title: Generation of a conditional null allele of Lbx1.
abstract: The homeobox gene Lbx1 not only plays critical roles in myogenesis and neurogenesis during embryonic development but is also expressed in activated satellite cells of adult mice. To address the potential postnatal functions of Lbx1, we generated conditional Lbx1-null mice using the Cre-loxP system. We generated a mouse in which Exon 2 of Lbx1 was floxed (Lbx1flox/flox), followed by cross-breeding between the Lbx1flox/flox mouse and either a transgenic mouse where a tamoxifen-inducible Cre-recombinase (Cre) was ubiquitously expressed, or a Myf5Cre mouse where Cre was inserted into the Myf5 locus. In both Lbx1-null mouse lines generated, Pax3-expressing limb muscle precursor cells were seriously reduced during embryonic development and eventually the limb extensor muscles were lost after birth. Since the conditional Lbx1-null mice generated were viable for a prolonged time, they will be useful in the investigation of Lbx1 function throughout the lifespan of the mouse.
authors.affiliation: Division of Molecular Embryology, Department of Biosciences, School of Science, Kitasato University, Kanagawa 228-8555, Japan.
authors.forename: Shuichi
authors.initials: S
authors.lastname: Watanabe
authors.forename: Shoko
authors.initials: S
authors.lastname: Matsushita
authors.forename: Michiko
authors.initials: M
authors.lastname: Hayasaka
authors.forename: Kazunori
authors.initials: K
authors.lastname: Hanaoka
mesh_terms: D000483:Alleles; D000818:Animals; D003433:Crosses, Genetic; D005121:Extremities / Q000196:embryology; D005260:Female; D019426:Integrases / Q000235:genetics* / Q000378:metabolism; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D008822:Mice, Transgenic; D009124:Muscle Proteins / Q000235:genetics* / Q000502:physiology*; D018482:Muscle, Skeletal / Q000166:cytology / Q000196:embryology / Q000378:metabolism; D051787:Myogenic Regulatory Factor 5 / Q000235:genetics*; D000072041:PAX3 Transcription Factor; D051761:Paired Box Transcription Factors / Q000096:biosynthesis* / Q000235:genetics
chemical_list: C491868:Lbx1h protein, mouse; D009124:Muscle Proteins; C497418:Myf5 protein, mouse; D051787:Myogenic Regulatory Factor 5; D000072041:PAX3 Transcription Factor; D051761:Paired Box Transcription Factors; C068686:Pax3 protein, mouse; C045073:Cre recombinase; D019426:Integrases