Abstract
The CYP3A subfamily enzymes are the most abundant and important drug-metabolizing enzymes. Wide variation in the CYP3A5 expression was well known. Recently, G−44 to A of CYP3AP1was found to segregate with CYP3A5*3 defective allele. The homozygous A−44 subjects showed low expression of CYP3A5. In Caucasian, only 9.2% of CYP3AP1 alleles were with G−44 and associated with the wild-type CYP3A5*1 allele, which expressed CYP3A5 significantly. By using polymerase chain reaction and FauI endonuclease digestion, we found that 28% of CYP3AP1 alleles are G−44in 110 Chinese subjects. The frequency is 3 times higher in Chinese than in Caucasian, implying more Chinese subjects are probably extensive CYP3A5 metabolizers. In two Chinese subjects, we also found a heterozygous G13048gt-to-G13048gc mutation at the intron 5 splicing donor site, leading to a splicing defect. A 6478-base pair minigene, including intron 4 to intron 7, was used for in vitro transcription. Both the wild-type and the mutated minigenes produced splicing variants. The wild-type minigene used Ggt13050 as the splicing donor. The mutant minigene used gt8504 in intron 4 or gt13112 in intron 5 as the splicing donor for various splicing acceptors. The splicing defect may result in a shorter peptide or cause the frame shift. In the other two Chinese subjects, we found A14763-to-G mutation in exon 7, resulting in the Q200R amino acid change. The consequence of the polymorphism site has not been known. In Caucasian, there is a reported T398N polymorphism. In these Chinese subjects, we did not find polymorphism at this site.
Footnotes
-
This work was supported by Grant NHRI-GT-EX89S831L from the National Health Research Institute of Republic of China (Taipei).
- Abbreviations used are::
- bp
- base pair
- PCR
- polymerase chain reaction
- SSCP
- single-strand conformational polymorphism
- RFLP
- restriction fragment length polymorphism
- RT-PCR
- reverse transcription-polymerase chain reaction
- nt
- nucleotide
- The American Society for Pharmacology and Experimental Therapeutics
DMD articles become freely available 12 months after publication, and remain freely available for 5 years.Non-open access articles that fall outside this five year window are available only to institutional subscribers and current ASPET members, or through the article purchase feature at the bottom of the page.
|