Developmental changes in the activity and cellular localization of hepatic casein kinase II in the rat.
The activity and cellular localization of hepatic casein kinase II (CKII) was examined during late fetal development in the rat. Cultured fetal hepatocytes displayed constitutive CKII activity which was not further activated by growth factor exposure. Similarly, fetal liver CKII showed approximately fivefold greater activity than adult liver. The fetal hepatic activity was, to a large degree, localized to a nuclear fraction. Postnuclear cytosol preparations from fetal and adult liver showed similar CKII activity. In all cases, FPLC ion exchange chromatography followed by Western immunoblotting showed that immunoreactive CKII coincided with kinase activity. However, parallel determinations of CKII activity and immunoreactive CKII levels showed a higher (five- to sixfold) CKII specific activity in nuclear extracts compared to cytosol. In summary, fetal hepatic CKII demonstrates coincident nuclear localization and activation. We hypothesize that the regulation of hepatic CKII is relevant to the mitogen-independent proliferation displayed by fetal rat hepatocytes.
Gruppuso
P A
PA
Department of Pediatrics, Rhode Island Hospital, Providence 02903, USA.
Boylan
J M
JM
D000818:Animals; D001798:Blood Proteins / Q000494:pharmacology; D015153:Blotting, Western; D047390:Casein Kinase II; D002455:Cell Division; D002467:Cell Nucleus / Q000378:metabolism*; D002478:Cells, Cultured; D002852:Chromatography, Ion Exchange; D004268:DNA-Binding Proteins / Q000276:immunology / Q000378:metabolism; D004789:Enzyme Activation; D005260:Female; D007328:Insulin / Q000494:pharmacology; D008099:Liver / Q000196:embryology / Q000378:metabolism*; D008297:Male; D010766:Phosphorylation; D011247:Pregnancy; D017346:Protein Serine-Threonine Kinases / Q000276:immunology* / Q000302:isolation & purification / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D016211:Transforming Growth Factor alpha / Q000494:pharmacology
D001798:Blood Proteins; D004268:DNA-Binding Proteins; D007328:Insulin; D016211:Transforming Growth Factor alpha; D047390:Casein Kinase II; D017346:Protein Serine-Threonine Kinases