title: Differential expression of the rat retinoid X receptor gamma gene during skeletal muscle differentiation suggests a role in myogenesis.
abstract: Even though previous studies have shown that transcripts encoding the murine retinoid X receptor gamma (RXRgamma) are present in skeletal muscle of mouse embryos and that cultured myoblasts are induced to differentiate upon retinoid treatment, a function for RXRgamma and retinoids in mammalian myogenesis has not yet been identified. To begin to understand the possible role of RXRgamma during mammalian myogenesis we isolated novel rat RXRgamma cDNA sequences and examined in detail the spatio-temporal expression pattern of RXRgamma transcripts in relation to skeletal muscle differentiation in rat embryos and cultured myoblasts. We show that the onset of RXRgamma expression coincides with the differentiation of limb myoblasts in vivo. In vitro, RXRgamma is expressed in differentiating myoblasts, but not in proliferating myoblasts. In the myotome, however, RXRgamma is first expressed after myoblast differentiation, with RXRgamma transcripts being confined initially to its ventral region. Subsequently, RXRgamma becomes expressed throughout limb and myotome-derived muscle masses, and by the end of the primary myogenic wave, RXRgamma transcripts are mainly confined to their periphery. This dynamic expression pattern of RXRgamma during myogenesis suggests its possible involvement in the differentiation of limb myoblasts but excludes a role in the differentiation of early myotomal myoblasts.
authors.affiliation: Department of Molecular Pathology, University College London Medical School, England.
authors.forename: P
authors.initials: P
authors.lastname: Georgiades
authors.forename: P M
authors.initials: PM
authors.lastname: Brickell
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002454:Cell Differentiation; D002478:Cells, Cultured; D018076:DNA, Complementary / Q000737:chemistry; D004268:DNA-Binding Proteins / Q000235:genetics*; D005786:Gene Expression Regulation; D051379:Mice; D008969:Molecular Sequence Data; D018482:Muscle, Skeletal / Q000166:cytology / Q000196:embryology*; D009687:Nuclear Proteins / Q000235:genetics*; D051381:Rats; D018168:Receptors, Retinoic Acid / Q000235:genetics*; D047488:Retinoid X Receptors; D014157:Transcription Factors / Q000235:genetics*
chemical_list: D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D018168:Receptors, Retinoic Acid; D047488:Retinoid X Receptors; D014157:Transcription Factors