MicroRNA-770 promotes polarization of macrophages and hemorrhoids by suppressing RYBP expression and monoubiquitination of histone H2A on Lys119 modification

Abstract

Hemorrhoid disease (HD) is a common proctological condition whose onset is associated with an abnormal inflammatory microenvironment; however, the underlying mechanisms remain unclear. In this study, pathological examination revealed a significant increase in MΦ1 macrophages in the hemorrhoidal tissue of patients with HD, along with elevated levels of inflammatory factors. qPCR results demonstrated that the expression of several members of the DLK1-DIO3 microRNA cluster, particularly miR-770, was significantly higher in the hemorrhoid tissue of patients with HD than in that of the control group. Luciferase reporter assays confirmed that RYBP is a target gene negatively regulated by miR-770. Additionally, qPCR and western blot analyses indicated that overexpression of miR-770 significantly downregulated the expression of PRC1 family genes and RYBP in THP-1 cells, while concurrently upregulating the expression of inflammatory factors such as NFKB, IL1b, IL4, TNF, and IFNG. The overexpression of miR-770 significantly induced the polarization of THP-1 cells toward MΦ1. Mechanistic studies using ChIP-seq revealed that miR-770 overexpression significantly reduced the number of gene promoters in MΦ1 cells that bind to histone H2AK119-Ub sites. Furthermore, the number of enriched DNA fragments from genes that bind to the + 1 transcription start site of histone H2AK119-Ub, such as NFKB1, IL1B, and TNF, was significantly lower than that observed in the control group. Therefore, we confirmed that miR-770, a genomic imprinted member of the DLK1-DIO3 region, negatively regulated the expression of the PRC1 family member RYBP, reduced the level of ubiquitination modification at histone H2AK119-Ub, and promoted the transcriptional activation of pro-inflammatory genes. This ultimately leads to MΦ1 polarization and the release of inflammatory factors, elucidating the epigenetic mechanisms underlying the occurrence of hemorrhoids.