title: Neural crest-specific deletion of Ldb1 leads to cleft secondary palate with impaired palatal shelf elevation.
abstract: BACKGROUND
  LIM domain binding protein 1 (LDB1) is a transcriptional co-factor, which interacts with multiple transcription factors and other proteins containing LIM domains. Complete inactivation of Ldb1 in mice resulted in early embryonic lethality with severe patterning defects during gastrulation. Tissue-specific deletions using a conditional knockout allele revealed additional roles of Ldb1 in the development of the central nervous system, hematopoietic system, and limbs. The goal of the current study was to determine the importance of Ldb1 function during craniofacial development in mouse embryos.
  
  
  RESULTS
  We generated tissue-specific Ldb1 mutants using Wnt1-Cre, which causes deletion of a floxed allele in the neural crest; neural crest-derived cells contribute to most of the mesenchyme of the developing face. All examined Wnt1-Cre;Ldb1(fl/-) mutants suffered from cleft secondary palate. Therefore, we performed a series of experiments to investigate how Ldb1 regulated palate development. First, we examined the expression of Ldb1 during normal development, and found that Ldb1 was expressed broadly in the palatal mesenchyme during early stages of palate development. Second, we compared the morphology of the developing palate in control and Ldb1 mutant embryos using sections. We found that the mutant palatal shelves had abnormally blunt appearance, and failed to elevate above the tongue at the posterior domain. An in vitro head culture experiment indicated that the elevation defect was not due to interference by the tongue. Finally, in the Ldb1 mutant palatal shelves, cell proliferation was abnormal in the anterior, and the expression of Wnt5a, Pax9 and Osr2, which regulate palatal shelf elevation, was also altered.
  
  
  CONCLUSIONS
  The function of Ldb1 in the neural crest-derived palatal mesenchyme is essential for normal morphogenesis of the secondary palate.
authors.forename: Asma
authors.initials: A
authors.lastname: Almaidhan
authors.forename: Jeffry
authors.initials: J
authors.lastname: Cesario
authors.forename: Andre
authors.initials: A
authors.lastname: Landin Malt
authors.forename: Yangu
authors.initials: Y
authors.lastname: Zhao
authors.forename: Neeti
authors.initials: N
authors.lastname: Sharma
authors.forename: Veronica
authors.initials: V
authors.lastname: Choi
authors.affiliation: Department of Basic Science and Craniofacial Biology, New York University College of Dentistry, 10010 New York, NY, USA. jj78@nyu.edu.
authors.forename: Juhee
authors.initials: J
authors.lastname: Jeong
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000235:genetics; D049109:Cell Proliferation; D002478:Cells, Cultured; D002972:Cleft Palate / Q000196:embryology / Q000235:genetics* / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D005260:Female; D005455:Fluorescent Antibody Technique; D018507:Gene Expression Regulation, Developmental; D017403:In Situ Hybridization; D060588:LIM Domain Proteins / Q000235:genetics* / Q000378:metabolism; D008648:Mesoderm / Q000196:embryology / Q000378:metabolism / Q000473:pathology; D051379:Mice; D018345:Mice, Knockout; D008822:Mice, Transgenic; D009432:Neural Crest / Q000196:embryology / Q000378:metabolism* / Q000473:pathology; D051764:PAX9 Transcription Factor; D051761:Paired Box Transcription Factors / Q000235:genetics / Q000378:metabolism; D010159:Palate / Q000196:embryology / Q000378:metabolism* / Q000473:pathology; D011247:Pregnancy; D013997:Time Factors; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D051153:Wnt Proteins / Q000235:genetics / Q000378:metabolism; D000071818:Wnt-5a Protein; D051155:Wnt1 Protein / Q000235:genetics / Q000378:metabolism
chemical_list: D004268:DNA-Binding Proteins; D060588:LIM Domain Proteins; C102084:Ldb1 protein, mouse; C438618:Osr2 protein, mouse; D051764:PAX9 Transcription Factor; D051761:Paired Box Transcription Factors; C488759:Pax9 protein, mouse; D014157:Transcription Factors; D051153:Wnt Proteins; D000071818:Wnt-5a Protein; D051155:Wnt1 Protein; C438615:Wnt5a protein, mouse