Evidence for the role of phosphorylase kinase, protein kinase C, and other Ca2+-sensitive protein kinases in the response of hepatocytes to angiotensin II and vasopressin.
J Biol Chem
; 259(5): 3283-92, 1984 Mar 10.
Article
em En
| MEDLINE
| ID: mdl-6230357
ABSTRACT
Angiotensin II, catecholamines, and vasopressin can stimulate the phosphorylation of 10 hepatic cytosolic proteins via a Ca2+-linked, cyclic AMP-independent mechanism. To explore the role of known Ca2+-sensitive protein kinases in this response, [32P]PO4(3-)-labeled hepatocytes were stimulated with various agonists, the cytoplasmic proteins were separated on two-dimensional gels, and the resulting autoradiographs were computer analyzed. The role of phosphorylase kinase was examined using hepatocytes from gsd/gsd rats which are deficient in this enzyme. The phosphorylation state of phosphorylase was not increased by glucagon, angiotensin II, or vasopressin in hepatocytes from the gsd/gsd animals. The phosphorylation state of all other substrates was changed by glucagon or the Ca2+-linked hormones to the same extent in gsd/gsd hepatocytes as in normal Wistar controls, suggesting that phosphorylase kinase plays a restricted role in the hormone response. The role of the Ca2+- and phospholipid-sensitive protein kinase (protein kinase C) was examined by stimulating hepatocytes with phorbol esters which are thought to activate protein kinase C by substituting for diacylglycerol. Phorbol esters increased the phosphorylation state of 3 of the 10 substrates affected by angiotensin II or vasopressin, but did not stimulate Ca2+ fluxes in hepatocytes. Treatment of hepatocytes with the Ca2+ ionophore A23187 mimicked the effect of the Ca2+-linked hormones on the phosphorylation of the other 7 substrates. The results demonstrate that at least three Ca2+-sensitive protein kinases are involved in the response of hepatocytes to Ca2+-linked hormones. Since these kinases can be activated independently by phorbol esters or A23187, the results imply that hormones such as vasopressin generate two intracellular messengers, diacylglycerol and Ca2+ ion.
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Base de dados:
MEDLINE
Assunto principal:
Fosforilase Quinase
/
Proteínas Quinases
/
Angiotensina II
/
Vasopressinas
/
Cálcio
/
Fígado
Tipo de estudo:
Diagnostic_studies
Limite:
Animals
Idioma:
En
Revista:
J Biol Chem
Ano de publicação:
1984
Tipo de documento:
Article