Dataset Information

14-3-3 epsilon is an intracellular component of TNFR2 receptor complex and its activation protects against osteoarthritis.

ABSTRACT:

Objectives

Osteoarthritis (OA) is the most common joint disease; however, the indeterminate nature of mechanisms by which OA develops has restrained advancement of therapeutic targets. TNF signalling has been implicated in the pathogenesis of OA. TNFR1 primarily mediates inflammation, whereas emerging evidences demonstrate that TNFR2 plays an anti-inflammatory and protective role in several diseases and conditions. This study aims to decipher TNFR2 signalling in chondrocytes and OA.

Methods

Biochemical copurification and proteomics screen were performed to isolate the intracellular cofactors of TNFR2 complex. Bulk and single cell RNA-seq were employed to determine 14-3-3 epsilon (14-3-3ε) expression in human normal and OA cartilage. Transcription factor activity screen was used to isolate the transcription factors downstream of TNFR2/14-3-3ε. Various cell-based assays and genetically modified mice with naturally occurring and surgically induced OA were performed to examine the importance of this pathway in chondrocytes and OA.

Results

Signalling molecule 14-3-3ε was identified as an intracellular component of TNFR2 complexes in chondrocytes in response to progranulin (PGRN), a growth factor known to protect against OA primarily through activating TNFR2. 14-3-3ε was downregulated in OA and its deficiency deteriorated OA. 14-3-3ε was required for PGRN regulation of chondrocyte metabolism. In addition, both global and chondrocyte-specific deletion of 14-3-3ε largely abolished PGRN's therapeutic effects against OA. Furthermore, PGRN/TNFR2/14-3-3ε signalled through activating extracellular signal-regulated kinase (ERK)-dependent Elk-1 while suppressing nuclear factor kappa B (NF-κB) in chondrocytes.

Conclusions

This study identifies 14-3-3ε as an inducible component of TNFR2 receptor complex in response to PGRN in chondrocytes and presents a previously unrecognised TNFR2 pathway in the pathogenesis of OA.

SUBMITTER: Fu W

PROVIDER: S-EPMC8595573 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BackgroundOsteoarthritis (OA) is the most common joint disease worldwide, but its cause remains unclear. Oestrogen protects against OA, but its clinical use is limited. G protein-coupled receptor 30 (GPR30) is a receptor that binds oestrogen, and GPR30 treatment has benefitted patients with some degenerative diseases. However, its effects on OA prevention and treatment remain unclear. Moreover, several studies have found that activation of estrogen receptors exerting anti-ferroptosis effects, which plays an important role in chondrocyte survival. Therefore, this study explored the general and ferroptosis-related effects and mechanisms of GPR30 in OA.MethodsGenome-wide RNA sequencing, western blotting, and immunohistochemistry were used to evaluate GPR30 expression and ferroptosis-related indicators in cartilage tissues from clinical patients. Next, we investigated the effects of G1 (a GPR30 receptor agonist) on the function and pathology of OA in an animal model. We also treated chondrocytes with erastin (ferroptosis agonist) plus G1, G15 (GPR30 receptor antagonist), GPR30 short hairpin RNA, or ferrostatin-1 (ferroptosis inhibitor), then measured cell viability and ferroptosis-related indices and performed proteomics analyses. Finally, western blotting and reverse transcription-polymerase chain reaction were used to assess the effects of G1 on yes-associated protein 1 (YAP1) and ferritin heavy chain 1 (FTH1) expression.ResultsGPR30 expression was lower in the OA cartilage tissues than in the normal tissues, and G1 treatment significantly improved the locomotor ability of mice. Moreover, chondrocyte cell viability significantly decreased after erastin treatment, but G1 treatment concentration-dependently mitigated this effect. Furthermore, G1 treatment decreased phosphorylated YAP1 expression, increased activated YAP1 expression, and increased FTH1 transcription and protein expression, protecting against ferroptosis.ConclusionGPR30 activation inhibited ferroptosis in chondrocytes by suppressing YAP1 phosphorylation, which regulates FTH1 expression.The Translational Potential of this Article: These results provide a novel potential target for therapeutic OA interventions.