Inducible Dysplastic Nephropathy in B2-Deficient Mice

描述（由申请人提供）：肾脏和尿路发育异常是儿童慢性肾衰竭的最常见原因。虽然单基因肾发育不全综合征继续被解开，相当大比例的病例是散发的，被认为是多基因或基因-环境相互作用的结果。在上一个资助期间，我们开发并表征了一种独特的肾发育不全小鼠模型，该模型是由定义的基因-环境相互作用产生的。该动物模型表明，缓激肽B2受体（B2 R）是胎儿应激条件下正常肾脏发育所必需的。作为对妊娠期盐负荷的反应，B2 R-无效胎儿获得以过度凋亡、间质扩张和抑制分化基因表达为特征的发育不良肾表型。两条独立的证据支持异常p53激活在介导肾发育不全中的核心作用。首先，发育不良的肾脏过度表达p53的促凋亡形式，P-Ser 46-p53。第二，遗传杂交导致生殖系p53单倍不足拯救盐胁迫B2 R无效突变体的肾脏发育。这项建议的长期目标是阐明导致发育中的肾脏中异常p53激活和终末上皮分化破坏的途径。具体目标1将检验以下假设：B2 R无效胚胎中p53的诱导是肾脏限制性的，并伴有上游p53应激诱导激酶的激活/表达。具体目标2将确定P-Ser 46-p53在肾发育不全的发病机制中的直接作用，使用两种互补的遗传方法。第一个涉及B2 R基因缺失小鼠生殖系中p53基因剂量的减少;第二个涉及B2 R基因缺失小鼠的世代，所述B2 R基因缺失小鼠具有突变的Ser 46-to-Ala p53等位基因。我们假设，在这两种情况下，B2 R-null后代将受到保护，从肾发育不全。具体目标3将检验P-Ser 46-p53通过将组蛋白脱乙酰酶（HDAC）募集到终末分化基因的启动子区来抑制分化基因表达的假设。此外，我们将探索HDAC抑制剂在恢复终末分化和阻止肾发育不全进展方面的潜在治疗益处。我们预计我们的研究将出现新的发病范式和治疗策略，有望应用于肾发育不全的治疗。

DESCRIPTION (provided by applicant): Abnormalities of kidney and urinary tract development are the most common cause of chronic renal failure in children. While monogenetic renal dysgenesis syndromes continue to be unraveled, a sizable proportion of cases are sporadic and considered polygenic or a result of gene-environment interactions. During the previous funding period, we developed and characterized a unique mouse model of renal dysgenesis that is produced by defined gene-environment interactions. This animal model demonstrated that the bradykinin B2 receptor (B2R) is required for normal renal development under conditions of fetal stress. In response to gestational salt loading, B2R-null fetuses acquire a dysplastic renal phenotype characterized by excessive apoptosis, stromal expansion, and suppressed differentiated gene expression. Two independent lines of evidence support a central role for aberrant p53 activation in mediating the renal dysgenesis. First, the dysplastic kidneys overexpress a pro-apoptotic form of p53, P-Ser46-p53. Second, genetic crosses resulting in germline p53 haploinsufficiency rescue kidney development in salt-stressed B2R-null mutants. The long-term objective of this proposal is to elucidate the pathways leading to aberrant p53 activation and disruption of terminal epithelial differentiation in the developing kidney. Specific Aim 1 will test the hypothesis that induction of p53 in B2R-null embryos is kidney-restricted and is accompanied by activation/expression of upstream p53 stress-induced kinases. Specific Aim 2 will determine the direct role of P-Ser46-p53 in the pathogenesis of the renal dysgenesis using two complementary genetic approaches. The first involves p53 gene dosage reduction in the germline of B2R-null mice; the second, generation of B2R null mice harboring a mutant Ser46-to-Ala p53 allele. We postulate that, in both cases, the B2R-null progeny will be protected from the renal dysgenesis. Specific Aim 3 will test the hypothesis that P-Ser46-p53 suppresses differentiated gene expression through recruitment of histone deacetylases (HDAC) to the promoter regions of terminal differentiation genes. In addition, we will explore the potential therapeutic benefit of HDAC inhibitors in the restoration of terminal differentiation and halting progression of the renal dysgenesis. We anticipate that new pathogenetic paradigms and therapeutic strategies will emerge from our studies that can hopefully be applied for the treatment of renal dysgenesis.