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Thyroid transcription factor-1, hepatocyte nuclear factor-3beta and surfactant protein A and B in the developing
X Zeng1, K E Yutzey, J A Whitsett
1Children's Hospital Medical Center, Division of Pulmonary Biology and Neonatology, Cincinnati, Ohio, USA.
Insights
Surfactant proteins SP-A and SP-B, along with transcription factors TTF-1 and HNF-3beta, were identified in developing chicken lungs. Their expression patterns suggest conserved roles in vertebrate respiratory epithelial development.
Area of Science:
- Developmental Biology
- Pulmonology
- Comparative Vertebrate Anatomy
Background:
- Surfactant proteins (SP-A, SP-B) and transcription factors (TTF-1, HNF-3beta) are crucial for mammalian lung function and development.
- Understanding these factors in avian models can reveal conserved evolutionary mechanisms in respiratory development.
Purpose of the Study:
- To investigate the expression patterns of SP-A, SP-B, TTF-1, and HNF-3beta during chicken lung development.
- To determine the conservation of these key lung development regulators between avian and mammalian species.
Main Methods:
- Immunohistochemistry was employed to detect the presence and localization of SP-A, SP-B, TTF-1, and HNF-3beta.
- Analysis was conducted on embryonic and posthatching chicken lung tissues at various developmental stages.
Main Results:
- SP-B was detected in parabronchial epithelial cells from day 15 of incubation, with high posthatching expression.
- SP-A was found in mesobronchial epithelial cells from day 15 and also in posthatching lungs.
- TTF-1 and HNF-3beta were present from early lung bud formation (day 4) throughout development, decreasing posthatching.
Conclusions:
- The expression of SP-A and SP-B in chick lungs highlights the conservation of these vital surfactant proteins across vertebrates.
- The overlapping expression patterns of TTF-1, HNF-3beta, SP-A, and SP-B support their roles in chick lung development.
- These findings demonstrate conserved regulatory mechanisms for respiratory epithelial gene expression in vertebrates.
Abstract:
Expression of surfactant proteins SP-A, SP-B and the transcription factors TTF-1 and HNF-3beta was identified by immunohistochemistry in the developing chicken. SP-B, a small hydrophobic peptide critical for lung function and surfactant homeostasis in mammals, was detected in the epithelial cells of parabronchi in embryonic chicken lung from the 15th day of incubation, prior to the onset of the breathing movements and was expressed at high levels in the posthatching chicken lung. SP-A, an abundant surfactant protein involved in innate defence of the mammalian lung, was detected in the chick embryo in subsets of epithelial cells in the mesobronchus, starting from d 15 and was detected in the posthatching chicken lung. The transcription factors hepatocyte nuclear factor 3beta (HNF-3beta) and thyroid transcription factor-1 (TTF-1), both regulators epithelial cell differentiation and gene expression in mammalian species, were detected at the onset of lung bud formation (d 4 of incubation) and throughout lung development. Abundant nuclear expression was detected in nuclei of respiratory epithelial cells of developing bronchial tubules for both transcription factors. In contrast to the surfactant proteins, expression of both TTF-1 and HNF-3beta decreased markedly in posthatching chicken lung. The expression of SP-A and SP-B in chick lung demonstrates the conservation of surfactant proteins in vertebrates. The temporospatial pattern of TTF-1 and HNF-3beta overlaps with that of SP-A and SP-B, supporting their potential roles in chick lung development and demonstrating the conservation of regulatory mechanisms contributing to gene expression in respiratory epithelial cells in vertebrates.