Circadian Clock and Muscle Health

我们已经证明，通过核心时钟基因的丢失， Bmal 1足以诱导显著的肌肉无力，并且令人惊讶地，增加死亡率。基于 这些发现，这项赠款的总体目标是追求的作用的基本理解， 肌肉生物钟在调节基因表达的日常程序，以及时钟中断如何导致 严重的肌肉无力和全身健康下降。 我们发现MyoD 1可以调节核心时钟基因的表达，Bmal 1使其成为真正的组织， 特异性生物钟调节剂1.我们还确定MyoD 1和CLOCK：BMAL 1共享峰值 在肌肉基因组中超过3000个位点上结合。这些新发现为我们的研究提供了支持， 将MyoD 1调节时钟机制的网络属性的机制定义为 以及了解MyoD 1作为生物钟辅助因子在日常基因组和转录组中的作用。 成人肌肉中的景观。 在MyoD 1和时钟因子的下游，我的实验室已经确定了两个肌肉特异性基因，Rbm 20和 我们建议将生物钟紊乱与肌肉无力联系起来。肌肉Bmal 1的损失，导致显著的 Rbm 20和Tcap表达减少，我们发现肌节结构的变化，包括 肌节长度、M和Z线扭曲以及肌丝方向改变。最后，全局Bmal 1 基因敲除小鼠Bmal 1 KO已被用作晚期衰老的模型，因为它表现出显著的类衰老 病理学，中位寿命为37周。在使用这种全局Bmal 1 KO的初步实验中， 我们使用具有肌肉特异性启动子的AAV载体拯救了小鼠骨骼肌中的Bmal 1。我们发现 这足以显着提高肌肉力量，但也显着延长寿命。这些 补充了我们的研究结果，即随着肌肉Bmal的丧失，死亡率增加1，并证明， 仅在骨骼肌中拯救Bmal 1改善全身健康。此外，随着衰老和许多慢性 这些结果表明，针对肌肉时钟机制， 作为一种翻译策略有潜力。我们建议测试以下三个具体目标： 具体目标1：定义MyoD 1在核心时钟机制中的作用，并作为日常生活的辅助因素。 骨骼肌中的转录组景观。 具体目标2：测试时钟控制基因Rbm 20和/或Tcap在肌节结构中的作用 和肌肉功能。 具体目标3：确定Bmal 1中延长寿命所需的骨骼肌特异性变化 KO小鼠。

We have shown that disruption of the muscle circadian clock mechanism through loss of the core clock gene, Bmal1, is sufficient to induce significant muscle weakness and surprisingly, increased mortality. Based on these findings, the overall objective of this grant is to pursue the fundamental understanding of the role of the muscle circadian clock in regulating a daily program of gene expression and how clock disruption leads to significant muscle weakness and diminished systemic health. We found that MyoD1 can modulate expression of the core clock gene, Bmal1 making it a bona fide tissue- specific circadian clock modifier1. We have also determined that MyoD1 and CLOCK:BMAL1 share peak binding at over 3000 sites across the muscle genome. These new findings provide support for our studies to define the mechanism(s) through which MyoD1 modulates the network properties of the clock mechanism as well as understanding the role of MyoD1 as a clock co-factor in the daily genomic and transcriptomic landscape in adult muscle. Downstream from MyoD1 and the clock factors, my lab has identified two muscle specific genes, Rbm20 and Tcap, that we propose link clock disruption with muscle weakness. Loss of muscle Bmal1, results in significant decreases in Rbm20 and Tcap expression and we find changes in sarcomere structure including variability of sarcomere length, distortions in M and Z lines and altered myofilament orientation. Lastly, the global Bmal1 knock out mouse, Bmal1KO, has been used as a model of advanced aging as it exhibits significant aging-like pathologies and has a median lifespan of 37wks. In preliminary experiments using this global Bmal1 KO mouse we rescued Bmal1 in skeletal muscles using an AAV vector with a muscle specific promoter. We found that this was sufficient to significantly improve muscle strength but also significantly extended lifespan. These are complementary to our findings of increased mortality with loss of muscle Bmal1 and demonstrate that rescuing Bmal1 only in skeletal muscle improves systemic health. In addition, with aging and many chronic diseases exhibiting muscle clock disruption, these results suggest that targeting the muscle clock mechanism holds potential as a translational strategy. We propose to test the following three specific aims: Specific Aim 1: To define the roles of MyoD1 within the core clock mechanism and as a co-factor for the daily transcriptomic landscape in skeletal muscle. Specific Aim 2: To test the clock controlled genes, Rbm20 and/or Tcap, for their roles in sarcomere structure and muscle function. Specific Aim 3: To determine the skeletal muscle specific changes required for improved lifespan in the Bmal1 KO mouse.