title: The expression of cAMP-dependent protein kinase subunits is differentially regulated during liver regeneration.
abstract: The levels of the regulatory (RI and RII) and catalytic (C) components of cAMP-dependent protein kinase and of their messages were studied during the first 36 h of liver regeneration after 70% hepatectomy. Both RI alpha mRNA and RII alpha mRNA started to increase 4 h after the resection, reaching peak levels after 9 h. RI mRNA decreased abruptly 9-12 h after resection, whereas RII mRNA stayed elevated. C alpha mRNA was rather constant during the period of study. In accordance with the mRNA data the level of C was constant while RI and RII increased during the prereplicative phase of liver regeneration. RI increased rapidly when its message became elevated. RII, however, increased noticeably only 6-8 h after its mRNA had become elevated. The increased expression of R led to a disproportion between R and C that was most pronounced 14 h after resection, i.e. coinciding with the prereplicative cAMP burst. The increased R/C ratio at that time of regeneration diminished the concentration of active C subunit during the cAMP burst. In that way the otherwise inhibitory effect of high concentrations of active C on the DNA replication may have been decreased. The fractional saturation of RI and RII by endogenous cAMP fluctuated in parallel as a function of liver cAMP levels, although there was a tendency that RI was more highly saturated than RII at high concentrations of cAMP.
authors.affiliation: Department of Anatomy, University of Bergen, Norway.
authors.forename: R
authors.initials: R
authors.lastname: Ekanger
authors.forename: O K
authors.initials: OK
authors.lastname: Vintermyr
authors.forename: G
authors.initials: G
authors.lastname: Houge
authors.forename: T E
authors.initials: TE
authors.lastname: Sand
authors.forename: J D
authors.initials: JD
authors.lastname: Scott
authors.forename: E G
authors.initials: EG
authors.lastname: Krebs
authors.forename: T S
authors.initials: TS
authors.lastname: Eikhom
authors.forename: T
authors.initials: T
authors.lastname: Christoffersen
authors.forename: D
authors.initials: D
authors.lastname: Ogreid
authors.forename: S O
authors.initials: SO
authors.lastname: Døskeland
mesh_terms: D000818:Animals; D000242:Cyclic AMP / Q000378:metabolism / Q000494:pharmacology*; D003600:Cytosol / Q000201:enzymology; D004261:DNA Replication; D005786:Gene Expression Regulation; D006498:Hepatectomy; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D008115:Liver Regeneration; D046911:Macromolecular Substances; D008297:Male; D009693:Nucleic Acid Hybridization; D011494:Protein Kinases / Q000096:biosynthesis / Q000235:genetics*; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D046911:Macromolecular Substances; D012333:RNA, Messenger; D000242:Cyclic AMP; D011494:Protein Kinases