
==== Front
Heliyon
Heliyon
Heliyon
2405-8440
Elsevier

S2405-8440(24)13222-7
10.1016/j.heliyon.2024.e37191
e37191
Review Article
The role of NF-κB-SOX9 signalling pathway in osteoarthritis
Tian Bin ab1
Zhang Liang a1
Zheng Jiang a1
Kang Xin honghuikangxin@163.com
a⁎
a Department of Sports Medicine, Honghui Hospital, Xi'an Jiao Tong University, Shaanxi, 710054, PR China
b Department of Orthopedics, the First Afffliated Hospital of Guizhou University of Traditional Chinese Medicine, Guiyang, China
⁎ Corresponding author. honghuikangxin@163.com
1 Authors contributed equally.

30 8 2024
15 9 2024
30 8 2024
10 17 e3719113 9 2023
28 8 2024
28 8 2024
© 2024 The Authors. Published by Elsevier Ltd.
2024

https://creativecommons.org/licenses/by-nc-nd/4.0/ This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
Abstrat

The nuclear factor-κB (NF-κB) signalling pathway exists in a variety of cells and is involved in the gene regulation of various physiological and pathological processes such as inflammation, immunity, cell proliferation and apoptosis. It has been shown that this signaling pathway is also involved in numerous events associated with osteoarthritis, including chondrocyte catabolism, chondrocyte survival, and synovial inflammation. SRY-related high mobility group-box 9(SOX9) is the “master regulator” of chondrocytes and one of the key transcription factors that maintain chondrocyte phenotype and cartilage homeostasis. NF-κB can positively regulate the expression of SOX9 by directly binding to its promoter region, and play a role in the formation and development of chondrocytes. This article reviews the regulatory effect of the NF-κB-SOX9 signaling axis on osteoarthritis.

Keywords

NF-κB
SOX9
Signalling pathway
Chondrocytes
OA
==== Body
pmc1 Introduction

Osteoarthritis (OA) is a chronic progressive Osteoarthritis characterized by articular cartilage injury and reactive hyperplasia of joint margins and subchondral bone [1]. Its pathogenesis is complex, and genetic factors, environmental factors and obesity are one of the causes [2]. The incidence and disability rate of OA are higher in the middle-aged and elderly population, with an incidence of 10 percent in men and 18 percent in women over the age of 60 [3]. OA is characterized by joint pain, swelling, deformity, and is accompanied by functional impairment, which seriously affects the normal life of middle-aged and elderly patients, and brings a serious economic burden to society and families. The destruction of articular cartilage during the pathogenesis of OA is not only related to the death of chondrocytes, but also to the loss of cartilage extracellular matrix. In addition, chondrocytes are the only resident cells in articular cartilage and play an important role in maintaining the function and structure of articular cartilage by controlling the synthesis and degradation of extracellular matrix [4].

SOX9 is the “main regulatory factor” of chondrocytes, one of the key transcription factors that maintain chondrocyte phenotype and cartilage homeostasis, and is closely related to the extracellular matrix (ECM) metabolism of articular chondrocytes [5]. During limb development, inactivation of SOX9 can lead to complete loss of bone and cartilage, while upregulation of SOX9 may inhibit chondrocyte apoptosis [6,7]. Inflammatory factors are overexpressed in OA and other diseases, which significantly inhibit the biological effects of SOX9 and weaken the regeneration and repair ability of damaged cartilage tissues [7]. NF-κB is a transcription factor that plays a key role in biological processes and has been found to be involved in inflammatory and immune responses as well as in the regulation of gene expression such as cell proliferation and apoptosis [8]. Most studies have revealed that SOX9 expression is regulated through the NF-κB signalling pathway. The mode of action of NF-κB and SOX9 may be to positively regulate the expression of SOX9 by directly binding to its promoter region [9]. In addition, studies have also shown that NF-κB signaling is abnormally activated in OA, and is considered to be one of the most important signalling pathways, and significantly regulates OA-related inflammatory mediators [10]. The purpose of this review is to reveal the role of SOX9 and NF-κB signalling pathways in OA disease, and to provide biomarkers and therapeutic targets for the diagnosis and treatment of OA.

