Polyamine depletion alters the relationship between f-actin, g
-actin, and thymosin #4 in migrating iec-6 cells.
McCormack, Shirley A., Ramesh M. Ray, Patrick M. Blanner, and Leonard
R. Johnson.
Department of Physiology and Biophysics, College of Medicine,
University of Tennessee, Memphis
APStracts 5:0290C, 1998.
The cause of reduced migration ability in polyamine (PA) deficient
cells is not known, but their actin cytoskeleton is clearly abnormal.
We depleted PAs with a-difluoromethylornithine (DFMO) in migrating
cells with or without stimulation by EGF and investigated filamentous
(F-) actin, monomeric (G-) actin, and thymosin #4 (T#4), using
immunofluorescent confocal microscopy, DNase assay, and immunoblot
analysis. DFMO reduced F-actin in the cell interior, increased it in
the cell cortex, redistributed G-actin, and increased nuclear
staining of T#4. However, DFMO did not affect the amount of T#4 mRNA.
EGF caused a rapid increase in the staining of F-actin in control
cells, but DFMO prevented this response to EGF. Despite the visible
changes shown by immunocytochemistry, statistically significant
changes in the amount of either actin isoform or of total actin did
not occur. We propose that DFMO reduces migration by interfering with
the sequestration of G-actin by T#4 and the association of F-actin
with activated EGF receptors.
Received 20 July 1998; accepted in final form 22 October 1998.
APS Manuscript Number C341-8.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1998 The American Physiological Society.
Published in APStracts on 20 November 1998