title: Microphthalmia transcription factor and PU.1 synergistically induce the leukocyte receptor osteoclast-associated receptor gene expression.
abstract: We have recently reported the identification of a novel member of the leukocyte receptor family, osteoclast-associated receptor (OSCAR), which has two Ig-like domains and functions as a bone-specific regulator of osteoclast differentiation. Here, we have cloned the OSCAR promoter region to examine its regulation by transcription factors. The 1.7-kb promoter region of the mouse OSCAR gene contains two potential E-box elements for microphthalmia transcription factor (MITF) and three putative PU.1 sites. MITF or PU.1 alone activates the OSCAR reporter construct 5-6-fold, and the combination of MITF and PU.1 synergistically activates the OSCAR reporter activity up to 110-fold. The mRNA expression patterns of MITF, PU.1, and OSCAR in TRANCE-treated (RAW 264.7) or TRANCE/M-CSF-treated cells (primary osteoclasts) reveal that MITF mRNA expression is induced at a much earlier time point than OSCAR gene expression. In contrast to MITF, PU.1 mRNA levels remain relatively constant at all time points, suggesting that TRANCE-induced MITF, not PU.1 expression, is one of the critical regulatory mechanisms for optimal OSCAR expression during osteoclastogenesis. In addition, we have shown that the combination of MITF and constitutively active MKK6-expressing plasmids synergistically activates OSCAR reporter activity. Taken together, our results strongly suggest that PU.1 and MITF transcription factors synergistically activate OSCAR gene expression. Moreover, the activation of OSCAR gene expression by PU.1/MITF is further enhanced by the TRANCE-induced MKK6/p38 signaling cascade.
authors.affiliation: Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA.
authors.forename: Hongseob
authors.initials: H
authors.lastname: So
authors.forename: Jaerang
authors.initials: J
authors.lastname: Rho
authors.forename: Daewon
authors.initials: D
authors.lastname: Jeong
authors.forename: Raekil
authors.initials: R
authors.lastname: Park
authors.forename: David E
authors.initials: DE
authors.lastname: Fisher
authors.forename: Michael C
authors.initials: MC
authors.lastname: Ostrowski
authors.forename: Yongwon
authors.initials: Y
authors.lastname: Choi
authors.forename: Nacksung
authors.initials: N
authors.lastname: Kim
mesh_terms: D000818:Animals; D001483:Base Sequence; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D002352:Carrier Proteins / Q000494:pharmacology; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins / Q000502:physiology*; D005786:Gene Expression Regulation; D048669:MAP Kinase Kinase 6; D020935:MAP Kinase Signaling System; D008562:Membrane Glycoproteins / Q000494:pharmacology; D051379:Mice; D008810:Mice, Inbred C57BL; D051739:Microphthalmia-Associated Transcription Factor; D008969:Molecular Sequence Data; D010010:Osteoclasts / Q000166:cytology; D011401:Promoter Regions, Genetic; D011518:Proto-Oncogene Proteins / Q000502:physiology*; D053245:RANK Ligand; D012333:RNA, Messenger / Q000032:analysis; D053246:Receptor Activator of Nuclear Factor-kappa B; D011956:Receptors, Cell Surface / Q000096:biosynthesis / Q000235:genetics*; D015534:Trans-Activators / Q000502:physiology*; D014157:Transcription Factors / Q000502:physiology*; D000099232:Proto-Oncogene Protein Spi-1
chemical_list: D017871:Calcium-Calmodulin-Dependent Protein Kinases; D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D048669:MAP Kinase Kinase 6; D008562:Membrane Glycoproteins; D051739:Microphthalmia-Associated Transcription Factor; D011518:Proto-Oncogene Proteins; D053245:RANK Ligand; D012333:RNA, Messenger; D053246:Receptor Activator of Nuclear Factor-kappa B; D011956:Receptors, Cell Surface; D015534:Trans-Activators; D014157:Transcription Factors; D000099232:Proto-Oncogene Protein Spi-1; C497235:Mitf protein, mouse; C450519:Oscar protein, mouse; C505687:Tnfrsf11a protein, mouse; C505689:Tnfsf11 protein, mouse; C482567:Map2k6 protein, mouse