A regulatory role for cAMP-dependent protein kinase in protein traffic along the exocytic route.
The influence of protein kinase A activity on transport of newly synthesized vesicular stomatitis virus G glycoprotein along the exocytic pathway was examined. Transport of vesicular stomatitis virus G glycoprotein to the cell surface was inhibited by N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinolinesulfonamide (H-89), a selective inhibitor of protein kinase A. This block occurred at the exit of the Golgi complex, whereas transport through the Golgi compartments or from the endoplasmic reticulum to the Golgi was decreased in the presence of H-89. As judged by immunofluorescence endoplasmic reticulum to Golgi transport was accelerated in cells incubated with activators of protein kinase A such as isobutylmethylxanthine (IBMX) or forskolin (FK). Treatment with IBMX and FK also increased transport from the trans-Golgi network to the cell surface. During incubation with IBMX and FK, the organization of the Golgi complex was altered showing intercisternae fusion and miscompartmentalization of resident proteins. These structural changes affected both the kinetics of acquisition of endoglycosidase H resistance and transport activities. These data support a differential regulatory role for protein kinase A in different transport steps along the exocytic pathway. In particular, transport from the trans-Golgi network to the cell surface was dependent on protein kinase A activity. In addition, the results suggest the involvement of this enzyme on the maintenance of the Golgi complex organization.
Muñiz
M
M
Department of Cell Biology, Faculty of Biology, University of Seville, 41012-Seville, Spain.
Alonso
M
M
Hidalgo
J
J
Velasco
A
A
D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002451:Cell Compartmentation / Q000187:drug effects; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism / Q000502:physiology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000502:physiology*; D004721:Endoplasmic Reticulum / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005089:Exocytosis / Q000187:drug effects; D006056:Golgi Apparatus / Q000378:metabolism*; D006596:Hexosaminidases / Q000378:metabolism; D007546:Isoquinolines / Q000494:pharmacology; D008562:Membrane Glycoproteins / Q000378:metabolism*; D008854:Microscopy, Electron; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D051381:Rats; D013449:Sulfonamides; D014759:Viral Envelope Proteins / Q000378:metabolism
D004791:Enzyme Inhibitors; C028391:G protein, vesicular stomatitis virus; D007546:Isoquinolines; D008562:Membrane Glycoproteins; D013449:Sulfonamides; D014759:Viral Envelope Proteins; D005576:Colforsin; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D006596:Hexosaminidases; C063509:N-(2-(4-bromocinnamylamino)ethyl)-5-isoquinolinesulfonamide; D015056:1-Methyl-3-isobutylxanthine