Bves Function in Cardiac Myogenesis

描述(由申请人提供)：心肌细胞-心肌细胞的相互作用对心脏发育和功能是必不可少的。我们发现了一个新的跨膜蛋白家族(BVES/Popye)，它具有高度保守的蛋白质序列。我们的工作表明，BVES作为一种细胞黏附分子，对于维持细胞间的相互作用是必不可少的。此外，BVES是最早定位于细胞-细胞接触点的蛋白质之一。在心脏发育中，BVES在发育初期首先存在于整个心肌细胞膜周围，但后来仅限于间盘。根据这些数据，我们预测BVES在心脏形态形成和椎间盘形成过程中调节黏附的一系列事件中发挥着重要的早期作用。我们已经确定了蛋白质中的两个新的相互作用结构域，它们对BVES功能和潜在的心脏发育至关重要，包括插入盘的产生。首先，已经定义了调控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取消BVES-BVES相互作用，导致细胞与细胞间黏附的完全抑制。其次，我们发现BVES通过其C末端与ZO1相互作用，ZO1是插入盘的一个重要成分。利用分子和生理挑战，我们已经确定，BVES功能的抑制会破坏细胞膜上的ZO1的稳定，并破坏细胞连接。根据这些数据，我们假设BVES在心脏发育过程中的心肌细胞黏附和间盘的形成中具有重要的功能。三个相互作用的特异性靶点将测试BVES-BVES细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形成过程中的作用。在这些区域突变的BVES的转基因表达将决定心源性上皮重塑、小梁形成、致密和间盘形成过程中的蛋白质功能。很明显，异常的细胞黏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组之一。确定胚胎心肌细胞如何相互作用对于理解心脏缺陷是至关重要的；在拟议的研究中，我们将阐明BVES在心脏形态发生和盘形成中的功能，但在更广泛的意义上，确定心肌细胞-心肌细胞相互作用如何调控心脏发育和功能。

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.