title: DNA binding-dependent and -independent functions of the Hand2 transcription factor during mouse embryogenesis.
abstract: The basic helix-loop-helix (bHLH) transcription factor Hand2 is required for growth and development of the heart, branchial arches and limb buds. To determine whether DNA binding is required for Hand2 to regulate the growth and development of these different embryonic tissues, we generated mutant mice in which the Hand2 locus was modified by a mutation (referred to as Hand2(EDE)) that abolished the DNA-binding activity of Hand2, leaving the remainder of the protein intact. In contrast to Hand2 null embryos, which display right ventricular hypoplasia and vascular abnormalities, causing severe growth retardation by E9.5 and death by E10.5, early development of the heart appeared remarkably normal in homozygous Hand2(EDE) mutant embryos. These mutant embryos also lacked the early defects in growth of the branchial arches seen in Hand2 null embryos and survived up to 2 to 3 days longer than did Hand2 null embryos. However, Hand2(EDE) mutant embryos exhibited growth defects in the limb buds similar to those of Hand2 null embryos. These findings suggest that Hand2 regulates tissue growth and development in vivo through DNA binding-dependent and -independent mechanisms.
authors.affiliation: Department of Molecular Biology, University of Texas Southwestern Medical Center, 6000 Harry Hines Boulevard, Dallas, TX 75390-9148, USA.
authors.forename: Ning
authors.initials: N
authors.lastname: Liu
authors.forename: Ana C
authors.initials: AC
authors.lastname: Barbosa
authors.forename: Shelby L
authors.initials: SL
authors.lastname: Chapman
authors.forename: Svetlana
authors.initials: S
authors.lastname: Bezprozvannaya
authors.forename: Xiaoxia
authors.initials: X
authors.lastname: Qi
authors.forename: James A
authors.initials: JA
authors.lastname: Richardson
authors.forename: Hiromi
authors.initials: H
authors.lastname: Yanagisawa
authors.forename: Eric N
authors.initials: EN
authors.lastname: Olson
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000378:metabolism*; D001934:Branchial Region / Q000196:embryology / Q000378:metabolism; D004247:DNA / Q000378:metabolism*; D004622:Embryo, Mammalian / Q000196:embryology / Q000378:metabolism; D005121:Extremities / Q000196:embryology; D018507:Gene Expression Regulation, Developmental; D006330:Heart Defects, Congenital; D051379:Mice; D009154:Mutation / Q000235:genetics; D011485:Protein Binding
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D004247:DNA; C498766:Hand2 protein, mouse