Regulation of myocardial GPCRs by USP20 in normal and hypertrophied heart

项目总结 慢性压力超负荷导致左心室肥厚和不利的心脏重构 是导致心力衰竭的主要原因之一，影响着数百万美国人。除了病理性的 侮辱和生物力学因素，神经激素途径，涉及通过β1和 β-2肾上腺素能受体(ARs)在心肌对压力超负荷的适应中发挥重要作用。影响因素 将心肌对压力超负荷的反应从适应性转变为非适应性LVH在很大程度上仍然存在 默默无闻。我们的研究重点是通过以下方式监管βAR交易和信号 泛素化/去泛素化机制。我们最近发现，β1AR和TIMP的差异调节 β-2AR的胞内转运可以通过被称为泛素特异性蛋白酶-20的脱泛素酶(DUB)实现 (USP20)，我们发现它能使两个βARs泛素化。响应βAR激动剂(-)异丙肾上腺素(ISO)， USP20在Ser333上被蛋白激酶A(PKA)磷酸化；这种磷酸化抑制USP20的DUB β2AR的活性，并调节β2AR向自噬小体的运输。USP20磷酸化 在体内也发生：(1)在衰竭的心脏中，USP20的磷酸化显著升高 与非心力衰竭心脏相比：(2)横动脉收缩(TAC)造成的压力超负荷 在WT小鼠的心肌细胞中触发USP20的磷酸化，但在β1AR KO小鼠中不能。因此，在左心室肥厚期间， USP20的磷酸化需要心脏中β1AR的激活，并可能在心脏病理重塑中发挥作用 左心室肥厚和/或心力衰竭。我们假设“USP20及其磷酸化状态微调βAR 信号转导、细胞内转运和自噬，从而影响左心室肥厚的心脏重构。 我们将通过解决以下具体目标来检验我们的假设：(1)确定 心肌细胞-USP20在心功能不全发展中的作用，(2)确定其调节作用 心肌βAR信号通过USP20Ser333的磷酸化和(3)来确定其协调性 β1AR和USP20在调节自噬蛋白Beclin1及其受体泛素化状态中的作用 在心肌细胞自噬中的作用。

PROJECT SUMMARY Chronic pressure overload that leads to left ventricular hypertrophy (LVH) and adverse cardiac remodeling is one of the leading causes of heart failure and affects millions of Americans. In addition to pathological insults and biomechanical factors, neurohormonal pathways that involve coordinated signaling through β1 and β2 adrenergic receptors (ARs) can play a major role in myocardial adaptation to pressure overload. The factors that shift the myocardial response to pressure overload from adaptive to maladaptive LVH remain largely obscure. Our research has focused on the regulation of βAR trafficking and signaling by ubiquitination/deubiquitination mechanisms. We recently discovered that differential regulation of β1AR and β2AR endocytic trafficking can be achieved by the deubiquitinase (DUB) called ubiquitin-specific protease-20 (USP20), which we found deubiquitinates both βARs. In response to the βAR agonist (-)isoproterenol (Iso), USP20 is phosphorylated on Ser333 by protein kinase A (PKA); this phosphorylation inhibits USP20 DUB activity toward the β2AR and regulates trafficking of the β2AR to autophagosomes. USP20 phosphorylation occurs in vivo, as well: (1) USP20 phosphorylation is significantly elevated in failing human hearts when compared with non-failing hearts and (2) pressure overload achieved by transverse aortic constriction (TAC) triggers USP20 phosphorylation in cardiomyocytes of WT, but not β1AR KO mice. Accordingly, during LVH, USP20 phosphorylation requires β1AR activation in the heart and may play a role in pathologic remodeling in LVH and/or heart failure. We hypothesize that “USP20 and its phosphorylation status fine-tune βAR signal transduction, endocytic trafficking and autophagy, thus impacting cardiac remodeling in LVH.” We will test our hypotheses by addressing the following specific aims: (1) To determine the role of cardiomyocyte-USP20 in the development of cardiac dysfunction, (2) To determine the regulation of myocardial βAR signaling by USP20 Ser333 phosphorylation and (3) To determine the coordinated roles of β1AR and USP20 in regulating ubiquitination status of the autophagy protein Beclin1 and its effect in cardiomyocyte autophagy.