Circ_0020093 ameliorates IL-1\u03b2-induced apoptosis and extracellular matrix degradation of human chondrocytes by upregulating SPRY1 via targeting miR-23b

Mingli Feng,Jingbo Cheng,Lin Jing,Shuai An,Jiang Huang,Qi Yan

doi:10.1007/s11010-021-04186-2

Abstract

Osteoarthritis (OA) is a chronic disease characterized by articular cartilage degeneration and uncontrolled chondrocyte apoptosis. At present, accumulating evidence introduces that circular RNA (circRNA) is involved in the development of OA. The aim of our study was to explore the role and the functional mechanism of circ_0020093 in OA cell model. Human chondrocytes were treated with interleukin-1 beta (IL-1β) to construct OA model. The expression of circ_0020093, miR-23b, and Sprouty 1 (SPRY1) mRNA was measured by quantitative real-time polymerase chain reaction (qRT-PCR). Cell apoptosis was assessed by flow cytometry assay. The expression of extracellular matrix (ECM)-associated markers and SPRY1 protein level was detected by qRT-PCR and Western blot. Bioinformatics analysis-predicted relationship between miR-23b and circ_0020093 or SPRY1 was further verified by dual-luciferase reporter assay and RNA pull-down assay. In this study, we found that the expression of circ_0020093 and SPRY1 was declined, while miR-23b expression was elevated in IL-1β-treated chondrocytes. IL-1β induced chondrocyte apoptosis and ECM degradation, while these negative effects were alleviated by circ_0020093 overexpression or miR-23b inhibition. MiR-23b was a target of circ_0020093, and SPRY1 was a downstream target of miR-23b. Rescue experiments showed that miR-23b enrichment reversed the role of circ_0020093 overexpression, and SPRY1 knockdown also reversed the effects of miR-23b inhibition. Importantly, circ_0020093 positively regulated SPRY1 expression by targeting miR-23b. In conclusion, circ_0020093 ameliorates IL-1β-induced apoptosis and ECM degradation of human chondrocytes by regulating the miR-23b/SPRY1 axis.

Highlights

Osteoarthritis (OA) is the most common disease of synovial joints, characterized by cellular stress and extracellular matrix (ECM) degradation due to micro- and macro-damages, thereby activating maladaptive repair responses [1, 2]
We found that the apoptotic rate in IL-1β-treated chondrocytes was significantly higher than control, while the reintroduction of circ_0020093 or in-miR-23b notably inhibited cell apoptosis (Fig. 2C, D)
In chondrocytes with IL-1β treatment, we found that the expression of circ_0020093 was significantly declined, which was consistent with the previous data that both IL-1β and tumor necrosis factor-α (TNF-α) treatment could diminish the expression level of circ_0020093 in chondrocytes [9]

Summary

Introduction

Osteoarthritis (OA) is the most common disease of synovial joints, characterized by cellular stress and extracellular matrix (ECM) degradation due to micro- and macro-damages, thereby activating maladaptive repair responses [1, 2]. It is estimated that by 2050, 130 million people worldwide. Mingli Feng and Lin Jing have contribute to this work as co-first authors. The landscapes of circular RNA (circRNA) arouse many public interests because increasing evidence supports that circRNA is implicated in the development of numerous human diseases [6]. CircRNA is produced by precursor mRNA via “back-splicing” and identified by its unique closed-loop structure [6]. In OA, partial circRNAs have been presented to be deregulated in OA synovial fluid or in vitro chondrocyte models, and their functions have been preliminarily discussed.

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