Regulation of the mTOR pathway in polycystic kidney disease

描述（由申请人提供）：常染色体显性遗传（ADPKD）是最常见的危及生命的遗传性疾病。多发性硬化症（TSC）比ADPKD少10倍。肾囊肿的症状有哪些？目前没有治疗方法可以减缓这两种疾病的发作或进展。我们最近发现，多囊蛋白-1（PC 1），在ADPKD中受影响的蛋白质，与tuberin，在TSC中受影响的蛋白质相互作用，并调节激酶mTOR的活性。mTOR在细胞生长和增殖中起重要作用，并且已知被块茎素抑制。我们提出了一个模型，其中PC 1的C-末端胞质尾区的功能是诱导形成一个复合物之间的tuberin和mTOR和其他调节蛋白。该复合物的功能是抑制正常肾上皮细胞中的mTOR活性。我们的研究结果表明，mTOR抑制是由顶端液流调节。我们发现mTOR在ADPKD患者的肾脏和患有多囊肾的小鼠中不适当地活跃。用mTOR抑制剂雷帕霉素治疗多囊肾小鼠导致肾脏和囊肿大小的显著减小以及肾功能的保留。这强烈表明ADPKD中异常的mTOR激活对肾囊肿生长至关重要。我们现在建议详细研究PC 1抑制mTOR活性的机制。在目的1中，我们将研究PC 1和mTOR之间的相互作用，并确定额外的调节因子和复合物的亚细胞定位。我们将测试这种复合体在肾囊肿中是否被破坏。在目标2中，我们将测试流体流动如何调节mTOR活性。在目标3中，使用来自ADPKD肾脏的样本和具有条件性失活PKD 1基因的小鼠模型，我们将表征mTOR的已知下游效应子和上游调节子中的哪一个在疾病中受到影响。在目标4中，为了准备未来可能的临床试验，我们将研究雷帕霉素对PKD 1小鼠模型的影响。我们将评估剂量和治疗方案，并研究对囊性上皮细胞增殖和凋亡的影响。这些研究对于指导未来可能的临床试验将是重要的。雷帕霉素已经是一种临床批准的药物，用于长期治疗肾移植患者的免疫抑制。根据我们的数据，我们对雷帕霉素有望成为第一种减缓ADPKD疾病进展的治疗方法持谨慎乐观态度。此外，这项研究的结果将加强我们对TSC肾脏参与机制的理解。

DESCRIPTION (provided by applicant): Autosomal-dominant (ADPKD) is the most common life-threatening genetic disease. Tuberous Sclerosis Complex (TSC) is 10-times less common than ADPKD. Both diseases are characterized by renal cysts. No treatment is currently available to slow the onset or progression of either disease. We have recently found that polycystin-1 (PC1), the protein affected in ADPKD, interacts with tuberin, the protein affected in TSC, and regulates the activity of the kinase mTOR. mTOR plays an important role in cell growth and proliferation and is known to be inhibited by tuberin. We propose a model in which the C-terminal cytoplasmic tail of PC1 functions to induce the formation of a complex between tuberin and mTOR and other regulatory proteins. The function of this complex is to suppress mTOR activity in normal renal epithelial cells. Our results suggest that mTOR inhibition is regulated by apical fluid flow. We found that mTOR is inappropriately active in the kidneys of ADPKD patients and in mice with polycystic kidneys. Treatment of polycystic kidney mice with the mTOR inhibitor rapamycin results in the dramatic reduction of renal and cyst sizes and in the preservation of kidney function. This strongly suggests that aberrant mTOR activation in ADPKD is critical for renal cyst growth. We now propose to study in detail the mechanism of the suppression of mTOR activity by PC1. In Aim 1, we will investigate the interaction between PC1 and mTOR and identify additional regulatory factors and the subcellular localization of the complex. We will test whether this complex is disrupted in renal cysts. In Aim 2, we will test how fluid flow regulates mTOR activity. In Aim 3, using samples from ADPKD kidneys and a mouse model with a conditionally inactivated PKD1 gene we will characterize which of the known downstream effectors and upstream regulators of mTOR are affected in the disease. In Aim 4, in preparation for possible future clinical trials, we will investigate the effects of rapamycin on the PKD1 mouse model. We will assess dosage and treatment regimens and investigate the effects on proliferation and apoptosis of cystic epithelial cells. These investigations will be important to guide possible future clinical trials. Rapamycin is already a clinically approved drug, used for long-term treatment for immunosuppression in renal transplant patients. Based on our data, we are cautiously optimistic that rapamycin has promise to become the first available treatment to slow the disease progression in ADPKD. Furthermore, results from this research will enhance our understanding of the mechanisms underlying the renal involvement in TSC.