LncRNA XIST facilitates S1P-mediated osteoclast differentiation via interacting with FUS

The Regulatory Role of Long Non-Coding RNAs in the Development and Progression of Osteoporosis

Osteoporosis (OP) is a disease affecting bone metabolism, characterized by low bone mineral density and the deterioration of the bone microarchitecture, leading to increased bone fragility and risk of fracture. OP mainly results from alterations in the balance between osteoclast-mediated bone resorption and osteoblast-mediated bone formation. Currently, there are several molecular mechanisms underlying the development of OP that are not entirely clear. One such mechanism is the role of long non-coding RNAs, which are key regulators of gene expression through various mechanisms. In the last decade, it has been shown that these molecules participate in multiple biological processes and play essential roles in the pathogenesis of different diseases. In this review, we address recent advances on the relationship of long non-coding RNAs with OP, mainly over their regulatory functions during osteoclastogenesis and osteogenesis. Furthermore, we analyze their potential application as clinical or therapeutic resources focused on OP.

Interactions between lncRNAs and cyclins/CDKs complexes; key players in determining cancer cell response to CDKs inhibitors

Transcription takes place over a significant portion of the human genome. However, only a small portion of the transcriptome, roughly 1.2 %, consists of RNAs translated into proteins; the majority of transcripts, on the other hand, comprise a variety of RNA families with varying sizes and functions. A substantial portion of this diverse RNA universe consists of sequences longer than 200 bases, called the long non-coding RNA (lncRNA). The control of gene transcription, changes to DNA topology, nucleosome organization and structure, paraspeckle creation, and assistance for developing cellular organelles are only a few of the numerous tasks performed by lncRNA. The main focus of this study is on the function of lncRNA in controlling the levels and actions of cyclin-dependent kinase inhibitors (CDKIs). The enzymes required for the mitotic cycle's regulated progression are called cyclin-dependent kinases (CDKs). They have many degrees of regulation over their activities and interact with CDKIs as their crucial mechanisms. Interestingly, culminating evidence has clarified that lncRNAs are associated with several illnesses and use CDKI regulation to control cellular function. Nonetheless, despite the abundance of solid evidence in the literature, it still seems unlikely that lncRNA will have much of an impact on controlling cell proliferation or modulating CDKIs.

LncRNA XIST regulates osteoclast formation and promotes orthodontically induced inflammatory root resorption through miR-130b-3p/PTEN axis

The long non-coding RNA (LncRNA) X-inactive specific transcript (XIST) regulates the biological process of osteoclasts and the process of related diseases. This study was attempted to investigate the mechanism of LncRNA XIST acting in osteoclast formation and orthodontic induced inflammatory root resorption (OIIRR). The compression force (CF) -induced cell model and the orthodontic tooth movement (OTM) rat model were designed and established in this study. The expression of LncRNA XIST, miR-130b-3p, phosphatase and tensin homolog deleted on chromosome 10 (PTEN) as well as osteoclast related marker genes and inflammatory factors level were measured in this study. The interaction among LncRNA XIST, microRNA-130b-3p (miR-130b-3p) and PTEN were researched through luciferase activity and western blot assay. Pathological sections were used to analyze root resorption and osteoclast formation. The OTM rat model was successfully constructed, which was characterized by increased tooth spacing and increased root resorption pits. PTEN and LncRNA XIST was overexpressed in OTM group. Mechanism analysis showed that the overexpression of LncRNA XIST enhanced the PTEN level by sponging miR-130b-3p. The overexpression of LncRNA XIST increased the secretion of inflammatory factors and positive osteoclasts number, but inhibited the differentiation of osteoclasts by sponging miR-130b-3p and promoting the level of PTEN. This finding demonstrates that LncRNA XIST regulates osteoclast formation and aggravated OIIRR through miR-130b-3p/PTEN axis, suggesting that LncRNA XIST may be used as potential targets for OIIRR therapy.

Exosomal lncRNA HCP5 derived from human bone marrow mesenchymal stem cells improves chronic periodontitis by miR-24-3p/HO1/P38/ELK1 pathway

Objective

The present study aimed to explore the function of human bone marrow mesenchymal stem cells (hBMMSCs)-derived exosomal long noncoding RNA histocompatibility leukocyte antigen complex P5 (HCP5) in the osteogenic differentiation of human periodontal ligament stem cells (hPDLSCs) to improve chronic periodontitis (CP).

