scholarly journals OP0036 IL-6 ACTIVATES YES-ASSOCIATED PROTEIN (YAP) IN FIBROBLASTS AND INDUCES YAP-SNAIL COMPLEX FORMATION TO DRIVE SYNOVIAL LINING PATHOLOGY IN INFLAMMATORY ARTHRITIS

2021 ◽  
Vol 80 (Suppl 1) ◽  
pp. 19.1-19
Author(s):  
R. Symons ◽  
F. Colella ◽  
F. Collins ◽  
A. Roelofs ◽  
C. De Bari
Keyword(s):  
Transcription Factor ◽  
Complex Formation ◽  
Inflammatory Arthritis ◽  
Normal Mouse ◽  
Joint Destruction ◽  
Proximity Ligation Assay ◽  
Synovial Lining ◽  
Arthritis Severity ◽  
Marginal Erosions

Background:In rheumatoid arthritis (RA), the fibroblast-like synoviocytes (FLS) in synovial lining become invasive and cause joint destruction. The molecular mechanisms underpinning this pathogenic FLS phenotype are incompletely understood. The FLS descend from Growth differentiation factor 5 (Gdf5)-expressing joint interzone cells in the embryo, and we showed that conditional ablation of the transcriptional co-activator Yes associated protein (Yap) in Gdf5-lineage cells prevents synovial lining hyperplasia after traumatic cartilage injury in mice [1].Objectives:Here, we investigated a potential role for Yap in pathogenic FLS in immune-mediated inflammatory arthritis.Methods:Immunohistochemistry was used to detect Yap in human RA synovium and Yap, Snail and Ctgf in mouse synovium following antigen-induced arthritis (AIA). To determine the effect of Yap knockout (KO) in synovial stromal cells, AIA was induced in Gdf5-Cre;tdTomato;Yapfl/fl (Yap cKO) and Gdf5-Cre;tdTomato;Yapwt/wt (control) mice, or in Pdgfrα-CreER;Yapfl/fl (Yap ciKO, targeting Pdgfrα-expressing fibroblasts) and Yapfl/fl or YapWT/fl (control) mice after adult tamoxifen induction. Yap KO in both models was confirmed by immunohistochemistry. After nine days, arthritis severity was determined by histological scoring of synovial lining hyperplasia, immune infiltrates, cellular exudate, and marginal erosions. TdTomato+ Gdf5-lineage cells in synovium were quantified. In vitro, Yap reporter cells were treated with inflammatory cytokines to evaluate their ability to stimulate Yap-induced GFP expression by flow cytometry. Snail overexpression, siRNA-mediated Yap knockdown, and IL-6/sIL-6R stimulation were performed on normal mouse FLS, AIA-FLS or human RA-FLS, and cell invasion through a matrigel-coated transwell was quantified. A proximity ligation assay was utilised to detect Yap/Snail complex formation.Results:Average expression levels of Yap (p<0.0001), its transcription factor partner Snail (p=0.002), and their downstream target Ctgf (p=0.0003), were increased in mouse synovium after AIA (n=5), and Yap was highly expressed by FLS in human RA synovium. Yap cKO mice (n=24) showed a significantly decreased arthritis severity (p=0.002) after AIA compared to controls (n=22), with significant reductions in synovial lining hyperplasia (p<0.001), synovial immune cell infiltrates (p=0.026) and marginal erosions (p=0.002). Similarly, Yap ciKO mice (n=6) showed a significant decrease in arthritis score (p=0.039) after AIA compared to controls (n=9). However, both control mice (p<0.001) and Yap cKO mice (p<0.001) showed an extensive expansion of tdTomato+ Gdf5-lineage synovial cells after AIA, with no significant difference between control and Yap cKO mice. In vitro, Yap knockdown prevented IL-6/sIL-6R-induced invasion of normal mouse FLS (p=0.037) and decreased the invasiveness of AIA-FLS (p=0.0057). Using Yap reporter cells, we found that Yap was activated by IL-6/sIL-6R (p=0.016), but not TNFα or IL-1β. Finally, IL-6/sIL-6R treatment of normal mouse FLS (p=0.033) or human RA-FLS (p=0.036) induced Yap-Snail complex formation, and Yap knockdown prevented FLS invasion induced by Snail overexpression (p=0.027).Conclusion:These data demonstrate that via activation by IL-6, and co-operation with the transcription factor Snail, Yap acts as a key modulator of the invasive and destructive phenotype of FLS in inflammatory arthritis. Therapeutic targeting of Yap could reduce joint destruction in RA.References:[1]A. J. Roelofs et al., “Joint morphogenetic cells in the adult mammalian synovium,” Nat. Commun., vol. 8, no. May, p. 15040, 2017. DOI: 10.1136/annrheumdis-2018-213799Acknowledgements:This work was funded by the Medical Research Council (MR/L020211/1 and MR/L022893/1) and Versus Arthritis (20775 and 21156).Disclosure of Interests:None declared

