GALNT1 drives aggressive phenotypes of rheumatoid synoviocytes via NEK9 O-glycosylation
Yaoyao Zou, Haobo Lin, Jianling Su, Jieying Wang, Qin Zeng, Tianxiao Feng, Yunxia Lei, Jianda Ma, Hudan Pan, Hanshi Xu, Lie Dai, Yang Li
Yaoyao Zou, Haobo Lin, Jianling Su, Jieying Wang, Qin Zeng, Tianxiao Feng, Yunxia Lei, Jianda Ma, Hudan Pan, Hanshi Xu, Lie Dai, Yang Li
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Research Article Bone biology

GALNT1 drives aggressive phenotypes of rheumatoid synoviocytes via NEK9 O-glycosylation

Abstract

Fibroblast-like synoviocytes (FLSs) are crucial in driving synovial inflammation and joint damage in rheumatoid arthritis (RA). This study explored the functions and underlying mechanisms of GALNT1-mediated O-glycosylation, which is markedly upregulated in RA FLSs, in synovial aggression and subsequent experimental joint damage. Targeted suppression of GALNT1 effectively curtailed migration and invasion in RA FLSs and mitigated arthritis severity in a collagen-induced arthritis model in rats. Mechanistically, NEK9 was identified as a pivotal substrate and downstream effector of GALNT1, affecting the aggressive phenotype of RA FLSs. In vitro experiments further demonstrated that O-glycosylation of NEK9, mediated by GALNT1, promotes the pathogenic phenotype of RA FLSs by promoting cytoskeleton reorganization and restraining excessive ER stress activation. Our study provides mechanistic insights into the activation of RA FLSs and identifies GALNT1 as a potential therapeutic target for RA.

Authors

Yaoyao Zou, Haobo Lin, Jianling Su, Jieying Wang, Qin Zeng, Tianxiao Feng, Yunxia Lei, Jianda Ma, Hudan Pan, Hanshi Xu, Lie Dai, Yang Li

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Figure 1

Enhanced O-glycosylation and GALNT1 expression in RA FLSs and synovial tissues.

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Enhanced O-glycosylation and GALNT1 expression in RA FLSs and synovial t...
(A) An overview of the numbers of DEGs with a fold-change of 2.0 or greater and P less than 0.05 identified by microarray analysis of RA FLSs (n = 5) and HC FLSs (n = 5) shown in heatmap. (B) KEGG enrichment analysis of the upregulated DEGs. (C) Expression levels of indicated genes in RA FLSs (n = 5) and HC FLSs (n = 5) groups. Differences between RA and HC groups were analyzed by 2-tailed unpaired t test with Benjamini-Hochberg FDR correction for multiple testing. (D) Differential expression of the indicated genes was validated by qRT-PCR. Differences between RA (n = 12) and HC (n = 14) groups were analyzed using a 2-tailed unpaired t test. (E) The protein expression level of GALNT1 in RA FLSs (n = 4) and HC FLSs (n = 4) was measured by Western blot. Differences were analyzed using 2-tailed Welch’s t test. (F) Expression and subcellular localization of GALNT1 in RA FLSs and HC FLSs were visualized by IF. (G) GALNT1 expression in RA synovial tissues (n = 66) and HC synovial tissues (n = 10) measured by IHC. Original magnification, ×1,000. (H) Semiquantitative analysis was performed for the evaluation of GALNT1 expression in synovial tissues. Differences were analyzed using the Mann-Whitney U test. (I) Detection of O-glycosylation modification in RA synovial tissues (n = 9) and HC synovial tissues (n = 8) by VVL staining. Original magnification, ×400. (J) Semiquantitative evaluation of O-glycosylation in synovial tissues. Differences were analyzed using the Mann-Whitney U test. The data are presented as mean ± SD. *P < 0.05, **P < 0.01, ***P < 0.001 versus HC.