INTEGRINS IN KIDNEY MORPHOGENESIS

在肾脏的发育和损伤后的恢复过程中， 形态发生的一个步骤是肾小管上皮细胞的极化。 肾上皮细胞的极化依赖于 细胞和细胞外基质，以及细胞-细胞接触。虽然 负责将这些粘附事件转换成 形态发生信号是未知的，主要候选者是整合素， 细胞粘附分子超家族。已知整合素是 多种细胞外基质蛋白的受体， 与肌动蛋白细胞骨架结合。最近人们认识到， 它们也参与细胞-细胞相互作用。其他信息 表明整合素可能影响细胞分化， 扩散，可能通过产生第二信使。最近 有证据表明，整合素的特征性表达是， 不同的肾单位节段，并可能在发育过程中发挥关键作用， 凝聚的间充质的极化。整合素也可以是 急性肾衰竭病理生理学中的重要因素。在这 项目整合素参与上皮极化将是 使用互补的体外和体内方法进行研究。的 MDCK细胞表达的整合素的功能将用 细胞粘附试验和免疫细胞化学及生物化学技术 使用亚单位特异性单克隆抗体和多克隆抗体以及cDNA 探针（特定目标1A）。整合素的表达、分布、活化， 在极化过程中， 在不同基质上培养的细胞， 细胞-细胞接触（特异性目标1B）。干扰整合素的作用 MDCK细胞极性的功能将被研究， 干扰整联蛋白配体结合的抗体， 整合素cDNA和反义构建体在MDCK细胞中的表达。（具体目标） lC）。整合素在肾脏分化过程中的功能将是 在小鼠胚胎、整个器官培养物和转移培养物中进行了研究， 使用封闭抗体和反义构建体的肾原基 （具体目标2A）。再生过程中整合素表达的改变 将在通过夹闭所述细胞而使小鼠肾脏缺血的小鼠肾脏中检查体内的 肾动脉（特定目标2B）。从长远来看， 实验将提供重要的信息， 细胞介导肾极化的相互作用 粘连这些研究也将帮助我们了解肾脏是如何 上皮发育并从损伤中恢复。

In the development of the kidney and in its recovery from injury, a key step in morphogenesis is polarization of the tubule epithelial cells. Polarization of kidney epithelial cells depends on interactions between cells and the extracellular matrix, and on cell-cell contacts. Although the molecules responsible for transducing these adhesive events into morphogenetic signals are unknown, prime candidates are the integrins, a superfamily of cell adhesion molecules. Integrins are known to be receptors for a variety of extracellular matrix proteins and to associate with the actin cytoskeleton. More recently it has been recognized that they are also involved in cell-cell interactions. Other information suggests that integrins may influence cell differentiation and proliferation, possibly through generation of second messengers. Recent evidence suggests that integrins are characteristically expressed in distinct nephron segments and may play a key role during development in the polarization of the condensed mesenchyme. Integrins may also be significant factors in the pathophysiology of acute renal failure. In this project the involvement of integrins in epithelial polarization will be investigated using complementary in vitro and in vivo approaches. The functions of integrins expressed by MDCK cells will be investigated with cell adhesion assays and immunocytochemical and biochemical techniques using subunit-specific monoclonaI and polyclonaI antibodies and cDNA probes (Specific Aim 1A). Integrin expression, distribution, activation, and targeting will be examined during the polarization process and in cells cultured on different substrata and under conditions which perturb cell-cell contacts (Specific Aim lB). The effects of disrupting integrin function on the polarity of MDCK cells will be investigated with antibodies that interfere with integrin ligand binding and by expression of integrin cDNAs and antisense constructs in MDCK cells. (Specific Aim lC). Integrin function during differentiation of the kidney will be studied in mouse embryos, whole organ cultures, and transfer cultures of kidney primordia using blocking antibodies and antisense constructs (Specific Aim 2A). Alterations in integrin expression during regeneration in vivo will be examined in mouse kidneys made ischemic by clamping of the renal artery (Specific Aim 2B). In the long-term, the results of these experiments will provide important information on the molecular interactions responsible for induction of kidney polarization by cell adhesion. These studies will also aid our understanding of how the kidney epithelium develops and recovers from injury.