scholarly journals Parallel G-quadruplexes recruit the HSV-1 transcription factor ICP4 to promote viral transcription in herpes virus-infected human cells

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Ilaria Frasson ◽  
Paola Soldà ◽  
Matteo Nadai ◽  
Sara Lago ◽  
Sara N. Richter
Keyword(s):  
Transcription Factor ◽  
Early Gene ◽  
Proximity Ligation Assay ◽  
Gene Promoters ◽  
Herpes Simplex Virus 1 ◽  
Direct Binding ◽  
Simplex Virus ◽  
In Cells ◽  
Hsv 1

AbstractG-quadruplexes (G4s) are four-stranded nucleic acid structures abundant at gene promoters. They can adopt several distinctive conformations. G4s have been shown to form in the herpes simplex virus-1 (HSV-1) genome during its viral cycle. Here by cross-linking/pull-down assay we identified ICP4, the major HSV-1 transcription factor, as the protein that most efficiently interacts with viral G4s during infection. ICP4 specific and direct binding and unfolding of parallel G4s, including those present in HSV-1 immediate early gene promoters, induced transcription in vitro and in infected cells. This mechanism was also exploited by ICP4 to promote its own transcription. Proximity ligation assay allowed visualization of G4-protein interaction at the single selected G4 in cells. G4 ligands inhibited ICP4 binding to G4s. Our results indicate the existence of a well-defined G4-viral protein network that regulates the productive HSV-1 cycle. They also point to G4s as elements that recruit transcription factors to activate transcription in cells.

scholarly journals Catalytic Roles of Yeast GSK3β/Shaggy Homolog Rim11p in Meiotic Activation

Genetics ◽  
1999 ◽  
Vol 153 (3) ◽  
pp. 1145-1152
Author(s):  
Krishnamurthy Malathi ◽  
Yang Xiao ◽  
Aaron P Mitchell
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Transcription Factor ◽  
Catalytic Activity ◽  
Protein Kinase ◽  
Complex Formation ◽  
Mutant Proteins ◽  
Tyrosine Residues ◽  
Low Level ◽  
Separable Functions

Abstract In Saccharomyces cerevisiae, many meiotic genes are activated by a heteromeric transcription factor composed of Ime1p and Ume6p. Ime1p-Ume6p complex formation depends upon the protein kinase Rim11p, which interacts with and phosphorylates both Ime1p and Ume6p in vitro. Rim11p may promote complex formation through its phosphorylation of Ime1p and Ume6p or simply through its interaction with both proteins. Here, we characterize mutant Ime1p derivatives that interact with Rim11p but are not phosphorylated in vitro. These mutant proteins are also defective in interaction with Ume6p. These results argue that Ime1p must be phosphorylated to interact with Ume6p. Our genetic observations suggest that Ime1p tyrosine residues are among the Rim11p phosphoacceptors, and we find that Ime1p reacts with an anti-phosphotyrosine antibody. Ime1p and Rim11p have been thought to act only through Ume6p, but we find that Ime1p and Rim11p promote meiosis at a very low level in the absence of Ume6p. A nonphosphorylatable mutant Ime1p derivative promotes sporulation through this Ume6p-independent pathway, as does a mutant Rim11p derivative that fails to interact with Ime1p. Therefore, Ime1p and Rim11p have two genetically separable functions in the sporulation program. However, catalytic activity of Rim11p is required for sporulation in the presence or absence of Ume6p.

scholarly journals Targeting the IL-6–Yap–Snail signalling axis in synovial fibroblasts ameliorates inflammatory arthritis

2021 ◽  
pp. annrheumdis-2021-220875
Author(s):  
Rebecca A Symons ◽  
Fabio Colella ◽  
Fraser L Collins ◽  
Alexandra J Rafipay ◽  
Karolina Kania ◽  
...  
Keyword(s):  
Inflammatory Arthritis ◽  
Critical Role ◽  
Joint Destruction ◽  
Synovial Fibroblasts ◽  
Tissue Growth ◽  
Lineage Tracing ◽  
Proximity Ligation Assay ◽  
Necrosis Factor Alpha ◽  
Fluorescent Reporters ◽  
Downstream Target