2 NF-kappa β family

NF-κB molecule is a protein complex, which was first discovered by RanjanSen (NIH) in the laboratory of Nobel laureate DavidBaltimore through its interaction with II base pairs in immunoglobulin light chain enhancers in B cells [11]. NF-κB exists in nearly all types of animal cells and is an important nuclear transcription factor in cells. It participates in cellular responses to stimuli, such as stress, cytokines, free radicals, heavy metals, ultraviolet radiation, oxidation of Low Density Lipoprotein (LDL) and bacterial or viral antigens. NF-κB plays a key role in regulating the immune response to infection, and the abnormal activation of NF-κB signal is closely related to cancer, inflammation and autoimmune diseases [12,13]. There are mainly five members of NF-κB family in mammals, namely RelA (p65), RelB, c-Rel, NF-κB1 (p50) and NF-κB2 (p52), which form homodimers and Heterodimers to play a role. There is a 300-amino acid region at the N-terminal of these five subunits, namely REL homology domain (RHD), which mediates their dimerization into the nucleus and binding to the corresponding DNA sites, thus regulating the transcription of target genes [14,15]. In the NF-κB family, only the subunit with a transactivation domain (TADS) at the C-terminal can activate transcription, while p50 and p52 do not. Only RelA (p65), RelB and c-Rel carry a transactivation domain. Therefore, NF-κB dimers formed by p50 and p52 subunits cannot be activated for transcription, and they can only promote transcription when they form heterodimers with other NF-κB subunits containing transactivation domains [[16], [17], [18]]. In the absence of stimulation, the dimer formed by these subunits binds to NF-κB inhibitor protein (IκB) to form complexes and is shelved in the cytoplasm; while stimulating by inflammatory factors or other substances, IκB is phosphorylated and the NF-κB dimer is released into the nucleus to activate transcription [19].

3 Activation mechanism of NF-κB signaling

The main function of IκB protein is closely related to the activation of NF-κB signal, that is, shielding the nuclear localization signal and preventing NF-κB dimer from entering the nucleus to regulate gene expression. The IκB protein is composed of IκBα, IκBβ, IκBγ, IκBδ, IκBε, etc. Its family structure is characterized by multiple repeat sequences of about 33 amino acids, called multiple ankyrin repeat domains, which are mainly involved in the RHD interaction with Rel protein [20]. Only after IκB is phosphorylated and degraded by proteasome can NF-κB dimer be released into the nucleus for transcriptional activation to regulate the expression of inflammatory factors [21,22]. The enzyme responsible for the phosphorylation of IκB is IκB kinase (IKK), which is an enzyme complex. The IKK complex consists of IKKα (IKK1), IKKβ (IKK2), and a regulatory subunit, the NF-κB essential modulator (NEMO) [23]. It has been found that although IKKα and IKKβ are structurally similar, the subunit involved in the phosphorylation of IκB in the IKK complex is mainly IKKβ, and IKKα is only responsible for a small part. Among them, IKKβ is mainly involved in activating of the classical NF-κB pathway. In addition, it may also be related to the maintenance of the homeostasis of the extracellular matrix microenvironment [24]. And IKKα is involved in the activation of the non-canonical NF-κB pathway [25]. Studies have shown that mice lacking NEMO will cause severe liver function damage and death due to the apoptosis of a large number of cells, which indicates that NEMO is an essential regulatory subunit for activating NF-κB signal. On the other hand, the N-terminal of NEMO binds to the IKKs, and the C-terminal mediates its interaction with upstream signal transducers [26,27]. The activation of NF-κB signal is not only stimulated by inflammatory factors, viruses and bacteria, but also related to its post-translational modification regulation, such as phosphorylation, ubiquitin, methylation and acetylation [28].

4 Activation pathway of NF-κB signalling pathway

The NF-κB signal pathway is activated, which may regulate a various of biological functions, such as inflammatory response, immune response, stress response and tumourigenesis. However, there are two activation pathways of NF-κB signal, namely the classical activation pathway and the non-classical (alternative) activation pathway. The activation mechanism, regulatory pathway and gene expression of the two pathways are different. Below we will elaborate on these two different activation pathways.

4.1 The classical NF-κB pathway

The classical activation pathway of NF-κB is mainly involved in rapid and reversible inflammatory responses, etc, and its pathways are mostly activated by stimuli such as inflammatory factors, bacteria, viruses, Toll-like receptors, antigen receptors, and ultraviolet radiation [29]. In the absence of various stimuli, NF-κB forms a complex with the IκB protein in the cytoplasm and exists in an inactive state with no regulating functions. Only after the complex is stimulated by the previous substance, the activity can be activated to exert its function. The activation of NF-κB complex is realized by IKK kinase acting on IκB protein, phosphorylation and proteasome degradation. The key activation subunit in IKK is IKKβ, and its activity depends on the oligomerization of IKKα, IKKβ and NEMO, the three subunits of its IKK complex [30]. It has been proved that NEMO is the basic regulator of NF-κB,binding to the ubiquitin chain can cause conformational changes and assist the activation of IKK kinase complex [15,31]. The activated subunit IKKβ of the IKK kinase exerts its phosphorylation effect to phosphorylate two conserved serine residues at positions 32 and 36 of the IκB protein in the NF-κB complex, and undergo polyubiquitination, which is finally processed by the 26S proteasome, thereby releasing NF-κB homologous or heterodimer into the nucleus. When the NF-κB signal is released into the nucleus, it can bind to the consensual binding sequence in the corresponding promoter and activator to target gene expression [32].

