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

肌肉减少症（肌肉质量和功能的丧失）普遍影响老年人， 对老年退伍军人的生活质量、独立生活和医疗保健费用产生巨大影响。 本研究的目的是测试一种潜在的新的药理学方法，激活 肌内质网（SR）钙ATP酶（SERCA），将Ca 2+泵回SR 在肌肉收缩后，调节肌肉减少症。这项工作至关重要， 目前存在有效的药物干预。在这里，我们采用了一种小鼠模型， 肌肉减少症（缺乏抗氧化酶的Sod 1-/-小鼠 CuZnSOD），它概括了衰老小鼠和人类肌肉减少症的许多特征， 临床前模型，以测试和表征潜在的干预措施。成功的干预措施可以 然后在衰老的野生型小鼠中进一步测试。细胞内钙稳态的破坏是 在衰老过程中骨骼肌质量和力量产生能力损失的潜在贡献者 和受损的SERCA功能可导致细胞溶质钙升高， 细胞过程我们假设增加SERCA活性以维持钙 稳态可能是治疗肌肉减少症有效机制。为了支持这一点，我们的 初步数据清楚地表明，用CDN 1163治疗2月龄Sod 1-/-小鼠， 别构SERCA激活剂，增加SERCA活性，减缓肌肉萎缩，提高力量 产生和减少肌肉线粒体ROS的产生，发生在未经处理的 Sod 1-/-小鼠。CDN 1163已报道对代谢和认知功能的有益作用， 但我们的研究是第一次测试它作为治疗干预的应用， 肌肉减少症在这个提议中，我们将测试SERCA激活可以 通过调节胞质钙信号传导预防/减少肌肉萎缩和无力， 线粒体功能和蛋白水解活性降低。首先，我们将定义剂量反应， 通过饮食在小鼠中口服施用CDN 1163的生物学效应。一旦我们 确定了最佳有效剂量，我们将继续研究我们令人兴奋的数据，并测试是否 CDN 1163治疗可以预防/减少年龄相关的肌肉质量损失和虚弱， Aim 2中的衰老野生型小鼠。将向雄性和雌性野生型C57 B16小鼠施用 CDN 1163从15个月大开始。我们将测量CDN 1163治疗对 调节细胞质钙信号，线粒体功能，收缩功能，减少 蛋白水解活性和其他肌肉减少症表型的基本标志物 月龄。SERCA活性也受内源性抑制剂肌磷脂（Sarcolipin，Sln）的调节。 我们的研究表明，在衰老过程中，肌磷脂在肌肉和Sod 1-/-小鼠中升高， 与降低的SERCA活性一致。在目标3中，我们将测试SERCA的激活是否 通过消耗SERCA抑制剂Sarcolipin调节衰老Sln-/-突变体中的肌肉减少症 小鼠我们将测量肌肉质量、肌肉质量、收缩功能和 在6、18和28个月大的雄性中， 雌性野生型和Sln-/-小鼠。如果肌磷脂消耗激活SERCA并调节肌肉 萎缩/虚弱，这将进一步支持使用SERCA激活剂作为治疗药物 干预总之，这些研究有很大的潜力揭示一种新的治疗方法， 干预以调节肌肉减少症。

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.