Identification and functional studies of human CYP26A1 Single Nucleotide Polymorphisms (SNPs) in racially diverse populations

Abstract

Retinoic acid is a critical regulator of gene expression during embryonic development and in the maintenance of adult epithelial tissues. Genetic polymorphisms of CYP26A1 may cause inter-individual variations in the metabolism of retinoic acid, resulting in different signaling in the development. A number of Single Nucleotide Polymorphisms (SNPs) were identified in CYP26A1 in 92 racially diverse individuals (24 Caucasians, 24 African-Americans, 24 Asians and 20 individuals of unknown racial origin). Three SNPs produced coding changes: R173S, F186L and C358R. cDNA constructs for wild-type and coding SNPs of CYP26A1 were prepared in pcDNA3.1 expression vector containing a FLAG tag at the C-terminal end which was used to quantitate the proteins when expressed in Cos-1 cells. CYP26A1 metabolizes all-trans-retinoic acid to 4-oxo-retinoic acid, 4-OH-retinoic acid and 18-OH-retinoic acid as well as water soluble metabolites. There were no metabolites of retinoic acid in cells transfected with pcDNA3.1 expression vector alone. When expressed in Cos-1 cells, CYP26A1 F186L and CYP26A1 C358R exhibited a significant decrease in metabolism (50–70%) compared to that of wild-type. CYP26A1 F186L and CYP26A1 C358R are predicted to be defective in retinoic acid metabolism in vivo. This in vitro characterization would be helpful to understand genotype/phenotype relationship in the future clinical study. This research was supported by the intramural division of the NIEHS.