The rapid activation of the classical NF-κB pathway induces inflammation and immune-related responses. Although it plays a role in protecting the body, uncontrolled activation can lead to damage or serious harm to the body, such as autoimmune diseases, chronic inflammation and tumorigenesis. Therefore, the NF-κB signalling pathway should be strictly controlled to protect the function of the organism. At present, it has been found that the classical NF-κB pathway is negatively regulated [33]. When the NF-κB complex is activated and released and enters the nucleus, the newly synthesized IκB α binds to NF-κB dimer in a concentration-dependent manner and promotes transfer to the cytoplasm, resulting in the termination of NF-κB signal transcription [34]. Studies have found that IκBβ can counteract the inhibitory effect of IκBα by binding to the nuclear dimer, resulting in continued transcriptional signaling [35,36], while IκBε can inhibit IκBα-mediated oscillations [27]. The three members of the IκB family, IκBα, IκBβ, and IκBε, cooperate with each other to ensure the normal operation of NF-κB signaling. In addition, we also found that deubiquitination plays a role in the negative regulatory mechanism of the classical NF-κB pathway, mainly in the upstream signal transduction of IKK [14]. The above results show that the negative regulation of NF-κB pathway is involved in many pathways and its standard operation is strictly regulated.

4.2 The alternative NF-κB pathway

The activation of the non-classical NF-κB pathway is a slow, long-lasting, irreversible response, and is closely related to the immune system, such as the occurrence of lymphoid organs, the development of B cells, and T cell responses [23]. Non-classical pathways are usually activated by the tumor necrosis factor receptor (TNFR) family, namely CD40 ligand (CD40L), B-cell tumor necrosis factor receptor (BAFF-R), and lymphotoxin receptor (LTβ-R) [37]. The non-classical NF-κB pathway is mediated by the transcriptional factor p100/Rel B complex, and both IKKα and NF-κB-induced kinase (NIK) are involved in its activation, but IKKβ and NEMO in the IKK complex have not been found to play a role in this pathway [38,39]. NIK, also known as mitogen-activated protein kinase kinase kinase 14 (MAP3K14), is a component of the non-classical NF-κB pathway, which is mainly responsible for the phosphorylation of IKKα and then participates in the processing of p100 [23]. P100 is an inhibitor and precursor protein of the P52 subunit. Without stimulation, P100 blocks the transcriptional activity of the P100/Rel B complex due to its N-terminal auto-inhibitory function [40]. After stimulation, the binding of TNF family receptors to ligands leads to the weakening or disappearance of ubiquitination on NIK, thereby activating NIK kinase. The restored NIK kinase can phosphorylate and activate IKKα, and then the activated IKKα can mediate the phosphorylation and ubiquitination of p100 to generate p52. Finally, p52 and Rel B form a dimer and enter the nucleus to activate target genes [20,41,42]. Therefore, NIK kinase is a key protein in activating the non-canonical NF-κB pathway [43], and the processing of p100 is an important step in this signalling pathway.

5 The functional role of NF-κΒ signaling in OA

Osteoarthritis is characterized by the destruction and loss of articular cartilage. Chondrocytes are resident cells in articular cartilage, embedded in the extracellular matrix. Due to the lack of blood vessels and nerve tissue on the surface of cartilage, the self-repair ability of chondrocytes is poor. As a consequence, injury, inflammation and degeneration can lead to dedifferentciation. In addition, the loss of chondrocyte phenotype will accelerate the degradation of cartilage matrix, leading to irreversible cartilage damage, resulting in OA [44]. The normal growth and development of cartilage is divided into four parts, namely, resting area, proliferative area, Prophase hypertrophic area and hypertrophic area, while the classical p65 pathway plays a role in the whole process of cartilage growth, but mainly in the resting zone and hypertrophic area [45,46]. In addition, it is also found that the non-classical NF-κB signal pathway is also involved in the development of cartilage growth plate, but in the surrounding area, this pathway is also involved in endochondral osteogenesis by regulating the proliferation and differentiation of chondrocytes [26]. However, in OA, NF-κB signalling pathway plays the opposite role due to abnormal activation. It has been found that the abnormally activated NF-κB signal pathway is closely related to chondrocyte differentiation, extracellular matrix degradation and synovitis in OA, and this pathway also plays the function of apoptosis and anti-proliferation in OA chondrocytes [47,48]. In the development of OA disease, it is primarily the NF-κB signal of the classical pathway that is abnormally activated, and the non-classical pathway plays a lesser role.

The classical NF-κB signal pathway plays a key role in the catabolism and inflammation of chondrocytes [16,49]. The abnormal activation of this pathway will lead to abnormal expression of regulatory genes after binding to corresponding DNA targets due to the increase of p65 in the nucleus, such as the overexpression of interleukin-1β (IL-1β), interleukin-6 (IL-6), C-C motif chemokine ligand 5 (CCL5), cyclooxygenase-2 (COX-2) and prostaglandin E2 (PGE2), which can induce chondrocyte differentiation, apoptosis and extracellular matrix degradation, and eventually lead to inflammation and degeneration of articular cartilage [50,51]. Studies have shown that tumor necrosis factor-α (TNF-α), IL-1β and IL-6 can promote the secretion of matrix metalloproteinase and reduce the production of collagen and proteoglycans. PGE2 and hypoxia inducible factor-2α can accelerate the apoptosis of chondrocytes mediated by Fas, but NF-κB can also prevent chondrocyte death induced by tumor necrosis factor-alpha, and this anti-apoptotic effect is also essential in chondrocytes [52,53]. In conclusion, NF-κB plays a bidirectional role in chondrocyte survival and apoptosis. And related researchers, using specific siRNA to inhibit the expression of NF-κB p65, found that it can block the overexpression of IL-1β, IL-6, COX-2, etc. [54]. It has also been reported that normal rat knee joint transfected with IKKβ lentivirus induces NF-κB P65 signalling pathway activity and synovial inflammation [55]. All of these demonstrate the importance of this pathway.

