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J Allergy Clin Immunol. 2018 May;141(5):1844-1853.e2. doi: 10.1016/j.jaci.2017.07.027. Epub 2017 Aug 30.

Novel signal transducer and activator of transcription 1 mutation disrupts small ubiquitin-related modifier conjugation causing gain of function.

Author information

1
Laboratory of Clinical Infectious Diseases, National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), Bethesda, Md; Leprosy Laboratory, Oswaldo Cruz Institute, FIOCRUZ, Rio de Janeiro, Brazil. Electronic address: sampaioe@niaid.nih.gov.
2
Laboratory of Clinical Infectious Diseases, National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), Bethesda, Md.
3
Fungal Pathogenesis Unit, Laboratory of Clinical Infectious Diseases, NIAID, NIH, Bethesda, Md.
4
Computational Biology Section, Bioinformatics and Computational Biosciences Branch (BCBB), OCICB/OSMO/OD, NIAID, NIH, Bethesda, Md.
5
Biological Imaging Section, NIAID, NIH, Bethesda, Md.
6
Saint Joseph Physician Network Practices, Infectious Diseases, Mishawaka, Ind.

Abstract

BACKGROUND:

Sumoylation is a posttranslational reversible modification of cellular proteins through the conjugation of small ubiquitin-related modifier (SUMO) and comprises an important regulator of protein function.

OBJECTIVE:

We sought to characterize the molecular mechanism of a novel mutation at the SUMO motif on signal transducer and activator of transcription 1 (STAT1).

METHODS:

STAT1 sequencing and functional characterization were performed in transfection experiments by using immunoblotting and immunoprecipitation in STAT1-deficient cell lines. Transcriptional response and target gene activation were also investigated in PBMCs.

RESULTS:

We identified a novel STAT1 mutation (c.2114A>T, p.E705V) within the SUMO motif (702IKTE705) in a patient with disseminated Rhodococcus species infection, Norwegian scabies, chronic mucocutaneous candidiasis, hypothyroidism, and esophageal squamous cell carcinoma. The mutation is located in the tail segment and is predicted to disrupt STAT1 sumoylation. Immunoprecipitation experiments performed in transfected cells confirmed absent STAT1 sumoylation for E705V, whereas it was present in wild-type (WT) STAT1 cells, as well as the loss-of-function mutants L706S and Y701C. Furthermore, stimulation with IFN-γ led to enhanced STAT1 phosphorylation, enhanced transcriptional activity, and target gene expression in the E705V-transfected compared with WT-transfected cells. Computer modeling of WT and mutant STAT1 molecules showed variations in the accessibility of the phosphorylation site Y701, which corresponded to the loss-of-function and gain-of-function variants.

CONCLUSION:

This is the first report of a mutation in the STAT1 sumoylation motif associated with clinical disease. These data reinforce sumoylation as a key posttranslational regulatory modification of STAT1 and identify a novel mechanism for gain-of-function STAT1 disease in human subjects.

KEYWORDS:

IFN-γ; Rhodococcus species infection; Signal transducer and activator of transcription 1; gain of function; small ubiquitin-related modifier; sumoylation

PMID:
28859974
PMCID:
PMC5832513
DOI:
10.1016/j.jaci.2017.07.027
[Indexed for MEDLINE]
Free PMC Article

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