Loss of MEN1 leads to renal fibrosis and decreases HGF‐Adamts5 pathway activity via an epigenetic mechanism

Abstract

Background Renal fibrosis is a serious condition that results in the development of chronic kidney diseases. The MEN1 gene is an epigenetic regulator that encodes the menin protein and its role in kidney tissue remains unclear. Methods Kidney histology was examined on paraffin sections stained with hematoxylin‐eosin staining. Masson’s trichrome staining and Sirius red staining were used to analyze renal fibrosis. Gene and protein expression were determined by quantitative real‐time PCR (qPCR) and Western blot, respectively. Immunohistochemistry staining in the kidney tissues from mice or patients was used to evaluate protein levels. Flow cytometry was used to analyze the cell cycle distributions and apoptosis. RNA‐sequencing was performed for differential expression genes in the kidney tissues of the Men1f/f and Men1∆/∆ mice. Chromatin immunoprecipitation sequencing (ChIP‐seq) was carried out for identification of menin‐ and H3K4me3‐enriched regions within the whole genome in the mouse kidney tissue. ChIP‐qPCR assays were performed for occupancy of menin and H3K4me3 at the gene promoter regions. Luciferase reporter assay was used to detect the promoter activity. The exacerbated unilateral ureteral obstruction (UUO) models in the Men1f/f and Men1∆/∆ mice were used to assess the pharmacological effects of rh‐HGF on renal fibrosis. Results The expression of MEN1 is reduce in kidney tissues of fibrotic mouse and human diabetic patients and treatment with fibrotic factor results in the downregulation of MEN1 expression in renal tubular epithelial cells (RTECs). Disruption of MEN1 in RTECs leads to high expression of α‐SMA and Collagen 1, whereas MEN1 overexpression restrains epithelial‐to‐mesenchymal transition (EMT) induced by TGF‐β treatment. Conditional knockout of MEN1 resulted in chronic renal fibrosis and UUO‐induced tubulointerstitial fibrosis (TIF), which is associated with an increased induction of EMT, G2/M arrest and JNK signaling. Mechanistically, menin recruits and increases H3K4me3 at the promoter regions of hepatocyte growth factor (HGF) and a disintegrin and metalloproteinase with thrombospondin motifs 5 (Adamts5) genes and enhances their transcriptional activation. In the UUO mice model, exogenous HGF restored the expression of Adamts5 and ameliorated renal fibrosis induced by Men1 deficiency. Conclusions These findings demonstrate that MEN1 is an essential antifibrotic factor in renal fibrogenesis and could be a potential target for antifibrotic therapy.

MEN1 is a regulator of alternative splicing and prevents R-loop-induced genome instability through suppression of RNA polymerase II elongation

“…Here we show that, in addition to having this quantitative effect, MEN1 also impacts the quality of transcripts by altering exon skipping in the pre-mRNAs of some genes. We and others have previously demonstrated that MEN1 inactivation or deletion leads to various human diseases, such as renal fibrosis ( 67 ), diabetes ( 68 ) and lung cancers ( 21 ). Since the AS program tightly controls the quantity and quality of post-transcriptional gene expression, which plays a crucial role in diverse cellular processes, including cell proliferation, differentiation and death, we therefore reason that these defects are caused in part by abnormal AS programs upon MEN1 dysfunction.…”

Research progress on the mechanism of renal interstitial fibrosis in obstructive nephropathy

“…This process is accompanied by inflammatory cell infiltration, the release of inflammatory mediators, and the activation of fibroblasts in the renal interstitium. These events culminate in renal interstitial fibrosis, causing the destruction of kidney structure and impairing its overall function [ [4] , [5] , [6] ]. The most significant pathological feature of obstructive nephropathy is renal interstitial fibrosis, the degree of which has close relation to the patient’s prognosis.…”