ObjectiveWe aimed to understand the role of the transcriptional co-factor Yes-associated protein (Yap) in the molecular pathway underpinning the pathogenic transformation of synovial fibroblasts (SF) in rheumatoid arthritis (RA) to become invasive and cause joint destruction.MethodsSynovium from patients with RA and mice with antigen-induced arthritis (AIA) was analysed by immunostaining and qRT-PCR. SF were targeted using Pdgfrα-CreER and Gdf5-Cre mice, crossed with fluorescent reporters for cell tracing and Yap-flox mice for conditional Yap ablation. Fibroblast phenotypes were analysed by flow cytometry, and arthritis severity was assessed by histology. Yap activation was detected using Yap–Tead reporter cells and Yap–Snail interaction by proximity ligation assay. SF invasiveness was analysed using matrigel-coated transwells.ResultsYap, its binding partner Snail and downstream target connective tissue growth factor were upregulated in hyperplastic human RA and in mouse AIA synovium, with Yap detected in SF but not macrophages. Lineage tracing showed polyclonal expansion of Pdgfrα-expressing SF during AIA, with predominant expansion of the Gdf5-lineage SF subpopulation descending from the embryonic joint interzone. Gdf5-lineage SF showed increased expression of Yap and adopted an erosive phenotype (podoplanin+Thy-1 cell surface antigen−), invading cartilage and bone. Conditional ablation of Yap in Gdf5-lineage cells or Pdgfrα-expressing fibroblasts ameliorated AIA. Interleukin (IL)-6, but not tumour necrosis factor alpha (TNF-α) or IL-1β, Jak-dependently activated Yap and induced Yap–Snail interaction. SF invasiveness induced by IL-6 stimulation or Snail overexpression was prevented by Yap knockdown, showing a critical role for Yap in SF transformation in RA.ConclusionsOur findings uncover the IL-6–Yap–Snail signalling axis in pathogenic SF in inflammatory arthritis.

scholarly journals Methanobacterium thermoautotrophicum RNA Polymerase and Transcription In Vitro

1999 ◽  
Vol 181 (14) ◽  
pp. 4424-4429 ◽  
Author(s):  
Trevor J. Darcy ◽  
Winfried Hausner ◽  
Donald E. Awery ◽  
Aled M. Edwards ◽  
Michael Thomm ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Complex Formation ◽  
Rna Polymerase ◽  
Transcription Initiation ◽  
Methanobacterium Thermoautotrophicum ◽  
Tata Binding Protein ◽  
Gene Promoters ◽  
Transcription In Vitro ◽  
Archaeal Histone

ABSTRACT RNA polymerase (RNAP) purified from Methanobacterium thermoautotrophicum ΔH has been shown to initiate transcription accurately in vitro from the hmtB archaeal histone promoter with either native or recombinant forms of the M. thermoautotrophicum TATA-binding protein and transcription factor TFB. Efforts to obtain transcription initiation from hydrogen-regulated methane gene promoters were, however, unsuccessful. Two previously unrecognized archaeal RNAP subunits have been identified, and complex formation by the M. thermoautotrophicum RNAP and TFB has been demonstrated.

Subnuclear compartmentalization of sequence-specific transcription factors and regulation of eukaryotic gene expression

2005 ◽  
Vol 83 (4) ◽  
pp. 535-547 ◽  
Author(s):  
Gareth N Corry ◽  
D Alan Underhill
Keyword(s):  
Gene Expression ◽  
Transcription Factor ◽  
Transcription Factors ◽  
Transcriptional Activation ◽  
Current Knowledge ◽  
Nuclear Architecture ◽  
Subnuclear Localization ◽  
Modular Structures

