Activation of the Sarcoplasmic/Endoplasmic Reticulum Calcium ATPase (SERCA) as a Therapeutic Intervention for Sarcopenia

骨质疏松症(肌肉质量和功能丧失)普遍影响老年人，并有 对老年退伍军人的生活质量、独立生活和医疗成本产生巨大影响。 这项研究的目的是测试一种潜在的新的药理学方法，即激活 肌内质网(SR)钙ATPase(SERCA)将钙泵回SR 肌肉收缩后，调节骨质疏松症。这项工作至关重要，因为没有 目前存在有效的药物干预措施。在这里，我们使用了一个小鼠模型 我实验室培育的石棺减少症(缺乏抗氧化酶的SOD1-/-小鼠 CuZnSOD)，它概括了衰老小鼠和人类骨质疏松症的许多特征 临床前模型，以测试和表征潜在的干预措施。成功的干预可以 然后在老化的野生型小鼠身上进一步测试。被破坏的细胞内钙稳态是一种 衰老过程中骨骼肌质量和力量产生能力丧失的潜在因素 而SERCA功能受损可导致细胞内钙升高，并对 细胞过程。我们假设增加SERCA活性以维持钙 动态平衡可能是治疗骨质疏松症的有效机制。为了支持这一点，我们 初步数据清楚地表明，CDN1163和CDN1163对2个月大的SOD1-/-小鼠的治疗作用 变构SERCA激活剂，增加SERCA活性，钝化肌肉萎缩，提高力量 产生并减少未经治疗的肌肉线粒体ROS的产生 SOD1-/-小鼠。CDN1163已经报道了对新陈代谢和认知功能的有益影响， 但我们的研究是第一次测试它作为一种治疗干预手段的应用 石棺减少症。在这个提案中，我们将测试SERCA激活可以 通过调节细胞内钙信号来预防/减轻肌肉萎缩和虚弱， 线粒体功能和蛋白水解酶活性降低。首先，我们将定义剂量响应和 口服CDN1163对小鼠的生物学效应。一旦我们有了 确定了最佳有效剂量，我们将跟踪我们的激动人心的数据，并测试 CDN1163治疗可以预防/减少与年龄相关的肌肉质量损失和虚弱 AIM 2.雄性和雌性野生型C57BL6小鼠将被注射 CDN1163从15个月龄开始。我们将测量CDN1163治疗对 细胞内钙信号调节、线粒体功能、收缩功能降低 15、20和28岁时石棺减少症表型的蛋白分解活性和其他基本标志物 几个月大的孩子。SERCA活性也受内源性抑制物--肌磷脂(SLN)的调节。 我们的研究表明，在衰老过程中和SOD1-/-小鼠的肌肉中，肌磷脂水平会升高， 与SERCA活性降低相一致。在目标3中，我们将测试SERCA的激活 SERCA抑制剂肌磷脂通过耗尽SERCA调节衰老SLN-/-突变体的骨骼减少 老鼠。我们将测量肌肉质量、肌肉质量、收缩功能和 6、18和28个月龄男性对肌磷脂耗竭的代谢功能 雌性野生型和SLN-/-小鼠。肌磷脂耗竭是否激活SERCA并调节肌肉 萎缩/虚弱，这将进一步支持使用SERCA激活剂作为治疗 干预。总之，这些研究有很大的潜力揭示一种新的治疗方法 干预调节骨质疏松症。

Sarcopenia (loss of muscle mass and function) universally affects the elderly and has a tremendous impact on quality of life, independent living, and healthcare costs in aging veterans. The goal of this study is to test a potential new pharmacological approach, activation of the sarcoendoplasmic reticulum (SR) calcium ATPase (SERCA) that pumps Ca2+ back into the SR following muscle contraction, to modulate sarcopenia. This work is critically important as no effective pharmacologic interventions currently exist. Here we have employed a mouse model of sarcopenia developed by my laboratory (the Sod1-/- mouse lacking the antioxidant enzyme CuZnSOD) that recapitulates many features of sarcopenia in aging mice and in humans as a pre-clinical model to test and characterize potential interventions. Successful interventions can then be tested further in aging wild type mice. Disrupted intracellular calcium homeostasis is a potential contributor to loss of skeletal muscle mass and force-generating capacity during aging and impaired SERCA function can lead to elevated cytosolic calcium and deleterious effects on cellular processes. We hypothesized that increasing SERCA activity to maintain calcium homeostasis may be an effective mechanism to treat sarcopenia. In support of this, our preliminary data clearly show that treatment of 2 month old Sod1-/- mice with CDN1163, an allosteric SERCA activator, increases SERCA activity, blunts muscle atrophy, improves force generation and reduces muscle mitochondrial ROS production that occurs in the untreated Sod1-/- mice. CDN1163 has reported beneficial effects on metabolism and cognitive function, but our study is the first to test its application as a therapeutic intervention for treating sarcopenia. In this proposal, we will test the hypothesis that SERCA activation can prevent/reduce muscle atrophy and weakness through regulation of cytosolic calcium signaling, mitochondrial function and reduced proteolytic activity. First, we will define dose response and biologic effects of oral administration of CDN1163 in mice through the diet. Once we have determined an optimal effective dose, we will follow up on our exciting data and test whether CDN1163 treatment can prevent/reduce age-related loss of muscle mass and weakness in aging wild type mice in Aim 2. Male and female wildtype C57Bl6 mice will be administered CDN1163 starting at 15 months of age. We will measure the effect of CDN1163 treatment on the regulation of cytosolic calcium signaling, mitochondrial function, contractile function, reduced proteolytic activity and other essential markers of the sarcopenia phenotype at 15, 20, and 28 months of age. SERCA activity is also regulated by an endogenous inhibitor, sarcolipin (Sln). Our studies have shown that sarcolipin is elevated in muscle during aging and in Sod1-/- mice, consistent with reduced SERCA activity. In Aim 3, we will test whether activation of SERCA through depletion of the SERCA inhibitor sarcolipin modulates sarcopenia in aging Sln-/- mutant mice. We will measure markers of muscle mass, muscle quality, contractile function and metabolic function in response to sarcolipin depletion in 6, 18 and 28 month old male and female wild type and Sln-/- mice. If sarcolipin depletion activates SERCA and modulates muscle atrophy/weakness, this will further support the use of SERCA activators as a therapeutic intervention. Together, these studies have significant potential to reveal a new therapeutic intervention to modulate sarcopenia.