Nuclear translocation of the catalytic subunit of protein kinase A induced by an antisense oligonucleotide directed against the RIalpha regulatory subunit.
The regulatory (R) subunits of cAMP-dependent protein kinase (PKA) are implicated in the regulation of cell proliferation and differentiation. There are two isoforms of PKA that are distinguished by two types of R subunit, RI and RII. Evidence suggests that RI is associated with proliferation and RII is associated with cell differentiation. Previous work in this laboratory has demonstrated that depletion of the RIalpha subunit by treatment with an antisense oligonucleotide (ODN) induces differentiation in leukemia cells and growth arrest and apoptosis in epithelial cancer cells. Using the prostate cancer cell line PC3M as a model system, we have developed a cell line that overexpresses a retroviral vector construct containing the RIalpha antisense gene. This cell line has been characterized and the effectiveness of the construct determined. In the work presented here, we demonstrate by immunocytochemistry that treatment with RIalpha antisense ODN induces translocation of the Calpha subunit of PKA to the nucleus of PC3M prostate cancer cells. The translocation of Calpha triggered by exogenous antisense ODN treatment mirrors that observed in cells endogenously overexpressing the antisense gene. Triggering the nuclear translocation of the Calpha subunit of PKA in the cell may be an important mechanism of action of RIalpha antisense that regulates cell growth independent of adenylate cyclase and cellular cAMP levels. The nuclear localization of the Calpha subunit of PKA may be an essential step in revealing the mechanism whereby this critical kinase regulates cell growth.
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Cellular Biochemistry Section, Basic Research Laboratories, The Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, MD 20892-1750, USA.
Cho-Chung
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D021581:Active Transport, Cell Nucleus / Q000187:drug effects; D020134:Catalytic Domain; D002467:Cell Nucleus / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D005576:Colforsin / Q000494:pharmacology; D054756:Cyclic AMP-Dependent Protein Kinase RIalpha Subunit; D017868:Cyclic AMP-Dependent Protein Kinases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008297:Male; D016376:Oligonucleotides, Antisense / Q000235:genetics / Q000494:pharmacology*; D021122:Protein Subunits; D013379:Substrate Specificity; D013997:Time Factors; D014407:Tumor Cells, Cultured
D054756:Cyclic AMP-Dependent Protein Kinase RIalpha Subunit; D016376:Oligonucleotides, Antisense; C517834:PRKAR1A protein, human; D021122:Protein Subunits; D005576:Colforsin; D017868:Cyclic AMP-Dependent Protein Kinases