Department of Pathology, School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai, China.
Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA.
Nephrol Dial Transplant. 2021 May 27;36(6):1006-1016. doi: 10.1093/ndt/gfab014.
Previously, by using proteomic analysis and RNA sequencing in isolated glomeruli, we identified several novel differentially expressed proteins in human and mouse diabetic nephropathy (DN) versus controls, including dishevelled associated activator of morphogenesis 2 (DAAM2). DAAM2 binds the Wnt effector Dvl. We aimed to study possible contributions of DAAM2 to DN.
We assessed DAAM2 by immunostaining in non-cancer regions of human nephrectomy (Nx), DN and normal donor kidney tissues. We also examined DAAM2 in DN mice (db/db eNOS-/-) and Nx mice. DN mice treated with angiotensin-converting enzyme inhibitor (ACEI), dipeptidyl peptidase 4 inhibitor (DPP4I) or vehicle were compared. DAAM2 was knocked down in primary cultured podocytes by small interfering RNA to study its effects on cell function.
In normal human glomeruli, DAAM2 was expressed only on podocytes. DAAM2 expression was increased in both Nx and DN versus normal donors. Podocyte DAAM2 expression was increased in DN and Nx mouse models. Glomerular DAAM2 expression correlated with glomerular size and was decreased significantly by ACEI while DPP4I only numerically reduced DAAM2. In primary cultured podocytes, knockdown of DAAM2 enhanced adhesion, slowed migration, activated Wnt-β-catenin signaling and downregulated mammalian target of rapamycin complex 1 (mTORC1) and Rho activity.
Podocyte DAAM2 is upregulated in both Nx and DN, which could be contributed to by glomerular hypertrophy. We hypothesize that DAAM2 regulates podocyte function through the mTORC1, Wnt/β-catenin and Rho signaling pathways.
此前，我们通过对分离的肾小球进行蛋白质组学分析和 RNA 测序，在人类和小鼠糖尿病肾病 (DN) 与对照中发现了几种新型差异表达蛋白，包括 Wnt 效应物 Dvl 的衔接蛋白 dishevelled 相关激活因子 2（DAAM2）。DAAM2 与 Wnt 效应物 Dvl 结合。我们旨在研究 DAAM2 对 DN 的可能贡献。
我们通过免疫染色法在非癌症区域的人类肾切除术 (Nx)、DN 和正常供体肾脏组织中评估 DAAM2。我们还检查了 DN 小鼠 (db/db eNOS-/-) 和 Nx 小鼠中的 DAAM2。比较了用血管紧张素转换酶抑制剂 (ACEI)、二肽基肽酶 4 抑制剂 (DPP4I) 或载体治疗的 DN 小鼠。通过小干扰 RNA 敲低原代培养的足细胞中的 DAAM2，研究其对细胞功能的影响。
在正常人类肾小球中，DAAM2 仅在足细胞上表达。与正常供体相比，Nx 和 DN 中的 DAAM2 表达均增加。DN 和 Nx 小鼠模型中足细胞的 DAAM2 表达增加。肾小球 DAAM2 表达与肾小球大小相关，ACEI 显著降低，而 DPP4I 仅在数值上降低 DAAM2。在原代培养的足细胞中，DAAM2 的敲低增强了黏附性，减缓了迁移速度，激活了 Wnt-β-catenin 信号通路，并下调了哺乳动物雷帕霉素靶蛋白复合物 1 (mTORC1) 和 Rho 活性。
在 Nx 和 DN 中，足细胞的 DAAM2 上调，这可能是由肾小球肥大引起的。我们假设 DAAM2 通过 mTORC1、Wnt/β-catenin 和 Rho 信号通路调节足细胞功能。
