Epithelial marker genes are expressed in cultured embryonic rat lung and in vivo with similar spatial and temporal patterns.
Explants of embryonic lung are often used to characterize lung growth, bronchial tree pattern, and cell differentiation. Most investigators culture lungs for 3-7 days in defined media lacking, e.g., added growth factors or hormones. If growth and differentiation are comparable to that in vivo, these cultures show considerable promise for identifying developmental regulatory molecules and target genes, and for elucidating molecular responses. We used in situ hybridization and RT-PCR to compare times and sites of expression of mRNAs of six epithelial genes in cultured and uncultured fetal rat lungs. These genes, expressed in distal lung of adult rats, are surfactant proteins (SP) A, B, and C; LAR, a receptor-type tyrosine phosphatase; Clara cell secretory protein (CC10, CCSP); and T1alpha. SP-A, SF-B, LAR, and CC10 are expressed by both Clara and Type II cells in adult animals. SP-C and T1alpha are unique markers for Type II and Type I cells, respectively. SP-C, LAR, and T1alpha are expressed before the lung is explanted (Day 13.5); SP-A, -B, and CC10 mRNAs are first detected later. The onset of expression is similar in vivo and in vitro. Although the patterns of expression differ for each mRNA, their sites of expression in culture match those in vivo relative to the bronchial tree. The explanted embryonic lung appears to be an excellent experimental model.
Meneghetti
A
A
Pulmonary Center and Department of Medicine, Boston University School of Medicine, Massachusetts 02118, USA.
Cardoso
W V
WV
Brody
J S
JS
Williams
M C
MC
D000818:Animals; D015415:Biomarkers; D004848:Epithelium / Q000378:metabolism / Q000648:ultrastructure; D005326:Fetal Proteins / Q000096:biosynthesis* / Q000235:genetics; D018507:Gene Expression Regulation, Developmental; D005865:Gestational Age; D017403:In Situ Hybridization; D008168:Lung / Q000166:cytology / Q000196:embryology / Q000378:metabolism*; D008562:Membrane Glycoproteins; D008565:Membrane Proteins / Q000096:biosynthesis* / Q000235:genetics; D009419:Nerve Tissue Proteins; D009924:Organ Culture Techniques; D016133:Polymerase Chain Reaction; D014176:Protein Biosynthesis; D017027:Protein Tyrosine Phosphatases; D011506:Proteins / Q000235:genetics; D011663:Pulmonary Surfactants / Q000096:biosynthesis* / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D054623:Receptor-Like Protein Tyrosine Phosphatases, Class 2; D011956:Receptors, Cell Surface / Q000096:biosynthesis* / Q000235:genetics; D014598:Uteroglobin; D000098853:Podoplanin
D015415:Biomarkers; D005326:Fetal Proteins; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D017027:Protein Tyrosine Phosphatases; D011506:Proteins; D011663:Pulmonary Surfactants; D012333:RNA, Messenger; D054623:Receptor-Like Protein Tyrosine Phosphatases, Class 2; D011956:Receptors, Cell Surface; D014598:Uteroglobin; C092025:Pdpn protein, rat; D000098853:Podoplanin; C556391:Scgb1a1 protein, rat; C516774:Ptprf protein, rat