title: Expression of the atrial-specific myosin heavy chain AMHC1 and the establishment of anteroposterior polarity in the developing chicken heart.
abstract: A unique myosin heavy chain cDNA (AMHC1), which is expressed exclusively in the atria of the developing chicken heart, was isolated and used to study the generation of diversified cardiac myocyte cell lineages. The pattern of AMHC1 gene expression during heart formation was determined by whole-mount in situ hybridization. AMHC1 is first activated in the posterior segment of the heart when these myocytes initially differentiate (Hamburger and Hamilton stage 9+). The anterior segment of the heart at this stage does not express AMHC1 although the ventricular myosin heavy chain isoform is strongly expressed beginning at stage 8+. Throughout chicken development, AMHC1 continues to be expressed in the posterior heart tube as it develops into the diversified atria. The early activation of AMHC1 expression in the posterior cardiac myocytes suggests that the heart cells are diversified when they differentiate initially and that the anterior heart progenitors differ from the posterior heart progenitors in their myosin isoform gene expression. The expression domain of AMHC1 can be expanded anteriorly within the heart tube by treating embryos with retinoic acid as the heart primordia fuse. Embryos treated with retinoic acid prior to the initiation of fusion of the heart primordia express AMHC1 throughout the entire heart-forming region and fusion of the heart primordia is inhibited. These data indicate that retinoic acid treatment produces an expansion of the posterior (atrial) domain of the heart and suggests that diversified fates of cardiomyogenic progenitors can be altered.
authors.affiliation: Department of Cell Biology and Anatomy, Cornell University Medical College, New York, NY 10021, USA.
authors.forename: K E
authors.initials: KE
authors.lastname: Yutzey
authors.forename: J T
authors.initials: JT
authors.lastname: Rhee
authors.forename: D
authors.initials: D
authors.lastname: Bader
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D024743:Atrial Myosins; D030161:Avian Proteins; D001483:Base Sequence; D015152:Blotting, Northern; D002454:Cell Differentiation / Q000187:drug effects; D002642:Chick Embryo; D004270:DNA, Circular / Q000235:genetics*; D005314:Embryonic and Fetal Development / Q000502:physiology*; D015870:Gene Expression; D006321:Heart / Q000187:drug effects / Q000196:embryology*; D006325:Heart Atria / Q000166:cytology / Q000187:drug effects / Q000196:embryology; D017403:In Situ Hybridization; D008969:Molecular Sequence Data; D018995:Myosin Heavy Chains; D009218:Myosins / Q000235:genetics*; D017422:Sequence Analysis, DNA; D014212:Tretinoin / Q000494:pharmacology
chemical_list: D030161:Avian Proteins; D004270:DNA, Circular; D014212:Tretinoin; D024743:Atrial Myosins; C094463:AMHC1 protein, chicken; D018995:Myosin Heavy Chains; D009218:Myosins