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Protein kinase C isozyme pattern in liver hyperplasia
L Tessitore1, G P Perletti, E Sesca
1Dipartimento di Medicina ed Oncologia Sperimentale, Università degli Studi di Torino, Italy.
Biochemical and Biophysical Research Communications
|November 30, 1994
Summary
Lead nitrate induces rat liver hyperplasia, with males showing greater growth and regression than females. Dietary choline shifts female response toward male patterns, involving specific protein kinase C (PKC) isoenzyme changes.
Area of Science:
- Hepatology
- Toxicology
- Molecular Biology
Background:
- Lead nitrate activates protein kinase C (PKC), a key enzyme in cell signaling.
- Lead exposure can induce liver hyperplasia, a condition characterized by an increase in liver cell growth.
- Sex-related differences in liver growth and regeneration are observed in various physiological and pathological conditions.
Purpose of the Study:
- To investigate the sex-related differences in lead-induced rat liver hyperplasia and its regression.
- To examine the role of dietary choline in modulating these sex-related differences.
- To analyze the involvement of specific protein kinase C (PKC) isoenzymes in the signal transduction pathway of lead-induced liver proliferation.
Main Methods:
- Induction of liver hyperplasia in male and female rats using lead nitrate.
- Administration of dietary choline to female rats to assess its effect on liver growth.
- Analysis of PKC isoenzyme activities (alpha, beta, epsilon) using hydroxylapatite column chromatography.
- Correlation of PKC activity fluctuations with DNA synthesis rates.
Main Results:
- Liver hyperplasia and its apoptotic regression occurred earlier and were more pronounced in male rats compared to females.
- Dietary choline administration to females shifted the growth pattern towards male values.
- A significant down-regulation of alpha and beta PKC activities and a marked activation of epsilon PKC were observed.
- Fluctuations in PKC isoenzyme activities correlated with the rates of DNA synthesis.
Conclusions:
- Protein kinase C (PKC) isoenzymes, particularly alpha, beta, and epsilon, are implicated in the signal transduction pathway of lead-induced liver proliferation.
- Sex-related differences in liver hyperplasia and regression are influenced by PKC signaling.
- Dietary choline can modulate lead-induced liver hyperplasia by altering PKC isoenzyme activities.