Examining protein interactions that stabilize the structure and function of SERCA pumps in muscle

我们身体中的肌肉细胞经常暴露于各种应激条件下，如热或氧化应激，或与各种疾病如肌肉萎缩症有关。当肌肉细胞暴露于压力时，细胞内的钙水平增加，并且据信细胞损伤甚至细胞死亡将由于细胞钙的增加而发生。压力下钙增加的一个主要原因是负责维持肌肉中正常钙水平的酶，即钙泵，在压力下受损。因此，可以预期，如果钙泵能够以某种方式得到保护，那么应激后细胞损伤将减少，存活率将增加。我们已经通过我们的研究确定了体内天然存在的蛋白质，称为热休克蛋白70（Hsp 70），可以在热应激期间保护肌肉中的钙泵;然而，我们还没有弄清楚这是如何工作的，或者其他蛋白质通常在肌肉中也可以保护钙泵。该研究计划的一个主要长期目标是了解Hsp 70和其他两种称为受磷蛋白（PLN）和肌磷脂（SLN）的肌肉蛋白如何在健康和患病肌肉的广泛条件下与钙泵相互作用并保护钙泵。为此，我们将使用转基因小鼠，这些小鼠要么具有高于正常肌肉水平的这些蛋白质之一（Hsp 70），要么完全缺乏蛋白质。（PLN和/或SLN），我们将使肌肉组织暴露于各种类型的应力（即热，低氧，氧化应激），以确定是否，以及如何，热休克蛋白70，PLN和SLN可以在这些条件下保护钙泵并保持肌肉功能。这项工作的第二个主要目标是了解PLN和SLN如何控制钙泵和肌肉收缩性能，从休息过渡到运动条件。在肌肉收缩开始的一秒钟内，骨骼肌的力产生和松弛诱导特性都有增强，但所涉及的机制还不完全清楚。我们将使用转基因小鼠来测试PLN和SLN在骨骼肌的这些经典特性中发挥重要作用的假设。总的来说，这项基础研究将更好地了解肌肉中钙泵的复杂调节以及在压力期间保护这些重要肌肉酶的结构和功能的细胞机制。这项工作可能具有重要的意义，可以扩展到许多领域（即癌症和心脏病研究），因为保护钙泵可以防止钙的增加，并改善压力和某些疾病后的细胞存活率。

Muscle cells in our body are often exposed to a variety of stressful conditions such as heat or oxidative stress or in association with a variety of diseases such as muscular dystrophy. When muscle cells are exposed to stress, the calcium level inside the cells increases and it is believed that cell damage and even cell death will occur as a result of the increased cellular calcium. One major reason for the increase in calcium with stress is that the enzyme responsible for maintaining normal calcium levels in muscle, namely the calcium pump, becomes damaged with stress. Therefore, it would be expected that cell damage would be reduced and survival would be increased after stress if the calcium pump could somehow be protected. We have established through our research that a naturally occurring protein in the body, called heat shock protein 70 (Hsp70), can protect the calcium pump in muscle during heat stress; however, we haven't figured out exactly how this works yet or whether other proteins normally found in muscle might also protect the calcium pump. One major, long-term objective of this program of research is to understand how Hsp70 and two other muscle proteins called phospholamban (PLN) and sarcolipin (SLN), interact with and protect the calcium pump under a wide range of conditions in both healthy and diseased muscle. For this objective, we will use genetically modified mice that either have higher than normal muscle levels of one of these proteins (Hsp70) or completely lack the protein(s) (PLN and/or SLN) and we will expose the muscle tissues to various types of stress (i.e. heat, low oxygen, oxidative stress) to determine if, and how, Hsp70, PLN and SLN can protect the calcium pump and preserve muscle function under those conditions. A second major objective this work addresses is understanding how PLN and SLN control calcium pumps and muscle contractile properties during transitions from rest to exercising conditions. Within one second of the onset of muscle contraction there are enhancements in both force producing and relaxation inducing properties of skeletal muscle but the mechanisms involved are not completely understood. We will use genetically modified mice to test the hypotheses that PLN and SLN play an important role in these classic properties of skeletal muscle. Overall, this basic research will build better understanding of the complex regulation of calcium pumps in muscle and the cellular mechanisms that exist to protect the structure and function of these vital muscle enzymes during stress. This work could have important implications that extend into a number of fields (i.e. cancer and heart disease research) because protecting the calcium pump could prevent increases in calcium and improve cell survival following stress and in certain diseases.