title: LIM homeobox transcription factor Lhx2 inhibits skeletal muscle differentiation in part via transcriptional activation of Msx1 and Msx2.
abstract: LIM homeobox transcription factor Lhx2 is known to be an important regulator of neuronal development, homeostasis of hair follicle stem cells, and self-renewal of hematopoietic stem cells; however, its function in skeletal muscle development is poorly understood. In this study, we found that overexpression of Lhx2 completely inhibits the myotube-forming capacity of C2C12 cells and primary myoblasts. The muscle dedifferentiation factors Msx1 and Msx2 were strongly induced by the Lhx2 overexpression. Short interfering RNA-mediated knockdown of Lhx2 in the developing limb buds of mouse embryos resulted in a reduction in Msx1 and Msx2 mRNA levels, suggesting that they are downstream target genes of Lhx2. We found two Lhx2 consensus-binding sites in the -2097 to -1189 genomic region of Msx1 and two additional sites in the -536 to +73 genomic region of Msx2. These sequences were shown by luciferase reporter assay to be essential for Lhx2-mediated transcriptional activation. Moreover, electrophoretic mobility shift assays and chromatin immunoprecipitation assays showed that Lhx2 is present in chromatin DNA complexes bound to the enhancer regions of the Msx1 and Msx2 genes. These data demonstrate that Msx1 and Msx2 are direct transcriptional targets of Lhx2. In addition, overexpression of Lhx2 significantly enhanced the mRNA levels of bone morphogenetic protein 4 and transforming growth factor beta family genes. We propose that Lhx2 is involved in the early stage of skeletal muscle development by inducing multiple differentiation inhibitory factors.
authors.affiliation: Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-0041, Japan.
authors.forename: Yusaku
authors.initials: Y
authors.lastname: Kodaka
authors.affiliation: Stem Cell Project, Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya-ku, Tokyo 156-8506, Japan.
authors.forename: Kiyoko
authors.initials: K
authors.lastname: Tanaka
authors.affiliation: Stem Cell Project, Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya-ku, Tokyo 156-8506, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Kitajima
authors.affiliation: Stem Cell Project, Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya-ku, Tokyo 156-8506, Japan.
authors.forename: Kosuke
authors.initials: K
authors.lastname: Tanegashima
authors.affiliation: Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-0041, Japan.
authors.forename: Ryoichi
authors.initials: R
authors.lastname: Matsuda
authors.affiliation: Stem Cell Project, Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya-ku, Tokyo 156-8506, Japan; Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan. Electronic address: hara-tk@igakuken.or.jp.
authors.forename: Takahiko
authors.initials: T
authors.lastname: Hara
mesh_terms: D000818:Animals; D001665:Binding Sites / Q000235:genetics; D055415:Bone Morphogenetic Protein 4 / Q000096:biosynthesis / Q000235:genetics; D002454:Cell Differentiation / Q000235:genetics; D002460:Cell Line; D024202:Electrophoretic Mobility Shift Assay; D004742:Enhancer Elements, Genetic / Q000235:genetics; D005260:Female; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental; D057809:HEK293 Cells; D018398:Homeodomain Proteins / Q000096:biosynthesis / Q000235:genetics*; D006801:Humans; D060850:LIM-Homeodomain Proteins / Q000235:genetics / Q000378:metabolism*; D051957:MSX1 Transcription Factor / Q000096:biosynthesis / Q000235:genetics*; D051379:Mice; D008810:Mice, Inbred C57BL; D024510:Muscle Development / Q000235:genetics*; D018485:Muscle Fibers, Skeletal / Q000166:cytology*; D032446:Myoblasts / Q000166:cytology*; D034622:RNA Interference; D012333:RNA, Messenger / Q000096:biosynthesis; D034741:RNA, Small Interfering; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D016212:Transforming Growth Factor beta / Q000096:biosynthesis / Q000235:genetics; D015854:Up-Regulation
chemical_list: C525810:Bmp4 protein, mouse; D055415:Bone Morphogenetic Protein 4; D018398:Homeodomain Proteins; D060850:LIM-Homeodomain Proteins; C489784:Lhx2 protein, mouse; D051957:MSX1 Transcription Factor; C084119:MSX2 protein; C484084:Msx1 protein, mouse; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D014157:Transcription Factors; D016212:Transforming Growth Factor beta
keywords: Lhx2; Limb bud; Msx1; Msx2; Skeletal muscle differentiation