Department of Medicine, Mount Sinai School of Medicine, New York, New York, United States of America.
PLoS One. 2013 Sep 26;8(9):e75572. doi: 10.1371/journal.pone.0075572. eCollection 2013.
Transforming growth factors beta (TGF-β) are multi-functional cytokines capable of inducing apoptosis in epithelial cells, including glomerular podocytes. We and others have previously shown that podocyte-selective genetic deletion of the microRNA (miR)-processing enzyme, Dicer, caused glomerulosclerosis that was associated with podocyte apoptosis, and the miR-30 family was implicated in the process. Here, we report that apoptosis-associated genes were highly enriched among the predicted targets of miR-30 when compared with randomly selected miRs (26% vs. 4.5 ± 2.1%) or with the known TGF-β-regulated miR-192 (6%), miR-216a (5.1%), and miR-217 (0%). miR-30 family members were abundantly expressed in podocytes in normal mice but were downregulated in albumin/TGF-β transgenic mice with podocyte apoptosis and glomerulosclerosis. In vitro, TGF-β downregulated miR-30s in wildtype and Smad3-deficient, but not Smad2- or Smad2/Smad3-deficient, podocytes. The TGF-β-induced activation of caspase 3 and an increase in TUNEL-positive nuclei were significantly inhibited by the lentivirus-mediated overexpression of miR-30d, but not by a scrambled control miR, in podocytes. TGF-β stimulated the phosphorylation of pro-apoptotic p53 in podocytes with lentiviral expression of a scrambled miR, but not in podocytes expressing miR-30d. In contrast, miR-30d had no effect on the phosphorylation of pro-apoptotic p38 MAP kinase induced by TGF-β. Thus, we report that Smad2-dependent inhibition of miR-30s in podocytes is required for the activation of p53 and the induction of apoptosis by TGF-β. These results demonstrate a novel functional role for miR-30 in podocyte survival and indicate that the loss of miR-30 survival signaling is a novel and specific mechanism of TGF-β-induced podocyte apoptosis during glomerulosclerosis. We propose the therapeutic replacement of miR-30 as a novel strategy to prevent the podocyte apoptosis that is characteristic of progressive glomerular diseases.
转化生长因子-β（TGF-β）是一种多功能细胞因子，能够诱导包括肾小球足细胞在内的上皮细胞凋亡。我们和其他人之前已经表明，足细胞特异性基因敲除微 RNA（miR）加工酶 Dicer 会导致肾小球硬化，与足细胞凋亡有关，miR-30 家族与此过程有关。在这里，我们报告说，与随机选择的 miR（26%比 4.5 ± 2.1%）或已知的 TGF-β调节的 miR-192（6%）、miR-216a（5.1%）和 miR-217（0%）相比，miR-30 家族成员在预测的靶基因中高度富集。miR-30 家族成员在正常小鼠的足细胞中大量表达，但在足细胞凋亡和肾小球硬化的白蛋白/TGF-β转基因小鼠中下调。在体外，TGF-β 下调野生型和 Smad3 缺陷型足细胞中的 miR-30s，但不下调 Smad2 或 Smad2/Smad3 缺陷型足细胞中的 miR-30s。慢病毒介导的 miR-30d 过表达显著抑制 TGF-β诱导的 caspase 3 活化和 TUNEL 阳性核的增加，但对照 miR 过表达则没有作用。TGF-β 刺激足细胞中 pro-apoptotic p53 的磷酸化，而表达 scrambled miR 的足细胞则没有。相反，miR-30d 对 TGF-β诱导的 pro-apoptotic p38 MAP 激酶的磷酸化没有影响。因此，我们报告说，Smad2 依赖性抑制足细胞中的 miR-30s 是 TGF-β 激活 p53 和诱导凋亡所必需的。这些结果表明 miR-30 在足细胞存活中的新的功能作用，并表明 miR-30 存活信号的丢失是 TGF-β 诱导肾小球硬化过程中足细胞凋亡的一种新的和特异性机制。我们提出用 miR-30 进行治疗性替代作为一种防止足细胞凋亡的新策略，这种凋亡是进行性肾小球疾病的特征。
