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cAMP-dependent protein kinase and protein phosphorylation in developing rat lung
Pediatric Research
|December 1, 1983
Summary
Cyclic adenosine monophosphate-dependent protein kinase (cAMP-PK) activity and binding in rat lung cytosol were characterized across development. cAMP-PK activity and binding capacity changed with age, peaking during the suckling period.
Area of Science:
- Biochemistry
- Molecular Biology
- Developmental Biology
Background:
- Cyclic adenosine monophosphate (cAMP) is a crucial second messenger regulating various cellular processes.
- cAMP-dependent protein kinase (cAMP-PK) plays a vital role in signal transduction pathways.
- Understanding cAMP-PK activity during lung development is essential for comprehending lung maturation and function.
Purpose of the Study:
- To characterize cAMP-PK activity, [3H]cAMP binding, and cAMP-dependent protein phosphorylation in rat lung cytosol from gestation to adulthood.
- To compare phosphoprotein profiles in whole lung cytosol with those from purified Type II epithelial cells.
- To investigate age-related changes in cAMP-PK binding capacity and kinase activity.
Main Methods:
- Preparation of cytosolic fractions from rat lung at various developmental stages.
- Measurement of [3H]cAMP binding to identify and quantify regulatory subunits of cAMP-PK.
- Assay of cAMP-dependent histone kinase activity and phosphorylation of endogenous proteins using SDS-PAGE and autoradiography.
Main Results:
- Both Type I and Type II regulatory subunits of cAMP-PK were present in fetal and adult rat lung cytosol.
- [3H]cAMP binding affinity (KD) remained constant with age, but binding capacity varied significantly.
- cAMP-PK activity and binding capacity showed developmental changes, decreasing slightly before birth, peaking during suckling, and declining in adulthood.
- cAMP enhanced histone kinase activity and phosphorylation of specific endogenous proteins (Mr = 260,000, 240,000, 97,000, 56,000, 44,000, and 28,000).
Conclusions:
- cAMP-PK is present and functional throughout rat lung development, with significant age-related modulation of its activity and binding capacity.
- The developmental pattern of cAMP-PK suggests its involvement in critical lung maturation processes.
- Specific phosphoproteins regulated by cAMP-PK may play key roles in lung development and function.