TPA causes divergent responses of Ca(2+)-dependent and Ca(2+)-independent isoforms of PKC in the nuclei of Caco-2 cells.
The present studies were undertaken to examine the expression of PKC isoforms within the nucleus of Caco-2 cells, a cell line widely used to investigate intestinal cell growth and differentiation, in order to begin to explore their roles in modulating gene expression. Purified nuclei were, therefore, prepared from Caco-2 cells and found to contain PKC-zeta, but not -alpha. The phorbol ester, 12-O-tetradecanoyl phorbol 13-acetate (TPA) caused an acute redistribution of PKC-alpha to the nucleus, but did not change the distribution of PKC-zeta. Chronic treatment with TPA down-regulated total PKC-alpha, but not -zeta. Moreover, in contrast to acute TPA treatment, after chronic treatment, nuclear PKC-alpha was no longer detectable, whereas nuclear PKC-zeta was unchanged. These studies demonstrate for the first time the constitutive expression and divergent responses to TPA of the Ca(2+)-dependent and Ca(2+)-independent isoforms of PKC in the nuclei of Caco-2 cells and suggest that these specific isoforms may be involved in modulating gene expression.
Frawley
B P
BP
Department of Medicine, University of Chicago, IL 60637.
Tien
X Y
XY
Hartmann
S C
SC
Wali
R K
RK
Niedziela
S M
SM
Davidson
N O
NO
Sitrin
M D
MD
Brasitus
T A
TA
Bissonnette
M
M
D002118:Calcium / Q000378:metabolism*; D002467:Cell Nucleus / Q000201:enzymology* / Q000648:ultrastructure; D004789:Enzyme Activation; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism*; D011493:Protein Kinase C / Q000378:metabolism*; D015398:Signal Transduction; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
D007527:Isoenzymes; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium