Premium
Selective nuclear translocation of protein kinase C α in Swiss 3T3 cells treated with IGF‐I, PDGF and EGF
Author(s) -
Neri Luca M.,
Billi Anna Maria,
Manzoli Lucia,
Rubbini Silvia,
Gilmour R.Stewart,
Cocco Lucio,
Martelli Alberto M.
Publication year - 1994
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(94)00508-7
Subject(s) - protein kinase c , microbiology and biotechnology , biology , nuclear localization sequence , cytoplasm , western blot , cell nucleus , isozyme , gene isoform , pkc alpha , 3t3 cells , signal transduction , cell culture , biochemistry , transfection , enzyme , gene , genetics
To determine the subcellular distribution of PKC after GFs treatment we have employed a combined immunochemical and in situ confocal microscopy analysis. In quiescent SvMs 3T3 cells only a faint PKC positivity was observable in the nucleus while a strong reaction was seen in the cytoplasm. IGF‐I and to a lesser extent PDGF and EGF induced, after 45 min of treatment, a nuclear translocation of PKC detected by a pan‐anti‐PKC antibody and nuclear fluorescence was distributed in the nuclear interior except for the nucleolar regions. Bombesin and FGF did not affect the sub‐cellular distribution of the enzyme. To further the understanding of which PKC isoform was involved in the transiocation process, we have tested nine isozyme‐speeffic anti‐PKC antibodies. Immunoblotting analysis revealed the presence in Swiss 3T3 fibroblasts of α, β I , ε and ζ isoforms. In isolated nuclei from GF‐exposed cells only the α isozyme was detected: immunostaining was very intense after IGF‐I treatment and clearly observable after PDGF and EGF stimulation. This result was strongly supported by the in situ confocal microscopy which parallels the Western blot analysis. These data demonstrate that several, but not all, GFs acting through tyrosine kinase receptor induce the intranuclear translocation of PKC α and, because of the dramatic effect of IGF‐I, strengthen the case for a link between the activation of nuclear inositol lipid cycle and PKC translocation induced by this GF.