Bcl-2 & Branching Morphogenesis

描述(由申请人提供)：bcl2保护细胞免受各种刺激引起的细胞凋亡，包括细胞粘附性丧失。Bcl2基因缺陷的小鼠(bcl2-/-)会发展成肾脏发育不良/囊性发育不良，这种情况会导致儿童的显著发病率和死亡率。Bcl2的确切作用机制尚未阐明。我们的假设是，早期胚胎中bcl2的表达通过支持前体细胞的存活来促进形态发生，使它们更少地黏附和迁移，而不会受到细胞凋亡的威胁。Bcl-2可能通过与其他蛋白质如paxlin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，在胚胎肾脏中，巴西林与bcl2BH4结构域相互作用。BCL-2BH4结构域是其细胞生存活动的充分和必要的结构域。缺失BH4结构域的BCL-2缺乏生存功能，但仍能与其他BCL-2家族成员强烈结合。我们将确定与bcl2相互作用的巴西林结构域(S)以及它们在肾脏发育过程中对细胞黏附机制的影响。我们的初步数据表明，bcl2-/-小鼠的输尿管芽(UB)分支形态发生受到不利影响。BCL-2-/-小鼠的后肾在器官培养中UB分支减少，BCL-2-/-UB细胞不能在胶原胶中发生分支形态发生。此外，bcl2BH4结构域肽孵育的野生型胚胎肾脏显示出缺陷的UB分支形态发生。我们将研究BCL-2在UB分支中的作用，以及UB分支异常是否导致BCL-2-/-小鼠后肾胚泡过度凋亡。我们将确定bcl2-/-小鼠的肾脏发育异常是主要还是完全由于后肾间充质中缺乏bcl2所致。因此，了解bcl2在肾脏形成过程中的正常功能及其与巴西林相互作用的后果，将对我们深入了解肾脏的形态发生和发病机制具有重要意义。

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.