Investigating the angiogenic role of Murine Double Minute-2 in contractile muscle cells

毛细血管是我们最小的血管。它们是血液和细胞交换的场所。在骨骼肌中，毛细血管在为活跃的肌肉细胞提供氧气和营养方面起着至关重要的作用。血管生成是新毛细血管形成的一个非常复杂的过程。众所周知，体育锻炼可以刺激骨骼肌血管生成。单次运动刺激调节肌肉血管生成过程的信号分子的表达。特别是，这些分子作用于内皮细胞，即形成毛细血管壁的细胞。为了获得更多的毛细血管，这些细胞需要被激活，这样它们才能增殖、迁移，并聚集在一起形成新的血管。如果在几个星期内每天重复运动刺激，如在长时间的运动训练中，骨骼肌中会形成新的功能性毛细血管，肌肉功能，特别是对运动的反应会得到改善。******我实验室的研究旨在识别和理解骨骼肌血管生成的细胞和分子机制。******在我之前的NSERC发现资助下，我们已经证明了一种名为小鼠Minute Double-2 （Mdm2）的分子是运动过程中肌肉血管生成的关键调节剂。我们观察到，运动可以强烈激活骨骼肌中的Mdm2。在肌肉组织水平上，我们已经证明，在运动过程中，激活Mdm2刺激了几种已知的激活内皮细胞的分子的表达。通过体外内皮细胞培养，我们发现活化的Mdm2强烈刺激了这些细胞的迁移，这是内皮细胞组装形成新毛细血管的关键步骤。本研究在肌肉组织水平和培养的内皮细胞中进行。在这里提出的研究计划中，我们的目标将集中在Mdm2在收缩肌肉细胞水平上对血管生成的作用。我们认为运动可以刺激肌肉细胞中Mdm2的激活，导致信号分子的产生和释放，这些信号分子反过来作用于邻近的内皮细胞，刺激新毛细血管的形成。******这将通过三个独立的研究目标来实现。* * * * * *目标# 1。研究运动对体内肌肉组织和体外培养肌肉细胞中Mdm2及其激活形态的影响。* * * * * * # 2为目标。目的：探讨Mdm2在体外培养肌肉细胞中的作用机制及其活化形式。* * * * * *目标# 3。为了研究体内肌肉组织，特别是在整个肌肉细胞水平上，Mdm2的作用机制及其激活形式是什么。******我们的研究计划将提供肌肉生理学和Mdm2生物学领域的新知识。这也将有助于在加拿大形成高素质人才。

Capillaries are our smallest blood vessels. They are the site of exchanges between blood and cells. In skeletal muscles, capillaries play a crucial role in providing oxygen and nutrients to the active muscle cells. Angiogenesis is the very complex process of formation of new capillaries. Physical exercise is a well-known stimulus for skeletal muscle angiogenesis. One single bout of exercise stimulates the expression of signal molecules that regulate the process of muscle angiogenesis. In particular, these molecules act on endothelial cells, the cells forming the wall of the capillaries. In order to get more capillaries, these cells need to be activated so they can proliferate, migrate, and assembly together into new vessels. If the exercise stimulus is repeated daily over a few weeks, like during prolonged exercise training, new functional capillaries will be formed in skeletal muscle, and the muscle function, especially in response to exercise, will be improved. ******Research in my laboratory aims to identify and to understand the cellular and molecular mechanisms that regulate angiogenesis in skeletal muscle.******With my previous NSERC Discovery Grant, we have demonstrated that a molecule named Murine Minute Double-2 (Mdm2) was a key regulator of muscle angiogenesis during exercise. We have observed that exercise strongly activates Mdm2 in skeletal muscle. At the level of the muscle tissue, we have shown that activated Mdm2 was stimulating the expression of several molecules known to activate endothelial cells during exercise. Using endothelial cell culture in vitro, we have then discovered that activated Mdm2 was strongly stimulating the migration of these cells, which is a crucial step in the assembly of endothelial cells to form new capillaries. This research was conducted at the muscle tissue level and in cultured endothelial cells. In the the research program proposed here, our goal will be to focus on the role that Mdm2 could play on angiogenesis specifically at the level of contractile muscle cells. We think that exercise could stimulate Mdm2 activation in muscle cells, leading to the production and release of signal molecules that will in turn act on the neighbouring endothelial cells to stimulate the formation of new capillaries. ******This will be achieved through three independent research aims.******Aim #1. To characterize in vivo in muscle tissue and in vitro in cultured muscle cells the effect of exercise on Mdm2 and its activated form. ******Aim #2. To investigate in vitro in cultured muscle cells what is the mechanism of action of Mdm2 and its activated form.******Aim #3. To investigate in vivo in muscle tissue, specifically at the level of muscle cells taken into the whole muscle context, what is the mechanism of action of Mdm2 and its activated form.******Our research program will provide new knowledge in the field of muscle physiology and Mdm2 biology. It will also contribute to the formation of Highly Qualified Personal in Canada.