Lactate programs CRIP1 protein lactylation to drive synovial proliferation in rheumatoid arthritis
Meican Ma, Yu Zhou, Qianlin Li, Zhao Wang, Shangqi Guan, Xiaoxue Wang, Han Zhao, Zhenke Wen, Ting Liu, Fenghong Yuan
Meican Ma, Yu Zhou, Qianlin Li, Zhao Wang, Shangqi Guan, Xiaoxue Wang, Han Zhao, Zhenke Wen, Ting Liu, Fenghong Yuan
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Research Article Metabolism

Lactate programs CRIP1 protein lactylation to drive synovial proliferation in rheumatoid arthritis

Abstract

Synovial hyperplasia is a hallmark of rheumatoid arthritis (RA), yet its mechanism remains unclear. RA synovium exhibits metabolic shift, characterized by upregulated glycolysis and enhanced lactate production. In this study, we elucidated the mechanism underlying the roles of lactate metabolism and protein lactylation in RA pathology. In patients with RA, both lactate production and protein lactylation were elevated and showed a positive correlation with clinical disease activity. These changes were further implicated in driving synovial proliferation. Among the lactylated proteins, Cysteine-rich intestinal protein 1 (CRIP1) exhibited a marked increase in modification and played a central role in promoting synovial proliferation. Mechanistically, CRIP1 underwent MOF-mediated lactylation in RA synovial fibroblasts. Lactylated CRIP1 hijacked the cell-cycle regulator p21, disrupting its interaction with cyclin-dependent kinase 2 (CDK2), thereby facilitating the G1/S phase transition. Functionally, AAV-mediated delivery of a lactylation-deficient CRIP1 K49R significantly reduced synovial proliferation compared with WT CRIP1. Peptide-based interventions targeting CRIP1 K49 lactylation effectively inhibited synovial hyperplasia and disease severity in both Collagen II–induced arthritis (CIA) and humanized NSG chimeric models. Collectively, CRIP1 protein lactylation drives synovial proliferation in RA by hijacking p21 from CDK2, thereby facilitating cell cycle progression. Targeting this pathway may serve as a promising strategy for RA.

Authors

Meican Ma, Yu Zhou, Qianlin Li, Zhao Wang, Shangqi Guan, Xiaoxue Wang, Han Zhao, Zhenke Wen, Ting Liu, Fenghong Yuan

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Figure 4

CRIP1 K49 lactylation facilitates synovial proliferation in RA.

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CRIP1 K49 lactylation facilitates synovial proliferation in RA. (A) MS/M...
(A) MS/MS spectrum of lysine lactylation at the K49 locus in CRIP1. (B) Sanger sequencing of the AAG to AGG substitution at the K49 locus in CRIP1. (C) Co-IP of CRIP1 followed by immunoblotting for Pan-Kla to assess CRIP1 protein lactylation in RA-FLSs expressing WT or CRIP1 K49R. (D and E) EdU incorporation assays and quantification of cell proliferation in RA-FLSs expressing Veh, WT and CRIP1 K49R (n = 6). Scale bar: 100 μm. (F) CCK-8 assay to quantify cell proliferation in RA-FLSs expressing Veh, WT, and CRIP1 K49R (n = 6). (G) Schematic presentation of CRIP1 protein domains and sequence of the K49 region. Synthetic peptides (K49-peptide 1–5, K49R-peptide 6) were designed for the study. (H) Co-IP of CRIP1 followed by immunoblotting for Pan-Kla to detect CRIP1 protein lactylation upon treatment with K49-peptide 1–5. (I) Co-IP of CRIP1 followed by immunoblotting for Pan-Kla showing CRIP1 protein lactylation after treatment with K49R or K49-peptide. (J and K) EdU incorporation assay and quantification of cell proliferation in RA-FLSs treated with Veh, K49R, or K49-peptide (n = 6). Scale bar: 100 μm. (L) CCK-8 assay to quantify cell proliferation in RA-FLSs treated with Veh, K49R, or K49-peptide (n = 6). **P < 0.01, ***P < 0.001, ****P < 0.0001. Data are presented as mean ± SEM, and P-values are calculated using 1-way ANOVA followed by Tukey’s post hoc test (E and K), or 2-way ANOVA with Bonferroni’s post hoc test (F and L).