Analysis of Neural Crest Cells in the Cx43 Knockout Mouse

Cx43缝隙连接在心脏形态发生中起着不可或缺的作用，因为Cx43缝隙连接缺失突变或敲除小鼠出生时死于涉及右室流出道的心脏缺陷(Reaumeet al.，1995)。使用转基因小鼠模型来操纵Cx43的功能，Lo博士已经确定在心脏形态发生中对Cx43缝隙连接的要求涉及心脏神经脊细胞(Ewart等人，1997；Sullivan等人，1998)。她的研究表明，Cx43缝隙连接通讯调节神经脊细胞的迁移。在下一个基金阶段，她建议研究一种假说，即在Crest细胞中，由生长因子/整合素信号触发的信号转导级联产生第二信使，该第二信使通过Cx43缝隙连接通道动员，通过这种方式，缝隙连接通信可能有助于调节和协调心脏神经脊细胞的迁移。在目标1中，她将表征心脏冠状细胞生长因子刺激和基质结合的体外迁移行为，并确定缝隙连接通讯是否会随着冠状细胞迁移的变化而改变。在目标2中，她将研究缝隙连接通讯水平的变化是否会影响生长因子/整合素信号和心脊细胞的迁移。在目标3中，她将使用基因敲除小鼠模型进一步研究Cx43缝隙连接在胚胎发育中心脏神经脊细胞介导内皮素/PDGF信号转导中的作用。在这些研究中，她将携带内皮素受体A(ET-A)或血小板衍生生长因子a受体(PDGFaR)基因敲除等位基因的小鼠与Cx43基因敲除小鼠进行杂交。如果缝隙连接通讯在心肌细胞的内皮素或PDGF信号传导中起作用，那么Cx43功能降低和PDGFaR或ET-A受体功能降低的复合杂合子动物可能会表现出与纯合子敲除动物相似的心脏缺陷。最终，这些研究将为鉴定穿过缝隙连接通道的信号分子铺平道路，从而有助于在分子水平上阐明缝隙连接在神经脊迁移中的作用。

Cx43 gap junctions play an indispensible role in cardiac morphogenesis, asnull mutant or knockout mice deficient in Cx43 gap junctions die at birthfrom cardiac defects involving the right ventricular outflow tract (Reaumeet al., 1995). Using transgenic mouse models to manipulate Cx43 function,Dr. Lo has determined that the requirement for Cx43 gap junctions in heartmorphogenesis involves the cardiac neural crest cells (Ewart et al., 1997;Sullivan et al., 1998). Her studies indicated that Cx43 gap junctioncommunication modulates neural crest cell migration. In the next fundingperiod, she proposes to investigate the HYPOTHESIS that in crest cells,signal transduction cascades triggered by growth factor/integrin signalinggenerate second messengers that are mobilized through Cx43 gap junctionchannels, and in this manner, gap junction communication may help regulateand coordinate the migration of cardiac neural crest cells. In Aim 1, shewill characterize the in vitro migratory behavior of cardiac crest cellsupon growth factor stimulation and matrix binding, and determine whethergap junction communication may be altered in parallel with changes in crestcell migration. In Aim 2, she will examine whether changes in the level ofgap junction communication may affect growth factor/integrin signaling andthe migration of cardiac crest cells. In Aim 3, she will use knockout mousemodels to further examine the role of Cx43 gap junctions in mediatingendothelin/PDGF signaling in cardiac neural crest cells in the developingembryo. For these studies, she will intercross mice harboring the endothelinreceptor A (ET-A) or platelet derived growth factor a receptor (PDGFaR)knockout alleles with the Cx43 knockout mice. If gap junctioncommunication has a role in endothelin or PDGF signaling in cardiac crestcells, then compound heterozygous animals with a decrease in Cx43 functionand a decrease in PDGFaR or ET-A receptor function may exhibit cardiacdefects similar to those found in the homozygous knockout animals.Ultimately these studies should pave the way towards the identification ofthe signaling molecules traversing through gap junctional channels, andthus help elucidate on the molecular level, the role of gap junctions inneural crest migration.