A novel G protein signaling pathway controlling Drosophila cardiac morphogenesis

描述(申请人提供)：参与心脏形成的早期形态发生机制在进化上是保守的。为了确定新的致心基因，我们对果蝇进行了大规模的遗传筛查。我们发现了一种独特的心脏缺陷，称为心碎(Bro)，心包细胞和成心细胞分离，导致心功能丧失和胚胎死亡。这种表型是由于甲氧丙酸途径中HMG-CoA还原酶及其下游酶编码基因的突变，以及香叶基香叶化的G蛋白G31的突变，从而代表了异戊二烯生物合成的终点。鉴定C在心脏形态发生中的重要作用为发现心脏形态发生所需的整个G蛋白遗传途径打开了大门。在这里，我们将研究G31的作用机制，并确定与G31形成心脏异源三聚体G蛋白复合体的G1和G2伙伴。从我们的筛选中，我们还鉴定了参与这一过程的两个G蛋白偶联受体(GPCRs)。我们将利用我们在初步研究中建立的心肌细胞类型特异性救援系统来研究这些GPCRs的作用。我们的筛查还发现了两个BRO突变，破坏了编码间隔连接成分的基因，表明间隔连接的形成参与了心脏的形态发生。我们将用电子显微镜描述果蝇心脏的细胞-细胞连接，并研究分隔连接蛋白在心脏发育中的作用。我们还将研究G蛋白信号突变如何影响心脏中隔连接的形成。这些研究将填补心脏发育研究领域的一个重大空白，促进我们对先天性心脏病分子机制的理解。 叙述：心脏发育由进化上保守的遗传网络控制。为了确定这个网络中的基因，我们对果蝇进行了大规模的遗传筛选，并确定了一组高度保守的心脏形成所需的基因。对这些基因的研究促进了我们对心脏发育和先天性心脏病机制的了解。

DESCRIPTION (provided by applicant): The early morphogenetic mechanisms involved in heart formation are evolutionarily conserved. To identify novel cardiogenic genes, we performed a large-scale genetic screen in Drosophila. We discovered a unique cardiac defect, called broken hearted (bro), in which pericardial cells and cardioblasts dissociate, causing loss of cardiac function and embryonic lethality. This phenotype resulted from mutations in genes encoding HMG-CoA reductase and its downstream enzymes in the mevalonate pathway, as well as G protein G31, which is geranylgeranylated, thus representing an end point of isoprenoid biosynthesis. Identification of the essential role of C in cardiac morphogenesis opened a door to discovery of the entire G protein genetic pathway required for cardiac morphogenesis. Here, we will investigate the functional mechanism of G31, and identify the G1 and G2 partners that form the cardiac heterotrimeric G protein complex with G31. From our screen, we also identified two G-protein coupled receptors (GPCRs) involved in this process. We will investigate the roles of these GPCRs using cardiac cell type specific rescue system established in our preliminary studies. Our screen also identified two bro mutations disrupting genes encoding septate junction components, indicating that septate junction formation is involved in cardiac morphogenesis. We will characterize the cell-cell junctions of Drosophila heart using electron microscopy and study the role of septate junction proteins during heart development. We will also examine how the G protein signaling mutants affect septate junction formation in the heart. These studies will fill a significant gap in the research field of heart development, and promote our understanding of the molecular mechanism of congenital heart disease. Narrative: Heart development is controlled by evolutionarily conserved genetic network. To identify genes in this network, we performed a large-scale genetic screen in Drosophila and identified a group of highly conserved genes required for heart formation. Studies of these genes promote our understanding of heart development and mechanism of congenital heart disease.