In addition, in chondrocyte culture of OA disease, silencing IKK α can inhibit the expression of Runx2, lead to chondrocyte hypertrophy, and increase the expression of collagen and proteoglycan [56], indicating that the non-classical NF-κB signal pathway is also involved in the development of osteoarthritis. Related studies have shown that in hypertrophic chondrocytes, the target genes bone morphogenetic protein-2 (BMP2), C-X-C motif chemokine ligand 8 (CXCL8), C-X-C motif chemokine ligand 1 (CXCL1) regulated by this pathway, together with ELF3 and HIF-2α pathway, promote the production of the type X collagen gene (COL10A1), Matrix metalloproteinase 9 (MMP9), Matrix metalloproteinase 13 (MMP13), alkaline phosphatase and osteocalcin hypertrophy markers, resulting in chondrocyte calcification and osteophyte formation [[57], [58], [59]]. Therefore, targeted down-regulation of NF-κB may be considered as an effective method for the treatment of osteoarthritis.

6 Role of SOX9 in OA

SOX9 is a member of the SRY-related HMG-box (SOX) transcription factor family, located on human chromosome 17 [6], which can act on other genes to regulate various functional changes of cells [60]. Human SOX9 protein consists of 509 amino acids and contains four different domains: two trans-activation domains, HMG domain and dimerization domain [6], through which the expression of target genes can be regulated.

SOX9 is a major transcription factor during cartilage development and endochondral osteogenesis. It is critical for chondrocyte ECM gene expression and also plays a role in chondrocyte differentiation [61]. Although many transcription factors are required for cartilage regeneration, SOX9 is considered indispensable [62,63]. During the growth of normal cartilage, SOX9 can promote the gene transcription of cartilage markers type II and IX collagen and proteoglycan aggrecan, and inhibit the expression of aggrecanase and matrix metalloproteinases, thereby maintaining the phenotype of articular chondrocytes [64]. However, the expression of SOX9 gene and protein in OA is significantly decreased, which is related to the activation of the NF-κB signalling pathway by inflammatory stimulation. Several studies have shown that a large amount of activation of this pathway will reduce or inhibit the normal expression of SOX9 [65], lead to phenotypic instability and dedifferentiation of chondrocytes, and their role in matrix degradation, decreased joint function, and progression of osteoarthritis [66,67]. SRY-related high mobility group-box 5 (SOX5) and SRY-related high mobility group-box 6 (SOX6) also belong to the transcription factor family. Studies have found that SOX5 and SOX6 can bind to form homologous dimer and heterodimer, but due to the lack of trans-activated domain, they often bind with SOX9 to form SOX Trio, which plays a role in cartilage formation. In the gene experiments of SOX5 and SOX6 in mice, knocking out any of these genes resulted in mild skeletal abnormalities at birth. When all knocked out, although SOX9 was expressed normally, mice die in the fetal abdomen because of incomplete bones [68], which indicates that SOX5 and SOX6 are also indispensable in cartilage formation, and their functions are closely related to SOX9. In addition, it was also found that the transactivation activity of SOX triplet was significantly higher than that of SOX9 alone, but the molecular interaction between them was not clear [69,70]. During the early stages of chondrocyte hypertrophy, Sox9 regulates the transcription of target genes by interacting with activator protein-1 (AP-1) family members such as Jun and Fosl2, thereby promoting chondrocyte hypertrophy [71]. However, in the late stage of hypertrophy, SOX9 can inhibit chondrocyte hypertrophy, thereby playing an important role in chondrocyte differentiation and inhibiting chondrocyte apoptosis [72]. SOX9 is a key transcription factor for the differentiation of cartilage mesenchymal cells into chondrocytes [73,74]. It is also involved in regulating various stages of chondrocyte differentiation. Therefore, targeting SOX9 would be a good option for OA treatment.

7 Functional role of NF-κB-SOX9 signalling pathway in OA

NF-κB transcription factor signaling and SOX9 gene are simultaneously expressed in the growth and development of cartilage (including pathological changes), and the regulated target gene expression is also significantly different under different stimulation environments. Whether it is physiological changes in cartilage growth or pathological changes of noxious stimuli, the specific binding mode between NF-κB signaling and SOX9 is not very clear, but several studies have found possible binding modes between them and mode of action. In OA, both the classical NF-κB signaling pathway and alternative NF-κB signaling pathway are involved in the gene regulation of SOX9, and the activation and regulation of their signaling pathways are shown in the structural diagram below Fig. 1.Fig. 1 The classical NF-κB signalling pathway and alternative NF-κB signalling pathway. The classical NF-κB pathway is activated by a large number of agonists, such as the inflammatory cytokines, bacteria and viruses e.t.c. Activation of this pathway depends on the IKK complex, which phosphorylates the inhibitor of IκBα to induce rapid degradation. The alternative NF-κB pathway is activated by a limited number of agonists, such as the CD40L, BAFF-R and LTβ-R e.t.c. This pathway requires NIK and IKKα to promote the processing of the p100 precursor into p52, which results in dimerization and activation of the p52/RelB heterodimer. When the NF-κB homologous or heterodimer enters the nucleus, it binds to the promoter site of SOX9 gene to regulate the phenotype of chondrocytes.

