Time‐dependent translocation of protein kinase in liver of glucagon‐treated rats

Schwoch, G; Hilz, Helmuth

doi:10.1016/0014-5793(78)80313-5

Cited by 8 publications

(1 citation statement)

References 11 publications

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“…Such molecular events constitute a relatively selective mechanism whereby the hormonal signal at the cell membrane is transduced to nuclear sites, resulting in the functional interaction of the subunits with nuclear components and subsequent physiological response. Similar translocation phenomena have been observed in several other cell systems (Corbin et al, 1977;Jungmann & Kranias, 1977;Schwoch & Hilz, 1978;Cho-Chung, 1980;Schwartz & Costa, 1980;Cho-Chung et al, 1981;Nesterova et al, 1981;Mednieks & Jungmann, 1982;Kuettel et al, 1984;Nigg et al, 1985a;Squinto et al, 1985;Schwoch & Freimann, 1986;.…”

Section: Discussionsupporting

confidence: 79%

Modulation of nuclear cyclic AMP-dependent protein kinase in dibutyryl cyclic AMP-treated rat H4IIE hepatoma cells

Squinto

Jungmann

1989

Biochemical Journal

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Biochemical and immunochemical studies were undertaken to quantify the effects of cyclic AMP on cyclic AMP-dependent protein kinase subunit levels in nuclei of H4IIE hepatoma cells. Dibutyryl cyclic AMP (10 microM) caused a significant biphasic (10 and 120 min after stimulation) increase in total nuclear protein kinase activity. The increase observed 10 min after dibutyryl cyclic AMP stimulation was primarily due to an approx. 3-fold increase of catalytic (C) subunit activity, whereas the change observed 120 min after stimulation consisted of an increase in both C subunit and cyclic AMP-independent protein kinase activities. Analysis of nuclear protein extracts by photoaffinity labelling with 8-azido cyclic [32P]AMP identified only the type II regulatory subunit (RII), but not the type I regulatory subunit (RI). Analysis of nuclear RII variants by two-dimensional gel electrophoresis demonstrated that dibutyryl cyclic AMP caused the appearance of two RII variant forms which were not present in the nuclei of unstimulated cells. Using affinity-purified polyclonal antibodies and immunoblotting procedures, we identified an approx. 2-fold increase in the RII and C subunits in nuclear extracts of dibutyryl cyclic AMP-treated hepatoma cells. Finally, the RI, RII and C subunits were quantified by an e.l.i.s.a. which indicated that dibutyryl cyclic AMP increased nuclear RII and C subunits levels biphasically, reaching peak values 10 and 120 min after the initial stimulation. Nuclear RI subunit levels were not affected. These results provide qualitative as well as quantitative evidence for a modulation by cyclic AMP of the nuclear RII and C subunit levels in rat H4IIE hepatoma cells, and indicate a relatively rapid but temporarily limited dibutyryl cyclic AMP-induced translocation of the RII and C subunits to nuclear sites.

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