Phosphorylation of vimentin is an intermediate step in protein kinase C-mediated glycoconjugate secretion
F. Bertrand, D. Veissiere, B. Hermelin, A. Paul, J. Capeau, J. Picard and G. Cherqui Laboratoire de Biochimie-Biologie Cellulaire, Institut National de la Sante et de la Recherche Medicale Unite 402, Faculte de Medecine Saint-Antoine, Paris, France. We have previously shown that fibroblasts from pat...
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Veröffentlicht in: | American Journal of Physiology: Cell Physiology 1994-03, Vol.266 (3), p.C611-C621 |
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Zusammenfassung: | F. Bertrand, D. Veissiere, B. Hermelin, A. Paul, J. Capeau, J. Picard and G. Cherqui
Laboratoire de Biochimie-Biologie Cellulaire, Institut National de la Sante et de la Recherche Medicale Unite 402, Faculte de Medecine Saint-Antoine, Paris, France.
We have previously shown that fibroblasts from patients with cystic
fibrosis (CF) display a higher response to 4 beta-phorbol 12-myristate
13-acetate (PMA) than control fibroblasts for stimulation of both protein
kinase C (PKC) cytosol-to-membrane translocation and glycoconjugate
secretion. In this study we took advantage of these cells with differential
responsiveness to PMA to investigate the endogenous substrate(s) involved
in PKC stimulation of glycoconjugate secretion after verification of cystic
fibrosis transmembrane conductance regulator gene expression in control and
CF fibroblasts. We show that a 57-kDa protein that was associated with
cytoskeleton and was identified as vimentin by immunoblotting emerged as a
good candidate for mediating PKC stimulation of glycoconjugate secretion.
1) Its phosphorylation by PMA was abolished by PKC inhibition or depletion.
2) In both control and CF fibroblasts, the PMA-induced increase in its
phosphorylation preceded the phorbol ester stimulation of glycoconjugate
secretion. 3) For both processes, the concentration-response curves were
superimposable, with higher maximal levels for CF fibroblasts relative to
controls. 4) PMA-stimulated 57-kDa protein phosphorylation, like
PMA-stimulated glycoconjugate secretion, was significantly increased by
Ca2+. 5) Increased PMA phosphorylation of the 57-kDa protein as a result of
okadaic acid inhibition of intracellular phosphatases was reflected in
increased PMA stimulation of glycoconjugate secretion. In conclusion, 1)
PMA phosphorylation of a cytoskeletal 57-kDa protein, identified as
vimentin, appears to be an intermediate step in PKC stimulation of
constitutive glycoconjugate secretion in human skin fibroblasts; and 2)
this process is impaired in CF disease. |
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ISSN: | 0363-6143 0002-9513 1522-1563 |
DOI: | 10.1152/ajpcell.1994.266.3.c611 |