Reciprocal regulation of mRNA and protein for subunits of cAMP-dependent protein kinase (RI alpha and C alpha) by cAMP in a neoplastic B cell line (Reh).
The present study examines the activity, levels of expression and regulation of cAMP-dependent protein kinase subunits during cAMP-mediated inhibition of Reh cell proliferation. Human Reh cells express mRNAs for the RI alpha and C alpha subunits of cAK at high levels and are practically devoid of cAMP-dependent protein kinase type II. Treatment with isoproterenol, forskolin, or a cAMP analog increased RI alpha mRNA in a time- and concentration-dependent manner (maximal, 4-fold, at 4-8 h). Messenger RNA for C alpha was also stimulated by cAMP, although with slower kinetics (maximal, 2-fold, at 16-24 h). Nuclear run-on assays showed a 2-fold increase in RI alpha gene transcription, whereas that of C alpha was unchanged. In spite of the stimulatory effects of cAMP on mRNAs for both RI alpha and C alpha, phosphotransferase activity and specific [3H]cAMP binding decreased rapidly after treatment with either cAMP or forskolin. Interestingly, the decrease in R and C activity preceded the increase in RI alpha and C alpha mRNA levels, raising the question whether increased mRNA levels may be secondary to the decrease in RI alpha or C alpha protein. The finding that the protein synthesis inhibitor cycloheximide gave changes in RI alpha and C alpha mRNA similar to cAMP and that co-treatment with cycloheximide and cAMP resulted in additive effects tend to support this notion.
Taskén
K
K
Institute of Medical Biochemistry, University of Oslo, Norway.
Andersson
K B
KB
Skålhegg
B S
BS
Taskén
K A
KA
Hansson
V
V
Jahnsen
T
T
Blomhoff
H K
HK
D000262:Adenylyl Cyclases / Q000378:metabolism*; D001402:B-Lymphocytes / Q000201:enzymology; D002455:Cell Division; D002460:Cell Line; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism / Q000494:pharmacology*; D054746:Cyclic AMP-Dependent Protein Kinase Type II; D017868:Cyclic AMP-Dependent Protein Kinases / Q000235:genetics / Q000378:metabolism*; D003513:Cycloheximide / Q000494:pharmacology; D015971:Gene Expression Regulation, Enzymologic; D016259:Genes, myc; D006131:Growth Inhibitors; D006706:Homeostasis; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism; D007545:Isoproterenol / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics; D014158:Transcription, Genetic
D006131:Growth Inhibitors; D007527:Isoenzymes; D012333:RNA, Messenger; D005576:Colforsin; D003513:Cycloheximide; D000242:Cyclic AMP; D054746:Cyclic AMP-Dependent Protein Kinase Type II; D017868:Cyclic AMP-Dependent Protein Kinases; D000262:Adenylyl Cyclases; D007545:Isoproterenol