Implications of variation in Volume-Regulated Anion Channel composition

 描述(由申请人提供)：调节细胞体积以应对渗透压力是体内每个细胞的基本功能。维持渗透平衡的一个很好的机制是通过体积调节阴离子通道(Vrac)释放氯离子。Vrac与许多病理生理状况有关，尤其是卒中时的缺血性脑损伤和水肿。正常的vrac活性包括在细胞膨胀时释放兴奋性氨基酸(EaaS)和牛磺酸。然而，在中风期间，这些化合物的释放会导致脑缺血引起的脑损伤。一种专门针对神经元vrac的治疗方法可能非常有价值。然而，直到最近，vrac的身份还不得而知。我们的实验室已经鉴定出vrac的一个重要成分Swell1(富含亮氨酸重复序列的蛋白8A，LRRC8A)。虽然Swell1是形成vrac所必需的，但这是不够的；LRRC8家族的其他四个成员中至少必须有一个存在才能正常的通道活动。鉴于目前尚不清楚构成单个vrac复合体的亚基的数量和种类，大量的vrac组合物可能会产生功能通道。LRRC8亚单位表达水平的组织特异性差异表明，了解vrac亚单位组成可能有助于在神经元组织中对vrac进行特定的治疗调节。我们将利用先进的膜蛋白生物化学、脂质双层电生理学来研究vrac的功能，并利用单粒子电子显微镜来确定高分辨率的结构特征，我们将探讨存在一组不同的vrac复合体的假设，以及这些变异所产生的结构和功能后果，可以作为治疗的靶点。

 DESCRIPTION (provided by applicant): Regulation of cell volume in response to osmotic stress is an essential function of every cell in the body. One well-characterized mechanism for maintaining osmotic balance is the release of Cl- via the Volume-Regulated Anion Channel (VRAC). VRAC is linked to many pathophysiological conditions, in particular, ischemic brain damage and edema during stroke. Normal VRAC activity includes the release of excitatory amino acids (EAAs) and taurine upon cell swelling. However, during a stroke, the release of these compounds contributes to ischemic-induced brain damage. A therapeutic approach that specifically targets neuronal VRAC could be extremely valuable. However, until recently, the identity of VRAC was unknown. Our lab has identified an essential component of VRAC, Swell1 (Leucine-rich-repeat-containing protein 8A, LRRC8A). Although Swell1 is necessary to form VRAC, it is not sufficient; at least one of the other four members of LRRC8 family must be present for normal channel activity. Given that the number and variety of subunits contributing to individual VRAC complexes is currently unknown, a large variety of VRAC compositions may yield functional channels. Tissue-specific differences in LRRC8 subunit expression levels suggest that knowledge of VRAC subunit composition might allow specific therapeutic modulation of VRAC in neuronal tissue. Using advanced membrane protein biochemistry, lipid bilayer electrophysiology to study VRAC function, and single-particle electron microscopy to determine high- resolution structural characteristics, we will investigate the hypothesis that a diverse set of VRAC complexes exist and there are the structural and functional consequences of these variations that could be targeted therapeutically.