Implications of variation in Volume-Regulated Anion Channel composition

 描述（由申请人提供）：响应渗透压的细胞体积调节是体内每个细胞的基本功能。维持渗透平衡的一种充分表征的机制是通过体积调节阴离子通道（VRAC）释放Cl-。VRAC与许多病理生理学状况相关，特别是中风期间的缺血性脑损伤和水肿。正常的VRAC活性包括在细胞肿胀时释放兴奋性氨基酸（EAA）和牛磺酸。然而，在中风期间，这些化合物的释放有助于缺血诱导的脑损伤。一种特异性靶向神经元VRAC的治疗方法可能非常有价值。然而，直到最近，VRAC的身份仍然不明。我们的实验室已经确定了VRAC的一个重要组成部分，Swell 1（Leucine-rich-repeat-containing protein 8A，LRRC 8A）。虽然Swell 1是形成VRAC所必需的，但这是不够的; LRRC 8家族的其他四个成员中至少有一个必须存在才能正常的通道活动。考虑到对单个VRAC复合物有贡献的亚基的数量和种类目前是未知的，各种各样的VRAC组合物可以产生功能通道。LRRC 8亚基表达水平的组织特异性差异表明，VRAC亚基组成的知识可能允许神经元组织中VRAC的特异性治疗调节。使用先进的膜蛋白生物化学，脂质双层电生理学研究VRAC功能，和单粒子电子显微镜，以确定高分辨率的结构特征，我们将调查的假设，一个不同的VRAC复合物的集合存在，并有这些变化的结构和功能的后果，可以有针对性的治疗。

 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.