Loss of myocardial retinoic acid receptor α induces diastolic dysfunction by promoting intracellular oxidative stress and calcium mishandling in adult mice. (October 2016)

• Record Type: Journal Article
• Authors: Zhu, Sen; Guleria, Rakeshwar S.; Thomas, Candice M.; Roth, Amanda; Gerilechaogetu, Fnu; Kumar, Rajesh; Dostal, David E.; Baker, Kenneth M.; Pan, Jing
• Is Part Of: Journal of molecular and cellular cardiology. Volume 99(2016:Oct.)
• Page Start: 100
• Page End: 112
• Publication Date: 2016-10
• Subjects: Retinoic acid receptor -- Diastolic dysfunction -- Oxidative stress -- Calcium handling; Cardiology -- Periodicals; Heart Diseases -- Periodicals; Molecular Biology -- Periodicals; Cardiologie -- Périodiques; Cardiology; Electronic journals; Periodicals; 616.12
• DOI: 10.1016/j.yjmcc.2016.08.009
• Languages: English
• ISSNs: 0022-2828

Abstract

Abstract: Retinoic acid receptor (RAR) has been implicated in pathological stimuli-induced cardiac remodeling. To determine whether the impairment of RARα signaling directly contributes to the development of heart dysfunction and the involved mechanisms, tamoxifen-induced myocardial specific RARα deletion (RARαKO) mice were utilized. Echocardiographic and cardiac catheterization studies showed significant diastolic dysfunction after 16 wks of gene deletion. However, no significant differences were observed in left ventricular ejection fraction (LVEF), between RARαKO and wild type (WT) control mice. DHE staining showed increased intracellular reactive oxygen species (ROS) generation in the hearts of RARαKO mice. Significantly increased NOX2 (NADPH oxidase 2) and NOX4 levels and decreased SOD1 and SOD2 levels were observed in RARαKO mouse hearts, which were rescued by overexpression of RARα in cardiomyocytes. Decreased SERCA2a expression and phosphorylation of phospholamban (PLB), along with decreased phosphorylation of Akt and Ca 2 + /calmodulin-dependent protein kinase II δ (CaMKII δ) was observed in RARαKO mouse hearts. Ca 2 + reuptake and cardiomyocyte relaxation were delayed by RARα deletion. Overexpression of RARα or inhibition of ROS generation or NOX activation prevented RARα deletion-induced decrease in SERCA2a expression/activation and delayed Ca 2 + reuptake. Moreover, the gene and protein expression of RARα was significantly decreased in aged or metabolic stressed mouse hearts. RARα deletion accelerated the development of diastolic dysfunction in streptozotocin (STZ)-induced type 1 diabetic mice or in high fat diet fed mice. In conclusion, myocardial RARα deletion promoted diastolic dysfunction, with a relative preserved LVEF. Increased oxidative stress have an important role in the decreased expression/activation of SERCA2a and Ca 2 + mishandling in RARαKO mice, which are major contributing factors in the development of diastolic dysfunction. These data suggest that impairment of cardiac RARα signaling may be a novel mechanism that is directly linked to pathological stimuli-induced diastolic dysfunction. Highlights: Cardiac specific gene deletion of RARα induces diastolic dysfunction with preserved LVEF. Loss of RARα signaling promotes cardiac oxidative stress and calcium mishandling. Oxidative stress plays a key role in SERCA2a inactivation and calcium mishandling in RARαKO mice. Cardiac expression of RARα is downregulated in mice with metabolic stress or aging. RARα deletion accelerates metabolic stress-induced diastolic dysfunction.