Exosomes from dysfunctional chondrocytes affect osteoarthritis in Sprague-Dawley rats through FTO-dependent regulation of PIK3R5 mRNA stability

Bone & Joint Research

article

Guohua Lv¹  Bing Wang¹  Lei Li¹  Yunchao Li¹  Xinyi Li¹  Haoyu He¹  Lei Kuang¹ 

[1] Department of Spine Surgery, The Second Xiangya Hospital of Central South University

关键词: Osteoarthritis;    Dysfunctional chondrocyte-derived exosomes;    Long non-coding RNA OANCT;    PIK3R5;    FTO;    Osteoarthritis (OA);    chondrocytes;    mRNAs;    Sprague-Dawley rats;    macrophages;    rat modelling;    cartilage tissues;    RNAs;    autophagy;    western blot;   

DOI  :  10.1302/2046-3758.119.BJR-2021-0443.R2

学科分类：骨科学

来源: British Editorial Society Of Bone And Joint Surgery

【 摘 要 】

AimsExosomes (exo) are involved in the progression of osteoarthritis (OA). This study aimed to investigate the function of dysfunctional chondrocyte-derived exo (DC-exo) on OA in rats and rat macrophages.MethodsRat-derived chondrocytes were isolated, and DCs induced with interleukin (IL)-1β were used for exo isolation. Rats with OA (n = 36) or macrophages were treated with DC-exo or phosphate-buffered saline (PBS). Macrophage polarization and autophagy, and degradation and chondrocyte activity of cartilage tissues, were examined. RNA sequencing was used to detect genes differentially expressed in DC-exo, followed by RNA pull-down and ribonucleoprotein immunoprecipitation (RIP). Long non-coding RNA osteoarthritis non-coding transcript (OANCT) and phosphoinositide-3-kinase regulatory subunit 5 (PIK3R5) were depleted in DC-exo-treated macrophages and OA rats, in order to observe macrophage polarization and cartilage degradation. The PI3K/AKT/mammalian target of rapamycin (mTOR) pathway activity in cells and tissues was measured using western blot.ResultsDC-exo inhibited macrophage autophagy (p = 0.002) and promoted M1 macrophage polarization (p = 0.002). DC-exo at 20 μg/ml induced collagen degradation (p < 0.001) and inflammatory cell infiltration (p = 0.023) in rats. OANCT was elevated in DC (p < 0.001) and in cartilage tissues of OA patients (p < 0.001), and positively correlated with patients’ Kellgren-Lawrence grade (p < 0.001). PIK3R5 was increased in DC-exo-treated cartilage tissues (p < 0.001), and OANCT bound to fat mass and obesity-associated protein (FTO) (p < 0.001). FTO bound to PIK3R5 (p < 0.001) to inhibit the stability of PIK3R5 messenger RNA (mRNA) (p < 0.001) and disrupt the PI3K/AKT/mTOR pathway (p < 0.001).ConclusionExosomal OANCT from DC could bind to FTO protein, thereby maintaining the mRNA stability of PIK3R5, further activating the PI3K/AKT/mTOR pathway to exacerbate OA.

【 授权许可】

CC BY-NC