Center for Immunology and Inflammation, Feinstein Institute for Medical Research and Donald and Barbara Zucker School of Medicine at Hofstra/Northwell, Great Neck, New York.
Ochsner Clinic , New Orleans, Louisiana.
Am J Physiol Renal Physiol. 2018 May 1;314(5):F832-F843. doi: 10.1152/ajprenal.00541.2017. Epub 2018 Jan 10.
The loss of podocyte (PD) molecular phenotype is an important feature of diabetic podocytopathy. We hypothesized that high glucose (HG) induces dedifferentiation in differentiated podocytes (DPDs) through alterations in the apolipoprotein (APO) L1-microRNA (miR) 193a axis. HG-induced DPD dedifferentiation manifested in the form of downregulation of Wilms' tumor 1 (WT1) and upregulation of paired box 2 (PAX2) expression. WT1-silenced DPDs displayed enhanced expression of PAX2. Immunoprecipitation of DPD cellular lysates with anti-WT1 antibody revealed formation of WT1 repressor complexes containing Polycomb group proteins, enhancer of zeste homolog 2, menin, and DNA methyltransferase (DNMT1), whereas silencing of either WT1 or DNMT1 disrupted this complex with enhanced expression of PAX2. HG-induced DPD dedifferentiation was associated with a higher expression of miR193a, whereas inhibition of miR193a prevented DPD dedifferentiation in HG milieu. HG downregulated DPD expression of APOL1. miR193a-overexpressing DPDs displayed downregulation of APOL1 and enhanced expression of dedifferentiating markers; conversely, silencing of miR193a enhanced the expression of APOL1 and preserved DPD phenotype. Moreover, stably APOL1G0-overexpressing DPDs displayed the enhanced expression of WT1 but attenuated expression of miR193a; nonetheless, silencing of APOL1 reversed these effects. Since silencing of APOL1 enhanced miR193a expression as well as dedifferentiation in DPDs, it appears that downregulation of APOL1 contributed to dedifferentiation of DPDs through enhanced miR193a expression in HG milieu. Vitamin D receptor agonist downregulated miR193a, upregulated APOL1 expression, and prevented dedifferentiation of DPDs in HG milieu. These findings suggest that modulation of the APOL1-miR193a axis carries a potential to preserve DPD molecular phenotype in HG milieu.
足细胞（PD）分子表型的丧失是糖尿病性足细胞病的一个重要特征。我们假设，高葡萄糖（HG）通过改变载脂蛋白（APO）L1-微小 RNA（miR）193a 轴诱导分化的足细胞（DPD）去分化。HG 诱导的 DPD 去分化表现为 Wilms' 肿瘤 1（WT1）下调和配对盒 2（PAX2）表达上调。沉默 WT1 的 DPD 表现出 PAX2 表达增强。用抗 WT1 抗体免疫沉淀 DPD 细胞裂解物显示形成包含多梳组蛋白、增强子 of zeste 同源物 2、menin 和 DNA 甲基转移酶（DNMT1）的 WT1 抑制复合物，而沉默 WT1 或 DNMT1 破坏了该复合物，导致 PAX2 表达增强。HG 诱导的 DPD 去分化与 miR193a 表达较高有关，而抑制 miR193a 可防止 HG 环境中的 DPD 去分化。HG 下调 DPD 中 APOL1 的表达。miR193a 过表达的 DPD 表现出 APOL1 下调和去分化标志物表达增强；相反，沉默 miR193a 增强了 APOL1 的表达并保持了 DPD 表型。此外，稳定过表达 APOL1G0 的 DPD 显示出 WT1 表达增强，但 miR193a 表达减弱；然而，沉默 APOL1 逆转了这些影响。由于沉默 APOL1 增强了 DPD 中的 miR193a 表达和去分化，因此似乎 APOL1 的下调通过增强 HG 环境中 miR193a 的表达导致 DPD 的去分化。维生素 D 受体激动剂下调 miR193a，上调 APOL1 表达，并防止 HG 环境中 DPD 的去分化。这些发现表明，调节 APOL1-miR193a 轴有可能在 HG 环境中保持 DPD 的分子表型。
