Interferon signature in patients with <i>STAT1</i> gain‐of‐function mutation is epigenetically determined

Kaleviste, Epp; Saare, Mario; Leahy, Timothy Ronan; Bondet, Vincent; Duffy, Darragh; Mogensen, Trine H.; Jørgensen, Sofie E.; Nurm, Helke; Ip, Winnie; Davies, E Graham; Sauer, Sascha; Syvänen, Ann‐Christine; Milani, Lili; Peterson, Pärt; Kisand, Kai

doi:10.1002/eji.201847955

Cited by 34 publications

(31 citation statements)

References 58 publications

(94 reference statements)

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“…We demonstrated that different mutations, associated with STAT1 GOF, result in a STAT1 GOF phenotype via distinct mechanisms using real-time imaging and tracking of GFPtagged proteins. Our results (summarized in Table 1) are in line with previous reports (50)(51)(52), indicating that different molecular mechanisms can result in a STAT1 GOF phenotype. It remains unknown whether these differences (altered nuclear mobility, increased DNA binding, or increased nuclear import) are biologically relevant in influencing the patients' phenotype.…”

Section: Discussionsupporting

confidence: 92%

Live Cell Imaging Demonstrates Multiple Routes Toward a STAT1 Gain-of-Function Phenotype

et al. 2020

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Signal transducer and activator of transcription 1 (STAT1) gain-of-function (GOF) mutations result in a primary immunodeficiency (PID) characterized typically by chronic mucocutaneous candidiasis (CMC), but a wider phenotypic range is reported and remains unexplained from a pathophysiological point-of-view. We hypothesized that different STAT1 GOF mutations may result in distinct molecular mechanisms, possibly explaining the variable phenotypes observed in patients. We selected STAT1 GOF mutants (R274W, R321S, T419R, and N574I) that are spread over the protein and studied their dynamic behavior in vitro in U3A and HeLa cell lines. All GOF mutants showed increased STAT1 phosphorylation compared to STAT1 WT. Real-time imaging demonstrated three underlying mechanisms for STAT1 GOF: (i) R274W showed a faster nuclear accumulation, (ii) both R321S and N574I showed a reduced nuclear mobility and slower dephosphorylation, whereas (iii) T419R was near-immobile in the nucleus, potentially due to enhanced binding to chromatin.

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Section: Discussionsupporting

confidence: 92%

Live Cell Imaging Demonstrates Multiple Routes Toward a STAT1 Gain-of-Function Phenotype

et al. 2020

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“…Treatment of the mice with the anti-IFNAR Ab rapidly and effectively reduced the expression of IFNresponse genes, suggesting that there is constant and ongoing TLR activation and IFN production in lupus. Reports suggest epigenetics may play a role in promoting and perpetuating the expression of IFN-response genes, even in the absence of high IFN levels (35,36). Conversely, the data reported in this study suggest that sustained elevated IFN-response gene expression is more dependent on constant levels of elevated IFN.…”

Section: Discussioncontrasting

confidence: 64%

TLR7 and TLR8 Differentially Activate the IRF and NF-κB Pathways in Specific Cell Types to Promote Inflammation

et al. 2020

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TLR7 and TLR8 are pattern recognition receptors that reside in the endosome and are activated by ssRNA molecules. TLR7 and TLR8 are normally part of the antiviral defense response, but they have also been implicated as drivers of autoimmune diseases such as lupus. The receptors have slightly different ligand-binding specificities and cellular expression patterns that suggest they have nonredundant specialized roles. How the roles of TLR7 and TLR8 differ may be determined by which cell types express each TLR and how the cells respond to activation of each receptor. To provide a better understanding of the effects of TLR7/8 activation, we have characterized changes induced by TLR-specific agonists in different human immune cell types and defined which responses are a direct consequence of TLR7 or TLR8 activation and which are secondary responses driven by type I IFN or cytokines produced subsequent to the primary response. Using cell sorting, gene expression analysis, and intracellular cytokine staining, we have found that the IFN regulatory factor (IRF) and NF-kB pathways are differentially activated downstream of the TLRs in various cell types. Studies with an anti-IFNAR Ab in human cells and lupus mice showed that inhibiting IFN activity can block secondary IFN-induced gene expression changes downstream of TLR7/8 activation, but not NF-kB-regulated genes induced directly by TLR7/8 activation at earlier timepoints. In summary, these results elucidate the different roles TLR7 and TLR8 play in immunity and inform strategies for potential treatment of autoimmune diseases driven by TLR7/8 activation. ImmunoHorizons, 2020, 4: 93-107.