Methods

Exosomes were extracted from hBMMSCs. Alizarin red S staining was used to detect mineralised nodules. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was used to measure HCP5 and miR-24-3p expression. The mRNA and protein levels of alkaline phosphatase (ALP), osteocalcin, osterix, runt-related transcription factor 2, bone morphogenetic protein 2, osteopontin, fibronectin, collagen 1, heme oxygenase 1 (HO1), P38, and ETS transcription factor ELK1 (ELK1) were detected using RT-qPCR and Western blot. Enzyme-linked immunosorbent assay (ELISA) kits were used to determine the HO1 and carbon monoxide concentrations. Heme, biliverdin, and Fe2+ levels were determined using detection kits. Micro-computed tomography, hematoxylin and eosin staining, ALP staining, tartrate-resistant acid phosphatase staining, ELISA, and RT-qPCR were conducted to evaluate the effect of HCP5 on CP mice. Dual luciferase, RNA immunoprecipitation, and RNA pulldown experiments were performed to identify the interactions among HCP5, miR-24-3p, and HO1.

Results

The osteogenic ability of hPDLSCs significantly increased when co-cultured with hBMMSCs or hBMMSCs exosomes. Overexpression of HCP5 and HO1 in hBMMSCs exosomes promoted the osteogenic differentiation of hPDLSCs, and knockdown of HCP5 repressed the osteogenic differentiation of hPDLSCs. HCP5 knockdown enhanced the inflammatory response and repressed osteogenesis in CP mice. MiR-24-3p overexpression diminished the stimulatory effect of HCP5 on the osteogenic ability of hPDLSCs. Mechanistically, HCP5 acted as a sponge for miR-24-3p and regulated HO1 expression, and HO1 activated the P38/ELK1 pathway.

Conclusion

HBMMSCs-derived exosomal HCP5 promotes the osteogenic differentiation of hPDLSCs and alleviates CP by regulating the miR-24-3p/HO1/P38/ELK1 signalling pathway.

lncRNA-Gm5532 regulates osteoclast differentiation through the miR-125a-3p/TRAF6 axis

Long noncoding RNAs (lncRNAs) are important regulators of bone metabolism. In this study, lncRNA microarray analysis was used to identify differentially expressed lncRNAs in differentiated osteoclasts. lncRNA-Gm5532 is highly expressed during osteoclast differentiation. lncRNA-Gm5532 knockdown impairs osteoclast formation and bone resorption. Mechanistic experiments show that lncRNA-Gm5532 functions as a competing endogenous RNA (ceRNA) and acts as a sponge for miR-125a-3p, which promotes TNF receptor-associated factor 6 (TRAF6) expression. miR-125a-3p mimics suppress osteoclast differentiation and TAK1/NF-κB/MAPK signaling. The miR-125a-3p inhibitor reverses the negative effects of siGm5532 on osteoclast differentiation. In summary, our study reveals that lncRNA-Gm5532 functions as an activator in osteoclast differentiation by targeting the miR-125a-3p/TRAF6 axis, making it a novel biomarker and potential therapeutic target for osteoporosis.

Role and Regulation of Transcription Factors in Osteoclastogenesis

Bones serve mechanical and defensive functions, as well as regulating the balance of calcium ions and housing bone marrow.. The qualities of bones do not remain constant. Instead, they fluctuate throughout life, with functions increasing in some situations while deteriorating in others. The synchronization of osteoblast-mediated bone formation and osteoclast-mediated bone resorption is critical for maintaining bone mass and microstructure integrity in a steady state. This equilibrium, however, can be disrupted by a variety of bone pathologies. Excessive osteoclast differentiation can result in osteoporosis, Paget's disease, osteolytic bone metastases, and rheumatoid arthritis, all of which can adversely affect people's health. Osteoclast differentiation is regulated by transcription factors NFATc1, MITF, C/EBPα, PU.1, NF-κB, and c-Fos. The transcriptional activity of osteoclasts is largely influenced by developmental and environmental signals with the involvement of co-factors, RNAs, epigenetics, systemic factors, and the microenvironment. In this paper, we review these themes in regard to transcriptional regulation in osteoclastogenesis.

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

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.

