title: Osteoblastic cells regulate mi gene expression in cultured bone marrow cells.
abstract: The microphthalmia (mi) gene encodes a bHLH-Zip protein and certain mutations in this gene are known to result in osteopetrosis. We examined mi gene expression in murine bone marrow (BM) cells and calvaria-derived osteoblastic (OB) cells. The mi message level in BM cells was three- to four-fold higher than that in OB cells. The mi message level in BM cells alone was not enhanced by 1,25(OH)2 vitamin D3 (vitamin D) which induces TRAP-positive multinucleated cells, but was enhanced two-fold by the addition of conditioned medium obtained from cultures of OB cells. The mi message levels in BM cells were also enhanced by macrophage colony-stimulating factor (M-CSF). The mi message levels in cocultures of BM cells and osteoblastic MC3T3-E1 cells, which do not support osteoclastogenesis, were similar to those in the cocultures of BM cells and OB cells. Cocultures of BM cells with MC3T3-E1 cells did not yield TRAP-positive multinucleated cells, but they did maintain osteoclast progenitor cells. These findings suggest that mi is expressed in BM cells that may be under the control of OB cells.
authors.affiliation: Department of Molecular Pharmacology, Medical Research Institute, Tokyo Medical and Dental University, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Kawaguchi
authors.forename: M
authors.initials: M
authors.lastname: Noda
mesh_terms: D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology / Q000502:physiology*; D002450:Cell Communication / Q000235:genetics*; D002454:Cell Differentiation / Q000235:genetics; D002478:Cells, Cultured; D018920:Coculture Techniques; D004268:DNA-Binding Proteins / Q000235:genetics*; D005786:Gene Expression Regulation; D016173:Macrophage Colony-Stimulating Factor / Q000494:pharmacology; D008297:Male; D051379:Mice; D051739:Microphthalmia-Associated Transcription Factor; D010006:Osteoblasts / Q000166:cytology / Q000502:physiology*; D014157:Transcription Factors / Q000235:genetics
chemical_list: D004268:DNA-Binding Proteins; D051739:Microphthalmia-Associated Transcription Factor; C497235:Mitf protein, mouse; D014157:Transcription Factors; D016173:Macrophage Colony-Stimulating Factor