title: Mitf regulates osteoclastogenesis by modulating NFATc1 activity.
abstract: Transcription factors Mitf and NFATc1 share many downstream targets that are critical for osteoclastogenesis. Since RANKL signals induce/activate both NFATc1 and Mitf isoform-E (Mitf-E), a tissue-restricted Mitf isoform in osteoclasts, it is plausible that the two factors work together to promote osteoclastogenesis. Although Mitf was shown to function upstream of NFATc1 previously, this study showed that expression of Mitf had little effects on NFATc1 and NFATc1 was critical for the induction of Mitf-E. In Mitf(mi/mi) mice, the semi-dominant mutation in Mitf gene leads to arrest of osteoclastogenesis in the early stages. However, when stimulated by RANKL, the Mitf(mi/mi) preosteoclasts responded with a significant induction of NFATc1, despite that the cells cannot differentiate into functional osteoclasts. In the absence of RANKL stimulation, very high levels of NFATc1 are required to drive osteoclast development. Our data indicate that Mitf functions downstream of NFATc1 in the RANKL pathway, and it plays an important role in amplifying NFATc1-dependent osteoclastogenic signals, which contributes to the significant synergy between the two factors during osteoclastogenesis. We propose that Mitf-E functions as a tissue-specific modulator for events downstream of NFATc1 activation during osteoclastogenesis.
authors.affiliation: Department of Diagnostic and Surgical Sciences, School of Dentistry, University of California, Los Angeles, CA, USA. Electronic address: ssuyilu@yahoo.com.tw.
authors.forename: Ssu-Yi
authors.initials: SY
authors.lastname: Lu
authors.affiliation: Department of Diagnostic and Surgical Sciences, School of Dentistry, University of California, Los Angeles, CA, USA; CHS 23-087, 10833 Le Conte Ave., Los Angeles, CA 90095, USA. Electronic address: mli@dentistry.ucla.edu.
authors.forename: Mengtao
authors.initials: M
authors.lastname: Li
authors.affiliation: Department of Diagnostic and Surgical Sciences, School of Dentistry, University of California, Los Angeles, CA, USA; Gene Regulation Program, Jonsson Comprehensive Cancer Center, University of California, Los Angeles, CA, USA. Electronic address: ylin@dentistry.ucla.edu.
authors.forename: Yi-Ling
authors.initials: YL
authors.lastname: Lin
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002454:Cell Differentiation; D049109:Cell Proliferation; D002478:Cells, Cultured; D005786:Gene Expression Regulation; D051379:Mice; D008810:Mice, Inbred C57BL; D051739:Microphthalmia-Associated Transcription Factor / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D050778:NFATC Transcription Factors / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D010010:Osteoclasts / Q000166:cytology* / Q000378:metabolism; D053245:RANK Ligand / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D051739:Microphthalmia-Associated Transcription Factor; C497235:Mitf protein, mouse; D050778:NFATC Transcription Factors; C494005:Nfatc1 protein, mouse; D053245:RANK Ligand; D012333:RNA, Messenger; D034741:RNA, Small Interfering; C505689:Tnfsf11 protein, mouse
keywords: Fusion; Mitf; NFATc1; Osteoclasts; RANKL; Transcription factors