Fig. 1

At present, it has been confirmed that there is a transactivation domain in the C-terminal of SOX9, and there is also a transactivation domain in the signal molecule of NF-κB and NF-κB signal in chondrocytes was also demonstrated to be responsible for the transactivation of SOX9 in Yoshida et al. [75,76]. Moreover,NF-κB enters the nucleus to play a role after activation, and SOX9 itself is a nuclear expression gene, so it is possible for them to bind in the nucleus and regulate the expression of target genes. In the latest study, Buhrmann et al. speculated that after activation of NF-κB signal into the nucleus, SOX9 gene expression was regulated by acting on the promoter region of SOX9. They first determined the genomic sequences of several highly conserved regions located in the proximal promoter region of the human and mouse SOX9 gene, and then found that NF-κB family member p65 had the strongest activation of human SOX9 promoter activity by luciferase reporter gene detection, and used immunohistochemical localization to verify that there was indeed an intermolecular interaction between them in the process of chondrocyte differentiation. Chromatin immunoprecipitation (ChIP) assay showed that the SOX9 promoter containing NF-κB motif was bound to p65 in vivo [77]. Colter et al. found that p65 binds to SOX9 through two CCAAT mods in its promoter, which are also located in the proximal element of SOX9 [78]. In addition, Hamadou et al. found in inflammatory bowel disease (IBD) that SOX9 may regulate NF-κB activity by allele-specific binding to its promoter at the SNP locus through experiments such as the dual luciferase reporter gene assay [79]. In summary, we can speculate that NF-κB in chondrocytes enters the nucleus and exerts its regulatory role by binding to the promoter of SOX9 to form the SOX9-p65-NF-κB complex. In a study of prostate cancer, changes in SOX9 gene and protein expression were found to be associated with stimulation of NF-κB signaling. Namely, the induction of SOX9 during development reprogramming may be the result of NF-κB signaling elevation [80]. This is the same result as our study of NF-κB signaling pathway and SOX9 gene in OA, and also further affirms their functions [81,82]. Under the stimulation of inflammatory factors such as IL-1 and TNF-α, the expression of SOX9 is restricted, at least regulated by NF-κB signaling; while in normal cartilage growth or cancer cells, the regulation of SOX9 by NF-κB is promoted, The two contradict each other. In fact, the negative regulation of SOX9 by NF-κB in OA and other contexts occurs at the post-transcriptional level through an RNA-sequence-dependent mechanism, rather than at the transcriptional level, which explains the dual outcomes of NF-κB regulation of SOX9 [83]. As a result, NF-κB signaling and SOX9 can interact with each other and regulate gene expression, which must be closely related to the transactivation domain that exists between the two. The specific mechanism for regulating chondrocyte differentiation and skeletal development needs further study.

8 Conclusions

SOX9 is one of the key genes regulating chondrocytes, and abnormal activation of NF-κB signaling in OA leads to decreased SOX9 gene expression, which affects the repair of chondrocytes and extracellular matrix, thereby aggravating the symptoms and progression of OA patients. Although biological agents targeting specific genes in osteoarthritis have been used clinically to reduce inflammation and delay disease progression, the therapeutic effect is not apparent. Recently, a study found that the significant reduction of chondrocyte extracellular matrix and chondrocyte production transcription factor SOX9 in OA was closely related to the abnormal activation of NF-κB signalling pathway, and demonstrated that both SOX9 and NF-κB act by forming a complex in chondrocytes [8]. The interaction between NF-κB and SOX9 genes may reveal many potential drug therapy targets; therefore, we can target the NF-κB-SOX9 signalling pathway, study and design inhibitors targeting this pathway, etc., to upregulate SOX9 genes expression, thereby improving the symptoms and progression of OA disease.

Data availability statement

Question: Has data associated with your study been deposited into a publicly available repository?

Response: No, data availability is not applicable to this article as no new data were created or analyzed in this study.

Ethics statement

Review and/or approval by an ethics committee was not needed for this study because it's a review article.

Funding

This research received no external funding.

