‐93, 2 μmol/L CAP, or 1 μmol/L KN‐93 plus 2 μmol/L CAP were added in culture media for 48 hours, and then cell extracts were analyzed by Western blotting for CaMKIIδ, ERKs, and p38 protein; β‐actin was used as internal control. Relative expression ratios of p‐CaMKIIδ to CaMKIIδ (E), p‐ERKs to ERKs (F), and p‐p38 to p38 (G) in cells with different treatment (5 independent experiments per group) are shown. **P<0.01, ***P<0.001. ANP indicates atrial natriuretic peptide; CaMKII, calmodulin‐dependent protein kinase II; CAP, capsaicin; ERK, extracellular signal–regulated kinase; p, phosphorylated; siRNA, small interfering RNA.

Mentions: To confirm whether phosphorylated CaMKIIδ was induced by TRPV1 activation and whether ERKs or p38 is downstream of phosphorylated CaMKIIδ, we knocked down expression of TRPV1 in H9C2 cells using Trpv1 siRNA and KN‐93, the selective inhibitor of CaMKIIδ. Compared with the scrambled siRNA–treated cardiac myocytes, CAP (0.5 and 2 μmol/L) was not able to induce an increase in expression of phosphorylated CaMKIIδ, ERKs, and p38 in TRPV1 siRNA–treated cells. Moreover, in the presence of 2 μmol/L KN‐93, CAP‐induced expression of phosphorylated ERKs or p38 protein was significantly attenuated (Figure 3).


Mitogen ‐ Activated Protein Kinase and Intracellular Polyamine Signaling Is Involved in TRPV1 Activation – Induced Cardiac Hypertrophy
Expression of CaMKIIδ‐dependent mitogen‐activated protein kinase signaling in TRPV1 siRNA–treated H9C2 cells. A, Morphologies of H9C2 cells were examined after CAP treatment on control or TRPV1 siRNA–treated groups for 48 hours. Scale bar=25 μm. B, Cardiomyocyte cross‐sectional area was measured after CAP treatment. C, Representative mRNA products of ANP in the CAP‐treated H9C2 cells (5 independent experiments per group) are shown. *P<0.05 versus control, #P<0.05 versus 2 μmol/L CAP. D, In scrambled siRNA– and TRPV1 siRNA–treated cells, 1 μmol/L CaMKIIδ inhibitor KN‐93, 2 μmol/L CAP, or 1 μmol/L KN‐93 plus 2 μmol/L CAP were added in culture media for 48 hours, and then cell extracts were analyzed by Western blotting for CaMKIIδ, ERKs, and p38 protein; β‐actin was used as internal control. Relative expression ratios of p‐CaMKIIδ to CaMKIIδ (E), p‐ERKs to ERKs (F), and p‐p38 to p38 (G) in cells with different treatment (5 independent experiments per group) are shown. **P<0.01, ***P<0.001. ANP indicates atrial natriuretic peptide; CaMKII, calmodulin‐dependent protein kinase II; CAP, capsaicin; ERK, extracellular signal–regulated kinase; p, phosphorylated; siRNA, small interfering RNA.
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jah31675-fig-0003: Expression of CaMKIIδ‐dependent mitogen‐activated protein kinase signaling in TRPV1 siRNA–treated H9C2 cells. A, Morphologies of H9C2 cells were examined after CAP treatment on control or TRPV1 siRNA–treated groups for 48 hours. Scale bar=25 μm. B, Cardiomyocyte cross‐sectional area was measured after CAP treatment. C, Representative mRNA products of ANP in the CAP‐treated H9C2 cells (5 independent experiments per group) are shown. *P<0.05 versus control, #P<0.05 versus 2 μmol/L CAP. D, In scrambled siRNA– and TRPV1 siRNA–treated cells, 1 μmol/L CaMKIIδ inhibitor KN‐93, 2 μmol/L CAP, or 1 μmol/L KN‐93 plus 2 μmol/L CAP were added in culture media for 48 hours, and then cell extracts were analyzed by Western blotting for CaMKIIδ, ERKs, and p38 protein; β‐actin was used as internal control. Relative expression ratios of p‐CaMKIIδ to CaMKIIδ (E), p‐ERKs to ERKs (F), and p‐p38 to p38 (G) in cells with different treatment (5 independent experiments per group) are shown. **P<0.01, ***P<0.001. ANP indicates atrial natriuretic peptide; CaMKII, calmodulin‐dependent protein kinase II; CAP, capsaicin; ERK, extracellular signal–regulated kinase; p, phosphorylated; siRNA, small interfering RNA.
Mentions: To confirm whether phosphorylated CaMKIIδ was induced by TRPV1 activation and whether ERKs or p38 is downstream of phosphorylated CaMKIIδ, we knocked down expression of TRPV1 in H9C2 cells using Trpv1 siRNA and KN‐93, the selective inhibitor of CaMKIIδ. Compared with the scrambled siRNA–treated cardiac myocytes, CAP (0.5 and 2 μmol/L) was not able to induce an increase in expression of phosphorylated CaMKIIδ, ERKs, and p38 in TRPV1 siRNA–treated cells. Moreover, in the presence of 2 μmol/L KN‐93, CAP‐induced expression of phosphorylated ERKs or p38 protein was significantly attenuated (Figure 3).

View Article: PubMed Central - PubMed

ABSTRACT

Background: The transient receptor potential vanilloid type 1 (TRPV1) is expressed in the cardiovascular system, and increased TRPV1 expression has been associated with cardiac hypertrophy. Nevertheless, the role of TRPV1 in the pathogenesis of cardiac hypertrophy and the underlying molecular mechanisms remain unclear.

Methods and results: In cultured cardiomyocytes, activation of TRPV1 increased cell size and elevated expression of atrial natriuretic peptide mRNA and intracellular calcium level, which was reversed by TRPV1 antagonist capsazepine. Increased expression of phosphorylated calmodulin&#8208;dependent protein kinase II&delta; and mitogen&#8208;activated protein kinases were found in TRPV1 agonist capsaicin&#8208;treated cardiomyocytes. Selective inhibitor of calmodulin&#8208;dependent protein kinase II&delta; decreased phosphorylation of extracellular signal&ndash;regulated kinases and p38. Capsaicin induced an increase in expression of ornithine decarboxylase protein, which is the key enzyme in polyamine biosynthesis in cardiomyocytes. Nevertheless, there was no obvious change of ornithine decarboxylase expression in TRPV1 knockdown cells after capsaicin treatment, and specific inhibitors of calmodulin&#8208;dependent protein kinase II&delta; or p38 downregulated the capsaicin&#8208;induced expression of ornithine decarboxylase. Capsazepine alleviated the increase in cross&#8208;sectional area of cardiomyocytes and the ratio of heart weight to body weight and improved cardiac function, including left ventricular internal end&#8208;diastolic and &#8208;systolic dimensions and ejection fraction and fractional shortening percentages, in mice treated with transverse aorta constriction. Capsazepine also reduced expression of ornithine decarboxylase and cardiac polyamine levels. Transverse aorta constriction induced increases in phosphorylated calmodulin&#8208;dependent protein kinase II&delta; and extracellular signal&ndash;regulated kinases, and p38 and Serca2a were attenuated by capsazepine treatment.

Conclusions: This study revealed that the mitogen&#8208;activated protein kinase signaling pathway and intracellular polyamines are essential for TRPV1 activation&ndash;induced cardiac hypertrophy.

No MeSH data available.