TGFβ-incurred epigenetic aberrations of miRNA and DNA methyltransferase suppress Klotho and potentiate renal fibrosis

Abstract

Renal fibrosis is a common pathological feature of chronic kidney diseases (CKD) and its development and progression are significantly affected by epigenetic modifications such as aberrant miRNA and DNA methylation. Klotho is an anti-aging and anti-fibrotic protein and its early decline after renal injury is reportedly associated with aberrant DNA methylation. However, the key upstream pathological mediators and the molecular cascade leading to epigenetic Klotho suppression are not exclusively established. Here we investigate the epigenetic mechanism of Klotho deficiency and its functional relevance in renal fibrogenesis. Fibrotic kidneys induced by unilateral ureteral occlusion (UUO) displayed marked Klotho suppression and the promoter hypermethylation. These abnormalities were likely due to deregulated transforming growth factor-beta (TGFβ) since TGFβ alone caused the similar epigenetic aberrations in cultured renal cells and TGFβ blockade prevented the alterations in UUO kidney. Further investigation revealed that TGFβ enhanced DNA methyltransferase (DNMT) 1 and DNMT3a via inhibiting miR-152 and miR-30a in both renal cells and fibrotic kidneys. Accordingly the blockade of either TGFβ signaling or DNMT1/3a activities significantly recovered the Klotho loss and attenuated pro-fibrotic protein expression and renal fibrosis. Moreover, Klotho knockdown by RNA interferences abolished the anti-fibrotic effects of DNMT inhibition in both TGFβ-treated renal cell and UUO kidney, indicating that TGFβ-mediated miR-152/30a inhibitions, DNMT1/3a aberrations and subsequent Klotho loss constitute a critical regulatory loop that eliminates Klotho's anti-fibrotic activities and potentiates renal fibrogenesis. Thus, our study elaborates a novel epigenetic cascade of renal fibrogenesis and reveals the potential therapeutic targets for treating the renal fibrosis-associated kidney diseases.

miR‑152 regulates TGF‑β1‑induced epithelial‑mesenchymal transition by targeting HPIP in tubular epithelial cells

“…Recently published data focused on the contribution of specific miRNAs to the progression of EMT in renal fibrosis (26,27). In the present study, downregulation of miR-152 in HK-2 cells was observed following stimulation with TGF-β1, which is consistent with the results of a previous study (15). Investigation of miRNA regulation in the kidney will improve the understanding of renal pathology and may eventually lead to the development of novel treatment strategies for reversing renal fibrosis and dysfunction.…”

“…The above results suggest important roles of miRNAs in renal fibrosis and EMT of tubular epithelial cells. A recent study demonstrated that TGF-β1 inhibits the expression of miR-152/30a, therfore enhancing DNA methyltransferase 1/3a and contributing to the promotion of pro-fibrotic protein expression and renal fibrosis (15). However, the association between miR-152 and TGF-β1-induced tubular epithelial cell EMT remains to be elucidated.…”

PPARγ preservation via promoter demethylation alleviates osteoarthritis in mice

“…C57BL/6 mice, PPARγWT and PPARγKO mice of around 10 weeks old were subjected to (1) Sham surgery (Sham); (2) 5Aza treatment (5-Aza-2'-deoxycytidine from Sigma-Aldrich, USA, 0.35 mg/kg, kilogram bodyweight, daily intraperitoneal injection based on our previous mouse study)22; (3) DMM (destabilisation of medial meniscus)23 and (4) DMM mice with 5Aza treatment. Both PPARγKO and the control mice received daily intraperitoneal tamoxifen injection (50 mL solution containing 2 mg tamoxifen) for five consecutive days and waited for additional 10 days before experiments 21…”

Urinary Extracellular Vesicles Carrying Klotho Improve the Recovery of Renal Function in an Acute Tubular Injury Model

“…For instance, miR-30a, transferred by uEVs, has been described to be involved in Klotho upregulation by suppressing the methylation of the promoter. 64 In addition, CTGF and a-SMA, molecules involved in Klotho-related pathways, 27,35,41 were significantly downregulated by uEVs. miR-30a has also been shown to directly target CTGF in cultured cardiomyocytes and fibroblasts.…”