Bves Function in Cardiac Myogenesis

描述（申请人提供）：心肌细胞-心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），它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，对维持细胞间相互作用至关重要。此外，Bves是最早定位于细胞-细胞接触点的蛋白质之一。在心脏发育过程中，Bves首先在整个肌细胞膜周围出现，但后来局限于间插椎间盘。根据这些数据，我们预测Bves在心脏形态发生和椎间盘形成过程中调节粘附的级联事件中起着重要的早期作用。我们已经在蛋白质中发现了两个新的相互作用域，它们对Bves功能和潜在的心脏发育（包括嵌入椎间盘的产生）至关重要。首先，已经确定了一个调节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会消除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端与ZO1相互作用，ZO1是嵌入椎间盘的重要组成部分。利用分子和生理挑战，我们已经确定抑制Bves功能会破坏细胞膜上ZO1的稳定性并破坏细胞连接。根据这些数据，我们假设Bves在心脏发育过程中对心肌细胞粘附和间插椎间盘形成具有重要作用。三个相互作用的特异性目的将测试Bves-Bves胞内相互作用结构域和Bves-ZO1相互作用结构域在体内和体外心肌发生中的作用。在这些结构域突变的Bves转基因表达将决定蛋白在心源性上皮重塑、小梁形成、压实和间插椎间盘形成过程中的功能。很明显，异常的细胞粘附可导致严重的心脏缺陷，心脏畸形是胚胎发生中最大和最有害的畸形之一。确定胚胎肌细胞如何相互作用对了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控制心脏发育和功能。

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.