The role of Cas-L/NEDD9 as a regulator of collagen-induced arthritis in a murine model

JAK Inhibitors in Rheumatoid Arthritis: Immunomodulatory Properties and Clinical Efficacy

Rheumatoid arthritis (RA) is a highly prevalent autoimmune disorder. The pathogenesis of the disease is complex and involves various cellular populations, including fibroblast-like synoviocytes, macrophages, and T cells, among others. Identification of signalling pathways and molecules that actively contribute to the development of the disease is crucial to understanding the mechanisms involved in the chronic inflammatory environment present in affected joints. Recent studies have demonstrated that the Janus kinase/signal transducer and activator of transcription (JAK/STAT) pathway regulates the behaviour of immune cells and contributes to the progression of RA. Several JAK inhibitors, such as tofacitinib, baricitinib, upadacitinib, and filgocitinib, have been developed, and their efficacy and safety in patients with RA have been comprehensively investigated in a number of clinical trials. Consequently, JAK inhibitors have been approved and registered as a treatment for patients with RA. In this review, we discuss the involvement of JAK/STAT signalling in the pathogenesis of RA and summarise the potential beneficial effects of JAK inhibitors in cells implicated in the pathogenesis of the disease. Moreover, we present the most important phase 3 clinical trials that evaluated the use of these agents in patients.

Treatment of rheumatoid arthritis with baricitinib or upadacitinib is associated with reduced scaffold protein NEDD9 levels in CD4+ T cells

The JAK/STAT pathway plays a crucial role in the pathogenesis of rheumatoid arthritis (RA) and JAK inhibitors have emerged as a new group of effective drugs for RA treatment. Recently, high STAT3 levels have been associated with the upregulation of the scaffold protein NEDD9, which is a regulator of T-cell trafficking and promotes collagen-induced arthritis (CIA). In this study, we aimed to reveal how treatment with JAK inhibitors affects NEDD9 in CD4+ T cells from RA patients. We analyzed NEDD9 expression in CD4+ T cells from 50 patients treated with either baricitinib, tofacitinib, or upadacitinib and performed cell migration assays to assess the potential influence of JAK inhibitor treatment on CD4+ T-cell migration. We observed that treatment with baricitinib and upadacitinib is associated with reduced NEDD9 expression in CD4+ T cells. In contrast, NEDD9 levels were not altered during treatment with tofacitinib. Moreover, treatment with baricitinib was associated with a significantly reduced migratory capacity of effector CD4+ T cells but not with impaired migration of Treg cells. This study reveals previously unknown associations between JAK inhibitor treatment and NEDD9 expression and indicates that JAK inhibitors could reduce effector T-cell migration.

NEDD9 Mediates the FAK/Src Signaling Pathway to Promote the Adhesion of Human Trabecular Meshwork Cells after Dexamethasone Treatment

PURPOSE

The differential gene expression of neural precursor cell expressed developmentally downregulated 9 (NEDD9) in human trabecular meshwork (HTM) cells after dexamethasone (Dex) treatment was confirmed through gene expression profiling. However, the regulatory mechanism of NEDD9 expression in HTM cells remains unknown. In this study, we investigated NEDD9 expression in HTM cells and gained a better understanding of glucocorticoid-induced glaucoma (GIG) pathophysiology.

METHODS

The Gene Expression Omnibus database and GEO2R tool were used to identify differentially expressed genes in the GSE37474 and GSE124114 datasets, and NEDD9 gene expression was found to be upregulated. Human corneoscleral segments and HTM cells were treated with 100 nM Dex or an equal volume of ethanol (0.01%) for 7 days. NEDD9 expression in TM tissues was evaluated by immunohistochemistry, and NEED9 expression in HTM cells was confirmed by RT-qPCR and western blotting. HTM cell adhesive behaviors were assessed with a cell adhesion detection kit. NEDD9 expression was knocked down with short hairpin RNA in HTM cells, and FAK/Src signaling pathway activation was found to be regulated by NEDD9.

RESULTS

After 7 days of HTM cell Dex treatment, NEDD9 expression was upregulated to be approximately twice that of control. FAK, Src, phospho-FAK, and phospho-Src expression in Dex-treated HTM cells was markedly increased. Downregulation of NEDD9 expression reduced HTM cell adhesion to the surface of culture wells and simultaneously led to a reduction in FAK, Src, phospho-FAK and phospho-Src expression.

CONCLUSIONS

NEDD9 expression is upregulated in HTM cells after Dex treatment and promotes HTM cell adhesion. These findings underscore the contribution of NEDD9 overexpression to altered HTM cell adhesion during glucocorticoid therapy and may play a key role in GIG pathological progression. Considering the similarity between GIG and primary open-angle glaucoma (POAG), our findings suggest that targeting NEDD9 may be a new therapeutic strategy for POAG patients.

Integrated proteome and malonylome analyses reveal the neutrophil extracellular trap formation pathway in rheumatoid arthritis

Rheumatoid arthritis (RA) is an autoimmune inflammatory disease of unknown etiology in which the posttranslational modifications (PTMs) of proteins play an important role. PTMs, such as those involved in the formation of neutrophil extracellular traps (NETs), have been well studied. The excessive formation and release of NETs can mediate inflammation and joint destruction in RA. It has been gradually recognized that lysine malonylation (Kmal) can regulate some biological processes in some prokaryotes and eukaryotes. However, less is known about the role of Kmal in RA. We therefore performed proteome and malonylome analyses to explore the proteomic characteristics of the peripheral blood mononuclear cells from 36 RA patients and 82 healthy subjects. In total, 938 differentially expressed proteins (DEPs) and 42 differentially malonylated proteins (DMPs) with 55 Kmal sites were detected through a liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based analysis. Functional analysis showed that two DEPs with four malonylated sites and one DMP with a malonylated site were identified in the neutrophil extracellular trap formation (NETosis) pathway. Altogether, this study not only describes the characteristics of the malonylome in RA for the first time, but it also reveals that malonylation may be involved in the NETosis pathway. SIGNIFICANCE: This is the first report that reveals the proteomic features of Kmal in RA through a LC-MS/MS-based method. In this study, we found that several key DMPs were associated with the NETosis pathway, which contributes to the development of RA. The present results provide an informative dataset for the future exploration of Kmal in RA.

Alteration of N6-methyladenosine epitranscriptome profile in lipopolysaccharide-induced mouse mesangial cells

N6-Methyladenosine (m6A) is the most prevalent internal modification of messenger RNA (mRNA) in eukaryotes. The underlying molecular mechanisms of m6A modification in chronic glomerulonephritis (CGN) remain unexplored. Here, we performed methylated RNA immunoprecipitation sequencing (MeRIP-seq) and RNA sequencing (RNA-seq) analyses to assess the alterations of epitranscriptome-wide m6A profile in lipopolysaccharide (LPS)-induced mouse mesangial cells (MMC). The results of our data showed 2153 significantly differential m6A peaks and 358 significantly differentially expressed genes. Furthermore, integrated analysis from MeRIP-seq and RNA-seq identified a total of 64 genes with differential m6A modification and expressed levels, of which 5 genes displayed hypermethylation and upregulation, 42 genes displayed hypermethylation and downregulation, 11 genes displayed hypomethylation and upregulation, and 8 genes displayed hypomethylation and downregulation. Many of them (including Fosl1, Sorbs1, Ambp, Fgfr3, Nedd9, Fgg, Trim13, Fgf22, Mylk, and Muc6) are implicated in the regulation of the immune and inflammatory response. Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) analysis found that differential 64 genes were mainly enriched in fatty acid oxidation, apoptosis signaling pathway, complement and coagulation cascades, and PPAR signaling pathway. Together, our study provided a new perspective on the understanding of molecular features of m6A modification in CGN pathogenic pathogenesis.

NEDD9 targets COL3A1 to promote endothelial fibrosis and pulmonary arterial hypertension

Germline mutations involving small mothers against decapentaplegic-transforming growth factor-β (SMAD-TGF-β) signaling are an important but rare cause of pulmonary arterial hypertension (PAH), which is a disease characterized, in part, by vascular fibrosis and hyperaldosteronism (ALDO). We developed and analyzed a fibrosis protein-protein network (fibrosome) in silico, which predicted that the SMAD3 target neural precursor cell expressed developmentally down-regulated 9 (NEDD9) is a critical ALDO-regulated node underpinning pathogenic vascular fibrosis. Bioinformatics and microscale thermophoresis demonstrated that oxidation of Cys18 in the SMAD3 docking region of NEDD9 impairs SMAD3-NEDD9 protein-protein interactions in vitro. This effect was reproduced by ALDO-induced oxidant stress in cultured human pulmonary artery endothelial cells (HPAECs), resulting in impaired NEDD9 proteolytic degradation, increased NEDD9 complex formation with Nk2 homeobox 5 (NKX2-5), and increased NKX2-5 binding to COL3A1 Up-regulation of NEDD9-dependent collagen III expression corresponded to changes in cell stiffness measured by atomic force microscopy. HPAEC-derived exosomal signaling targeted NEDD9 to increase collagen I/III expression in human pulmonary artery smooth muscle cells, identifying a second endothelial mechanism regulating vascular fibrosis. ALDO-NEDD9 signaling was not affected by treatment with a TGF-β ligand trap and, thus, was not contingent on TGF-β signaling. Colocalization of NEDD9 with collagen III in HPAECs was observed in fibrotic pulmonary arterioles from PAH patients. Furthermore, NEDD9 ablation or inhibition prevented fibrotic vascular remodeling and pulmonary hypertension in animal models of PAH in vivo. These data identify a critical TGF-β-independent posttranslational modification that impairs SMAD3-NEDD9 binding in HPAECs to modulate vascular fibrosis and promote PAH.

Identification of Nedd9 as a TGF-β-Smad2/3 Target Gene Involved in RANKL-Induced Osteoclastogenesis by Comprehensive Analysis

TGF-ß is a multifunctional cytokine that is involved in cell proliferation, differentiation and function. We previously reported an essential role of the TGF-ß -Smad2/3 pathways in RANKL-induced osteoclastogenesis. Using chromatin immunoprecipitation followed by sequencing, we comprehensively identified Smad2/3 target genes in bone marrow macrophages. These genes were enriched in the gene population upregulated by TGF-ß and downregulated by RANKL. Recent studies have revealed that histone modifications, such as trimethylation of histone H3 lysine 4 (H3K4me3) and lysine 27 (H3K27me3), critically regulate key developmental steps. We identified Nedd9 as a Smad2/3 target gene whose histone modification pattern was converted from H3K4me3(+)/H3K4me27(+) to H3K4me3(+)/H3K4me27(-) by TGF-ß. Nedd9 expression was increased by TGF-ß and suppressed by RANKL. Overexpression of Nedd9 partially rescued an inhibitory effect of a TGF-ß inhibitor, while gene silencing of Nedd9 suppressed RANKL-induced osteoclastogenesis. RANKL-induced osteoclastogenesis were reduced and stimulatory effects of TGF-ß on RANKL-induced osteoclastogenesis were partially abrogated in cells from Nedd9-deficient mice although knockout mice did not show abnormal skeletal phenotypes. These results suggest that Nedd9 is a Smad2/3 target gene implicated in RANKL-induced osteoclastogenesis.