title: Tenascin is expressed in the mesenchyme of the embryonic lung and down-regulated by dexamethasone in early organogenesis.
abstract: Tenascin (TN) is a hexameric extracellular matrix glycoprotein that is temporally and spatially restricted during lung development. This study examines the expression and regulation of TN in early lung organogenesis. Two TN isoforms were detected in total RNA isolated from embryonic day 14 rat lung tissues by reverse transcriptase polymerase chain reaction. The localization of TN in embryonic day 14 rat lung tissues was investigated by using in situ hybridization performed with an antisense RNA probe. TN mRNA was expressed exclusively by the mesenchyme but not by the epithelium of embryonic rat lungs. The intense expression of TN was observed in the mesenchyme that immediately surrounds the growing epithelial cells of the developing bronchi. The effect of the synthetic glucocorticoid hormone dexamethasone on the regulation of TN expression was examined by in vitro lung explant culture. Two TN polypeptides, the larger (M(r) 230 kDa, TN230) polypeptide and the smaller (M(r) 180 kDa, TN180) isoform, were detected in embryonic day 21 rat lungs by immunoblot analysis with anti-TN antibody. Dexamethasone inhibited both TN230 and TN180 biosynthesis. The study demonstrates the expression of TN at the early stage of lung organogenesis and presents evidence of hormonal regulation of TN in lung development, suggesting a potential role of TN in the communication between the epithelial and mesenchymal cells during lung branching morphogenesis.
authors.affiliation: Duke University Medical Center and Research Service, Durham Veterans Affairs Medical Center, Durham, North Carolina 27710, USA. zhaoyun@duke.edu
authors.forename: Y
authors.initials: Y
authors.lastname: Zhao
mesh_terms: D000818:Animals; D001980:Bronchi / Q000196:embryology / Q000378:metabolism; D003907:Dexamethasone / Q000494:pharmacology*; D005314:Embryonic and Fetal Development; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects / Q000502:physiology*; D017403:In Situ Hybridization; D007413:Intestinal Mucosa / Q000378:metabolism; D007422:Intestines / Q000196:embryology; D008168:Lung / Q000196:embryology* / Q000378:metabolism; D008648:Mesoderm / Q000502:physiology*; D020320:Oligoribonucleotides, Antisense; D020033:Protein Isoforms / Q000096:biosynthesis / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D020545:Respiratory Mucosa / Q000196:embryology / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019063:Tenascin / Q000096:biosynthesis / Q000235:genetics*; D014158:Transcription, Genetic
chemical_list: D020320:Oligoribonucleotides, Antisense; D020033:Protein Isoforms; D012333:RNA, Messenger; D019063:Tenascin; D003907:Dexamethasone