CRediT authorship contribution statement

Bin Tian: Methodology, Investigation, Formal analysis, Data curation, Conceptualization. Liang Zhang: Writing – original draft, Project administration. Jiang Zheng: Writing – original draft, Software. Xin Kang: Writing – review & editing.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgments

Special thanks go to other Department of Joint Surgery colleagues for their insightful comments on this study and to Professor Xin Kang for his guidance.
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References

1 Roseti L. Articular cartilage regeneration in osteoarthritis Cells 8 11 2019
2 Vincent T.L. Mechanoflammation in osteoarthritis pathogenesis Semin. Arthritis Rheum. 49 3s 2019 S36 s38 31779850
3 Biver E. Gut microbiota and osteoarthritis management: an expert consensus of the European society for clinical and economic aspects of osteoporosis, osteoarthritis and musculoskeletal diseases (ESCEO) Ageing Res. Rev. 55 2019 100946
4 Yang S. Hypoxia-inducible factor-2alpha is a catabolic regulator of osteoarthritic cartilage destruction Nat. Med. 16 6 2010 687 693 20495569
5 Akiyama H. The transcription factor Sox9 has essential roles in successive steps of the chondrocyte differentiation pathway and is required for expression of Sox5 and Sox6 Genes Dev. 16 21 2002 2813 2828 12414734
6 Symon A. Harley V. SOX9: a genomic view of tissue specific expression and action Int. J. Biochem. Cell Biol. 87 2017 18 22 28323209
7 Lefebvre V. Dvir-Ginzberg M. SOX9 and the many facets of its regulation in the chondrocyte lineage Connect. Tissue Res. 58 1 2017 2 14 27128146
8 Buhrmann C. Curcumin attenuates environment-derived osteoarthritis by Sox9/NF-kB signaling Axis Int. J. Mol. Sci. 22 14 2021
9 Sun L. Epigenetic regulation of SOX9 by the NF-κB signaling pathway in pancreatic cancer stem cells Stem Cell. 31 8 2013 1454 1466
10 Chen C. Baicalin suppresses IL-1β-induced expression of inflammatory cytokines via blocking NF-κB in human osteoarthritis chondrocytes and shows protective effect in mice osteoarthritis models Int. Immunopharm. 52 2017 218 226
11 Sen R. Baltimore D. Inducibility of kappa immunoglobulin enhancer-binding protein Nf-kappa B by a posttranslational mechanism Cell 47 6 1986 921 928 3096580
12 Hayden M.S. Ghosh S. NF-κB, the first quarter-century: remarkable progress and outstanding questions Genes Dev. 26 3 2012 203 234 22302935
13 Sokolova O. Naumann M. NF-κB signaling in gastric cancer Toxins 9 4 2017
14 Wertz I.E. Dixit V.M. Signaling to NF-kappaB: regulation by ubiquitination Cold Spring Harbor Perspect. Biol. 2 3 2010 a003350
15 Prescott J.A. Mitchell J.P. Cook S.J. Inhibitory feedback control of NF-κB signalling in health and disease Biochem. J. 478 13 2021 2619 2664 34269817
16 Zhang Q. Lenardo M.J. Baltimore D. 30 Years of NF-κB: a blossoming of relevance to human pathobiology Cell 168 1–2 2017 37 57 28086098
17 De Luca F. Role of nuclear factor kappa B (NF-κB) in growth plate chondrogenesis Pediatr. Endocrinol. Rev. 13 4 2016 720 730 27464415
18 Riedlinger T. The direct and indirect roles of NF-κB in cancer: lessons from oncogenic fusion proteins and knock-in mice Biomedicines 6 1 2018
19 Wang P. Curcumin exerts a protective effect on murine knee chondrocytes treated with IL-1β through blocking the NF-κB/HIF-2α signaling pathway Ann. Transl. Med. 9 11 2021 940 34350255
20 Jimi E. Fei H. Nakatomi C. NF-κB signaling regulates physiological and pathological chondrogenesis Int. J. Mol. Sci. 20 24 2019
21 Karin M. Ben-Neriah Y. Phosphorylation meets ubiquitination: the control of NF-[kappa]B activity Annu. Rev. Immunol. 18 2000 621 663 10837071
22 Hayden M.S. Ghosh S. Shared principles in NF-kappaB signaling Cell 132 3 2008 344 362 18267068
23 De Luca F. Regulatory role of NF-κB in growth plate chondrogenesis and its functional interaction with Growth Hormone Mol. Cell. Endocrinol. 514 2020 110916
24 Haseeb A. A polyphenol-rich pomegranate fruit extract suppresses NF-κB and IL-6 expression by blocking the activation of IKKβ and NIK in primary human chondrocytes Phytother Res. 31 5 2017 778 782 28276100
25 Ruland J. Return to homeostasis: downregulation of NF-κB responses Nat. Immunol. 12 8 2011 709 714 21772279
26 Nakatomi C. Constitutive activation of the alternative NF-κB pathway disturbs endochondral ossification Bone 121 2019 29 41 30611922
