An Increased Circular RNA, circRNPS1, in T Cells of Ankylosing Spondylitis Patients Enhances the MEK/ERK Signaling and Inflammation Mediated by T Cell Activation via Stabilization of hnRNPK and VAV1
Aug 2026· International Journal of Molecular Sciences· 0 citations· 48 references
TL;DR
Disrupting the interaction between circRNPS1 and hnRNPK therefore warrants further investigation as a potential therapeutic strategy for AS.
Abstract
Ankylosing spondylitis (AS) is a chronic inflammatory disease strongly associated with human leukocyte antigen B27 (HLA-B27). However, the incomplete penetrance of HLA-B27 suggests that additional molecular mechanisms contribute to AS pathogenesis. Circular RNAs (circRNAs) have emerged as important regulators of immune responses, but their roles in AS pathogenesis remain incompletely understood. In this study, circRNA expression profiles were examined by high-throughput RNA sequencing and selected circRNAs were validated by quantitative RT-PCR in T cells from AS patients and healthy controls. Among the validated circRNAs, circRNPS1 was significantly up-regulated in T cells from AS patients. Overexpression of circRNPS1 in activated Jurkat cells increased IL-2, IL-17A, and interferon-γ expression and enhanced JAK2/STAT1 and MEK1/2-ERK signaling. RNA pull-down followed by proteomic analysis identified heterogeneous nuclear ribonucleoprotein K (hnRNPK) that binds to the back-splicing junction region of circRNPS1. CircRNPS1 increased the stability of hnRNPK and VAV1, whereas hnRNPK knockdown attenuated circRNPS1-mediated MEK1/2-ERK activation and inflammatory cytokine expression. Furthermore, an antisense RNA fragment targeting the back-splicing junction region of circRNPS1 suppressed IL-2, IL-17A, and interferon-γ expression in activated circRNPS1-overexpressing Jurkat cells and T cells from AS patients. Disrupting the interaction between circRNPS1 and hnRNPK therefore warrants further investigation as a potential therapeutic strategy for AS.
Myasthenia gravis (MG) is an autoimmune disease driven by autoantibodies targeting the neuromuscular junction, leading to muscle weakness. Although emerging evidence implicates circular RNAs (circRNAs) in MG, their specific regulatory mechanisms remain largely unknown. In particular, the role of circNUP214 in MG has not been characterized. CircNUP214 expression in PBMCs and CD4+ T cells from MG patients and healthy controls was determined by qRT-PCR. Its circular structure and cytoplasmic localization were verified. Furthermore, the interaction between circNUP214 and miR-31 was confirmed, and the regulatory effect of circNUP214 on CD4+ T cell proliferation was evaluated. In 31 pure AChR antibody-positive MG patients, circNUP214 expression was significantly elevated in PBMCs compared with healthy controls (HC). Elevated circNUP214 expression was also observed in CD4+ T cells. Functionally, circNUP214 promoted CD4+ T cell proliferation, while its knockdown suppressed this process. Mechanistically, circNUP214 directly bound miR-31 and upregulated NFAT5 via sponging miR-31. Rescue experiments in Jurkat cells further validated the circNUP214/miR-31/NFAT5 ceRNA regulatory axis. In conclusion, circNUP214 is highly expressed in PBMCs from 31 pure AChR antibody positive MG patients and is also elevated in CD4+ T cells. It upregulates NFAT5 expression by sponging miR-31 to promote proliferation. These findings suggest that the circNUP214/miR-31/NFAT5 axis may contribute to aberrant CD4+ T cell proliferation in MG.
Fanfan Xu, Xiaotong Kong, Shanshan Peng et al.· Frontiers in Neurology· 0 citations
The identification of the circTLL1-90aa/NT5C2/Ras/PI3K axis not only expands the functional repertoire of the non-coding genome but also provides new insights into the complexity of drug resistance.
