Brody MJ, Feng L, Grimes AC, Hacker TA, Olson TM, Kamp TJ, Balijepalli RC, Lee Y. LRRC10 is required to maintain cardiac function in response to pressure overload. Am J Physiol Heart Circ Physiol 310: H269 -H278, 2016. First published November 25, 2015 doi:10.1152/ajpheart.00717.2014.-We previously reported that the cardiomyocyte-specific leucine-rich repeat containing protein (LRRC)10 has critical functions in the mammalian heart. In the present study, we tested the role of LRRC10 in the response of the heart to biomechanical stress by performing transverse aortic constriction on Lrrc10-null (Lrrc10 Ϫ/Ϫ ) mice. Mild pressure overload induced severe cardiac dysfunction and ventricular dilation in Lrrc10 Ϫ/Ϫ mice compared with control mice. In addition to dilation and cardiomyopathy, Lrrc10 Ϫ/Ϫ mice showed a pronounced increase in heart weight with pressure overload stimulation and a more dramatic loss of cardiac ventricular performance, collectively suggesting that the absence of LRRC10 renders the heart more disease prone with greater hypertrophy and structural remodeling, although rates of cardiac fibrosis and myocyte dropout were not different from control mice. Lrrc10 Ϫ/Ϫ cardiomyocytes also exhibited reduced contractility in response to -adrenergic stimulation, consistent with loss of cardiac ventricular performance after pressure overload. We have previously shown that LRRC10 interacts with actin in the heart. Here, we show that His 150 of LRRC10 was required for an interaction with actin, and this interaction was reduced after pressure overload, suggesting an integral role for LRRC10 in the response of the heart to mechanical stress. Importantly, these experiments demonstrated that LRRC10 is required to maintain cardiac performance in response to pressure overload and suggest that dysregulated expression or mutation of LRRC10 may greatly sensitize human patients to more severe cardiac disease in conditions such as chronic hypertension or aortic stenosis. CARDIOMYOCYTE HYPERTROPHY in response to extracellular stimuli, such as neurohumoral or growth factor stimulation of membrane-bound receptors (13, 23, 44), or in response to mechanical stretch or strain that is sensed by mechanosensory machinery embedded in the Z-disc cytoskeleton, and sarcolemma (25, 38, 49). At the whole organ level, the heart undergoes hypertrophy as an adaptive mechanism to maintain cardiac output and reduce ventricular wall stress (20,23,38). While initially beneficial, prolonged cardiac hypertrophy becomes maladaptive and progresses to cardiac dilation, decompensation, heart failure, and/or sudden death (20,23,38). Cardiac hypertrophy can be induced by a number of cardiovascular diseases, such as myocardial infarction or chronic hypertension (23, 37). Indeed, high blood pressure is a common precursor to heart disease, particularly in the United States, where chronic hypertension is widespread (18,21,42). Despite increased awareness and treatment of hypertension, recent epidemiological studies have suggested that its prevalence con...