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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.


Related in: MedlinePlus

Therapeutic effect of CPZ in TAC‐induced cardiac hypertrophy by inhibiting the CaMKIIδ–MAPK signaling pathway in vivo. A, Expression of proteins were analyzed by Western blotting for CaMKIIδ, ERKs, p38, JNK, PLN, and Serca2a in the sham‐operated group (panel 1), the TAC group (panel 2), and the group treated with CPZ 2.5 mg/kg per day (panel 3). In the TAC group at 4 or 8 weeks after TAC operation, β‐actin was used as an internal control. Relative expression ratios of p‐CaMKIIδ to CaMKIIδ (B), p‐ERKs to ERKs(C), p‐JNK to JNK(D), p‐p38 to p38 (E), p‐PLN to PLN (F), and Serac2a to β‐actin (G) in left ventricle tissue from the above groups (6 independent experiments per group) are shown. *P<0.05, **P<0.01, ***P<0.001. CaMKII indicates calmodulin‐dependent protein kinase II; CPZ, capsazepine; ERK, extracellular signal–regulated kinase; JNK, c‐Jun N‐terminal kinase; p, phosphorylated; p, phosphorylated; PLN, phospholamban; TAC, transverse aorta constriction.
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jah31675-fig-0008: Therapeutic effect of CPZ in TAC‐induced cardiac hypertrophy by inhibiting the CaMKIIδ–MAPK signaling pathway in vivo. A, Expression of proteins were analyzed by Western blotting for CaMKIIδ, ERKs, p38, JNK, PLN, and Serca2a in the sham‐operated group (panel 1), the TAC group (panel 2), and the group treated with CPZ 2.5 mg/kg per day (panel 3). In the TAC group at 4 or 8 weeks after TAC operation, β‐actin was used as an internal control. Relative expression ratios of p‐CaMKIIδ to CaMKIIδ (B), p‐ERKs to ERKs(C), p‐JNK to JNK(D), p‐p38 to p38 (E), p‐PLN to PLN (F), and Serac2a to β‐actin (G) in left ventricle tissue from the above groups (6 independent experiments per group) are shown. *P<0.05, **P<0.01, ***P<0.001. CaMKII indicates calmodulin‐dependent protein kinase II; CPZ, capsazepine; ERK, extracellular signal–regulated kinase; JNK, c‐Jun N‐terminal kinase; p, phosphorylated; p, phosphorylated; PLN, phospholamban; TAC, transverse aorta constriction.

Mentions: Our results showed that activation of TRPV1 induced an increase in intracellular calcium and phosphorylated CaMKIIδ–dependent MAPK signaling and that expression of TRPV1 was upregulated in TAC‐induced hypertrophic hearts in vivo; therefore, we assayed the expression of CaMKIIδ and MAPK proteins in TAC‐induced cardiac hypertrophy in vivo. Western blot analysis showed that TAC treatment for 4 or 8 weeks also induced an increase in phosphorylated CaMKIIδ in cardiac myocytes (Figure 8A and 8B) that was attenuated by CPZ treatment of 2.5 mg/kg per day in vivo. To observe the change of MAPK signaling components after CPZ treatment in TAC‐induced cardiac hypertrophy in vivo, we further measured the expression of phosphorylated ERKs, p38, and JNK proteins in the sham‐ and TAC‐operated mice and analyzed the effect of CPZ on expression of these MAPKs. The results showed increased expression of phosphorylated ERKs and p38 but not phosphorylated JNK in TAC vehicle groups, and this effect was reversed by CPZ treatment of 2.5 mg/kg per day (Figure 8A, 8C–8E).


Mitogen ‐ Activated Protein Kinase and Intracellular Polyamine Signaling Is Involved in TRPV1 Activation – Induced Cardiac Hypertrophy
Therapeutic effect of CPZ in TAC‐induced cardiac hypertrophy by inhibiting the CaMKIIδ–MAPK signaling pathway in vivo. A, Expression of proteins were analyzed by Western blotting for CaMKIIδ, ERKs, p38, JNK, PLN, and Serca2a in the sham‐operated group (panel 1), the TAC group (panel 2), and the group treated with CPZ 2.5 mg/kg per day (panel 3). In the TAC group at 4 or 8 weeks after TAC operation, β‐actin was used as an internal control. Relative expression ratios of p‐CaMKIIδ to CaMKIIδ (B), p‐ERKs to ERKs(C), p‐JNK to JNK(D), p‐p38 to p38 (E), p‐PLN to PLN (F), and Serac2a to β‐actin (G) in left ventricle tissue from the above groups (6 independent experiments per group) are shown. *P<0.05, **P<0.01, ***P<0.001. CaMKII indicates calmodulin‐dependent protein kinase II; CPZ, capsazepine; ERK, extracellular signal–regulated kinase; JNK, c‐Jun N‐terminal kinase; p, phosphorylated; p, phosphorylated; PLN, phospholamban; TAC, transverse aorta constriction.
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Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC5015292&req=5

jah31675-fig-0008: Therapeutic effect of CPZ in TAC‐induced cardiac hypertrophy by inhibiting the CaMKIIδ–MAPK signaling pathway in vivo. A, Expression of proteins were analyzed by Western blotting for CaMKIIδ, ERKs, p38, JNK, PLN, and Serca2a in the sham‐operated group (panel 1), the TAC group (panel 2), and the group treated with CPZ 2.5 mg/kg per day (panel 3). In the TAC group at 4 or 8 weeks after TAC operation, β‐actin was used as an internal control. Relative expression ratios of p‐CaMKIIδ to CaMKIIδ (B), p‐ERKs to ERKs(C), p‐JNK to JNK(D), p‐p38 to p38 (E), p‐PLN to PLN (F), and Serac2a to β‐actin (G) in left ventricle tissue from the above groups (6 independent experiments per group) are shown. *P<0.05, **P<0.01, ***P<0.001. CaMKII indicates calmodulin‐dependent protein kinase II; CPZ, capsazepine; ERK, extracellular signal–regulated kinase; JNK, c‐Jun N‐terminal kinase; p, phosphorylated; p, phosphorylated; PLN, phospholamban; TAC, transverse aorta constriction.
Mentions: Our results showed that activation of TRPV1 induced an increase in intracellular calcium and phosphorylated CaMKIIδ–dependent MAPK signaling and that expression of TRPV1 was upregulated in TAC‐induced hypertrophic hearts in vivo; therefore, we assayed the expression of CaMKIIδ and MAPK proteins in TAC‐induced cardiac hypertrophy in vivo. Western blot analysis showed that TAC treatment for 4 or 8 weeks also induced an increase in phosphorylated CaMKIIδ in cardiac myocytes (Figure 8A and 8B) that was attenuated by CPZ treatment of 2.5 mg/kg per day in vivo. To observe the change of MAPK signaling components after CPZ treatment in TAC‐induced cardiac hypertrophy in vivo, we further measured the expression of phosphorylated ERKs, p38, and JNK proteins in the sham‐ and TAC‐operated mice and analyzed the effect of CPZ on expression of these MAPKs. The results showed increased expression of phosphorylated ERKs and p38 but not phosphorylated JNK in TAC vehicle groups, and this effect was reversed by CPZ treatment of 2.5 mg/kg per day (Figure 8A, 8C–8E).

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.


Related in: MedlinePlus