title: Capsulin: a novel bHLH transcription factor expressed in epicardial progenitors and mesenchyme of visceral organs.
abstract: Members of the basic helix-loop-helix (bHLH) family of transcription factors have been shown to control development and differentiation of a variety of cell types. We describe a novel bHLH protein, called capsulin, which is expressed specifically in mesodermally-derived cells that surround the epithelium of the developing gastrointestinal, genitourinary and respiratory systems during mouse embryogenesis. Capsulin transcripts also mark the spiral septum of the heart and progenitor cells that give rise to the pericardium and coronary arteries. Capsulin shares high homology with a recently identified bHLH protein from Drosophila, called bHLH102C, which is expressed in visceral muscle cells that surround the midgut. Capsulin binds a specific E-box consensus sequence (CANNTG) as a heterodimer with the widely-expressed bHLH protein E12, but it does not activate transcription through that sequence on its own. Its restricted expression pattern and DNA binding activity suggest that capsulin regulates gene expression in specific subtypes of visceral mesodermal cells involved in organogenesis and in precursor cells that contribute to the pericardium, coronary arteries and regions of the heart.
authors.affiliation: Department of Molecular Biology and Oncology, The University of Texas, Southwestern Medical Center, 6000 Harry Hines Boulevard, Dallas, TX 75235-9148, USA.
authors.forename: J
authors.initials: J
authors.lastname: Lu
authors.forename: J A
authors.initials: JA
authors.lastname: Richardson
authors.forename: E N
authors.initials: EN
authors.lastname: Olson
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins; D004268:DNA-Binding Proteins / Q000378:metabolism; D016208:Databases, Factual; D004064:Digestive System / Q000196:embryology; D019281:Dimerization; D018507:Gene Expression Regulation, Developmental; D018257:Helix-Loop-Helix Motifs / Q000235:genetics; D006801:Humans; D008648:Mesoderm / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D010496:Pericardium / Q000196:embryology / Q000378:metabolism*; D011817:Rabbits; D012137:Respiratory System / Q000196:embryology; D013234:Stem Cells / Q000378:metabolism*; D014157:Transcription Factors / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D014566:Urogenital System / Q000196:embryology
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D004268:DNA-Binding Proteins; D014157:Transcription Factors; C491825:TCF21 protein, human; C112923:Tcf21 protein, mouse