Zinc rescues obesity‐induced cardiac hypertrophy via stimulating metallothionein to suppress oxidative stress‐activated BCL 10/ CARD 9/p38 MAPK pathway

Obesity often leads to obesity‐related cardiac hypertrophy ( ORCH ), which is suppressed by zinc‐induced inactivation of p38 mitogen‐activated protein kinase (p38 MAPK ). In this study, we investigated the mechanisms by which zinc inactivates p38 MAPK to prevent ORCH . Mice (4‐week old) were fed either high fat diet ( HFD , 60% kcal fat) or normal diet ( ND , 10% kcal fat) containing variable amounts of zinc (deficiency, normal and supplement) for 3 and 6 months. P38 MAPK si RNA and the p38 MAPK inhibitor SB 203580 were used to suppress p38 MAPK activity in vitro and in vivo , respectively. HFD activated p38 MAPK and increased expression of B‐cell lymphoma/ CLL 10 ( BCL 10) and caspase recruitment domain family member 9 ( CARD 9). These responses were enhanced by zinc deficiency and attenuated by zinc supplement. Administration of SB 203580 to HFD mice or specific si RNA in palmitate‐treated cardiomyocytes eliminated the HFD and zinc deficiency activation of p38 MAPK , but did not significantly impact the expression of BCL 10 and CARD 9. In cultured cardiomyocytes, inhibition of BCL 10 expression by si RNA prevented palmitate‐induced increased p38 MAPK activation and atrial natriuretic peptide ( ANP ) expression. In contrast, inhibition of p38 MAPK prevented ANP expression, but did not affect BCL 10 expression. Deletion of metallothionein abolished the protective effect of zinc on palmitate‐induced up‐regulation of BCL 10 and phospho‐p38 MAPK . HFD and zinc deficiency synergistically induce ORCH by increasing oxidative stress‐mediated activation of BCL 10/ CARD 9/p38 MAPK signalling. Zinc supplement ameliorates ORCH through activation of metallothionein to repress oxidative stress‐activated BCL 10 expression and p38 MAPK activation.