title: Ldb1 Is Essential for the Development of Isthmic Organizer and Midbrain Dopaminergic Neurons.
abstract: LIM domain-binding protein 1 (Ldb1) is a nuclear cofactor that interacts with LIM homeodomain proteins to form multiprotein complexes that are important for transcription regulation. Ldb1 has been shown to play essential roles in various processes during mouse embryogenesis. To determine the role of Ldb1 in mid- and hindbrain development, we have generated a conditional mutant with a specific deletion of the Ldb1 in the Engrailed-1-expressing region of the developing mid- and hindbrain. Our study showed that the deletion impaired the expression of signaling molecules, such as fibroblast growth factor 8 (FGF8) and Wnt1, in the isthmic organizer and the expression of Shh in the ventral midbrain. The midbrain and the cerebellum were severely reduced in size, and the midbrain dopaminergic (mDA) neurons were missing in the mutant. These defects are identical to the phenotype that has been observed previously in mice with a deletion of the LIM homeodomain gene Lmx1b. Our results thus provide genetic evidence supporting that Ldb1 and Lmx1b function cooperatively to regulate mid- and hindbrain development. In addition, we found that mouse embryonic stem cells lacking Ldb1 failed to generate several types of differentiated neurons, including the mDA neurons, serotonergic neurons, cholinergic neurons, and olfactory bulb neurons, indicating an essential cell-autonomous role for Ldb1 in the development of these neurons.
authors.affiliation: 1 Department of Biomedical Sciences, Korea University Medical School , Seoul, South Korea .
authors.forename: Soojin
authors.initials: S
authors.lastname: Kim
authors.affiliation: 2 Program on Genomics of Differentiation, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health , Bethesda, Maryland.
authors.forename: Yangu
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: 1 Department of Biomedical Sciences, Korea University Medical School , Seoul, South Korea .
authors.forename: Ja-Myong
authors.initials: JM
authors.lastname: Lee
authors.affiliation: 1 Department of Biomedical Sciences, Korea University Medical School , Seoul, South Korea .
authors.forename: Woon Ryoung
authors.initials: WR
authors.lastname: Kim
authors.affiliation: 2 Program on Genomics of Differentiation, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health , Bethesda, Maryland.
authors.forename: Marat
authors.initials: M
authors.lastname: Gorivodsky
authors.affiliation: 2 Program on Genomics of Differentiation, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health , Bethesda, Maryland.
authors.forename: Heiner
authors.initials: H
authors.lastname: Westphal
authors.affiliation: 1 Department of Biomedical Sciences, Korea University Medical School , Seoul, South Korea .
authors.forename: Dongho
authors.initials: D
authors.lastname: Geum
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D002454:Cell Differentiation; D002531:Cerebellum / Q000196:embryology; D004268:DNA-Binding Proteins / Q000378:metabolism*; D059290:Dopaminergic Neurons / Q000166:cytology* / Q000378:metabolism*; D004622:Embryo, Mammalian / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D060588:LIM Domain Proteins / Q000378:metabolism*; D008636:Mesencephalon / Q000166:cytology* / Q000196:embryology; D051379:Mice; D000066450:Mouse Embryonic Stem Cells / Q000166:cytology / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D020897:Organizers, Embryonic / Q000196:embryology* / Q000378:metabolism*
chemical_list: D015415:Biomarkers; D004268:DNA-Binding Proteins; D060588:LIM Domain Proteins; C102084:Ldb1 protein, mouse