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“…Increased levels of pSTAT1 occur following stimulation with IFNγ, IFNα, IL-6, IL-21, and IL-27 (2–5). Previous data showed that pSTAT1 level peaks 30 min after IFNα stimulation and declines gradually thereafter (18). We verified this in two patients and two healthy donors (Figure 6A).…”

Section: Resultsmentioning

confidence: 91%

STAT1 Gain-of-Function Mutations Cause High Total STAT1 Levels With Normal Dephosphorylation

et al. 2019

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Signal transducer and activator of transcription (STAT1)1 gain of function (GOF) pathogenic variants have been associated with increased levels of phosphorylated STAT1 and STAT1-dependent cellular responses. Delayed dephosphorylation was proposed as the underlying mechanism leading to the characteristically raised pSTAT1 levels. We examined the levels of STAT1 protein and message as well as rates of STAT1 phosphorylation, dephosphorylation, and degradation associated with STAT1 GOF pathogenic variants. Fresh peripheral blood mononuclear cells (PBMC) from 14 STAT1 GOF patients carrying 10 different pathogenic variants in the coiled-coil, DNA binding, and SH2 domains and healthy donors were used to study STAT1 levels and phosphorylation (pSTAT1) following IFNγ and IFNα stimulation. STAT1 protein levels were measured by flow cytometry and immunoblot. STAT1 mRNA levels were measured using quantitative reverse transcription PCR. STAT1 protein degradation was studied using cycloheximide. Patient IFNγ and IFNα induced peak pSTAT1 was higher than in healthy controls. The velocity of pSTAT1 dephosphorylation after treatment of IFNγ stimulated CD14 + monocytes with the Janus Kinase (JAK)-inhibitor ruxolitinib was significantly faster in patient cells. STAT1 protein levels in patient CD14 + monocytes and CD3 + T cells were higher than in healthy donors. There was a strong and positive correlation between CD14 + STAT1 protein levels and peak pSTAT1 levels. Patient fresh PBMC STAT1 mRNA levels were increased at rest and after 16 h of incubation. STAT1 protein degradation was similar in patient and healthy volunteer cells. Patient IFNγ receptors 1 and 2 and JAK2 levels were normal. One patient in our cohort was treated with the oral JAK inhibitor ruxolitinib. Treatment was associated with normalization of both STAT1 protein and peak pSTAT1 levels. After JAK inhibitor treatment was stopped the patient's CD14 + monocyte STAT1 protein and peak phosphorylation levels increased proportionally. These findings suggest that patients with STAT1 GOF mutations have higher levels of total STAT1 protein, leading to high levels of pSTAT1 after stimulation, despite rapid STAT1 dephosphorylation and normal degradation.

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Interferon signature in patients with STAT1 gain‐of‐function mutation is epigenetically determined

Cited by 34 publications

References 58 publications

Live Cell Imaging Demonstrates Multiple Routes Toward a STAT1 Gain-of-Function Phenotype

Live Cell Imaging Demonstrates Multiple Routes Toward a STAT1 Gain-of-Function Phenotype

TLR7 and TLR8 Differentially Activate the IRF and NF-κB Pathways in Specific Cell Types to Promote Inflammation

STAT1 Gain-of-Function Mutations Cause High Total STAT1 Levels With Normal Dephosphorylation

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