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Subcellular compartmentalization of cAMP-dependent protein kinase regulatory subunits during palate ontogeny
1Department of Anatomy, Thomas Jefferson University, Philadelphia, PA 19107.
Insights
During mammalian palatal development, cyclic AMP-dependent protein kinase (cAMP-dPK) regulatory subunits RI and RII show distinct cellular locations. This differential compartmentalization may regulate cAMP-dependent responses in developing palates.
Area of Science:
- Developmental Biology
- Molecular Biology
- Biochemistry
Background:
- Palatal ontogeny in mammals involves complex cellular processes like epithelial-mesenchymal interactions.
- During mouse embryonic development (days 12-14), transient elevations in intracellular cyclic AMP (cAMP) and cAMP-dependent protein kinase (cAMP-dPK) occur in the palate.
- cAMP-dPK activity is modulated by binding to regulatory subunits RI and RII.
Purpose of the Study:
- To investigate the differential compartmentalization of cAMP-dPK regulatory subunits (RI and RII) during mammalian palatal development.
- To determine if the distribution of these subunits changes across cytosolic, nuclear, and particulate fractions of embryonic palatal tissue.
Main Methods:
- Preparation of cytosolic, nuclear, and particulate fractions from embryonic C57BL/6J mouse palatal and maxillary tissue on days 12, 13, and 14 of gestation.
- Photo-affinity labeling of these fractions using 8-azido [32P] cAMP.
- Analysis of labeled subunits via SDS-PAGE and autoradiography, followed by densitometric analysis.
Main Results:
- The RI isoform of cAMP-dPK regulatory subunits was predominantly found in the nuclear and particulate fractions.
- The RII isoform of cAMP-dPK regulatory subunits showed a predominance in the cytosolic fractions.
- These distribution patterns for both RI and RII were consistent across all three developmental days examined.
Conclusions:
- Differential compartmentalization of cAMP-dPK regulatory subunits RI and RII occurs during mammalian palatal ontogeny.
- This distinct localization suggests a regulatory mechanism for cAMP-dependent cellular responses during palatogenesis.
Abstract:
Mammalian palatal ontogeny involves epithelial-mesenchymal interactions, cell differentiation, and cell movements. These events occur on days 12, 13, and 14 of gestation in the C57BL/6J mouse embryo. During this period intracellular cAMP levels and cAMP-dependent protein kinase (cAMP-dPK) levels in the palate transiently elevate. Cyclic AMP activates cAMP-dPK by binding primarily to two types of regulatory subunits of this enzyme, designated as RI and RII. To assess whether differential compartmentalization of the regulatory subunits occurs during palatal ontogeny, cytosolic, nuclear, and particulate fractions were prepared from day 12, 13, and 14 embryonic maxillary and palatal tissue. After photo-affinity labeling of each fraction with 8-azido [32P] cAMP, SDS-PAGE, and autoradiography, autoradiograms were analyzed densitometrically. The RI isoform predominated in the nuclear and particulate fractions on all three developmental days; whereas RII predominated in the cytosolic fractions. Thus, differential compartmentalization of cAMP-dPK may be a means by which cAMP dependent responses are regulated during palatogenesis.