Grass Carp (Ctenopharyngodon Idella) STAT6 Up-regulates The Expression Of CCL20 And BCL-XL

Signal transducer and activator of transcription 6(STAT6)belongs to the class of classified DNA-binding proteins and is a broad-spectrum transcriptional regulator with some conserved domains,such as the N-terminal domain,coiled-coil domain,and DNA-binding structure.Domain and SH2 domain.In mammals,viruses,growth factors,cytokines,and IFN-α all activate STAT6.Phosphorylated STAT6 undergoes homodimerization and then translocates to the nucleus,transferring signals from the receptor complex to the nucleus to regulate the transcription and expression of related genes and participate in normal cellular responses.In recent years,studies have shown that STAT6 not only plays an important role in the regulation of the immune system,but also participates in activities such as cell proliferation and apoptosis.STAT6 is involved in cellular immune responses and apoptosis by modulating immune-related genes and various apoptotic functional genes.STAT6 regulates the transcription and expression of various immune cells,chemokines CCL2,CCL20 and CCL26,and is responsible for homing of immune cells and participating in cellular inflammatory responses.On the other hand,STAT6 inhibits apoptosis by up-regulating the expression of various anti-apoptotic genes.For example,the anti-apoptotic activity of IL-4 is mediated by activation of STAT6 and subsequent transcriptional expression of Bcl-xl.In contrast,STAT6 silencing induced the expression of the apoptosis-related gene Bax and inhibited the expression of the antiapoptotic gene Bcl-xl.In short,STAT6 has a variety of biological functions.The structure,expression and tyrosine-based phosphorylation of STAT6 are conserved from fish to mammals.However,in addition to sporadic literature on zebrafish,literature on the function of fish STAT6 has rarely been published.In order to study the activation mechanism and potential function of STAT6 in the innate immune signaling pathway,we first cloned and identified the full-length cDNA sequence of STAT6 gene of grass carp,which is 2747 bp,and the open reading frame(ORF)is 2313 bp,encoding a polypeptide of 770 amino acids.Phylogenetic tree analysis showed that grass carp STAT6 had the greatest homology with carp STAT6.Secondly,the simulated RNA virus was extracted from cells and tissues under the stimulation of poly I:C.The expression of STAT6 was up-regulated by Q-PCR.Finally,by co-immunoprecipitation and immunofluorescence co-localization experiments,STAT6 can undergo homodimerization after poly I:C stimulation,while in cells that have not been stimulated by poly I:C,grass carp STAT6 cannot occur homologous.Polymerization.In the grass carp cell line,overexpression of STAT6,Q-PCR detection of CCL20 and Bcl-xl expression up-regulation;knockdown STAT6,Q-PCR detection of CCL20 and Bcl-xl expression down-regulated.The STAT6 transfected grass carp in the grass carp cell line can activate the promoter activities of CCL20 and Bcl-xl mainly through the DBD domain rather than the SH2 domain.Overexpression of grass carp STAT6 can enhance cell viability and inhibit apoptosis,and when knocking down STAT6,the result is reversed.Taken together,grass carp STAT6 plays an important role in innate immunity and anti-apoptosis.