Abstract
BackgroundType I and type II interferons (IFNs) exert their effects mainly through the JAK/STAT pathway, which is presently best described in mammals. STAT1 is involved in signaling pathways induced by both types of IFNs. It has a domain-like structure including an amino-terminus that stabilizes interaction between STAT dimers in a promoter-binding situation, a coiled coil domain facilitating interactions to other proteins, a central DNA-binding domain, a SH2 domain responsible for dimerization of phosphorylated STATs and conserved phosphorylation sites within the carboxy terminus. The latter is also the transcriptional activation domain.ResultsA salmon (Salmo salar) STAT1 homologue, named ssSTAT1a, has been identified and was shown to be ubiquitously expressed in various cells and tissues. The ssSTAT1a had a domain-like structure with functional motifs that are similar to higher vertebrates. Endogenous STAT1 was shown to be phosphorylated at tyrosine residues both in salmon leukocytes and in TO cells treated with recombinant type I and type II IFNs. Also ectopically expressed ssSTAT1 was phosphorylated in salmon cells upon in vitro stimulation by the IFNs, confirming that the cloned gene was recognized by upstream tyrosine kinases. Treatment with IFNs led to nuclear translocation of STAT1 within one hour. The ability of salmon STAT1 to dimerize was also shown.ConclusionsThe structural and functional properties of salmon STAT1 resemble the properties of mammalian STAT1.
Highlights
Type I and type II interferons (IFNs) exert their effects mainly through the JAK/STAT pathway, which is presently best described in mammals
Cloning of STAT1 With primers derived from a rainbow trout (Oncorhynchus mykiss) STAT1 sequence we obtained a 2.3 kB DNA fragment by PCR using cDNA from salmon ovaries and head kidney (HK)
The major differences found between the three salmon sequences were located in the C-terminal end (Figure 1), where EU016199 has two single nucleotide deletions when compared to ssSTAT1a (T missing in position 2190, and T missing in position 2201), which leads to frame shifts and subsequently a premature stop
Summary
Type I and type II interferons (IFNs) exert their effects mainly through the JAK/STAT pathway, which is presently best described in mammals. STAT1 is involved in signaling pathways induced by both types of IFNs. STAT1 is involved in signaling pathways induced by both types of IFNs It has a domain-like structure including an amino-terminus that stabilizes interaction between STAT dimers in a promoter-binding situation, a coiled coil domain facilitating interactions to other proteins, a central DNA-binding domain, a SH2 domain responsible for dimerization of phosphorylated STATs and conserved phosphorylation sites within the carboxy terminus. The latter is the transcriptional activation domain. STAT1 can be found in both the cytoplasm and the nucleus without cytokine stimulation of cells [13]
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