Miao He, Kun-peng Li, Wan-Xia Yang et al.· Cellular Signalling· 0 citations
Background Psoriasis is a chronic immune-mediated inflammatory skin disorder hallmarked by keratinocyte hyperproliferation and impaired apoptosis. N6-methyladenosine (m6A) RNA modification is emerging as a critical regulator of inflammatory gene expression. RNA-binding motif protein 15 (RBM15), a core m6A methyltransferase complex adaptor, promotes oncogenic processes across tissue types; however, its role in psoriatic keratinocyte biology and its potential regulation of interleukin-10 (IL-10)—a pivotal anti-apoptotic and immunomodulatory cytokine—remain unexplored. Methods Single-cell RNA sequencing data from a publicly deposited psoriasis dataset (GSE248121; 23,851 cells from two paired libraries) were analyzed using Seurat, Monocle3, CellChat, and pySCENIC. Bulk transcriptomic datasets (GSE54456, GSE30999) were used for cross-dataset validation of RBM15 and IL10 expression. In vitro, RBM15 was silenced in IL-17A/M5-stimulated HaCaT keratinocytes by siRNA. m6A modification of IL10 mRNA was mapped by methylated RNA immunoprecipitation-qPCR (MeRIP-qPCR) and validated by mRNA stability assay, luciferase reporter, and YTHDF2 RNA immunoprecipitation. Apoptosis was quantified by flow cytometry (Annexin V/PI), caspase-3/7 activity, CCK-8 viability, and Western blotting of Bcl-2 family proteins and JAK1/STAT3 pathway components. Results Integrated single-cell analysis resolved 23,851 cells into six principal cell types across psoriatic lesional (PP) and clinically normal (NS) skin. RBM15 was markedly upregulated in psoriatic keratinocytes (log2FC = 1.93 [fold change ≈3.82] ± 0.31 vs. NS; p < 0.001) and correlated inversely with IL10 along keratinocyte pseudotime trajectories (r = −0.52, p < 0.001). Cross-dataset validation confirmed concordant RBM15 upregulation and IL10 downregulation in PP lesions. Mechanistically, RBM15 installed m6A marks at two RRACH motifs in the IL10 3′UTR, promoting YTHDF2-mediated mRNA degradation (half-life reduction 53.3%; p < 0.001) and 62% suppression of IL10 protein. In vitro, RBM15 knockdown restored IL10, reduced apoptosis from 22.8% to 8.4% (p < 0.001), augmented JAK1/STAT3 phosphorylation, and elevated Bcl-2/Bcl-xL while suppressing Bax and cleaved caspase-3. IL10 neutralization fully reversed these pro-survival effects. Conclusion RBM15-driven m6A modification of IL10 mRNA constitutes a previously unrecognized epitranscriptomic mechanism suppressing IL-10-mediated survival signaling in psoriatic keratinocytes. Targeting the RBM15–m6A–IL10 axis represents a mechanistically grounded and potentially tractable therapeutic direction for psoriasis, pending further in vivo and clinical validation.
Mo Li, Yuyao Jiang, Cheng-cheng Zhu et al.· Frontiers in Cell and Develo...· 0 citations
Non‑small cell lung cancer (NSCLC), particularly lung adenocarcinoma (LUAD), exhibits a high rate of primary resistance to immune checkpoint inhibitors, underscoring the need to decipher the molecular mechanisms of immune evasion. Here, we identify ANKRD49 as a critical regulator of PD‑L1 expression and immunosuppression in LUAD. Immunohistochemical analysis of clinical LUAD specimens revealed that high ANKRD49 expression correlates with reduced CD4+ and CD8+ T cell infiltration, increased FOXP3+ regulatory T cells, and elevated PD‑L1 levels. Functional experiments demonstrated that ANKRD49 overexpression in LUAD cells suppresses T cell cytotoxicity, promotes T cell apoptosis, and impairs granzyme B and IFN‑γ production in vitro. Mechanistically, ANKRD49 directly binds the transcription factor MEF2A via its second ankyrin repeat domain, upregulates MEF2A expression, and promotes its transcriptional activity at two specific sites within the PD‑L1 promoter. Chromatin immunoprecipitation and luciferase reporter assays confirmed that MEF2A directly activates PD‑L1 transcription in an ANKRD49‑dependent manner. In subcutaneous and metastatic mouse models, ANKRD49 overexpression accelerates tumor growth and metastasis, while PD‑L1 blockade reverses these effects and restores antitumor immunity. Collectively, our findings establish the ANKRD49-MEF2A-PD‑L1 axis as a novel driver of immune evasion in LUAD, and identify ANKRD49 ankyrin repeat domain 2 as a potential therapeutic target for overcoming immunotherapy resistance.
