Inhibition of lncRNA NEAT1 induces dysfunction of fibroblast-like synoviocytes in rheumatoid arthritis via miRNA-338-3p-mediated regulation of glutamine metabolism.

Rheumatoid arthritis (RA) is a systemic chronic autoimmune disease; cellular glutamine metabolism in fibroblast-like synoviocytes (FLSs) of RA was known to be essential for RA pathogenesis and progression. NEAT1, a long non-coding RNA, functions as an oncogene in diverse cancers. The exact roles and molecular mechanisms of NEAT1 in fibroblast-like synoviocytes (FLSs) of RA patients are unknown. Expression of NEAT1 and miR-338-3p was measured by qRT-PCR. lncRNA-miRNA and miRNA-mRNA interactions were predicted from starBase and validated by RNA pull-down and luciferase assay. The glutamine metabolism of FLSs was evaluated by glutamine uptake and glutaminase activity. Cell death in FLSs in response to H2O2 was assessed by MTT and Annexin V assays. NEAT1 was significantly upregulated, and miR-338-3p was significantly downregulated in FLSs from RA patients compared to normal FLSs. Silencing of NEAT1 and overexpression of miR-338-3p suppressed glutamine metabolism in FLSs-RA and promoted H2O2-induced apoptosis. Bioinformatics analysis showed that NEAT1 sponges miR-338-3p to form competing endogenous RNA (ceRNAs), which was verified by RNA pull-down assay and luciferase assay FLSs-RA had an increased rate of glutamine metabolism compared to normal FLSs increased compared to normal FLSs. The results confirmed that GLS (Glutaminase), a key enzyme in glutamine metabolism, is a direct target of miR-338-3p in FLSs-RA. miR-338-3p inhibition of glutamine metabolism was verified by rescue experiments verified. Finally, restoration of miR-338-3p in FLSs-RA expressing NEAT1 overcomes NEAT1-promoted glutamine metabolism and resistance to apoptosis. This study reveals the essential role and molecular targets of NEAT1-regulated glutamine metabolism and FLSs-RA dysfunction in fibroblast-like synoviocytes of RA and indicates that blocking the molecular pathway via non-coding RNAs may be beneficial for RA patients.

Zhang M ，Lu N ，Li HJ ，Guo XY ，Lu L ，Guo Y ... -  《Journal of Orthopaedic Surgery and Research》

Influences of the lncRNA TUG1-miRNA-34a-5p network on fibroblast-like synoviocytes (FLSs) dysfunction in rheumatoid arthritis through targeting the lactate dehydrogenase A (LDHA).

Rheumatoid arthritis (RA) is a systemic and chronic inflammatory disease. The cellular glucose metabolism of fibroblast-like synoviocytes (FLSs) of RA has been revealed to be essential to the pathogenesis and development of RA. To date, the precise roles and molecular mechanisms of long noncoding RNA TUG1 in RA have not been elucidated. TUG1 and miR-34a-5p were detected by qRT-PCR. Interactions between lncRNA-miRNA and miRNA-mRNA were validated by RNA pull-down assay and luciferase assay. The glucose metabolism was evaluated by glucose uptake and extracellular acidification rate (ECAR). Cell viability was determined by MTT assay and Annexin V assay. TUG1 expression was significantly upregulated in synovial fibroblast-like synoviocytes (FLSs) compared with normal FLSs. Functional assays uncovered that silence of TUG1 suppressed FLSs-RA invasion, migration, glucose metabolism, and increased apoptosis. Bioinformatics analysis indicated that TUG1 interacted with miR-34a-5p. RNA pull-down assay and luciferase assay validated that TUG1 sponged miR-34a-5p in FLSs-RA. Overexpression of miR-34a-5p effectively inhibited glucose metabolism of FLSs-RA. Furthermore, the glucose metabolism of FLSs-RA was significantly elevated compared with normal FLSs. The glucose metabolism enzyme, LDHA, was directly targeted by miR-34a-5p in FLSs. Rescue experiments validated that the miR-34a-5p-inhibited glucose metabolism of FLSs-RA was through targeting LDHA. Finally, we showed restoration of miR-34a-5p in TUG1-overexpressing FLSs-RA successfully overcame the TUG1-promoted glucose metabolism and apoptosis resistance via targeting LDHA. The present study uncovered critical roles and molecular mechanisms underlying the TUG1-mediated glucose metabolism and apoptosis of FLSs-RA through modulating the miR-34a-5p-LDHA pathway in fibroblast-like synoviocytes of rheumatoid arthritis.

