CircZNF367 promotes osteoclast differentiation and osteoporosis by interacting with FUS to maintain CRY2 mRNA stability

Abstract

Background Osteoporosis, characterized by reduced bone mass and deterioration of bone quality, is a significant health concern for postmenopausal women. Considering that the specific role of circRNAs in osteoporosis and osteoclast differentiation remains poorly understood, this study aims to shed light on their involvement in these processes to enhance our understanding and potentially contribute to improved treatment strategies for osteoporosis. Methods An osteoporotic model was constructed in vivo in ovariectomized mouse. In vitro, we induced osteoclast formation in bone marrow-derived macrophages (BMDMs) using M-CSF + RANKL. To assess osteoporosis in mice, we conducted HE staining. We used MTT and TRAP staining to measure cell viability and osteoclast formation, respectively, and also evaluated their mRNA and protein expression levels. In addition, RNA pull-down, RIP and luciferase reporter assays were performed to investigate interactions, and ChIP assay was used to examine the impact of circZNF367 knockdown on the binding between FUS and CRY2. Results We observed increased expression of CircZNF367, FUS and CRY2 in osteoporotic mice and M-CSF + RANKL-induced BMDMs. Functionally, knocking down circZNF367 inhibited osteoporosis in vivo. Furthermore, interference with circZNF367 suppressed osteoclast proliferation and the expression of TRAP, NFATc1, and c-FOS. Mechanistically, circZNF367 interacted with FUS to maintain CRY2 mRNA stability. Additionally, knocking down CRY2 rescued M-CSF + RANKL-induced osteoclast differentiation in BMDMs promoted by circZNF367 and FUS. Conclusion This study reveals that the circZNF367/FUS axis may accelerate osteoclasts differentiation by upregulating CRY2 in osteoporosis and suggests that targeting circZNF367 may have potential therapeutic effects on osteoporosis.

Highlights on the Effects of Non-Coding RNAs in the Osteonecrosis of the Jaw

“…Standardizing the diagnosis of ONJ might be possible by a valuable biomarker, which could be also used to evaluate the risk in patients undergoing bisphosphonates treat-ment [52][53][54][55]. Numerous studies have hypothesized that circRNAs may sequester miRNAs to modify mRNA expression [56] and some of them, via their effects on ONJ-related miR-NAs, are essential in RANKL-induced RAW264.7 cells treated with bisphosphonates [57] (Figure 2).…”

“…Standardizing the diagnosis of ONJ might be possible by a valuable biomarker, which could be also used to evaluate the risk in patients undergoing bisphosphonates treatment [52][53][54][55]. Numerous studies have hypothesized that circRNAs may sequester miRNAs to modify mRNA expression [56] and some of them, via their effects on ONJ-related miRNAs, are essential in RANKL-induced RAW264.7 cells treated with bisphosphonates [57] (Figure 2). Patients with ONJ showed higher blood levels of miR-23a and lower serum levels of miR-145: miR-23a targets specific genes such as osteoclast stimulating factor 1 (OSTF1), secreted protein acidic and rich in cysteine (SPARC) and SPOCK1, low-density lipoprotein receptor-related protein 5 (LRP5), while miR-145 acts on interleukin (IL) and genes related to bone homeostasis, such as osteomodulin, and secreted protein acidic and rich in cysteine.…”

Exploring the Role of Circular RNA in Bone Biology: A Comprehensive Review

“…Thus, by regulating key signaling pathways involved in this process, circRNAs have been implicated in modulating osteoclastogenesis. For instance, Deng et al reported that CircZNF367 promotes osteoclasogenesis and can contribute to osteoporosis through the interaction with FUS, maintaining the stability of CRY2 mRNA and thus enhancing proliferation and TRAP, NFATc1, and c-FOS expression in osteoclast [ 70 ]. Tang et al have demonstrated that circ_0029463 drives osteoclast differentiation through the modulation of the miR-134-5p/Rab27a axis and promoting RANKL-induced differentiation [ 10 ].…”

“…Profiling studies have identified distinct circRNA expression patterns in pathological bone tissues compared to healthy controls, offering insights into disease mechanisms and potential therapeutic targets [ 22 ]. Indeed, dysregulation of most of the aforementioned circRNAs associated with osteogenesis or osteoclastogenesis is involved in the pathogenesis of skeletal diseases [ 9 , 55 , 56 , 67 , 68 , 70 ]. However, research in recent years has significantly increased the number of identified circRNAs associated with skeletal pathologies and many other circRNA molecules are continually being discovered.…”