Fine-tuning osteoclastogenesis: An insight into the cellular and molecular regulation of osteoclastogenesis

Osteoclasts, the bone-resorbing cells, are essential for the bone remodeling process and are involved in the pathophysiology of several bone-related diseases. The extensive corpus of in vitro research and crucial mouse model studies in the 1990s demonstrated the key roles of monocyte/macrophage colony-stimulating factor, receptor activator of nuclear factor kappa B ligand (RANKL) and integrin αvβ3 in osteoclast biology. Our knowledge of the molecular mechanisms by which these variables control osteoclast differentiation and function has significantly advanced in the first decade of this century. Recent developments have revealed a number of novel insights into the fundamental mechanisms governing the differentiation and functional activity of osteoclasts; however, these mechanisms have not yet been adequately documented. Thus, in the present review, we discuss various regulatory factors including local and hormonal factors, innate as well as adaptive immune cells, noncoding RNAs (ncRNAs), etc., in the molecular regulation of the intricate and tightly regulated process of osteoclastogenesis. ncRNAs have a critical role as epigenetic controllers of osteoclast physiologic activities, including differentiation and bone resorption. The primary ncRNAs, which include micro-RNAs, circular RNAs, and long noncoding RNAs, form a complex network that affects gene transcription activities associated with osteoclast biological activity. Greater knowledge of the involvement of ncRNAs in osteoclast biological activities will contribute to the treatment and management of several skeletal diseases such as osteoporosis, osteoarthritis, rheumatoid arthritis, etc. Moreover, we further outline potential therapies targeting these regulatory pathways of osteoclastogenesis in distinct bone pathologies.

New insights into the role of long non-coding RNAs in osteoporosis

Osteoporosis is a common disease in elderly individuals, and osteoporosis can easily lead to bone and hip fractures that seriously endanger the health of elderly individuals. At present, the treatment of osteoporosis is mainly anti-osteoporosis drugs, but there are side effects associated with anti-osteoporosis drugs. Therefore, it is very important to develop early diagnostic indicators and new therapeutic drugs for the prevention and treatment of osteoporosis. Long noncoding RNAs (lncRNAs), noncoding RNAs longer than 200 nucleotides, can be used as diagnostic markers for osteoporosis, and lncRNAs play an important role in the progression of osteoporosis. Many studies have shown that lncRNAs can be the target of osteoporosis. Therefore, herein, the role of lncRNAs in osteoporosis is summarized, aiming to provide some information for the prevention and treatment of osteoporosis.

Exosomes from artesunate-treated bone marrow-derived mesenchymal stem cells transferring SNHG7 to promote osteogenesis via TAF15-RUNX2 pathway

Aim: Effect of artesunate (ART)-treated bone marrow-derived mesenchymal stem cells-derived exosomes (BMSC-Exos) on osteogenesis and its underlying mechanisms were investigated. Materials & methods: Proliferation, alkaline phosphatase activity and calcified nodule formation of osteoblasts were determined. A mouse model of osteoporosis was established by ovariectomy. Results: SNHG7 was upregulated in BMSC-Exos by twofold, which was further enhanced in ART-BMSC-Exos by about twofold. ART intensified BMSC-Exos-induced proliferation, alkaline phosphatase activity by about fourfold, calcified nodule formation by about threefold and upregulation of osteogenesis related molecules RUNX2 (by 50%), BMP2 (by 30%) and ATF4 (by 40%) via delivering SNHG7. Mechanistically, SNHG7 recruited TAF15 to facilitate RUNX2 stability. Conclusion: ART-BMSC-Exos facilitated osteogenesis via delivering SNHG7 by modulating TAF15/RUNX2 axis.

The effect of long non-coding RNAs in joint destruction of rheumatoid arthritis

Rheumatoid arthritis (RA) is a systemic autoimmune disease accompanied with joint destruction. Serious joint destruction will eventually lead to disability and the decline of life quality in RA patients. At present, the therapeutic effect of drugs to alleviate joint destruction in RA is limited. Recently, accumulating evidences have shown that long non-coding RNAs (lncRNAs) play an important role in the pathogenesis of joint diseases. Therefore, this paper reviews the expression change and the action mechanism of lncRNAs in joint destruction of RA in recent years. A more comprehensive understanding of the role of lncRNAs in joint destruction will help the treatment of RA.