title: Genetic variation at a Yin-Yang 1 response site regulates the transcription of cyclin-dependent kinase inhibitor p18INK4C transcript in lupus-prone mice.
abstract: We have previously shown that a novel -74 C-to-T mutation in the promoter of the cyclin-dependent kinase inhibitor p18(Ink4c) (p18) gene was associated with a reduced p18 expression in B cells from mice carrying the Sle2c1 lupus susceptibility locus. To determine the function of the -74 C/T single nucleotide polymorphism, we have characterized the proximal promoter of the mouse p18 gene. Functional analysis of the 5' flanking region by sequential deletions revealed crucial elements between -300 and +1, confirming the in silico prediction that the -74 T allele created a novel Yin-Yang 1 (YY-1) binding site adjacent to an existing one common to both alleles. Moreover, we found that YY-1, E2F1, and Sp-1 can synergistically enhance the activity of the p18 promoter. Mutational inactivation revealed that YY-1 binding regulates the p18 activity in an allele-dependent fashion. EMSAs with splenic B cell extracts directly demonstrated that YY-1 binds to the p18 promoter with differences between the C and the T alleles. We also determined in vivo by chromatin immunoprecipitation that the T allele resulted in increased YY-1 and decreased Nrf-2 binding to the p18 promoter as compared with the C allele in B cells. Thus, YY-1 is a direct regulator of p18 gene expression in an allele-dependent fashion that is consistent with the lupus-associated T allele, inducing a lower p18 transcriptional activity by increasing YY-1 binding. These results establish the p18 -74 C/T mutation as the leading causal variant for the B1a cell expansion that characterizes the NZB and NZM2410 lupus-prone strains.
authors.affiliation: Department of Pathology, Immunology, and Laboratory Medicine, University of Florida, Gainesville, FL 32610, USA.
authors.forename: Hari-Hara S K
authors.initials: HH
authors.lastname: Potula
authors.forename: Laurence
authors.initials: L
authors.lastname: Morel
mesh_terms: D000818:Animals; D001483:Base Sequence; D050763:Cyclin-Dependent Kinase Inhibitor p18 / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics*; D015536:Down-Regulation / Q000235:genetics / Q000276:immunology; D020022:Genetic Predisposition to Disease; D014644:Genetic Variation / Q000276:immunology*; D008180:Lupus Erythematosus, Systemic / Q000235:genetics* / Q000276:immunology*; D051379:Mice; D008810:Mice, Inbred C57BL; D008814:Mice, Inbred NZB; D008969:Molecular Sequence Data; D009154:Mutation; D041681:NIH 3T3 Cells; D020641:Polymorphism, Single Nucleotide / Q000276:immunology; D011401:Promoter Regions, Genetic / Q000235:genetics; D014158:Transcription, Genetic / Q000276:immunology*; D050986:YY1 Transcription Factor / Q000235:genetics* / Q000502:physiology
chemical_list: D050763:Cyclin-Dependent Kinase Inhibitor p18; D050986:YY1 Transcription Factor; C494699:Yy1 protein, mouse