Analyses of 5' regulatory region polymorphisms in human SLC22A6 (OAT1) and SLC22A8 (OAT3).
Kidney excretion of numerous organic anionic drugs and endogenous metabolites is carried out by a family of multispecific organic anion transporters (OATs). Two closely related transporters, SLC22A6, initially identified by us as NKT and also known as OAT1, and SLC22A8, also known as OAT3 and ROCT, are thought to mediate the initial steps in the transport of organic anionic drugs between the blood and proximal tubule cells of the kidney. Coding region polymorphisms in these genes are infrequent and pairing of these genes in the genome suggests they may be coordinately regulated. Hence, 5' regulatory regions of these genes may be important factors in human variation in organic anionic drug handling. We have analyzed novel single nucleotide polymorphisms in the evolutionarily conserved 5' regulatory regions of the SLC22A6 and SLC22A8 genes (phylogenetic footprints) in an ethnically diverse sample of 96 individuals (192 haploid genomes). Only one polymorphism was found in the SLC22A6 5' regulatory region. In contrast, seven polymorphisms were found in the SLC22A8 5' regulatory region, two of which were common to all ethnic groups studied. Computational analysis permitted phase and haplotype reconstruction. Proximity of these non-coding polymorphisms to transcriptional regulatory elements (including potential sex steroid response elements) suggests a potential influence on the level of transcription of the SLC22A6 and/or SLC22A8 genes and will help define their role in variation in human drug, metabolite and toxin excretion. The clustering of OAT genes in the genome raises the possibility that nucleotide polymorphisms in SLC22A6 could also effect SLC22A8 expression, and vice versa.
Bhatnagar
Vibha
V
Departments of Pediatrics, Medicine, Cellular and Molecular Medicine, Family, Preventative Medicine, and the San Diego Veterans Administration Medical Center, University of California-San Diego, 9500 Gilman Dr., 0693, La Jolla, CA, 92093-0693, USA. vbhatnag@ucsd.edu.
Xu
Gang
G
Departments of Pediatrics, Medicine, Cellular and Molecular Medicine, Family, Preventative Medicine, and the San Diego Veterans Administration Medical Center, University of California-San Diego, 9500 Gilman Dr., 0693, La Jolla, CA, 92093-0693, USA.
Hamilton
Bruce A
BA
Departments of Pediatrics, Medicine, Cellular and Molecular Medicine, Family, Preventative Medicine, and the San Diego Veterans Administration Medical Center, University of California-San Diego, 9500 Gilman Dr., 0693, La Jolla, CA, 92093-0693, USA.
Truong
David M
DM
Departments of Pediatrics, Medicine, Cellular and Molecular Medicine, Family, Preventative Medicine, and the San Diego Veterans Administration Medical Center, University of California-San Diego, 9500 Gilman Dr., 0693, La Jolla, CA, 92093-0693, USA.
Eraly
Satish A
SA
Departments of Pediatrics, Medicine, Cellular and Molecular Medicine, Family, Preventative Medicine, and the San Diego Veterans Administration Medical Center, University of California-San Diego, 9500 Gilman Dr., 0693, La Jolla, CA, 92093-0693, USA.
Wu
Wei
W
Departments of Pediatrics, Medicine, Cellular and Molecular Medicine, Family, Preventative Medicine, and the San Diego Veterans Administration Medical Center, University of California-San Diego, 9500 Gilman Dr., 0693, La Jolla, CA, 92093-0693, USA.
Nigam
Sanjay K
SK
Departments of Pediatrics, Medicine, Cellular and Molecular Medicine, Family, Preventative Medicine, and the San Diego Veterans Administration Medical Center, University of California-San Diego, 9500 Gilman Dr., 0693, La Jolla, CA, 92093-0693, USA.
D000818:Animals; D001483:Base Sequence; D004247:DNA / Q000235:genetics; D018983:DNA Footprinting; D005006:Ethnicity / Q000235:genetics; D006239:Haplotypes; D006801:Humans; D051379:Mice; D005810:Multigene Family; D027362:Organic Anion Transport Protein 1 / Q000235:genetics*; D029362:Organic Anion Transporters, Sodium-Independent / Q000235:genetics*; D002679:Pan troglodytes; D010802:Phylogeny; D020641:Polymorphism, Single Nucleotide; D050436:Regulatory Elements, Transcriptional; D014158:Transcription, Genetic
D027362:Organic Anion Transport Protein 1; D029362:Organic Anion Transporters, Sodium-Independent; C114338:organic anion transport protein 3; D004247:DNA