Heterogeneous activation of protein kinase C during rat liver regeneration induced by carbon tetrachloride administration

Sasaki, Yutaka; Hayashi, Norio; Ito, Toshifumi; Fusamoto, Hideyuki; Sato, Nobuhiro; Kamada, Takenobu

doi:10.1016/0014-5793(89)81009-9

Cited by 14 publications

(3 citation statements)

References 20 publications

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“…This hypothesis might also be an alternative explanation for the increased taurine excretion after damage of liver cells by hepatotoxic compounds (Sanins et al, 1990;Timbrell et al, 1995;Timbrell and Waterfield, 1996;Waterfield et al, 1991Waterfield et al, , 1993a, as such damage is another strong trigger for liver regeneration (e.g. Holtta et al, 1973;Nakata et al, 1985;Sasaki et al, 1989;Clawson et al, 1991). Therefore, measuring urinary taurine excretion does not seem to be a specific (non-invasive) method for monitoring alterations in protein synthesis .…”

Section: Discussionmentioning

confidence: 91%

Changes in urinary taurine and hypotaurine excretion after two-thirds hepatectomy in the rat

1998

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This study followed the time course of urinary taurine and hypotaurine excretion after two-thirds hepatectomy in rats. The excretion of both taurine and hypotaurine was elevated during 18 h following the hepatectomy, with maximal excretion during the first 6 h. Twelve and 24 h after partial hepatectomy, the hepatic hypotaurine concentration was increased but liver taurine did not differ significantly from controls. No changes were observed in hypotaurine and taurine concentrations of heart, kidney, lung, muscle tissue and spleen. We postulate that partial hepatectomy induces a rapid increase of hepatic (hypo)taurine synthesis from precursor amino acids. The increased (hypo)taurine concentrations spill over into urine.

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Section: Discussionmentioning

confidence: 91%

Changes in urinary taurine and hypotaurine excretion after two-thirds hepatectomy in the rat

1998

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“…For example, PKC activity is greatly reduced in fatty bovine liver (Katoh and Kimura, 1989). Altered PKC activity and PKC-dependent phosphorylation of liver proteins have been reported in experimentally induced fatty liver in rats (Pofi et al, 1988;Sasaki et al, 1989;Katoh, 1992). Moreover, reduced hepatic PKC activity and protein phosphorylation were observed after dexamethasone administration to fasted cows (Yoshino et aL, 1993).…”

Section: Introductionmentioning

confidence: 92%

Reduced protein kinase C activity and endogenous protein phosphorylation in ethionine-induced fatty liver in cows

Katoh

1994

Vet Res Commun

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Protein kinase C (PKC) activity was evaluated and the phosphorylation of its endogenous substrates was explored in fatty liver induced by administration of ethionine (an analogue of methionine) to cows in order to assess the relevance of PKC-dependent phosphorylation in the development of fatty liver. PKC activity was decreased in both the cytosolic and the total particulate fractions from fatty livers, compared to the corresponding fractions from control liver. The mode of activation by the PKC cofactors (1-oleoyl-2-acetyl-sn-glycerol, 12-O-tetradecanoylphorbol-13-acetate, phosphatidyl-serine and Ca2+) was similar in both control and fatty livers, suggesting a quantitative but not a qualitative change in PKC in fatty liver. At least three substrate proteins (34 kDa, 26 kDa and 19 kDa) were found in the cytosolic fraction and their phosphorylation was reduced in fatty liver. These results suggest that impairment of the signal transduction pathway mediated by PKC is involved in the pathogenesis of fatty liver in cows.

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“…For instance, in different cellular systems the mitogenic stimulation is reported to be related to the induction or activation of isoforms ζ, δ or ε. In rat liver hyperplasia induced by lead nitrate, PKCα and β seem to be involved while in the liver compensative growth induced by CCl4 the ε isoform seems to be important [17,18]. PKCα expression has been shown to vary during the differentiation of many cell types [19] .…”

Section: Introductionmentioning

confidence: 99%

Mitogenic Signal of Epidermal Growth Factor in Chick Embryo Hepatocytes: Role of PKCα

Mele¹,

Marino²,

Spagnuolo³

et al. 2000

Cell Physiol Biochem

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In the present study we investigated the role of two isoforms of protein kinase C in the mitogenic signal of epidermal growth factor (EGF) in primary culture of chick embryo hepatocytes. The down-regulation of PKCα by long-term exposure to phorbol myristate acetate (PMA) provoked a reduced mitogenic response to EGF while the down-regulation of PKCε with oligonucleotide antisense had no effect on the stimulation of DNA synthesis, assayed as thymidine incorporation. EGF enhanced H3 diacylglycerol (DAG) production by cells preincubated with H3myristic acid, but did not increase the production of inositol 1-4-5-trisphosphate (IP3). EGF produced an increase in the release of arachidonic acid and prostaglandin E2 (PGE2) in the extracellular medium. The increase was blocked by specific inhibitors (quinacrine and AACOCF3) of phospholipase A2 (PLA2) and was inhibited by down-regulation of PKCα, demostrating that this isoform is involved in arachidonic acid production. DAG and arachidonic acid produced an additional effect on thymidine incorporation. The treatment with PLA2 inhibitors, which block the increase in arachidonic acid, decreased the effect of EGF on DNA synthesis. These results suggest that in chick embryo hepatocytes PKCα is the main isoform involved in EGF-induced DNA synthesis. Its rapid activation is dependent on DAG production and induces an increased production of arachidonic acid and prostaglandin which are involved in the mitogenic activity.

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Heterogeneous activation of protein kinase C during rat liver regeneration induced by carbon tetrachloride administration

Cited by 14 publications

References 20 publications

Changes in urinary taurine and hypotaurine excretion after two-thirds hepatectomy in the rat

Changes in urinary taurine and hypotaurine excretion after two-thirds hepatectomy in the rat

Reduced protein kinase C activity and endogenous protein phosphorylation in ethionine-induced fatty liver in cows

Mitogenic Signal of Epidermal Growth Factor in Chick Embryo Hepatocytes: Role of PKCα

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