Aortic specimens from patients with large vessel vasculitis (LVV) have shown prominent B cells organizing into arterial tertiary lymphoid structures with germinal centers. We hypothesized that B cells in LVV patients would show transcriptional changes associated with enhanced B cell activation and function.
To test this hypothesis, CD19+ cells were flow cytometry purified from peripheral blood mononuclear cells (PBMCs) of patients with Takayasu arteritis (TAK) (n = 7), giant cell arteritis (GCA) (n = 1), or healthy controls (n = 4) and single-cell RNA-seq/BCR-seq profiling was performed using the 10X Genomics platform. Pathway analysis was performed using g:Profiler.
Seurat analysis identified n = 12 transcriptionally defined clusters, with no major differences in cluster distribution noted between TAK or HC individuals. TAK patients showed upregulated genes relative to healthy donors (FC > 1.5, padj < 0.05) in naïve (n = 119 genes), transitional (n = 21 genes), activated (n = 19 genes), and memory (n = 192 genes) B cell subsets. In Memory B cells, upregulated genes were involved in RNA alternative splicing (RBFOX2), mitochondrial function (MT-ND3 and MT-ATP8), protein synthesis (RPS18 and RPL3), T cell co-stimulation (CD86), actin cytoskeleton rearrangement (TAGLN2 and ACTG1), and cell proliferation (DHFR and GAREM1). Pathway analysis on memory B cells identified upregulation of B cell receptor signaling (THEMIS2 and GCSAM). In activated B cells, upregulated genes were involved in endocytosis (RABGAP1L and BMP2K), cell migration (ARHGEF18), and cell proliferation (DLEU2 and IKZF3).
In conclusion, TAK patient B cells exhibit a distinct transcriptional program that might support interactions with autoreactive T cells and contribute to autoimmune disease liability. Future studies will be required to evaluate the functional consequences of these changes with respect to tissue damage in vasculitis.
NIH Grants R01 DK131070 (R.H.B.), T32 AR059039 (G.J.R.), and a VICTR Pilot & Feasibility Award (R.H.B. and J.M.S.) supported this work.
Basic Autoimmunity (BA)
Gabriel J. Rodriguez-Garcia, Robert W Corty, Amber Gooch et al.· Journal of Immunology· 0 citations
BACKGROUND
Neurogranin (NRGN) has been extensively studied as a neuron-enriched synaptic regulatory protein, yet its function in cancer remains largely unexplored. Immune evasion driven by defective antigen presentation and CD8⁺ T cell dysfunction is a hallmark of hepatocellular carcinoma (HCC). This study aimed to determine whether NRGN contributes to immune escape in HCC and to elucidate its underlying molecular mechanism.
METHODS
NRGN expression and clinical relevance were analyzed in public datasets and validated in HCC tissues. Transcriptomic and enrichment analyses assessed antigen presentation. Gain- and loss-of-function experiments were performed in human and murine HCC cells, while orthotopic and subcutaneous models with CD8⁺ T cell exhaustion, β2M knockout, and H-2Kb blockade evaluated immune dependence in vivo. RNA stability, RNA pulldown, RIP, co-immunoprecipitation, ubiquitination, and luciferase assays were conducted to define the molecular mechanisms.
RESULTS
NRGN was significantly upregulated in HCC and associated with advanced stage and poor survival, correlating inversely with GZMB⁺ CD8⁺ T cell infiltration. NRGN knockdown enriched MHC-I antigen presentation pathways and restored MHC-I/β2M expression, tumor cell surface antigen presentation, and CD8⁺ T cell cytotoxicity. In vivo, NRGN silencing suppressed tumor growth and prolonged survival in a CD8⁺ T cell-dependent manner, effects reversed by β2m deletion or H-2Kb blockade. Mechanistically, NRGN downregulated IRF8 by reducing its mRNA stability through FMR1 and stabilizing FMR1 protein via inhibition of MYCBP2-mediated ubiquitination, thereby sustaining suppression of antigen presentation.
CONCLUSIONS
NRGN suppresses antigen presentation via the FMR1-IRF8-MHC-I axis, thereby impairing CD8⁺ T cell-specific effector functions and promoting immune evasion in HCC. Modulation of the NRGN-IRF8-MHC-I axis could represent a potential strategy for improving immunotherapeutic responses.
Dongjie Ye, Jiacheng Qiu, Haoyi Yang et al.· Journal of experimental & cl...· 0 citations
