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Ontogeny of platelet-derived growth factor receptor in fetal rat lung
1Department of Paediatrics, Hospital for Sick Children Research Institute, Toronto, Ontario, Canada.
Insights
Platelet-derived growth factor receptors (PDGFR) are present in developing rat lungs, indicating their role in fetal lung growth. PDGFR expression changes with gestation, suggesting regulation of platelet-derived growth factor (PDGF) activity during lung development.
Area of Science:
- Developmental Biology
- Cell Biology
- Molecular Biology
Background:
- Platelet-derived growth factor (PDGF) and PDGF-like molecules are increasingly recognized for their roles in fetal lung morphogenesis.
- Previous studies confirmed the presence of PDGF-AA and PDGF-BB homodimers in fetal rat lung.
Purpose of the Study:
- To investigate the target cells of PDGF during fetal lung development.
- To map the expression patterns of PDGF receptors (PDGFR) in embryonic and fetal rat lung.
Main Methods:
- Immunolocalization studies were performed on rat lung tissue from day 13 to day 21 of gestation.
- Two polyclonal PDGFR antibodies were used: one recognizing both alpha and beta receptors (PDGFR-alpha/beta), and another specific for the beta receptor (PDGFR-beta).
Main Results:
- PDGFR immunoreactivity was observed in both epithelial and mesenchymal cells from 13 days gestation, increasing with gestational age.
- Intense PDGFR staining was noted in epithelial and interstitial cells during the saccular stage, localized to the apical/luminal side of airway epithelial cells.
- PDGFR-positive bronchial and vascular smooth muscle cells were detected during the canalicular and saccular stages; endothelial cells of internal vascular plexuses showed PDGFR from days 14-16.
Conclusions:
- PDGF receptors are expressed in airway epithelial cells, interstitial cells, and bronchial and vascular smooth muscle cells during rat lung development.
- Gestation-dependent regulation of PDGFR expression suggests a role in modulating PDGF bioactivity critical for lung morphogenesis.
Abstract:
There is increasing evidence that platelet-derived growth factor (PDGF) or PDGF-like molecules play a role in fetal lung morphogenesis. Our previous studies demonstrated the presence of PDGF-AA and PDGF-BB homodimers in fetal rat lung. To study further the target cells of PDGF in lung development, immunolocalization studies of PDGF receptors (PDGFR) were conducted on embryonic and fetal rat lung from day 13 to day 21 of gestation (term = 22 days) using two polyclonal PDGFR antibodies, one of which one recognizes both alpha and beta receptors (PDGFR-alpha/beta), while the other is specific for the beta receptor (PDGFR-beta). A similar immunostaining pattern for both antibodies was noted. Immunoreactivity to PDGFR was evident in both epithelial and mesenchymal cells of the embryonic lung bud as early as 13 days gestation. The number of PDGFR immunoreactive cells increased with advancing gestation. Intense immunoreactivity was noted in both epithelial cells and interstitial cells during the saccular stage of lung development. The immunoreactivity to PDGFR was localized to the apical/luminal side of bronchial and distal airway epithelial cells. PDGFR-immunopositive bronchial and vascular smooth muscle cells were detected only during the canalicular and saccular stages of lung development. Immunopositive endothelial cells lining the internal vascular plexuses were observed from days 14-16 of gestation. No PDGFR was detected in endothelial cells of large pulmonary vessels. We conclude that PDGFR are present in airway epithelial cells, interstitial cells, and bronchial and vascular smooth muscle cells and that gestation-dependent up- and down-regulation of PDGFR may play a role in developmental regulation of PDGF bioactivity during lung morphogenesis.