To date, the majority of the research regarding eukaryotic transcription factors has focused on characterizing their function primarily through in vitro methods. These studies have revealed that transcription factors are essentially modular structures, containing separate regions that participate in such activities as DNA binding, protein–protein interaction, and transcriptional activation or repression. To fully comprehend the behavior of a given transcription factor, however, these domains must be analyzed in the context of the entire protein, and in certain cases the context of a multiprotein complex. Furthermore, it must be appreciated that transcription factors function in the nucleus, where they must contend with a variety of factors, including the nuclear architecture, chromatin domains, chromosome territories, and cell-cycle-associated processes. Recent examinations of transcription factors in the nucleus have clarified the behavior of these proteins in vivo and have increased our understanding of how gene expression is regulated in eukaryotes. Here, we review the current knowledge regarding sequence-specific transcription factor compartmentalization within the nucleus and discuss its impact on the regulation of such processes as activation or repression of gene expression and interaction with coregulatory factors.Key words: transcription, subnuclear localization, chromatin, gene expression, nuclear architecture.

scholarly journals Integrin α3β1 Promotes Invasive and Metastatic Properties of Breast Cancer Cells through Induction of the Brn-2 Transcription Factor

Cancers ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 480
Author(s):  
Rakshitha Pandulal Miskin ◽  
Janine S. A. Warren ◽  
Abibatou Ndoye ◽  
Lei Wu ◽  
John M. Lamar ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Transcription Factor ◽  
Cancer Cells ◽  
Cell Invasion ◽  
Breast Cancer Cells ◽  
Gene Promoter ◽  
Akt Inhibitor ◽  
Integrin Α3β1

In the current study, we demonstrate that integrin α3β1 promotes invasive and metastatic traits of triple-negative breast cancer (TNBC) cells through induction of the transcription factor, Brain-2 (Brn-2). We show that RNAi-mediated suppression of α3β1 in MDA-MB-231 cells caused reduced expression of Brn-2 mRNA and protein and reduced activity of the BRN2 gene promoter. In addition, RNAi-targeting of Brn-2 in MDA-MB-231 cells decreased invasion in vitro and lung colonization in vivo, and exogenous Brn-2 expression partially restored invasion to cells in which α3β1 was suppressed. α3β1 promoted phosphorylation of Akt in MDA-MB-231 cells, and treatment of these cells with a pharmacological Akt inhibitor (MK-2206) reduced both Brn-2 expression and cell invasion, indicating that α3β1-Akt signaling contributes to Brn-2 induction. Analysis of RNAseq data from patients with invasive breast carcinoma revealed that high BRN2 expression correlates with poor survival. Moreover, high BRN2 expression positively correlates with high ITGA3 expression in basal-like breast cancer, which is consistent with our experimental findings that α3β1 induces Brn-2 in TNBC cells. Together, our study demonstrates a pro-invasive/pro-metastatic role for Brn-2 in breast cancer cells and identifies a role for integrin α3β1 in regulating Brn-2 expression, thereby revealing a novel mechanism of integrin-dependent breast cancer cell invasion.

scholarly journals The acute transcriptional responses to dietary methionine restriction are triggered by inhibition of ternary complex formation and linked to Erk1/2, mTOR, and ATF4

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Kirsten P. Stone ◽  
Sujoy Ghosh ◽  
Jean Paul Kovalik ◽  
Manda Orgeron ◽  
Desiree Wanders ◽  
...  
Keyword(s):  
Stress Response ◽  
Complex Formation ◽  
Ternary Complex ◽  
Target Genes ◽  
Bioinformatic Analysis ◽  
Transcriptional Responses ◽  
Metabolomics Data ◽  
Ternary Complex Formation ◽  
Methionine Restriction

AbstractThe initial sensing of dietary methionine restriction (MR) occurs in the liver where it activates an integrated stress response (ISR) that quickly reduces methionine utilization. The ISR program is regulated in part by ATF4, but ATF4’s prototypical upstream regulator, eIF2α, is not acutely activated by MR. Bioinformatic analysis of RNAseq and metabolomics data from liver samples harvested 3 h and 6 h after initiating MR shows that general translation is inhibited at the level of ternary complex formation by an acute 50% reduction of hepatic methionine that limits formation of initiator methionine tRNA. The resulting ISR is induced by selective expression of ATF4 target genes that mediate adaptation to reduced methionine intake and return hepatic methionine to control levels within 4 days of starting the diet. Complementary in vitro experiments in HepG2 cells after knockdown of ATF4, or inhibition of mTOR or Erk1/2 support the conclusion that the early induction of genes by MR is partially dependent on ATF4 and regulated by both mTOR and Erk1/2. Taken together, these data show that initiation of dietary MR induces an mTOR- and Erk1/2-dependent stress response that is linked to ATF4 by the sharp, initial drop in hepatic methionine and resulting repression of translation pre-initiation.

Sign in / Sign up

Export Citation Format

Share Document