CYP3A4 intronic SNP rs35599367 (CYP3A4*22) alters RNA splicing.
Cytochrome P450 3A4 (CYP3A4) metabolizes 30-50% of clinically used drugs. Large interperson variability in CYP3A4 activity affects response to CYP3A4 substrate drugs. We had demonstrated that an intronic single nucleotide polymorphism rs35599367 (CYP3A4*22, located in intron 6) reduces mRNA/protein expression; however, the underlying mechanism remained unknown. Here we show that CYP3A4*22 is associated with a two-fold or greater increase in formation of a nonfunctional CYP3A4 alternative splice variant with partial intron 6 retention in human liver (P=0.006), but not in small intestines. Consistent with this observation, in-vitro transfection experiments with a CYP3A4 minigene (spanning from intron 5 to intron 7) demonstrated that plasmids carrying the rs35599367 minor T allele caused significantly greater intron 6 retention than the C allele in liver derived HepG2 cells, but not in intestine-derived LS-174T cells. These results indicate that tissue-specific increased formation of nonfunctional alternative splice variant causes reduced CYP3A4 mRNA/protein expression in CYP3A4*22 carriers.
Center for Pharmacogenomics, Department of Molecular Virology, Immunology and Medical Genetics, The Ohio State University, Columbus, Ohio, USA.
Danxin
D
Wang
Wolfgang
W
Sadee
D002460:Cell Line; D051544:Cytochrome P-450 CYP3A / Q000235:genetics*; D056945:Hep G2 Cells; D006801:Humans; D007422:Intestines / Q000166:cytology; D007438:Introns; D008099:Liver / Q000166:cytology; D009928:Organ Specificity; D020641:Polymorphism, Single Nucleotide; D012326:RNA Splicing; D012333:RNA, Messenger / Q000378:metabolism
D012333:RNA, Messenger; D051544:Cytochrome P-450 CYP3A; C510163:CYP3A4 protein, human