Differential Localization of Protein Kinase A Type II Isozymes in the Golgi–Centrosomal Area

• Published in: Experimental cell research Vol. 249; no. 1; pp. 131 - 146
• Main Authors: Keryer, Guy, Skålhegg, Bjørn S., Landmark, Brynjar F., Hansson, Vidar, Jahnsen, Tore, Taskén, Kjetil
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 25-05-1999
• Subjects: AKAP; Antibodies, Monoclonal - immunology; Bone Neoplasms - pathology; cAMP-dependent protein kinase; Cell Line, Transformed; Cells, Cultured; centrosome; Centrosome - enzymology; Cyclic AMP - physiology; Cyclic AMP-Dependent Protein Kinase Type II; Cyclic AMP-Dependent Protein Kinases - analysis; Cyclic AMP-Dependent Protein Kinases - immunology; Female; Fibroblasts - enzymology; Fibroblasts - ultrastructure; Golgi apparatus; Golgi Apparatus - enzymology; Granulosa Cells - enzymology; Granulosa Cells - ultrastructure; Humans; Isoenzymes - analysis; Isoenzymes - immunology; Keratinocytes - enzymology; Keratinocytes - ultrastructure; Lymphocytes - enzymology; Lymphocytes - ultrastructure; Macrophages - enzymology; Macrophages - ultrastructure; Microscopy, Confocal; Microscopy, Fluorescence; Microtubules - drug effects; Neoplasm Proteins - analysis; Nocodazole - pharmacology; Osteosarcoma - pathology; Paclitaxel - pharmacology; PKA; Second Messenger Systems - physiology; Subcellular Fractions - enzymology; subcellular localization; Trophoblasts - cytology; Trophoblasts - enzymology; Tumor Cells, Cultured; cAMP-dependent protein kinase; centrosome; subcellular localization; PKA; AKAP; Golgi apparatus
• ISSN: 0014-4827; 1090-2422
• DOI: 10.1006/excr.1999.4447

Selectivity in the action of cAMP may be mediated by compartmentalized pools of cyclic AMP-dependent protein kinase (PKA). PKA type II is directed to different subcellular loci by interaction of the type II regulatory subunits (RIIα, RIIβ) with A-kinase anchoring proteins. In order to separately investigate the subcellular localization of PKA type II isozymes, monospecific antibodies to human RIIα and RIIβ subunits of PKA were developed. We demonstrate that centrosomes bind both RIIα and RIIβ. Centrosomes were the preferred intracellular anchoring site for RIIβ. However, centrosomal localization of RIIβ was observed only in some highly differentiated cells such as keratinocytes, granulosa cells, and macrophages and in all neoplastic cell lines examined. Centrosomal localization of RIIβ was not observed in normal undifferentiated cells such as fibroblasts, myoblasts, and T and B cells. In contrast, RIIα was abundant in the Golgi area and in thetrans-Golgi network (TGN). Furthermore, although RIIα appeared to colocalize with microtubules in the Golgi/TGN, extractions with nonionic detergent demonstrated that RIIα was mainly membrane-associated. In addition, alterations of microtubule dynamics with Nocodazole or Taxol affected the distribution of the detergent-extractable pool of RIIα, indicating that RIIα may localize with microtubule-associated vesicles. Thus, RIIα and RIIβ clearly localize differently in the Golgi–centrosomal region. This indicates specific roles for PKA isozymes containing either RIIα or RIIβ.