title: Calcineurin-independent regulation of plasma membrane Ca2+ ATPase-4 in the vascular smooth muscle cell cycle.
abstract: Calcineurin mediates repression of plasma membrane Ca2+-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 45Ca efflux rates decreased 50%, fura 2-AM-based intracellular Ca2+ concentrations ([Ca2+]i) increased twofold, and real-time RT-PCR and Western blot revealed a approximately 40% decrease in PMCA4 expression levels from G0 to G1/S in the cell cycle, where PMCA4 constituted approximately 20% of total PMCA protein. Although calcineurin activity increased fivefold as MOVAS progressed from G0 to G1/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 G1/S. By contrast, Ca2+-independent activity of the calmodulin-dependent protein kinase-II (CaMK-II) increased eightfold as MOVAS progressed from G0 to G1/S, and treatment with an inhibitor of CaMK-II (KN-93) or transduction of a c-Myb-neutralizing antibody significantly alleviated the G1/S-associated repression of PMCA4. These data show that G1/S-specific PMCA4 repression in proliferating VSMC is brought about by c-Myb and CaMK-II and that calcineurin may regulate cell cycle-associated [Ca2+]i through alternate targets.
authors.affiliation: Department of Medicine, University of Toronto, Toronto, Ontario, Canada M5G-2C4.
authors.forename: Talat
authors.initials: T
authors.lastname: Afroze
authors.forename: Li L
authors.initials: LL
authors.lastname: Yang
authors.forename: Changsen
authors.initials: C
authors.lastname: Wang
authors.forename: Robert
authors.initials: R
authors.lastname: Gros
authors.forename: Waseem
authors.initials: W
authors.lastname: Kalair
authors.forename: Abu N
authors.initials: AN
authors.lastname: Hoque
authors.forename: Imran N
authors.initials: IN
authors.lastname: Mungrue
authors.forename: Ziping
authors.initials: Z
authors.lastname: Zhu
authors.forename: Mansoor
authors.initials: M
authors.lastname: Husain
mesh_terms: D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D001596:Benzylamines / Q000494:pharmacology; D019703:Calcineurin / Q000378:metabolism*; D065095:Calcineurin Inhibitors; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D000252:Calcium-Transporting ATPases / Q000235:genetics / Q000378:metabolism*; D002352:Carrier Proteins / Q000235:genetics; D027682:Cation Transport Proteins; D002460:Cell Line; D002462:Cell Membrane / Q000201:enzymology; D048429:Cell Size / Q000502:physiology; D002614:Chelating Agents / Q000494:pharmacology; D004533:Egtazic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D016193:G1 Phase / Q000502:physiology; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology; D051379:Mice; D008810:Mice, Inbred C57BL; D009131:Muscle, Smooth, Vascular / Q000166:cytology* / Q000201:enzymology*; D009842:Oligopeptides / Q000235:genetics; D010641:Phenotype; D053499:Plasma Membrane Calcium-Transporting ATPases; D020598:Proto-Oncogene Proteins c-myb / Q000276:immunology / Q000378:metabolism; D016196:S Phase / Q000502:physiology; D013449:Sulfonamides / Q000494:pharmacology; D014162:Transfection; D000096926:Benzenesulfonamides
chemical_list: D000906:Antibodies; D001596:Benzylamines; D019703:Calcineurin; D065095:Calcineurin Inhibitors; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D000252:Calcium-Transporting ATPases; D002352:Carrier Proteins; D027682:Cation Transport Proteins; D002614:Chelating Agents; D004533:Egtazic Acid; D004791:Enzyme Inhibitors; D009842:Oligopeptides; D053499:Plasma Membrane Calcium-Transporting ATPases; D020598:Proto-Oncogene Proteins c-myb; D013449:Sulfonamides; C121611:VIVIT peptide; C072105:KN 93; D000096926:Benzenesulfonamides; C506954:Atp2b1 protein, mouse; C025603:1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid