Dataset Information

Long non-coding RNA HOTAIR induces GLI2 expression through Notch signalling in systemic sclerosis dermal fibroblasts.

ABSTRACT: Objectives: Systemic sclerosis (SSc) is characterised by tissue fibrosis of the major organs of the body including the skin, lungs and heart. We have previously reported that the lncRNA HOTAIR plays a central role in the activation of SSc myofibroblasts, the key cellular elements of fibrosis. HOTAIR induces fibroblast activation through H3K27me3-mediated activation of the Notch signalling pathway. Here we aimed to identify the signalling events downstream of Notch that drive SSc myofibroblast activation.

Methods: Patient fibroblasts were obtained from full-thickness forearm skin biopsies of 3 adult patients with SSc of recent onset. The lncRNA HOTAIR was expressed in healthy dermal fibroblasts by lentiviral transduction. Hedgehog signalling pathway was inhibited with GANT61 and GLI2 siRNA. Gamma secretase inhibitors RO4929097 and DAPT were used to block Notch signalling. GSK126 was used to inhibit Enhancer of Zeste 2 (EZH2).

Results: Overexpression of HOTAIR in dermal fibroblasts induced the expression of the Hedgehog pathway transcription factor GLI2. This is mediated by activation of Notch signalling following epigenetic downregulation of miRNA-34a expression. Inhibition of H3K27 methylation and Notch signalling reduced expression of GLI2 in HOTAIR-expressing fibroblasts as well as in SSc dermal fibroblasts. Importantly, the inhibition of GLI2 function using GANT61 or siRNA mitigates the pro-fibrotic phenotype induced by HOTAIR.

Conclusions: Our data indicates that GLI2 expression is stably upregulated in SSc myofibroblasts through HOTAIR and that GLI2 mediates the expression of pro-fibrotic markers downstream of Notch.

SUBMITTER: Wasson CW

PROVIDER: S-EPMC7726858 | biostudies-literature | 2020 Dec

REPOSITORIES: biostudies-literature

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Long non-coding RNA HOTAIR induces GLI2 expression through Notch signalling in systemic sclerosis dermal fibroblasts.

Wasson Christopher W CW Ross Rebecca L RL Wells Rebecca R Corinaldesi Clarissa C Georgiou Ioanna Ch IC Riobo-Del Galdo Natalia A NA Del Galdo Francesco F

Arthritis research & therapy 20201210 1

<h4>Objectives</h4>Systemic sclerosis (SSc) is characterised by tissue fibrosis of the major organs of the body including the skin, lungs and heart. We have previously reported that the lncRNA HOTAIR plays a central role in the activation of SSc myofibroblasts, the key cellular elements of fibrosis. HOTAIR induces fibroblast activation through H3K27me3-mediated activation of the Notch signalling pathway. Here we aimed to identify the signalling events downstream of Notch that drive SSc myofibrob ...[more]

PMID: 33303026

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Project description:Systemic sclerosis (SSc) is characterized by severe and often progressive fibrosis of the skin and multiple internal organs. The mechanisms responsible for these alterations remain obscure, although excessive reactive oxygen species (ROS)-mediated oxidative stress has been implicated. NOX-4 is 1 of 7 isoforms of NADPH oxidase responsible for the generation of ROS. The purpose of this study was to examine NOX-4 expression in skin and cultured dermal fibroblasts from SSc patients and to examine its regulation by transforming growth factor ?1 (TGF?1).NOX-4 was assessed in normal and SSc skin by immunohistologic analysis and in normal and SSc cultured dermal fibroblasts by quantitative polymerase chain reaction analysis, fluorescence microscopy, and Western blotting. ROS levels were assessed by fluorescence measurement of H2 O2 production. Specific kinase inhibitors were used to study the TGF?1 signaling involved in NOX-4 stimulation. NOX-4 inhibition/down-regulation was induced with a selective NOX-4 small-molecule inhibitor and NOX-4 small interfering RNA (siRNA).In contrast with normal skin fibroblasts, those from SSc skin showed intense NOX-4 staining. Cultured SSc fibroblasts displayed increased NOX-4 expression. TGF?1 caused potent NOX-4 protein and messenger RNA stimulation in normal and SSc fibroblasts, which was mediated by the protein kinase C? (PKC?) and Smad2/3 pathways. NOX-4 knockdown in SSc fibroblasts reduced the production of ROS and lowered the expression of type I collagen.NOX-4 expression and production were found to be constitutively elevated in SSc skin and cultured SSc dermal fibroblasts. TGF?1 stimulated NOX-4 expression in normal and SSc fibroblasts through PKC? and Smad2/3 signaling pathways. A small-molecule NOX-4 inhibitor decreased collagen and fibronectin production by normal and SSc fibroblasts, and NOX-4 siRNA knockdown reduced ROS and collagen production by SSc fibroblasts. These results demonstrate the involvement of NOX-4 in SSc-associated fibrosis and indicate NOX-4 inhibitors as novel therapeutic approaches for SSc.

Project description:Background. The etiology and reasons underlying the ethnic disparities in systemic sclerosis (SSc) remain unknown. African-Americans (AA) are disproportionally affected by SSc, yet dramatically underrepresented in research. The role of DNA methylation in disease risk remains unclear. This analysis was conducted to comprehensive identify differentially methylated loci associated with SSc in AA. Methods. Genomic DNA was isolated from cultured dermal fibroblasts isolated from 15 AA SSc cases and 15 AA controls. All patients met the 2013 ACR/EULAR classification criteria for SSc, most (93%) presenting with diffuse cutaneous SSc. DNA methylation patterns were profiled through reduced representation bisulfite sequencing (RRBS). Alignment and methylation calling were performed using Bismarck v0.16.3 and the GRCh37/hg19 reference genome. Data was filtered, normalized, and analyzed with RnBeads v1.6.1. Differential methylation analysis was conducted on CpG, promoter, gene and system level. Results. We generated DNA methylation data for over 5 million CpGs in each sample and between 10x to 40x coverage in CpGs sites. Using the Combined Score approach implemented in RnBeads, a total of 9 CpG islands, 17 genes and 11 promoters showed significant differential methylation levels between cases and controls at the gene-level. The top differentially methylated genes constitute mostly non-coding RNA genes (42%), followed by pseudogenes (27%), then protein coding genes (19%). Enrichment analysis revealed that both hypo- and hypermethylated genes and their promoter regions were enriched for cell differentiation and immune-related gene ontology terms (hypermethylated regions: mesenchymal cell transition and differentiation; hypomethylated regions: type I IFN signaling). Conclusion. The observed DNA methylation differences between cases and controls support a modest role for DNA methylation differences in mediating susceptibility to SSc in AA. Instead of protein-coding, most differentially methylated genes comprise non-coding RNA genes, supporting a larger contribution of dysregulated regulatory elements to disease. While previous DNA methylation profiling analyses in European-Americans reported an enrichment of extracellular matrix and focal adhesion genes, our data supports a potentially stronger immune-driven etiology in AA.

Dataset Information

Long non-coding RNA HOTAIR induces GLI2 expression through Notch signalling in systemic sclerosis dermal fibroblasts.

Publications

Long non-coding RNA HOTAIR induces GLI2 expression through Notch signalling in systemic sclerosis dermal fibroblasts.

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