BLR&D Research Career Scientist Award Application

本研究的主要目的是探讨肿瘤发生、发展的机制， 糖尿病肾病（DN）。糖尿病在20岁及以上的人群中很普遍。的人口结构 退伍军人人口福尔斯属于这个年龄组。在美国，糖尿病是第六大死亡原因; 然而，糖尿病作为死亡原因的报告不足。近50%的糖尿病患者 肾病最近的一项研究表明，患有肾脏疾病的糖尿病患者患糖尿病的风险增加了87%。 心血管疾病死亡率与无肾脏疾病者相比。早期病理改变 DN涉及肾脏特别是肾小球肥大和基质蛋白如胶原的扩张， 纤连蛋白和层粘连蛋白。我的实验室研究导致疾病进展的信号转导机制 的DN。为了验证我们的概念，我们使用肾细胞（肾小球系膜细胞和近端肾小管上皮细胞） 细胞）以及小鼠和大鼠糖尿病模型。由于高血糖症的许多病理作用是 通过转化生长因子-β（TGFβ）介导的细胞因子，我们研究了这种细胞因子在 系膜和近端肾小管上皮细胞。我们发现肿瘤抑制蛋白的表达 PTEN（10号染色体缺失的磷酸酶和张力蛋白同源物）在糖尿病肾和糖尿病肾病中减少。 在高糖或TGFβ存在下培养的肾细胞。近年来，我们广泛调查了 糖尿病啮齿动物肾细胞和肾脏中PTEN下调的机制。结果表明 TGFβ参与高糖诱导的肾细胞中PTEN水平的抑制。我们的研究结果 首次证实microRNA（miR）-21、miR-26和miR-214在抑制PTEN中的作用 在糖尿病环境中的表达。这些研究为抗microRNA的新应用打开了大门 DN的治疗。最近，我们将这些研究扩展到包括mTOR的作用（mTOR的机制靶点）。 雷帕霉素）复合物1和2在糖尿病肾病中的作用。我们提供了第一个证据的要求 mTOR复合物1的独有PRAS 40亚基失活导致肾小球系膜细胞肥大， DN的病理特征。与其他VA研究人员一起，我们发现雷帕霉素改善了 糖尿病小鼠的肾脏病理。然而，雷帕霉素介导的mTOR活性的完全抑制可能 导致有害的临床结果。事实上，小鼠近端肾小管上皮细胞中mTORC 1的缺失诱导 进行性纤维化因此，最近我们集中研究了一种新的蛋白质，称为deptor，它是一种 mTOR复合物1和2的组分。事实上，deptor是mTOR活性的内源性抑制剂。为 我们第一次发现，在糖尿病患者中， 在糖尿病啮齿类动物中，这种减少有助于增加mTOR活性。培养 高糖孵育的肾小球系膜和近端肾小管上皮细胞中，deptor的表达明显高于高糖孵育的肾小球系膜和近端肾小管上皮细胞。 显著降低，这导致mTORC 1和mTORC 2的持续激活。照经上所 因此，研究高血糖引起的降血糖机制具有重要意义。我们目前正在调查 糖尿病肾病脱蛋白酶减少表观遗传、转录后和翻译后机制 疾病此外，最近的研究表明，糖尿病和肾细胞 肾癌（RCC）。此外，肾细胞癌的发病率在30岁后增加，并在60岁时达到高峰， 属于退伍军人群体。我们发现，通过增加PTEN的表达， 特异性microRNA的表达有助于肾癌细胞的增殖和侵袭。 因此，我们的研究目标是探讨糖尿病进展的分子机制， 肾病和肾细胞癌，并确定信号分子，可以靶向小分子药物， 抗microRNA治疗。

The main focus of our research is to investigate the mechanism of development and progression of diabetic nephropathy (DN). Diabetes is prevalent in the people aged 20 years and older. The demographic of veterans population falls in this age group. In the US, diabetes represents the 6th leading cause of death; however, diabetes as a cause of death is underreported. Nearly 50% of the patients with diabetes develop nephropathy. A recent study demonstrated that diabetic patients with kidney disease had 87% higher risk of cardiovascular mortality when compared with those without kidney disease. The early pathologic changes in DN involve renal especially glomerular hypertrophy and expansion of matrix proteins such as collagen, fibronectin and laminin. My laboratory studies the signal transduction mechanisms that lead to the progression of DN. To test our concepts, we use both renal cells (glomerular mesangial and proximal tubular epithelial cells) in culture and mouse and rat models of diabetes. Since many pathologic effects of hyperglycemia are mediated by transforming growth factor-β (TGFβ), we investigate the signaling mechanisms of this cytokine in mesangial and proximal tubular epithelial cells. We discovered that the expression of tumor suppressor protein PTEN (phosphatase and tensin homolog deleted in chromosome 10) is reduced in the diabetic kidney and in renal cells cultured in the presence of high glucose or TGFβ. In recent years, we have extensively investigated the mechanism of PTEN downregulation in renal cells and in kidneys of diabetic rodents. The results showed the involvement of TGFβ in high glucose-induced suppression of PTEN levels in renal cells. Our results for the first time demonstrated the role of microRNA (miR)-21, miR-26 and miR-214 in the inhibition of PTEN expression in the diabetic milieu. These studies opened the door to the novel application of anti-microRNA therapy for DN. More recently, we extended these studies to include the role of mTOR (mechanistic target of rapamycin) complexes 1 and 2 in diabetic kidney disease. We provided the first evidence for the requirement of inactivation of the exclusive PRAS40 subunit of mTOR complex 1 for glomerular mesangial cell hypertrophy, a pathologic feature of DN. Together with other VA investigators, we showed that rapamycin ameliorated the renal pathologies in diabetic mice. However, rapamycin-mediated complete inhibition of mTOR activity may cause deleterious clinical outcome. In fact, loss of mTORC1 in proximal tubular epithelial cells of mice induces progressive fibrosis. Therefore, more recently we have focused on a novel protein, called deptor, which is a component of both mTOR complexes 1 and 2. In fact, deptor is an endogenous inhibitor of mTOR activity. For the first time, we showed that the renal expression of deptor was significantly reduced in humans with diabetes and in diabetic rodents and that this reduction contributed to the increased mTOR activity. In cultured mesangial and proximal tubular epithelial cells incubated with high glucose, the expression of deptor was significantly reduced, which resulted in sustained activation of both mTORC1 and mTORC2. Thus, it is important to study the mechanisms of deptor downregulation by hyperglycemia. We are currently investigating the epigenetic, post-transcriptional and post-translational mechanisms of deptor reduction in diabetic kidney disease. Furthermore, recent studies have demonstrated a strong correlation between diabetes and renal cell carcinoma (RCC). Also, the incidence of RCC increases after 30 years of age and peaks at the 6th decades, which fall in the demographic of veterans population. We showed that downregulation of PTEN by increased expression of specific microRNAs contributes to the proliferation and invasion of renal carcinoma cells. Thus, the goal of our studies is to investigate the molecular mechanisms of the progression of diabetic nephropathy and RCC, and identify signaling molecules that can be targeted by small molecular drugs and anti-microRNA based therapies.