27 Yu H. Targeting NF-κB pathway for the therapy of diseases: mechanism and clinical study Signal Transduct. Targeted Ther. 5 1 2020 209
28 Huang B. Posttranslational modifications of NF-kappaB: another layer of regulation for NF-kappaB signaling pathway Cell. Signal. 22 9 2010 1282 1290 20363318
29 Liu T. NF-κB signaling in inflammation Signal Transduct. Targeted Ther. 2 2017 17023
30 Israël A. The IKK complex, a central regulator of NF-kappaB activation Cold Spring Harbor Perspect. Biol. 2 3 2010 a000158
31 Shih V.F. A single NFκB system for both canonical and non-canonical signaling Cell Res. 21 1 2011 86 102 21102550
32 Pai P. Sukumar S. HOX genes and the NF-κB pathway: a convergence of developmental biology, inflammation and cancer biology Biochim. Biophys. Acta Rev. Canc 1874 2 2020 188450
33 Hymowitz S.G. Wertz I.E. A20: from ubiquitin editing to tumour suppression Nat. Rev. Cancer 10 5 2010 332 341 20383180
34 Sun S.C. NF-kappa B controls expression of inhibitor I kappa B alpha: evidence for an inducible autoregulatory pathway Science 259 5103 1993 1912 1915 8096091
35 Rao P. IkappaBbeta acts to inhibit and activate gene expression during the inflammatory response Nature 466 7310 2010 1115 1119 20740013
36 Scheibel M. IkappaBbeta is an essential co-activator for LPS-induced IL-1beta transcription in vivo J. Exp. Med. 207 12 2010 2621 2630 20975042
37 Claudio E. BAFF-induced NEMO-independent processing of NF-kappa B2 in maturing B cells Nat. Immunol. 3 10 2002 958 965 12352969
38 Gerlach B. Linear ubiquitination prevents inflammation and regulates immune signalling Nature 471 7340 2011 591 596 21455173
39 Grossmann M. The anti-apoptotic activities of Rel and RelA required during B-cell maturation involve the regulation of Bcl-2 expression EMBO J. 19 23 2000 6351 6360 11101508
40 Hayden M.S. Ghosh S. Regulation of NF-κB by TNF family cytokines Semin. Immunol. 26 3 2014 253 266 24958609
41 Bonizzi G. Activation of IKKalpha target genes depends on recognition of specific kappaB binding sites by RelB:p52 dimers EMBO J. 23 21 2004 4202 4210 15470505
42 Sun S.C. The non-canonical NF-κB pathway in immunity and inflammation Nat. Rev. Immunol. 17 9 2017 545 558 28580957
43 Sun S.C. Controlling the fate of NIK: a central stage in noncanonical NF-kappaB signaling Sci. Signal. 3 123 2010 pe18 20501935
44 Garcia-Perez J.L. Widmann T.J. Adams I.R. The impact of transposable elements on mammalian development Development 143 22 2016 4101 4114 27875251
45 Hata K. Transcriptional network controlling endochondral ossification J Bone Metab 24 2 2017 75 82 28642850
46 Kobayashi H. Biphasic regulation of chondrocytes by Rela through induction of anti-apoptotic and catabolic target genes Nat. Commun. 7 2016 13336
47 Song J. MicroRNA-9 regulates survival of chondroblasts and cartilage integrity by targeting protogenin Cell Commun. Signal. 11 2013 66 24007463
48 Wan H.Y. Regulation of the transcription factor NF-kappaB1 by microRNA-9 in human gastric adenocarcinoma Mol. Cancer 9 2010 16 20102618
49 Hoesel B. Schmid J.A. The complexity of NF-κB signaling in inflammation and cancer Mol. Cancer 12 2013 86 23915189
50 Rodriguez-Trillo A. Non-canonical WNT5A signaling through RYK contributes to aggressive phenotype of the rheumatoid fibroblast-like synoviocytes Front. Immunol. 11 2020 555245
51 Zhao X. The synovium attenuates cartilage degeneration in KOA through activation of the smad2/3-runx1 cascade and chondrogenesis-related miRNAs Mol. Ther. Nucleic Acids 22 2020 832 845 33230479
52 Wang Y. Increase of TNFα-stimulated osteoarthritic chondrocytes apoptosis and decrease of matrix metalloproteinases 9 by NF-κB inhibition Biomed. Environ. Sci. 26 4 2013 277 283 23534468
53 Zhong J.H. Effects of microRNA-146a on the proliferation and apoptosis of human osteoarthritis chondrocytes by targeting TRAF6 through the NF-κB signalling pathway Biosci. Rep. 37 2 2017
54 Hu Z.C. Inhibition of PI3K/Akt/NF-κB signaling with leonurine for ameliorating the progression of osteoarthritis: in vitro and in vivo studies J. Cell. Physiol. 234 5 2019 6940 6950 30417459
55 Tak P.P. Inhibitor of nuclear factor kappaB kinase beta is a key regulator of synovial inflammation Arthritis Rheum. 44 8 2001 1897 1907 11508443
56 Olivotto E. Differential requirements for IKKalpha and IKKbeta in the differentiation of primary human osteoarthritic chondrocytes Arthritis Rheum. 58 1 2008 227 239 18163512
