The Effect Of -286 Site SNP On The Expression Of CRP

As typical acute phase protein,C-reaction protein(CRP)was mainly expressed in hepatocytes.The level of CRP exaggerated very soon when body was under inflammation or tissue injury.Previous work indicated that the tissue specific and acute phase expression of CRP were regulated by transcription factors within proximal promoter.Interestingly,the promoter of CRP was highly conserved between human and rodent,while it presented typical acute phase only in human.Transcription factor regulation could not explain that solely,implicating there existing other modulation pathways.Being one of the most pivotal mechanisms regulating transcription,DNA methylation might play an important role in the tissue specific and acute phase expression.The level of methylation and demethylation were determined in cell lines Hep3 B and rabbit hepatocytes.Results revealed that the DNA methylation within CRP promoter was lower either in Hep3 B or rabbit hepatocyte consistent with CRP mRNA expression.Moreover,CRP expression during acute phase may depend on rapid demethylation.To discover the mechanisms of rapid demethylation,the level of DNA 5-hydroxymethyl cytosine(5hmC)was examined.In Hep3 B cells,rarely any 5hmC in promoter during acute phase was detected while it presented very low level on baseline.In the gene body,5hmC was detected neither during acute phase nor baseline.Assuming that 5hmC was under pre-excitation state,it underwent rapid demethylation thoroughly when stimulation occurred.Our previous work and other researches proved that-286 position rs3091244 on the promoter of CRP gene had huge impact on CRP level in plasma,which was also supported by luciferase report gene test.To explore the mechanisms whereby rs3091244 regulated CRP expression,we analyzed the transcription factors binding to this site.It indicated that there is no binding site whether this site was occupied by A or C.It implicated that this site was regulated by DNA methylation.