Bves Function in Cardiac Myogenesis

描述（由申请方提供）：肌细胞-肌细胞相互作用对心脏发育和功能至关重要。我们发现了一个新的跨膜蛋白家族（Bves/Popeye），具有高度保守的蛋白质序列。我们的工作表明，Bves作为细胞粘附分子，是维持细胞间相互作用所必需的。此外，Bves是第一个定位于细胞-细胞接触点的蛋白质之一。在心脏发育中，Bves首先在发育开始时存在于整个肌细胞膜周围，但后来仅限于闰盘。从这些数据中，我们预测，Bves起着重要的和早期的作用，在级联事件调节心脏形态发生过程中的粘附，并在光盘的生成。我们已经确定了两个新的相互作用结构域的蛋白质是至关重要的Bves功能和潜在的心脏发育，包括生成的闰盘。首先，已经定义了调节Bves-Bves细胞内相互作用的特定结构域。该结构域的缺失或突变消除了Bves-Bves相互作用，并导致细胞-细胞粘附的完全抑制。其次，我们发现Bves通过其C-末端与ZO 1相互作用，ZO 1是闰盘的重要组成部分。使用分子和生理学的挑战，我们已经确定，抑制Bves功能不稳定ZO 1在细胞膜和破坏细胞连接。根据这些数据，我们推测Bves在心脏发育过程中的肌细胞粘附和闰盘的形成中具有重要功能。三个相互作用的具体目标将测试Bves-Bves细胞内相互作用结构域和Bves-ZO 1相互作用结构域在体内和体外心肌发生过程中的作用。在这些结构域中突变的Bves的转基因表达将决定心源性上皮重塑、小梁形成、致密化和闰盘形成期间的蛋白质功能。很明显，异常的细胞粘附可导致严重的心脏缺陷，心脏畸形是胚胎发育中最大和最有害的异常之一。确定胚胎肌细胞如何相互作用对于理解心脏缺陷至关重要;在拟议的研究中，我们将阐明Bves在心脏形态发生和椎间盘形成中的功能，但在更大的意义上，确定肌细胞-肌细胞相互作用如何支配心脏发育和功能。

DESCRIPTION (provided by applicant): Myocyte-myocyte interaction is essential for heart development and function. We have discovered a novel family of transmembrane proteins (Bves/Popeye) that has a highly conserved protein sequence. Our work demonstrates that Bves acts as a cell adhesion molecule and is essential for maintenance of cell-cell interaction. Additionally, Bves is one of the first proteins to localize to points of cell-cell contact. In heart development, Bves is first present around the entire myocyte membrane at the onset of development but is later restricted to the intercalated disc. From these data, we predict that Bves plays an essential and early role in the cascade of events regulating adhesion during cardiac morphogenesis and in the generation of the disc. We have identified two novel interaction domains within the protein that are critical for Bves function and potentially for heart development including generation of the intercalated disc. First, a specific domain that regulates Bves-Bves intracellular interaction has been defined. Deletion or mutation of this domain abolishes Bves-Bves interaction and leads to complete inhibition of cell-cell adhesion. Second, we have discovered that Bves interacts through its C-terminus with ZO1, an essential component of the intercalated disc. Using molecular and physiological challenges, we have determined that inhibition of Bves function destabilizes ZO1 at the cell membrane and disrupts cell junctions. From these data, we hypothesize that Bves has essential functions in myocyte adhesion during heart development and in the formation of the intercalated disc. Three interactive specific aims will test the roles of the Bves-Bves intracellular interaction domain and Bves-ZO1 interaction domain during cardiac myogenesis in vivo and in vitro. Transgenic expression of Bves mutated in these domains will determine protein function during remodeling of cardiogenic epithelium, trabeculation, compaction and formation of the intercalated disc. It is clear that aberrant cell adhesion can lead to severe heart defects and that malformation of the heart represents one of the largest and most deleterious groups of abnormalities in embryogenesis. Determining how embryonic myocytes interact is essential in understanding heart defect; in the proposed studies, we will elucidate Bves function in cardiac morphogenesis and disc formation but, in a larger sense, determine how myocyte- myocyte interaction governs heart development and function.