Cyclic amp-independent regulation of cystic fibrosis transmembrane
conductance regulator by the actin cytoskeleton.
Prat, Adriana G., Yong-Fu Xiao, Dennis A. Ausiello, and Horacio F.
Cantiello.
Renal Unit, Massachusetts General Hospital East, Charlestown, MA
02129, and Department of Medicine, Harvard Medical School, Boston, MA
02115
APStracts 2:0133C, 1995.
Protein kinase A (PKA)-activation of epithelial Na+ channels requires
actin filaments. Mouse mammary adenocarcinoma cells expressing the
human cystic fibrosis transmembrane conductance regulator (CFTR) or
mock transfectants were used to determine whether CFTR is also
modulated by the actin cytoskeleton. The actin filament disrupter
cytochalasin D (CD, 5 [mu]g/ml) readily activated whole-cell currents
in CFTR but not MOCK cells. Addition of actin to the cytosolic side
of quiescent excised inside-out patches of CFTR but not MOCK cells
also activated CFTR. The actin-activated Cl- channels (symmetrical
Cl-) had a linear conductance of 9.3 pS, and were inhibited by DPC
and monoclonal antibodies raised against CFTR. Channel activity was
also blocked by addition of the actin-binding proteins DNAse I and
filamin. Incubation of CFTR cells with CD (15 [mu]g/ml) for >6
hours prevented CFTR activation by the addition of either 8-Br-cAMP
plus forskolin under whole-cell conditions, or PKA under excised
inside-out conditions. However, CFTR activation was restored by
subsequent addition of actin. The data indicate that CFTR is
regulated by actin filaments whose effect may, in turn, be associated
with the PKA-dependent pathway.
Received 2 December 1994; accepted in final form 27 February
1995.
APS Manuscript Number C704-4.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 21 March 1995.