The calcineurin regulatory subunit polymorphism and the treatment efficacy of tacrolimus for idiopathic membranous nephropathy.

Tacrolimus is considered to be one of the main therapeutic options for idiopathic membranous nephropathy (IMN). This study aimed to investigate the association of variants in genes encoding the binding protein and the drug target (calcineurin) of tacrolimus with the efficacy in IMN patients and the potential mechanism. Sixty-seven IMN patients treated with tacrolimus were enrolled retrospectively. Sanger sequencing was performed to search for variants in all exons of the genes in 8 IMN patients and genotype for the detected variants in the other 59 patients. The molecular mechanism underlying the relationship between the variants and the efficacy was explored in human peripheral blood mononuclear cells (PBMCs) and other cell lines. Single nucleotide polymorphism rs875 (T > C) in the 3'untranslated region (3'UTR) of PPP3R1 encoding calcineurin regulatory subunit was found to be associated with the treatment efficacy of tacrolimus for IMN. Patients carrying TT genotype had a significantly higher remission rate than those carrying TC/CC genotype (83% vs. 47%, P = 0.008). Western blot showed that the TT genotype carriers exhibited reduced PPP3R1 protein levels in PBMCs (P = 0.02). Compared with C allele, T allele displayed increased binding affinity for miR-582-5p in the luciferase reporter assay (P < 0.001). Moreover, knockdown of PPP3R1 in Jurkat T cell line enhanced the immunosuppressive effect of tacrolimus. Our study revealed the association of PPP3R1 3'UTR polymorphism rs875 with the efficacy of tacrolimus in IMN patients. The functional polymorphism might alter PPP3R1 expression via modulating the interaction of miR-582-5p with PPP3R1, which further affected the immunosuppressive effect of tacrolimus.