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Coiled-coil domain of Signal Transducer and Activator of Transcription 1 (STAT1) This family consists of the coiled-coil (alpha) domain of the STAT1 proteins (Signal Transducer and Activator of Transcription 1, or Signal Transduction And Transcription 1). STAT1 plays an essential role in mediating responses to all types of interferons (IFN), transducing signals from cytoplasmic domains of transmembrane receptors into the nucleus where it regulates gene expression. Thus STAT1 is involved in modulating diverse cellular processes, such as antimicrobial activities, cell proliferation and cell death. STAT1 function is crucial in the innate and adaptive arm of immunity and protects from pathogen infections; phosphorylation of a critical tyrosine by Janus kinases (JAKs) leads to its activation and nuclear translocation, while phosphorylation of a critical serine is required for full transcriptional activation upon IFN stimulation and in response to cellular stress. Transcription of protein-encoding genes (including Stat1 itself) as well as expression of microRNAs (miRNAs) is regulated by activated STAT1. Animal studies have shown that STAT1 is generally considered a tumor suppressor but it can also act as a tumor promoter; its functions are not restricted to tumor cells, but extend to parts of the tumor microenvironment such as immune cells, endothelial cells. STAT1 abundance is a reliable marker for good prognosis in selected tumor types, but it can also correlate with disease progression. In head and neck cancer (HNC) patients, upregulation of STAT1-induced HLA class I enhances immunogenicity and clinical response to anti-EGFR mAb cetuximab therapy. In systemic juvenile idiopathic arthritis (sJIA) characterized by systemic inflammation and arthritis, STAT1 phosphorylation downstream of IFNs is impaired. It exerts anti-oncogenic activities through interferon-gamma and interferon-alpha. STAT1 may inhibit hepatocellular carcinoma cell growth by regulating p53-related cell cycling and apoptosis. Studies also show a significant correlation of high STAT1 activity with longer colorectal cancer patient overall survival. Recent studies have shown that STAT1 suppresses mouse mammary gland tumorigenesis by immune regulatory as well as tumor cell-specific functions of STAT1. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",