环状 ITCH 通过 IGF2BP2 介导的 mA 修饰稳定 BRCA1 mRNA，促进 HOXC10 的泛素化降解，以促进废用性骨质疏松症中的成骨分化。

Circ-ITCH promotes the ubiquitination degradation of HOXC10 to facilitate osteogenic differentiation in disuse osteoporosis through stabilizing BRCA1 mRNA via IGF2BP2-mediated mA modification.

作者信息

Zhong Da, Li Xi, Yin Zhen, Chen Peng, Li Yusheng, Tian Jian, Wang Long, Liu Hua, Yin Ke, Zhu Lemei, Kong Lingyu, Chen Kunli, Li Yaochun, Hong Chungu, Wang Chenggong

机构信息

Department of Orthopaedics, Xiangya Hospital of Central South University, Changsha, China.

Hunan Key Laboratory of Aging Biology, Xiangya Hospital, Central South University, Changsha, China.

出版信息

J Transl Med. 2025 Mar 27;23(1):376. doi: 10.1186/s12967-024-06050-5.

DOI:10.1186/s12967-024-06050-5

PMID:40148953

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC11951756/

Abstract

BACKGROUND

Osteogenic differentiation of bone marrow mesenchymal stem cells (BM-MSCs) facilitated by mechanical loading is a promising therapy for disuse osteoporosis (DOP), however, it is difficult to implement mechanical loading for a majority of patients. Our study aims to identify circ-ITCH-mediated novel approach to facilitate osteogenic differentiation in DOP.

METHODS

A rat DOP model and human BM-MSCs under microgravity condition were generated as in vivo and in vitro models of DOP, respectively. The bone mineral density (BMD) and bone parameters were examined in rats. The histological changes of bones and mineralization were monitored by H&E, Alcian blue and Alizarin red S staining. Co-IP was employed to examine the ubiquitination of HOXC10 and the interaction between HOXC10 and BRCA1. The direct associations among circ-ITCH, IGFBP2 and BRCA1 mRNA were assessed by RIP, FISH and RNA pull-down assays.

RESULTS

Circ-ITCH was downregulated in rat model of DOP and BM-MSCs under microgravity stimulation. Circ-ITCH overexpression promoted osteogenic differentiation in BM-MSCs under microgravity condition. The altered bone parameters, such as BMD, trabecular number (Tb.N), trabecular separation (Tb.Sp), trabecular thickness (Tb.Th), and bone microstructure in DOP rats were rescued by circ-ITCH overexpression. Mechanistically, circ-ITCH enhanced the ubiquitination degradation of HOXC10 through enhancing BRCA1 mRNA stability. Circ-ITCH directly bound to IGF2BP2 protein to stabilize BRCA1 mRNA via mA modification, thus facilitating osteogenic differentiation in BM-MSCs under microgravity condition.

CONCLUSION

Circ-ITCH stabilized BRCA1 mRNA via IGF2BP2-mediated mA modification, thereby facilitating the ubiquitination degradation of HOXC10 to promote osteogenic differentiation in DOP.

摘要

背景

机械负荷促进骨髓间充质干细胞（BM-MSCs）向成骨分化是一种很有前景的废用性骨质疏松症（DOP）治疗方法，然而，大多数患者难以实施机械负荷。我们的研究旨在确定circ-ITCH介导的促进DOP中成骨分化的新方法。

方法

分别建立大鼠DOP模型和模拟微重力条件下的人BM-MSCs，作为DOP的体内和体外模型。检测大鼠的骨密度（BMD）和骨参数。通过苏木精-伊红（H&E）、阿尔辛蓝和茜素红S染色监测骨组织学变化和矿化情况。采用免疫共沉淀（Co-IP）检测HOXC10的泛素化以及HOXC10与BRCA1之间的相互作用。通过RNA免疫沉淀（RIP）、荧光原位杂交（FISH）和RNA下拉实验评估circ-ITCH、胰岛素样生长因子结合蛋白2（IGFBP2）和BRCA1 mRNA之间的直接关联。

结果

在DOP大鼠模型和模拟微重力刺激下的BM-MSCs中，circ-ITCH表达下调。circ-ITCH过表达促进了模拟微重力条件下BM-MSCs的成骨分化。circ-ITCH过表达挽救了DOP大鼠中改变的骨参数，如BMD、骨小梁数量（Tb.N）、骨小梁间距（Tb.Sp）、骨小梁厚度（Tb.Th）和骨微结构。机制上，circ-ITCH通过增强BRCA1 mRNA稳定性增强HOXC10的泛素化降解。circ-ITCH直接与IGF2BP2蛋白结合，通过m6A修饰稳定BRCA1 mRNA，从而促进模拟微重力条件下BM-MSCs的成骨分化。