New Mechanisms in the Pathogenesis of Diabetic Nephropathy

描述（由申请人提供）：糖尿病肾病（DN）是糖尿病的主要并发症之一。它几乎占所有需要透析的终末期肾病患者的一半，因此是一个主要的卫生保健问题。然而，基本的潜在分子机制尚不清楚。转化生长因子- β （TGF-¿）参与了DN的发病机制。它是在糖尿病条件下诱导的，可以增加系膜细胞中胶原蛋白等细胞外基质蛋白的表达，导致肾小球功能障碍。在基因阵列筛选中，我们在系膜细胞中发现了两个新的TGF-¿基因靶点。其中一个被认为是一个关键的转录因子，可以调节胶原蛋白的表达。有趣的是，我们发现了这个转录因子家族和一个名为微rna （miRs）的小非编码rna新家族的两个成员之间的新联系。最近的证据表明，miRs可以通过结合靶基因的mrna抑制靶基因的翻译，在基因调控中发挥重要作用。虽然已经预测了miRs的几个靶点，但要确定它们的生物学和疾病相关性还需要做很多工作。此外，在糖尿病并发症包括DN的背景下，我们一无所知，我们建议在这方面探索我们的创新理念。我们发现，我们新发现的TGF-¿转录因子靶点参与胶原蛋白调节，也是肾脏中表达的两种miRs的靶点。此外，有趣的是，这些转录因子反过来可以抑制这些miRs的表达，从而表明一种新的串扰和前馈回路可以促进系膜细胞和肾小球基质的表达。因此，我们提出了一个创新的假设，即DN是这些miRs在肾脏和系膜细胞中响应TGF-¿异常表达和作用的结果。具体目标1和2将研究功能的获得和丧失方法以及转录组学机制，以评估新的TGF-¿靶点和两个miRs在小鼠系膜细胞基因表达中的作用。随后，Specific Aim 3将通过检测肾皮质miR和靶基因的表达以及下调关键miR的影响，在小鼠DN模型中测试其体内功能相关性。总体而言，我们将探索DN发展中的新的相关机制和参与者。这项工作将在肾脏研究领域开辟新的领域并产生重大影响，并为破译肾脏中这些难以捉摸的因素的生物学功能奠定基础。它们还可以为治疗包括肾病在内的各种糖尿病并发症的新疗法铺平道路。

DESCRIPTION (provided by applicant): Diabetic nephropathy (DN) is one of the major complications of diabetes. It accounts for almost half of all patients with end stage renal disease needing dialysis and is therefore a major health care problem. However the basic underlying molecular mechanisms are not very clear. Transforming growth factor-beta (TGF-¿) has been implicated in the pathogenesis of DN. It is induced under diabetic conditions and can increase the expression of extracellular matrix proteins such as collagen in mesangial cells, leading to glomerular dysfunction. In a gene array screen, we identified two new gene targets of TGF-¿ in mesangial cells. One of these was noted to be a key transcription factor that could modulate the expression of collagen. Interestingly, we uncovered a novel connection between this family of transcription factors and two members of a new family of small non-coding RNAs called micro-RNAs (miRs). Recent evidence shows that miRs play important roles in gene regulation since they can suppress translation of target genes by binding to their mRNAs. Although several targets of miRs have been predicted, much needs to be done to determine their biological and disease relevance. Furthermore, nothing is known in the context of diabetic complications including DN and we propose to explore our innovative idea in this context. We discovered that our newly identified transcription factor targets of TGF-¿ that are involved in collagen regulation, are also targets of two miRs that are expressed in the kidney. Furthermore, interestingly, these transcription factors in turn can inhibit the expression of these miRs, thereby suggesting a novel cross talk and feed forward loop that can contribute to mesangial cell and glomerular matrix expression. We therefore put forward the innovative hypothesis that DN is a result of aberrant expression and actions of these miRs in the kidney and mesangial cells in response to TGF-¿. Specific Aims 1 and 2 will examine gain and loss of function approaches as well as transcriptomic mechanisms to evaluate the involvement of the new TGF-¿ targets and two miRs in mouse mesangial cell gene expression. Specific Aim 3 will then test the in vivo functional relevance in a mouse model of DN by examining the renal cortical expression of miRs and target genes and the effects of downregulation of a key miR. Overall, we will explore new related mechanisms and players in the development of DN. This work could break new ground and have a major impact in the field of renal research as well as lay the foundation for deciphering the biological functions of these elusive factors in the kidney. They could also pave the way for novel new therapies for various complications of diabetes including nephropathy.