title: Characterization of two splice variants of human organic anion transporting polypeptide 3A1 isolated from human brain.
abstract: In the present study we isolated two splice variants of organic anion transporting polypeptide 3A1 (OATP3A1_v1 and OATP3A1_v2) from human brain. OATP3A1_v2 lacks 18 amino acids (aa) at the COOH-terminal end (692 aa) but is otherwise similar in sequence to OATP3A1_v1 (710 aa). OATP3A1_v1 exhibits a wide tissue distribution, with expression in testis, various brain regions, heart, lung, spleen, peripheral blood leukocytes, and thyroid gland, whereas OATP3A1_v2 is predominantly expressed in testis and brain. On the cellular and subcellular levels OATP3A1_v1 could be immunolocalized in testicular germ cells, the basolateral plasma membrane of choroid plexus epithelial cells, and neuroglial cells of the gray matter of human frontal cortex. Immunolocalization of OATP3A1_v2 included Sertoli cells in testis, apical and/or subapical membranes in choroid plexus epithelial cells, and neurons (cell bodies and axons) of the gray and white matter of human frontal cortex. The rodent ortholog Oatp3a1 was also widely distributed in rat brain, and its localization included somatoneurons as well as astroglial cells. Transport studies in cRNA-injected Xenopus laevis oocytes and in stably transfected Chinese hamster ovary FlpIn cells revealed a similar broad substrate specificity for both splice variants. Transported substrates include prostaglandin (PG)E(1) and PGE(2), thyroxine, and the cyclic oligopeptides BQ-123 (endothelin receptor antagonist) and vasopressin. These studies provide further evidence for the involvement of OATPs in oligopeptide transport. They specifically suggest that OATP3A1 variants might be involved in the regulation of extracellular vasopressin concentration in human brain and thus might influence the neuromodulation of neurotransmission by cerebral neuropeptides such as vasopressin.
authors.affiliation: Univ. Hospital, Dept. of Internal Medicine, Institute of Clinical Pharmacology and Toxicology, 8091 Zurich, Switzerland.
authors.forename: Robert D
authors.initials: RD
authors.lastname: Huber
authors.forename: Bo
authors.initials: B
authors.lastname: Gao
authors.forename: Marguerite-Anne
authors.initials: MA
authors.lastname: Sidler Pfändler
authors.forename: Wenting
authors.initials: W
authors.lastname: Zhang-Fu
authors.forename: Simone
authors.initials: S
authors.lastname: Leuthold
authors.forename: Bruno
authors.initials: B
authors.lastname: Hagenbuch
authors.forename: Gerd
authors.initials: G
authors.lastname: Folkers
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Meier
authors.forename: Bruno
authors.initials: B
authors.lastname: Stieger
mesh_terms: D000527:Alprostadil / Q000378:metabolism; D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D001921:Brain / Q000378:metabolism*; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D015232:Dinoprostone / Q000378:metabolism; D065128:Endothelin Receptor Antagonists; D006801:Humans; D008969:Molecular Sequence Data; D009928:Organ Specificity; D027361:Organic Anion Transporters / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D051381:Rats; D014667:Vasopressins / Q000378:metabolism; D014982:Xenopus laevis
chemical_list: D065128:Endothelin Receptor Antagonists; D027361:Organic Anion Transporters; C479544:SLCO3A1 protein, human; D014667:Vasopressins; D000527:Alprostadil; D015232:Dinoprostone