The Role of MicroRNA-29 in Osteoarthritis

Smith, Perry (2022) The Role of MicroRNA-29 in Osteoarthritis. Doctoral thesis, University of East Anglia.

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Osteoarthritis (OA) is the most common type of joint disease, characterised by destruction of the articular cartilage and progressive joint failure, ultimately resulting in restricted mobility and chronic pain. Current treatments for OA are mainly limited to lifestyle changes, short-term pain relief and eventual joint replacement surgery. MicroRNAs are short non-coding RNAs which primarily downregulate expression of target genes by binding to complimentary sequences in the 3’-UTR of mRNAs. Previous research in our group highlighted a potential role for miR-29 in OA. MiR-29 family members were upregulated in OA cartilage and directly regulated the expression of several genes involved in OA. In this study, the role of miR-29 in cartilage and OA was further explored using in vitro and in vivo models.

Members of the ADAMTS family of metalloproteinases were targeted by miR-29b-3p in 3’-UTR luciferase reporter assays. In SW1353 cells and HACs overexpression of miR-29b-3p downregulated expression of ADAMTS12. TGF-β1 treatment of HACs downregulated expression of ADAMTS1, ADAMTS3, ADAMTS5, ADAMTS9, ADAMTS12, ADAMTS13, ADAMTS15, ADAMTS19 and ADAMTS20, whereas expression of ADAMTS2, ADAMTS4, ADAMTS6, ADAMTS10 and ADAMTS14 was upregulated. The miR-29 family are recognised as key epi-miRNAs and overexpression of miR-29b-3p in SW1353 cells and HACs downregulated expression of DNMT3A, TET2 and TDG. In SW1353 cells miR-29b-3p reduced global 5-methylcytosine levels but methylation array and bisulfite PCR pyrosequencing analyses failed corroborate this.

To investigate the role of miR-29 in vivo, mice with cartilage-specific knockout of miR-29ab1 and miR-29b2c, independently (AB1-KO and B2C-KO) and simultaneously (DKO), were generated. AB1-KO and DKO mice were born at lower frequencies and weighed less than littermate controls at 12 weeks. MiR-29 knockout mice also had shorter femurs by 12 weeks with no differences in femur width or bone density. For DKO mice, preliminary analyses (n ≤ 3) of 12-week aged legs found reduced growth plate area and cell count, and increased OA following surgical induction. Analysis of a larger sample size will be needed confirm this. In 3-week aged DKO hip cartilage, mRNA-sequencing identified 1324 differentially expressed genes (683 upregulated and 641 downregulated) with upregulated genes enriched for extracellular matrix, TGF-β signalling and endochondral ontologies.

In conclusion, these data suggest an important role for miR-29 in cartilage development and the pathogenesis of osteoarthritis through antifibrotic effects, mediated by regulation of ADAMTSs and TGF-β signalling.

Item Type: Thesis (Doctoral)
Faculty \ School: Faculty of Science > School of Biological Sciences
Depositing User: Chris White
Date Deposited: 18 Jan 2023 10:58
Last Modified: 18 Jan 2023 10:58


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