CD146参与Wnt5a/JNK信号通路及其对糖尿病肾病足细胞损伤和上皮间充质转变现象的作用机制研究

“上皮间充质转变（EMT）现象”是糖尿病肾病（DN）足细胞损伤的核心环节，Wnt非经典通路“Wnt5a/JNK”在肾脏疾病时激活，与足细胞损伤相关。研究发现跨膜受体蛋白CD146介导Wnt5a/JNK通路，在维持细胞形态、促进细胞分化等方面发挥重要作用。在我们前期研究中，证实了DN患者血清和肾组织中CD146表达增强且与疾病进程相关；验证了CD146在肾小管细胞和足细胞表达，参与Wnt5a/JNK通路，与足细胞间充质表型获得有关；发现了Wnt5a基因敲除小鼠能通过抑制肾脏CD146表达改善单侧输尿管结扎侧的肾小管间质损伤和“EMT现象”。本项目将基于既往的工作基础，通过构建Wnt5a基因敲除小鼠单侧肾切除联合STZ诱导的DN模型，结合体外实验和DN患者肾脏组织学研究，多层次探讨CD146介导Wnt5a/JNK通路在足细胞损伤和“EMT现象”中的机制，为DN的发病机制研究开拓新的思路。

Podocytes are specialized, terminally differentiated visceral epithelial cells that cover the outer aspect of the glomerular basement membrane (GBM), playing a crucial role in the regulation of glomerular function. Podocytes undergo Epithelial-Mesenchymal Transition (EMT) after injury, which is considered a key event in the progression of diabetic nephropathy (DN). Recent years, EMT is more properly termed as “EMT-like change”, defining as the acquisition of mesenchymal properties by epithelial cells and the activation of related intracellular signaling pathways, rather than a full-way epithelial-to-fibroblast transition. Wnt5a/JNK is one of the major non-canonical Wnt pathways activated in DN. Wnt5a signaling plays an important role in podocyte depletion and dedifferentiation. A recent striking study identified CD146 as a transmembrane receptor of Wnt5a in regulating cell differentiation and migration. CD146 is a novel recognized gene related with kidney diseases, yet its underlying mechanism in kidney diseases remains poorly understood. In our previous studies, we identified the expression of CD146 in podocytes and renal tubular epithelial cells. We demonstrated a significant increase of CD146 expression in both serum and kidney biopsy tissues in patients with DN. We also verified the role of CD146 in Wnt5a/JNK pathway in vitro and found a possible role of CD146 in “EMT-like change” of podocytes. Furthermore, we found that Wnt5a knockout mice were protected from the development of renal fibrosis and “EMT-like change” in the unilateral ureteral obstruction (UUO) model via suppression of CD146/Wnt5a/JNK signaling. . Therefore, in the present study, we like to make further functional study of CD146 in DN. We plan to investigate the role of CD146 in podocyte injury and “EMT-like change” under high glucose or albumin over-loading conditions in vitro; we will explore the relationship between CD146 and podoctye injury in human kidney biopsies of DN by conducting a pathological study on CD146 and podoctye markers in vivo; Also, we will study CD146 mediated Wnt5a/JNK signaling in Wnt5a conventional knockout mice. Since STZ induced type 1-diabetes mice with uninephrictomy present more pronounced kidney and podocyte injury, therefore, we try to investigate whether suppression of CD146/Wnt5a attenuates podoctye injury and “EMT-like change” in the kidneys of STZ induced diabetic nephropathy with uninephrectomy. Thus targeting CD146/Wnt5a signaling could be an attractive strategy for therapeutic intervention of diabetic kidney disease.