STAT1 Rabbit Polyclonal Antibody

Function

All STAT molecules are phosphorylated by receptor associated kinases, that causes activation, dimerization by forming homo- or heterodimers and finally translocate to nucleus to work as transcription factors. Specifically STAT1 can be activated by several ligands such as Interferon alpha (IFNα), Interferon gamma (IFNγ), Epidermal Growth Factor (EGF), Platelet Derived Growth Factor (PDGF), Interleukin 6 (IL-6), or IL-27. Type I interferons (IFN-α, IFN-ß) bind to receptors, cause signaling via kinases, phosphorylate and activate the Jak kinases TYK2 and JAK1 and also STAT1 and STAT2. STAT molecules form dimers and bind to ISGF3G/IRF-9, which is Interferon stimulated gene factor 3 complex with Interferon regulatory Factor 9. This allows STAT1 to enter the nucleus.[6] STAT1 has a key role in many gene expressions that cause survival of the cell, viability or pathogen response. There are two possible transcripts (due to alternative splicing) that encode 2 isoforms of STAT1. STAT1α, the full-length version of the protein, is the main active isoform, responsible for most of the known functions of STAT1. STAT1ß, which lacks a portion of the C-terminus of the protein, is less-studied, but has variously been reported to negatively regulate activation of STAT1 or to mediate IFN-γ-dependent anti-tumor and anti-infection activities. STAT1 is involved in upregulating genes due to a signal by either type I, type II, or type III interferons. In response to IFN-γ stimulation, STAT1 forms homodimers or heterodimers with STAT3 that bind to the GAS (Interferon-Gamma-Activated Sequence) promoter element; in response to either IFN-α or IFN-β stimulation, STAT1 forms a heterodimer with STAT2 that can bind the ISRE (Interferon-Stimulated Response Element) promoter element. In either case, binding of the promoter element leads to an increased expression of ISG (Interferon-Stimulated Genes). Expression of STAT1 can be induced with diallyl disulfide, a compound in garlic.

Background References

1. "Fibroblast growth factor receptor-induced phosphorylation of STAT1 at the Golgi apparatus without translocation to the nucleus." Citores L., Bai L., Sorensen V., Olsnes S. J. Cell. Physiol. 212:148-156(2007)

2. "Analysis of STAT1 activation by six FGFR3 mutants associated with skeletal dysplasia undermines dominant role of STAT1 in FGFR3 signaling in cartilage." Krejci P., Salazar L., Kashiwada T.A., Chlebova K., Salasova A., Thompson L.M., Bryja V., Kozubik A., Wilcox W.R. PLoS ONE 3:E3961-E3961(2008)

3. "A novel form of human STAT1 deficiency impairing early but not late responses to interferons." Kong X.F., Ciancanelli M., Al-Hajjar S., Alsina L., Zumwalt T., Bustamante J., Feinberg J., Audry M., Prando C., Bryant V., Kreins A., Bogunovic D., Halwani R., Zhang X.X., Abel L., Chaussabel D., Al-Muhsen S., Casanova J.L., Boisson-Dupuis S. Blood 116:5895-5906(2010)

Sequence Similarity

Belongs to the transcription factor STAT family.

Post-translational Modification

Phosphorylated on tyrosine and serine residues in response to a variety of cytokines/growth hormones including IFN-alpha, IFN-gamma, PDGF and EGF. Activated KIT promotes phosphorylation on tyrosine residues and subsequent translocation to the nucleus. Upon EGF stimulation, phosphorylation on Tyr-701 (lacking in beta form) by JAK1, JAK2 or TYK2 promotes dimerization and subsequent translocation to the nucleus. Growth hormone (GH) activates STAT1 signaling only via JAK2. Tyrosine phosphorylated in response to constitutively activated FGFR1, FGFR2, FGFR3 and FGFR4. Phosphorylation on Ser-727 by several kinases including MAPK14, ERK1/2 and CAMKII on IFN-gamma stimulation, regulates STAT1 transcriptional activity. Phosphorylation on Ser-727 promotes sumoylation though increasing interaction with PIAS. Phosphorylation on Ser-727 by PRKCD induces apoptosis in response to DNA-damaging agents. Phosphorylated on tyrosine residues when PTK2/FAK1 is activated; most likely this is catalyzed by a SRC family kinase. Dephosphorylation on tyrosine residues by PTPN2 negatively regulates interferon-mediated signaling. Upon viral infection or IFN induction, phosphorylation on Ser-708 occurs much later than phosphorylation on Tyr-701 and is required for the binding of ISGF3 on the ISREs of a subset of IFN-stimulated genes IKBKE-dependent. Phosphorylation at Tyr-701 and Ser-708 are mutually exclusive, phosphorylation at Ser-708 requires previous dephosphorylation of Tyr-701.; Sumoylated with SUMO1, SUMO2 and SUMO3. Sumoylation is enhanced by IFN-gamma-induced phosphorylation on Ser-727, and by interaction with PIAS proteins. Enhances the transactivation activity.; ISGylated.; Mono-ADP-ribosylated at Glu-657 and Glu-705 by PARP14; ADP-ribosylation prevents phosphorylation at Tyr-701. However, the role of ADP-ribosylation in the prevention of phosphorylation has been called into question and the lack of phosphorylation may be due to sumoylation of Lys-703.; Monomethylated at Lys-525 by SETD2; monomethylation is necessary for phosphorylation at Tyr-701, translocation into the nucleus and activation of the antiviral defense.

Subcellular Location

Cytoplasm, nucleus

UNIPROT

SwissProt: P42224 Human

SwissProt: P42225 Mouse

Entrez Gene: 25124 Rat

Synonyms