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Calcineurin-independent regulation of plasma membrane Ca2+ ATPase-4 in the vascular smooth muscle cell cycle
Heart and Stroke Richard Lewar Centre of Excellence, University of Toronto, Division of Cell and Molecular Biology, Toronto General Hospital Research Institute, and Department of Medicine, University of Toronto, Toronto, Ontario, Canada M5G-2C4 Submitted 7 November 2002 ; accepted in final form 17 M...
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Published in: | American Journal of Physiology: Cell Physiology 2003-07, Vol.285 (1), p.C88-C95 |
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Main Authors: | , , , , , , , , |
Format: | Article |
Language: | English |
Subjects: | |
Online Access: | Get full text |
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Summary: | Heart and Stroke Richard Lewar Centre of Excellence, University of
Toronto, Division of Cell and Molecular Biology, Toronto General Hospital
Research Institute, and Department of Medicine, University of Toronto,
Toronto, Ontario, Canada M5G-2C4
Submitted 7 November 2002
; accepted in final form 17 March 2003
Calcineurin mediates repression of plasma membrane
Ca 2 + -ATPase-4 (PMCA4) expression in neurons, whereas
c-Myb is known to repress PMCA1 expression in vascular smooth muscle cells
(VSMC). Here, we describe a novel mouse VSMC line (MOVAS) in which
45 Ca efflux rates decreased 50%, fura 2-AM-based intracellular
Ca 2 + concentrations
([Ca 2 + ] i ) increased twofold, and real-time
RT-PCR and Western blot revealed a 40% decrease in PMCA4 expression
levels from G 0 to G 1 /S in the cell cycle, where PMCA4
constituted 20% of total PMCA protein. Although calcineurin activity
increased fivefold as MOVAS progressed from G 0 to G 1 /S,
inhibition of this increase with either BAPTA or retroviral transduction with
peptide inhibitors of calcineurin (CAIN), or its downstream target nuclear
factor of activated T cells (NFAT) (VIVIT), had no effect on the repression of
PMCA4 mRNA expression at G 1 /S. By contrast,
Ca 2 + -independent activity of the calmodulin-dependent
protein kinase-II (CaMK-II) increased eightfold as MOVAS progressed from
G 0 to G 1 /S, and treatment with an inhibitor of CaMK-II
(KN-93) or transduction of a c-Myb-neutralizing antibody significantly
alleviated the G 1 /S-associated repression of PMCA4. These data show
that G 1 /S-specific PMCA4 repression in proliferating VSMC is
brought about by c-Myb and CaMK-II and that calcineurin may regulate cell
cycle-associated [Ca 2 + ] i through alternate
targets.
calcineurin; c-Myb; plasma membrane Ca 2 + -ATPase-4; cell cycle
Address for reprint requests and other correspondence: M. Husain, Div. of Cell
and Molecular Biology, Toronto General Hospital Research Institute, Dept. of
Medicine, Univ. of Toronto, EN12-221, 200 Elizabeth St., Toronto, Ontario,
Canada M5G 2C4 (E-mail:
mansoor.husain{at}utoronto.ca ). |
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ISSN: | 0363-6143 1522-1563 |
DOI: | 10.1152/ajpcell.00518.2002 |