Inhibition of H3K9 histone methyltransferase G9a attenuates renal fibrosis and retains klotho expression

Abstract

H3K9 methyltransferase G9a is reportedly induced by transforming growth factor-β1 (TGF-β1) and has an important role in the development of epithelial-mesenchymal transposition in cancer cells. Since the transcriptional activity of the Klotho gene is regulated by H3K9 modification, we investigated the effects of G9a on renal fibrosis and klotho expression. G9a levels were significantly upregulated by day 7 in the kidneys of unilateral ureteral-obstructed mice, but this was inhibited by TGF-β1-neutralizing antibody. Administration of G9a small interfering RNA not only decreased α-smooth muscle actin and fibronectin but also increased klotho expression in the ureteral-obstructed mice. Similarly, intraperitoneal injection of BIX01294, a specific inhibitor of G9a, showed beneficial effects on renal fibrosis and klotho expression with decreased monomethylation of H3K9 (me1). In in vitro experiments, BIX01294 also inhibited TGF-β1-induced fibrotic changes and klotho downregulation along with suppressed H3K9me1. In human kidney biopsy specimens, areas of G9a immunostaining correlated positively with H3K9me1 levels, as well as fibrotic markers, but correlated negatively with klotho expression. Thus, TGF-β1-induced G9a has an important role in the progression of renal fibrosis and reduced klotho expression through H3K9me1.

Inhibition of H3K9 methyltransferase G9a ameliorates methylglyoxal-induced peritoneal fibrosis

“…In terms of peritoneal fibrosis, previous studies have reported that a histone acetyltransferase inhibitor, C646, suppresses TGF-β1-induced fibrotic changes in HPMCs [28], and that suberoylanilide hydroxamic acid, a histone deacetylase inhibitor, attenuates peritoneal fibrosis in mice via induction of bone morphogenetic protein (BMP)-7 [29]. Notably, our previous report demonstrated that TGF-β1-induced H3K9me1 is responsible for the progression of renal fibrosis [19]. Because histone methylation is regulated by specific enzymes, its regulation is considered to be a more specific therapy for peritoneal fibrosis than regulation of enzymes involved in other histone modifications.…”

“…Among epigenetic regulations, methylation of the histone tail is regulated by specific enzymes [18], indicating that TGF-β1-induced histone methyltransferases are therapeutic targets for peritoneal fibrosis. Recently, we have demonstrated that TGF-β1-induced G9a is responsible for renal fibrosis through mono-methylation of lysine 9 in histone H3 (H3K9me1), but not di-methylation (H3K9me2) [19]. G9a-induced H3K9 methylation causes transcriptional silencing [20], raising the possibility that BIX01294, a selective inhibitor of G9a, can suppress the loss of cellular properties and subsequent fibrotic processes through inhibition of H3K9me1.…”

Epigenetic Modifications to H3K9 in Renal Tubulointerstitial Cells after Unilateral Ureteric Obstruction and TGF-β1 Stimulation

“…Histone mark regulation of fibroblast-like differentiation is recognized in a multiplicity of pathologies including liver (Mann et al, 2010; Perugorria et al, 2012), nasal mucosa (Cho et al, 2012), cornea (Zhou et al, 2010), lung (Guo et al, 2009), and kidney (Irifuku et al, 2016) fibrosis. Consistent with this, TGF-β1 has been shown to enrich various active histone marks and decrease levels of repressive marks at pro-fibrotic gene promoters in renal mesangial cells (Sun et al, 2010; Yuan et al, 2013), epithelial cells (Sasaki et al, 2016), and fibroblasts (Irifuku et al, 2016; Sasaki et al, 2016).…”

Human alternative Klotho mRNA is a nonsense-mediated mRNA decay target inefficiently spliced in renal disease

“…*P < 0.05, **P < 0.01, ***P < 0.001, as tested by one-way ANOVA with Bonferroni's post-hoc test. dysregulation of its splicing as possible mechanisms contributing to Klotho downregulation, in addition to transcriptional regulation (16,53,54), epigenetic regulation (55)(56)(57), and miRNAs (58,59).…”