Dual-specificity Phosphatase 14 Protects The Heart From Aortic Banding Induced Cardiac Hypertrophy And Dysfunction Through Inactivation Of TAK1-P38MAPK/-JNK1/2 Signaling Pathway

Objective: Cardiac hypertrophy usually occurs in response to mechanical and neurohormonal stimuli such as hypertension,valvular insufficiency,which is the strongest predictor for the development of heart failure,arrhythmia,and sudden death.Signaling pathways controlling cardiac hypertrophy are intricate but coordinated networks which remain to be explored.The objective of this study is to investigate the function of dual specificity phosphatase 14(DUSP14)in the pathogenesis of cardiac remodeling.Methods: To investigate the functional contribution of Dusp14 to cardiac hypertrophy,we performed gain-and loss-of-function studies in neonatal rat cardiomyocytes(NRCMs).NRCMs size and morphology were determined by immunostaining assay.Next,Dusp14-/-knockout mice and cardiac-specific Dusp14 transgenic mice were generated and subjected to aortic banding(AB)for 4 weeks.Heart weight/bodyweight(HW/BW)ratio,lung weight/bodyweight(LW/BW)ratio,heart weight/tibia length(HW/TL)ratio were counted.Left ventricular sections stained with hematoxylin and eosin(H&E)and wheat germ agglutinin(WGA)for histopathology or with picrosirius red(PSR)to quantify cardiac fibrosis.Echocardiographic assessment was performed to evaluate ventricular function.m RNA expression of hypertrophy markers and fibrosis markers were determined by real-time PCR analysis.To determine candidate signaling molecules related to the antihypertrophic effects of Dusp14,we analyzed the expression and activity of Mitogen-activated protein kinase(MAPK)cascade components by Western blot.Co-immunoprecipitation(IP)experiments and TGFβ-activated kinase 1(TAK1)inhibitor 5Z-7-ox were used to further determine whether TAK1-P38 MAPK /-c-Jun N-terminal kinases(JNK1/2)signaling pathways is required for Dusp14-mediated antihypertrophic effects post AB.Results: In vitro,adenoviral overexpression of constitutive DUSP14 blocked angiotensin II-induced hypertrophic growth of cardiomyocytes,while DUSP14 knockdown led to opposite effects.In vivo,our results demonstrated that genetic loss of DUSP14 significantly aggravated cardiac hypertrophy,fibrosis,ventricular dilation and dysfunction,whereas transgenic cardiac-specific DUSP14 overexpression significantly attenuated AB-induced cardiac dysfunction and remodeling.Mechanistically,excessive phosphorylation of TAK1,P38 MAPK and JNK1/2 was evidenced in DUSP14-/-knockout mice post AB,while AB induced less upregulation of phosphor-P38 MAPK and phosphor-J NK1/2 in hearts from TG mice overexpressing DUSP14 at 4 weeks post AB,and inactivation of TAK1-P38 MAPK and-JNK1/2 signaling using TAK1 inhibitor 5Z-7-ox shares similarly antihypertrophic effect as DUSP14 overexpression.Moreover,we show that DUSP14 directly interacted with TAK1.Conclusion: Taken together,results from present experiments indicate that Dusp14 protects the heart from AB induced cardiac hypertrophy and dysfunction possibly through inactivation of TAK1-P38MAPK/-JNK1/2 signaling pathway.Future studies are warranted to test the feasibility of overexpressing Dusp14 as a therapeutic strategy to attenuate cardiac hypertrophy and failure.