Bcl-2 & Branching Morphogenesis

描述（由申请人提供）：Bcl-2保护细胞免于由多种刺激（包括细胞粘附丧失）引发的细胞凋亡。缺乏bcl-2（bcl-2 -/-）的小鼠会发生肾发育不良/囊性发育不良，这是一种导致儿童显著发病率和死亡率的疾病。bcl-2的确切作用机制尚未阐明。我们的假设是，早期胚胎表达的bcl-2促进形态发生支持前体细胞的生存，使他们能够较少的粘附和迁移，而没有凋亡的威胁。Bcl-2可能通过与其他蛋白质如桩蛋白相互作用促进前体细胞的存活和/或在形态发生过程中发挥更“积极”的作用。我们的数据表明，桩蛋白相互作用的bcl-2 BH 4结构域在胚胎肾脏。bcl-2 BH 4结构域对于其细胞存活活性是足够的和必需的。BH 4结构域缺失的Bcl-2缺乏存活功能，但仍然与其他bcl-2家族成员强烈结合。我们将确定与bcl-2相互作用的桩蛋白的结构域及其对肾脏发育过程中细胞粘附机制的影响。我们的初步数据表明，输尿管芽（UB）分支形态发生在bcl-2 -/-小鼠受到不利影响。来自bcl-2 -/-小鼠的后肾在器官培养中经历了减少的UB分支，并且bcl-2 -/- UB细胞在胶原凝胶中未能经历分支形态发生。此外，野生型胚胎肾脏与bcl-2 BH 4结构域肽孵育表现出缺陷UB分支形态发生。我们将研究bcl-2在UB分支过程中所起的作用，以及异常UB分支是否有助于bcl-2 -/-小鼠后肾胚基的过度凋亡。我们将确定bcl-2 -/-小鼠的肾脏发育异常是否主要或完全是UB或后肾间充质中bcl-2缺失的结果。因此，了解bcl-2在肾发生过程中的正常功能及其与桩蛋白相互作用的后果，将为我们提供重要的洞察肾脏形态发生和发病机制。

DESCRIPTION (provided by applicant): Bcl-2 protects cells from apoptosis initiated by a variety of stimuli including loss of cell adhesion. Mice deficient in bcl-2 (bcl-2 -/-) develop renal hypoplastic/cystic dysplasia, a condition that leads to significant morbidity and mortality in children. The precise mechanism of action of bcl-2 has not been elucidated. Our hypothesis is that early embryonic expression of bcl-2 facilitates morphogenesis by supporting survival of precursor cells allowing them to be less adherent and migratory without the threat of apoptosis. Bcl-2 may facilitate survival of precursor cells and/or play a more "active" role during morphogenesis by interacting with other proteins such as paxillin. Our data demonstrate that paxillin interacts with the bcl-2 BH4 domain in embryonic kidneys. The bcl-2 BH4 domain is sufficient and necessary for its cell survival activity. Bcl-2 with the BH4 domain deleted lacks the survival function but still avidly binds to other bcl-2 family members. We will determine the domain(s) of paxillin that interact with bcl-2 and their influence on cell adhesive mechanisms during kidney development. Our preliminary data indicate that ureteric bud (UB) branching morphogenesis is adversely affected in bcl-2 -/- mice. Metanephroi from bcl-2 -/- mice undergo decreased UB branching in organ culture and bcl-2 -/- UB cells fail to undergo branching morphogenesis in collagen gels. Furthermore, wild-type embryonic kidneys incubated with bcl-2 BH4 domain peptide exhibit defective UB branching morphogenesis. We will investigate the role bcl-2 plays during UB branching and whether aberrant UB branching contributes to excessive apoptosis of the metanephric blastema in bcl-2 -/- mice. We will determine whether the abnormalities of renal development in bcl-2 -/- mice is primarily or exclusively the result of the absence of bcl-2 in the UB or metanephric mesenchyme. Therefore, understanding the normal functions of bcl-2 during nephrogenesis and the consequences of its interaction with paxillin will give us important insight into kidney morphogenesis and pathogenesis.