title: Regulation of murine osteoblast macrophage colony-stimulating factor production by 1,25(OH)2D3.
abstract: Macrophage colony stimulating factor (MCSF) is important for formation of osteoclasts. We investigated the ability of 1,25(OH)2D3 to regulate osteoblast production of MCSF. Mouse calvarial osteoblasts were cultured for 2 days +/- 1,25(OH)2D3. Since 1, 25(OH)2D3 decreased osteoblast proliferation by 17.6 +/- 1% at 10 nM and 11 +/- 4% at 1 nM, the effect of growth rate on MCSF secretion was examined. Limiting cell proliferation by serum did not affect MCSF production. 1,25(OH)2D3 (1 nM) increased MCSF production (U/10(5) cells) maximally by 68 +/- 33% (n = 3) with an ED50 for 1, 25(OH)2D3 of 5 x 10(-11) M. To investigate effects of 1,25(OH)2D3 on MCSF gene regulation, RT-PCR primers were designed to identify the mRNA coding for the membrane-bound isoform of MCSF. Simultaneous RT-PCR of glyceraldehyde-phosphate dehydrogenase (GAP) allowed semiquantitative assessment of MCSF mRNA between treatment groups expressed as the MCSF/GAP RT-PCR product ratio; both MCSF and GAP (+) primers were labeled with 32P-ATP for phosphorimage quantitation. The membrane-bound MCSF/GAP PCR product ratio was not affected by proliferative rate when growth was limited by [serum]. The MCSF/GAP RT-PCR product ratio was dose dependently increased by 1,25(OH)2D3, maximally at 1 nM at 2.2 +/- 0.2 = fold (n = 10). 1,25 (OH)2D3 also increased the expression of an RT-PCR MCSF/GAP product ratio which represented the secreted isoform of MCSF. The ability of 1,25(OH)2D3 to pretranslationally regulate expression of membrane-bound osteoblast MCSF may be important in osteoblast:osteoclast interactions.
authors.affiliation: Department of Medicine, Veterans Affairs Medical Center, 1670 Clairmont Road, Decatur, Georgia 30033, USA.
authors.forename: J
authors.initials: J
authors.lastname: Rubin
authors.forename: X
authors.initials: X
authors.lastname: Fan
authors.forename: D
authors.initials: D
authors.lastname: Thornton
authors.forename: R
authors.initials: R
authors.lastname: Bryant
authors.forename: D
authors.initials: D
authors.lastname: Biskobing
mesh_terms: D000818:Animals; D002117:Calcitriol / Q000494:pharmacology*; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D005786:Gene Expression Regulation / Q000187:drug effects; D016173:Macrophage Colony-Stimulating Factor / Q000096:biosynthesis* / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D010006:Osteoblasts / Q000378:metabolism*; D012333:RNA, Messenger / Q000096:biosynthesis*
chemical_list: D012333:RNA, Messenger; D016173:Macrophage Colony-Stimulating Factor; D002117:Calcitriol