Zhang M ，Lu N ，Guo XY ，Li HJ ，Guo Y ，Lu L ... -  《-》

LncRNA NEAT1 Targets Fibroblast-Like Synoviocytes in Rheumatoid Arthritis via the miR-410-3p/YY1 Axis.

LncRNA NEAT1 functions as an oncogene in multiple human cancers. However, its expression and role in fibroblast-like synoviocytes (FLSs) from patients with rheumatoid arthritis (RA) remain unclear. Thus, we investigated the expression of NEAT1 in synovial tissues and FLSs in RA, to determine its role in the development of RA. Quantitative real-time polymerase chain reaction was used to measure the expression of NEAT1. FLS proliferation was evaluated using cell proliferation assays. Flow cytometry was used to analyze cell cycle progression and apoptosis in FLSs. Binding between NEAT1 and miR-410-3p was demonstrated by dual-luciferase assays. We found that NEAT1 was upregulated in synovial tissues and FLSs in RA. Upregulation of NEAT1 promoted cell proliferation, induced S-to G2/M phase transition, and suppressed apoptosis in RA FLSs. NEAT1 directly bound to and negatively modulated miR-410-3p expression, while positively regulating YinYang 1(YY1; a miR-410-3p target). Inhibiting miR-410-3p and upregulating YY1 partially restored the inhibitory role in cell viability induced by the depletion of NEAT1 in RA FLSs. Besides pro-proliferative and anti-apoptotic roles, upregulation of NEAT1 promoted migration, invasion, and inflammatory cytokines secretion in RA FLSs. Taken together, our results suggest that the NEAT1 may serve as a novel diagnostic and therapeutic target for patients with RA.

Wang Y ，Hou L ，Yuan X ，Xu N ，Zhao S ，Yang L ，Zhang N ... -  《Frontiers in Immunology》

LncRNA NEAT1 regulates the proliferation and production of the inflammatory cytokines in rheumatoid arthritis fibroblast-like synoviocytes by targeting miR-204-5p.

Xiao J ，Wang R ，Zhou W ，Cai X ，Ye Z ... -  《Human Cell》

LncRNA NEAT1_1 suppresses tumor-like biologic behaviors of fibroblast-like synoviocytes by targeting the miR-221-3p/uPAR axis in rheumatoid arthritis.

Fibroblast-like synoviocytes (FLSs) are the predominant effector cells in the pathological progression of rheumatoid arthritis (RA). Therefore, elucidating the underlying molecular mechanism of the biologic behaviors in RA-FLSs will be helpful in developing the potent targets for the treatment of RA. We have previously documented that the tumor-like biologic behaviors of RA-FLSs are exacerbated by urokinase-type plasminogen activator receptor (uPAR), a specifically up-regulated receptor in RA-FLSs. Here, we investigate the further mechanism of uPAR and clarify its function in RA-FLSs. We demonstrate that miR-221-3p positively correlates to uPAR and regulates uPAR level in RA-FLSs. Simultaneously, one long noncoding RNA, nuclear paraspeckle assembly transcript 1_1 (NEAT1_1) is identified, which can predictively target miR-221-3p at three sites, indicating a strong possibility of being a competing endogenous RNA in RA-FLSs. Interestingly, NEAT1_1 and miR-221-3p can colocate in the nucleus and cytoplasm in RA-FLSs. Importantly, NEAT1_1 can act as a rheostat for the miR-221-3p/uPAR axis and the downstream JAK signaling. In line with the biologic function, NEAT1_1 negatively regulates the tumor-like characters, and cytokine secretions of RA-FLSs. Collectively, our data provide new insight into the mechanisms of NEAT1_1 in modulating RA-FLSs tumor-like behaviors. The targeting of NEAT1_1 and miR-221-3p/uPAR axis may have a promising therapeutic role in patients with RA.

Wang M ，Chen Y ，Bi X ，Luo X ，Hu Z ，Liu Y ，Shi X ，Weng W ，Mo B ，Lu Y ，Pan Y ... -  《-》