Role and Mechanisms of cGMP-PDE Compartmentation in Cardiac Stress

摘要 心力衰竭(HF)是全球主要的死亡原因，影响着美国近600万人 只有一个州。其中高达50%的患者将在确诊后五年内死亡，并对 机械基础势在必行，这样才能评估它们的治疗潜力。 我们实验室的证据表明，降解环鸟苷的磷酸二酯酶(PDE) 一磷酸(CGMP)作为心力衰竭的药物靶点具有很大的应用价值。这些PDE 最终阻断蛋白激酶G(PKG)信号，这是一种已知的心脏保护途径；因此阻断 PDE活动的结果是心脏保护。心脏中存在几个cGMP特异的PDE， 即一氧化氮连接的PDE5a和利钠肽连接的PDE9a。这些PDE是 被划分到细胞的特定区域，尽管人们对这种划分知之甚少 对于PDE5，对于PDE9则一无所知。这项提案的一部分旨在研究这种划分 使用新的分子工具，如隔室靶向的PKG抑制剂和标记的PDE，可以 用于确定亚细胞定位和隔室特定蛋白质组。了解 PDE5和PDE9隔室的细节可以阐明如何操作这些PDE 治疗学。以往的体内研究表明，对PDE5的抑制作用很大 在雄性动物心力衰竭模型中的治疗作用，但在缺乏雌激素的雌性小鼠中效果不佳 (与绝经后妇女的心力衰竭相当)和射血分数保留的人心力衰竭 病人。这些缺陷是由于雌激素对一氧化氮的调节和抑郁症造成的。 分别检测心衰患者的一氧化氮水平。最近我们发现，抑制或基因缺失 PDE9a是心脏中另一种cGMP特异性PDE，可减轻雄性小鼠的心肌肥厚。这个 PDE9途径独立于一氧化氮/PDE5途径发挥作用，使其成为一种有前途的药物 在PDE5抑制无效的情况下的目标。我们假设抑制PDE9将 在非性别和非性别的啮齿动物压力超负荷模型中结果改善心功能 荷尔蒙状况。这一假设将在使用C57BL6的女性压力过载HF模型中进行验证 接受PDE9抑制剂治疗的小鼠和缺乏雌激素的PDE9a基因敲除小鼠。

Abstract Heart failure (HF) is a leading cause of death globally, affecting almost 6 million people in the United States alone. Up to 50% of these patients will die within five years of diagnosis, making elucidation of the mechanistic underpinnings imperative so they can be evaluated for therapeutic potential. Evidence from our lab has shown that phosphodiesterases (PDEs) that degrade cyclic guanosine monophosphate (cGMP) have great utility as druggable targets in heart failure. These PDEs ultimately block protein kinase G (PKG) signaling, a known cardioprotective pathway; hence blockade of PDE activity results in cardioprotection. Several cGMP-specific PDEs are present in the heart, namely the nitric oxide-linked PDE5a and the natriuretic peptide-linked PDE9a. These PDEs are compartmentalized to specific regions of the cell, although little is known about this compartmentation for PDE5, and nothing is known for PDE9. Part of this proposal aims to study this compartmentation using novel molecular tools such as compartment-targeted PKG inhibitors and tagged PDEs that can be used to determine subcellular localization and compartment-specific proteomes. Knowing the specifics of the PDE5 and PDE9 compartments may clarify how these PDEs can be manipulated for therapeutics. Previous in vivo studies have demonstrated that inhibition of PDE5 has great therapeutic utility in male animal HF models, but has fallen short in female mice lacking estrogen (comparable to HF in postmenopausal women) and in human HF with preserved ejection fraction patients. These shortcomings are due to the regulation of nitric oxide by estrogen and the depression of nitric oxide levels in HF, respectively. Recently we revealed that inhibition or genetic deletion of PDE9a, the other cGMP-specific PDE in the heart, attenuates cardiac hypertrophy in male mice. The PDE9 pathway acts independently of the nitric oxide/PDE5 pathway, making it a promising drug target in situations where PDE5 inhibition is ineffective. We hypothesize that inhibition of PDE9 will result in improved cardiac function in rodent pressure-overload models independent of sex and sex hormone status. This hypothesis will be tested in a female pressure-overload HF model using C57Bl6 mice treated with PDE9 inhibitors and PDE9a knockout mice lacking estrogen.