57 Merz D. IL-8/CXCL8 and growth-related oncogene alpha/CXCL1 induce chondrocyte hypertrophic differentiation J. Immunol. 171 8 2003 4406 4415 14530367
58 Ijiri K. Differential expression of GADD45beta in normal and osteoarthritic cartilage: potential role in homeostasis of articular chondrocytes Arthritis Rheum. 58 7 2008 2075 2087 18576389
59 Goldring M.B. Roles of inflammatory and anabolic cytokines in cartilage metabolism: signals and multiple effectors converge upon MMP-13 regulation in osteoarthritis Eur. Cell. Mater. 21 2011 202 220 21351054
60 Ferrari S. SRY, like HMG1, recognizes sharp angles in DNA EMBO J. 11 12 1992 4497 4506 1425584
61 Ikeda T. The combination of SOX5, SOX6, and SOX9 (the SOX trio) provides signals sufficient for induction of permanent cartilage Arthritis Rheum. 50 11 2004 3561 3573 15529345
62 Song H. Park K.H. Regulation and function of SOX9 during cartilage development and regeneration Semin. Cancer Biol. 67 Pt 1 2020 12 23 32380234
63 Luo Z. Peiminine inhibits the IL-1β induced inflammatory response in mouse articular chondrocytes and ameliorates murine osteoarthritis Food Funct. 10 4 2019 2198 2208 30942801
64 Yang Z. Sox-9 facilitates differentiation of adipose tissue-derived stem cells into a chondrocyte-like phenotype in vitro J. Orthop. Res. 29 8 2011 1291 1297 21400575
65 Smolen J.S. New therapies for treatment of rheumatoid arthritis Lancet 370 9602 2007 1861 1874 17570481
66 Ashraf S. Regulation of senescence associated signaling mechanisms in chondrocytes for cartilage tissue regeneration Osteoarthritis Cartilage 24 2 2016 196 205 26190795
67 Singh P. Phenotypic instability of chondrocytes in osteoarthritis: on a path to hypertrophy Ann. N. Y. Acad. Sci. 1442 1 2019 17 34 30008181
68 Smits P. The transcription factors L-Sox5 and Sox6 are essential for cartilage formation Dev. Cell 1 2 2001 277 290 11702786
69 Han Y. Lefebvre V. L-Sox5 and Sox6 drive expression of the aggrecan gene in cartilage by securing binding of Sox9 to a far-upstream enhancer Mol. Cell Biol. 28 16 2008 4999 5013 18559420
70 Yamashita S. L-Sox5 and Sox6 proteins enhance chondrogenic miR-140 microRNA expression by strengthening dimeric Sox9 activity J. Biol. Chem. 287 26 2012 22206 22215 22547066
71 He X. AP-1 family members act with Sox9 to promote chondrocyte hypertrophy Development 143 16 2016 3012 3023 27471255
72 Takigawa Y. The transcription factor Znf219 regulates chondrocyte differentiation by assembling a transcription factory with Sox9 J. Cell Sci. 123 Pt 21 2010 3780 3788 20940257
73 Lefebvre V. Angelozzi M. Haseeb A. SOX9 in cartilage development and disease Curr. Opin. Cell Biol. 61 2019 39 47 31382142
74 Zhang X. Regeneration of hyaline-like cartilage in situ with SOX9 stimulation of bone marrow-derived mesenchymal stem cells PLoS One 12 6 2017 e0180138
75 Rockel J.S. Regulation of Sox9 activity by crosstalk with nuclear factor-kappaB and retinoic acid receptors Arthritis Res. Ther. 10 1 2008 R3 18182117
76 Yoshida T. Transcriptional regulation of the alpha-1 type II collagen gene by nuclear factor B/p65 and Sox9 in the chondrocytic phenotype of uterine carcinosarcomas Hum. Pathol. 44 9 2013 1780 1788 23618358
77 Ushita M. Transcriptional induction of SOX9 by NF-kappaB family member RelA in chondrogenic cells Osteoarthritis Cartilage 17 8 2009 1065 1075 19254740
78 Colter D.C. Regulation of the human Sox9 promoter by the CCAAT-binding factor Matrix Biol. 24 3 2005 185 197 15908194
79 Hamadou I. Inherited variant in NFκB-1 promoter is associated with increased risk of IBD in an Algerian population and modulates SOX9 binding Cancer Rep (Hoboken) 3 3 2020 e1240 32671985
80 Nouri M. Transient Sox9 expression facilitates resistance to androgen-targeted therapy in prostate cancer Clin. Cancer Res. 26 7 2020 1678 1689 31919137
81 Jouan Y. Lin28a induces SOX9 and chondrocyte reprogramming via HMGA2 and blunts cartilage loss in mice Sci. Adv. 8 34 2022 eabn3106 36026443
82 Chen H. Rhoifolin ameliorates osteoarthritis via the Nrf2/NF-κB axis: in vitro and in vivo experiments Osteoarthritis Cartilage 30 5 2022 735 745 35139424
83 Sitcheran R. Cogswell P.C. Baldwin A.S. Jr. NF-kappaB mediates inhibition of mesenchymal cell differentiation through a posttranscriptional gene silencing mechanism Genes Dev. 17 19 2003 2368 2373 14522944
