The Research On Regulation Of G Protein ?q(G?q) Subunit Expression

The prevalence rate of autoimmune diseases which is an important disease with high morbidity and mortality has significantly risen in recent years.Gaq,the a-subunit of the Gq protein,a member of the Gq/11 sub-family,is encoded by the GNAQ gene.It was reported to inhibit phosphatidylinositol-3-Kinase(PI3K)activation and prevent the activation of Akt.Previous studies demonstrated that Gaq mRNA expression was decreased in PBMCs from rheumatoid arthritis(RA)and systemic lupus erythematosus(SLE)compared to healthy individuals.Correlation analyses showed that Gaq expression in these autoimmune diseases patients was associated with disease activity and production of relevant cytokines and autoantibody.These data suggested that Gaq might be involved in the pathogenesis of autoimmune diseases.But the mechanism of regulating the expression of GNAQ gene still remain unknown.The modification of histone acetylation plays an important role in regulating the gene expression of eucaryon.Acetylation and deacetylation of histones are controlled by histone acetyltransferases(HAT)and histone deacetylases(HDACs),respectively.HATs promote a loose chromatin state and facilitate transcription factors and the RNA polymerase complex to gene promoter regions.The role of HDACs are in reverse.In the present study,using TSA as an histone acetylation inducer,we examined the effects of histone acetylation on the GNAQ expression in 293T cells.Also,we analysis the GNAQ gene promoter region and predict relevant transcription factors to further explore the mechanism of the decreased expression of Gaq.Firstly,our results showed that treatment with TSA may dose-dependently increase the GNAQ mRNA level as well as protein level in 293T cells.We verify acetylated histone H3 and H4 increased by TSA.This confirmed that the expression of Gaq is connection with histone acetylation.Secondly,we used promoter analysis and found several binding sites of transcription factors in promoter region.One positive regulatory region was screened out.The significant increased expression of GATA-1 after treatment with TSA is in accordance with the trend of Gaq expression.Data from immunoprecipitation and Western blot analyses further revealed that TSA may directly increases the GATA-1 protein level.And then transcription factor GATA-1 specificly binding to the GNAQ promoter was demonstrated by EMSA and ChIP assays,and TSA treatment increases connection of GATA-1 to the GNAQ promoter region.In conclusion,we have demonstrated the regulation of the GNAQ gene expression in 293T cells is mediated by histone acetylation and transcription factor GATA-1.And the study provided a new perspective for the treatment of AID.