title: Characterization and localization of side population (SP) cells in zebrafish kidney hematopoietic tissue.
abstract: We previously showed that side population (SP) cells, characterized by specific Hoechst dye efflux pattern in flow cytometric analysis, were present in teleost kidney hematopoietic tissue, and that kidney SP cells were enriched in hematopoietic stem cells (HSCs). ABCG2/Abcg2 is an ATP-binding cassette (ABC) transporter that is known to be associated with Hoechst dye efflux activity of mammalian HSCs. In the present study, we examined the expression and function of Abcg2 in kidney SP cells from zebrafish (Danio rerio). Although the zebrafish genome has 4 paralogous copies of ABCG2 (zAbcg2a, b, c, and d), zAbcg2a and zAbcg2c mRNA was expressed in kidney SP cells. Transfection of COS-7 cells with zAbcg2a and zAbcg2c showed that zAbcg2a was directly associated with the SP phenotype. These results indicate that zAbcg2a mRNA is a useful marker for zebrafish HSCs. In situ hybridization in kidney tissue showed that zAbcg2a-positive cells were sporadically localized on the surface of renal tubules, and tightly adhered to renal tubule epithelial cells. This result suggests that teleost HSCs adhere to the surface of renal tubules, and that renal tubule epithelial cells are a key component of HSC niche in teleosts.
authors.affiliation: Department of Veterinary Medicine, Nihon University, Fujisawa, Kanagawa, Japan.
authors.forename: Isao
authors.initials: I
authors.lastname: Kobayashi
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Saito
authors.forename: Tadaaki
authors.initials: T
authors.lastname: Moritomo
authors.forename: Kyosuke
authors.initials: K
authors.lastname: Araki
authors.forename: Fumio
authors.initials: F
authors.lastname: Takizawa
authors.forename: Teruyuki
authors.initials: T
authors.lastname: Nakanishi
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000737:chemistry / Q000145:classification / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D019556:COS Cells; D002522:Chlorocebus aethiops; D017124:Conserved Sequence; D005786:Gene Expression Regulation; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000378:metabolism*; D006801:Humans; D007668:Kidney / Q000166:cytology* / Q000378:metabolism*; D008969:Molecular Sequence Data; D010802:Phylogeny; D016415:Sequence Alignment; D015027:Zebrafish / Q000235:genetics / Q000378:metabolism*
chemical_list: D018528:ATP-Binding Cassette Transporters