title: Induction of calbindin D-28K in Madin-Darby bovine kidney cells by 1,25(OH)2D3.
abstract: Renal calbindin D-28K is a calcium binding protein, localized to the distal nephron, whose expression is reduced in vitamin D deficiency and increased upon administration of 1,25(OH)2D3, the active form of vitamin D. Investigation into the molecular regulation of renal calbindin D-28K expression has been limited by the lack of an established cell line which expresses calbindin D-28K in a vitamin D responsive manner. In the studies described here, we compared the expression of calbindin D-28K and the vitamin D receptor (VDR) in four renal cell lines: Madin-Darby bovine kidney (MDBK) cells, Madin-Darby canine kidney (MDCK) cells, LLC-PK1 pig kidney cells and opossum kidney (OK) cells. We report that MDBK cells express the highest relative levels of calbindin D-28K and the VDR, and that 1,25(OH)2D3 increases calbindin D-28K expression in these cells. No expression of calbindin D-28K was detected in MDCK, LLC-PK1 or OK cells. Kinetic studies indicated that calbindin D-28K protein increased with time for up to 24 hours after a single dose of 1,25(OH)2D3 (10(-7) M) in MDBK cells. Immunofluorescence studies indicated that in control MDBK cells, the majority of calbindin D-28K was localized in cytosol, with a definite concentration in the peri-nuclear region. In 1,25(OH)2D3 treated cells, calbindin D-28K was enhanced in cytosol and was detected within the nucleus. In contrast to heterogeneous primary culture systems, in which a minority of cells express calbindin D-28K, virtually all MDBK cells expressed calbindin D-28K, even in the absence of 1,25(OH)2D3.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Biochemistry, Faculty of Medicine, University of Ottawa, Ontario, Canada.
authors.forename: A M
authors.initials: AM
authors.lastname: Gagnon
authors.forename: M
authors.initials: M
authors.lastname: Simboli-Campbell
authors.forename: J E
authors.initials: JE
authors.lastname: Welsh
mesh_terms: D000818:Animals; D015415:Biomarkers; D001790:Blood Physiological Phenomena; D064026:Calbindins; D002117:Calcitriol / Q000494:pharmacology*; D002417:Cattle; D002455:Cell Division; D002460:Cell Line; D004285:Dogs; D007668:Kidney / Q000166:cytology / Q000378:metabolism*; D007686:Kidney Tubules, Distal / Q000378:metabolism; D018167:Receptors, Calcitriol / Q000378:metabolism; D064030:S100 Calcium Binding Protein G / Q000378:metabolism*; D013552:Swine
chemical_list: D015415:Biomarkers; D064026:Calbindins; D018167:Receptors, Calcitriol; D064030:S100 Calcium Binding Protein G; D002117:Calcitriol