TGF-beta signaling in the kidney

描述(申请人提供)：转化生长因子-β1(转化生长因子-β1)是一种多效性细胞因子，控制多种细胞功能，包括细胞增殖、分化、凋亡和细胞外基质(ECM)合成。转化生长因子-SS1是ECM蛋白合成和积累的有效诱导剂，在进展性疾病的发病机制中起着关键作用，是包括肾脏在内的各种组织中纤维化形成的中心介质。转化生长因子-SS1的作用是通过转化生长因子-生长因子受体I型(TssRI)和II型受体(TssRII)来激活细胞内通路。许多核心问题仍然与不同的受体如何以细胞特异性和上下文特异性的方式介导转化生长因子-SS1信号以引发多种细胞反应有关。我们研究的总体目标是了解肾损伤和纤维化的细胞和分子机制。主要目的是研究转化生长因子-SS1信号通路的机制及其在肾脏损伤反应中的调节和功能作用。我们的假设是，自噬是一种适应性应激反应，通过抑制细胞凋亡和促进肾细胞存活来保护肾脏免受损伤，而转化生长因子-SS1通过调节自噬发挥细胞保护作用。此外，我们假设，通过TAK1-MKK3-p38传递的转化生长因子-SS1信号是组织损伤反应的关键介质，其中转化生长因子-SS1调节自噬蛋白，从而防止细胞凋亡和过度的细胞外基质积聚。这项建议将集中于研究转化生长因子-SS1信号通过TAK1在肾细胞中的机制和功能作用，以及自噬的调节和它在实验性肾纤维化模型中的生理功能作用。特异性目的为：特异性目的1：确定转化生长因子-SS1通过TAK1在肾细胞中的作用机制和功能；特异性目的2：确定转化生长因子-SS1诱导的肾细胞自噬的调节和功能。具体目的3：在实验性肾纤维化模型中确定自噬在体内的生理功能作用。我们将使用最先进的方法，包括信号转导分子MAPKs的各种显性负突变，重点放在TAK1-MKK3信号轴，使用短干扰RNA(SiRNA)进行基因沉默，以及转基因小鼠，各种TAK1，MKK3，Cavelin-1，以及自噬基因Lc3和Beclin 1的缺失小鼠。相关性：尽管转化生长因子-SS1在肾纤维化发展中的核心作用已被很好地证明，但不分青红皂白地完全抑制转化生长因子-SS1作用的一般策略可能被证明是不谨慎的。这项研究将为我们进一步了解转化生长因子-SS1信号转导的分子机制提供重要而新颖的信息，即我们可能能够选择性地阻断信号转导转化生长因子-SS1的有害作用的途径。

DESCRIPTION (provided by applicant): Transforming growth factor-beta 1 (TGF-ss1) is a pleiotropic cytokine which controls multiple cellular functions including cell proliferation, differentiation, apoptosis, and extracellular matrix (ECM) synthesis. TGF-ss1 is a potent inducer of ECM protein synthesis and accumulation, and plays a key role in the pathogenesis of progressive diseases as a central mediator of fibrogenesis in a variety of tissues, including the kidney. TGF-ss1 actions are mediated via TGF-ss type I (TssRI) and type II (TssRII) receptors to activate intracellular pathways. Many central questions remain relating to how the distinct receptors mediate TGF-ss1 signals in a cell-specific and context-specific manner to elicit multiple cellular responses. The overall objective of our research is to understand the cellular and molecular mechanisms of renal injury and fibrosis. The major goals are to investigate the mechanisms of TGF-ss1 signaling pathways and their regulation and functional role in injury responses in the kidney. Our hypothesis is that autophagy represents an adaptive stress response to protect against renal injury by inhibiting apoptosis and promoting renal cell survival, and that TGF-ss1 exerts cytoprotective effects via regulating autophagy. Furthermore, we hypothesize that TGF-ss1 signaling via TAK1- MKK3-p38 is the critical mediator of tissue injury response in which TGF-ss1 regulates autophagy proteins which in turn prevents apoptosis and excessive ECM accumulation. This proposal will focus on examining the mechanism and functional role of TGF-ss1 signaling via TAK1 in renal cells, and the regulation of autophagy and its physiological functional role in an experimental model of renal fibrosis. The Specific Aims are: Specific Aim 1: To determine the mechanism and functional role of TGF-ss1 signaling via TAK1 in renal cells Specific Aim 2: To determine the regulation and function of autophagy induced by TGF-ss1 in renal cells. Specific Aim 3: To determine the in vivo physiological functional role of autophagy in an experimental model of renal fibrosis. We will employ state-of-the art approaches including a variety of dominant negative mutants of the signal transducing molecules, the MAPKs, focusing on the TAK1-MKK3 signaling axis, gene silencing by the use short interfering RNA (siRNA), and genetically altered mice, the null mice for the various TAK1, MKK3, Caveolin-1, and the autophagy genes, LC3 and Beclin 1. Relevance: Although the central role of TGF-ss1 in the development of renal fibrosis is well documented, general strategies to indiscriminately inhibit TGF-ss1 actions altogether may prove to be imprudent. The studies in this proposal will yield important and novel information in furthering our understanding of the molecular mechanisms of TGF-ss1 signal transduction, that we may be able to selectively block the pathway that signals the deleterious effects of TGF-ss1.