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Maturational differences in hyperoxic AP-1 activation in rat lung.
1Department of Pediatrics, Stanford University, Palo Alto, California 94305, USA.
Summary
Neonatal lungs show different activator protein (AP)-1 binding complexes than adults when exposed to hyperoxia. These maturational differences in AP-1 may explain varying gene regulation responses to oxygen.
Area of Science:
- Pulmonary Medicine
- Molecular Biology
- Developmental Biology
Background:
- Hyperoxic injury affects neonates and adults differently.
- Activator protein (AP)-1 is involved in hyperoxic gene regulation.
Purpose of the Study:
- To evaluate lung AP-1 binding and its subunit proteins in neonatal and adult responses to hyperoxia.
- To investigate maturational differences in AP-1 complexes.
Main Methods:
- Exposure of neonatal and adult organisms to hyperoxia (>95% O2) for 3 days.
- Evaluation of lung AP-1 binding and subunit proteins (c-Fos, c-Jun, phosphorylated c-Jun, Jun B, Jun D) using supershift and sequential immunoprecipitation assays.
Main Results:
- Neonatal lungs showed no increased AP-1 binding in hyperoxia, unlike adults.
- Neonatal lungs exhibited two distinct AP-1 binding complexes (Fos/Jun family and Jun family, predominantly Jun D), while adult lungs had one complex possibly involving other proteins.
- Neonatal lungs had higher levels of Jun B and Jun D proteins under both air and hyperoxia compared to adults.
Conclusions:
- Significant maturational differences exist in lung AP-1 complexes between neonates and adults.
- These differences in AP-1 complex composition may underlie distinct transcriptional responses to hyperoxic gene regulation in immature versus adult lungs.