Role of Calcium Channels in Aging Skeletal Muscle

描述（由申请人提供）：本提案旨在建立维克森林大学健康科学PI Osvaldo Delbono博士和阿根廷国立拉普拉塔大学Claudia Hereqz博士之间的合作，作为R 01 AG 013934 -12（PI：O. Delbono），专注于老化的骨骼肌。这项研究将主要在拉普拉塔国立大学进行。该项目的长期目标是阐明骨骼肌性能随年龄增长而下降的细胞和分子机制。该FIRCA项目通过探索（1）二氢吡啶受体（DHPR）11亚基和21 a亚基相互作用的替代途径以及（2）21上调是否会导致11 a随着衰老而下调来扩展和丰富母基金。具体来说，我们的目标是确定是否持续表达DHPR 11 S或防止21 a内源性过表达改善电压门控SR Ca 2+释放，因此，在老化骨骼肌的比力。我们将调查替代机制，在父母资助研究和使用创新的分子工具，不仅为这个项目，但骨骼肌生理学和病理学领域的一般。FIRCA提案的具体目标是：目标1。为了确定持续的DHPR 21 a过表达是否通过与发动蛋白（一种参与受体介导的内吞作用的GTP酶）结合而导致DHPR 11亚基的表达降低。该系统是否在骨骼肌中起作用，特别是在21 a亚基内源性过表达而11亚基下调的衰老肌肉中，尚不清楚。过表达病毒介导的21 a亚基将回答21 a是否导致来自年轻小鼠的肌肉和基因缺陷和2-null肌细胞中DHPR 11亚基的下调。我们还将确定DHPR 11亚基的长期均匀表达是否能阻止衰老小鼠中21 a介导的内吞作用。 目标二。确定肌肉IGF-1过表达是否阻止衰老骨骼肌中年龄依赖性21 a过表达，并因此阻止21 a依赖性11亚基下调和兴奋-收缩解偶联（ECU）。这些实验将检验IGF-1在DHPR 21 a亚基表达和ECU随衰老中起主要作用的假设。使用转基因和IGF-1病毒载体靶向骨骼肌将使我们能够检查IGF-1和11/21 a表达之间的关系。 公共卫生相关性：在包括人类在内的几种哺乳动物物种中，已报告了与年龄相关的绝对和特定肌肉收缩力下降。发展中国家阿根廷2005年的全国人口普查显示，65岁以上人口占总人口的10.1%，与美国的12.1%相似。这两个国家的老年病中心的激增证明，越来越需要支持越来越多的老年人，他们有可能失去或已经失去独立性。尽管肌肉力量在预防老年人残疾方面的重要性，但对此负责的生物学机制仅部分了解。该FIRCA提案旨在建立维克森林大学健康科学PI博士Osvaldo Delbono和阿根廷国立拉普拉塔大学Claudia Hereqz博士之间的合作，以阐明骨骼肌性能随年龄增长而下降的细胞和分子机制。

DESCRIPTION (provided by applicant): This proposal aims to establish a collaboration between PI Dr. Osvaldo Delbono at Wake Forest University Health Sciences, NC, and Dr. Claudia Hereqz at the National University of La Plata, Argentina, as an extension of R01AG013934-12 (PI: O. Delbono), which focuses on aging skeletal muscle. This research will be done primarily at the National University of La Plata. This project's long- term goal is to elucidate the cellular and molecular mechanisms responsible for the decline in skeletal muscle performance with aging. This FIRCA project extends and enriches the parent grant by enabling exploration of (1) alternative pathways for dihydropyridine receptor (DHPR)11subunit and 21a subunit interaction and (2) whether 21 upregulation causes 11a downregulation with aging. Specifically, we aim to determine whether sustained expression of DHPR11S or preventing 21a endogenous overexpression improves voltage-gated SR Ca2+ release and, consequently, specific force in aging skeletal muscle. We will investigate alternative mechanisms to those studied in the parent grant and use molecular tools that are innovative, not only for this project, but for the field of skeletal muscle physiology and pathology generally. The specific aims of the FIRCA proposal are: Aim 1. To determine whether sustained DHPR 21a overexpression results in decreased expression of the DHPR11 subunit by association with dynamin, a GTPase involved in receptor- mediated endocytosis. Whether this system operates in skeletal muscle, particularly aging muscle in which the 21a subunit is endogenously over expressed and 11 is down regulated, is not known. Over-expressing the viral-mediated 21a subunit will answer whether 21a leads to downregulation of the DHPR11 subunit in muscles from young mice and dysgenic and 2-null muscle cells. We will also determine whether prolonged, homogeneous expression of the DHPR11 subunit prevents 21a-mediated endocytosis in senescent mice. Aim 2. To determine whether muscle IGF-1 overexpression prevents age-dependent 21a over- expression and, consequently, 21a-dependent 11 subunit downregulation and excitation-contraction uncoupling (ECU) in aging skeletal muscle. These experiments will test the hypothesis that IGF-1 plays a major role in DHPR 21a subunit expression and ECU with aging. The use of transgenic and IGF-1 viral vectors targeted to skeletal muscle will allow us to examine the relationship between IGF-1 and 11/21a expression. PUBLIC HEALTH RELEVANCE: The age-related decline in absolute and specific muscle contractile force has been reported in several mammalian species, including humans. The 2005 national census in Argentina, a developing country, showed that those 65 years or older comprise 10.1% of the population, similar to the 12.1% in the United States. The proliferation of geriatric centers in both countries attests to the increasing need to support the growing population of elders who are at risk of losing or have lost their independence. Despite the importance of muscle strength in preventing disability in the elderly, the biological mechanisms responsible are only partially understood. This FIRCA proposal aims to establish collaboration between PI Dr. Osvaldo Delbono at Wake Forest University Health Sciences, NC, and Dr. Claudia Hereqz at the National University of La Plata, Argentina to elucidate the cellular and molecular mechanisms responsible for the decline in skeletal muscle performance with aging.