Subject(s)
Disease Models, Animal , Dysbiosis/immunology , Gastrointestinal Microbiome/immunology , Lupus Erythematosus, Systemic/immunology , Angiotensin-Converting Enzyme Inhibitors/therapeutic use , Animals , Congresses as Topic , Drug Evaluation, Preclinical/methods , Drug Repositioning , Dysbiosis/microbiology , Gene Expression Regulation/immunology , Humans , Lupus Erythematosus, Systemic/drug therapy , Lupus Erythematosus, Systemic/genetics , Lupus Erythematosus, Systemic/microbiology , Metformin/therapeutic use , Mice , RNA-Seq , Single-Cell Analysis , Ubiquinone/analogs & derivatives , Ubiquinone/therapeutic use , VideoconferencingABSTRACT
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.