title: The proto-oncogene c-myb mediates an intracellular calcium rise during the late G1 phase of the cell cycle.
abstract: The intracellular concentration of ionized calcium is involved in regulating mitosis. However, little is known about intracellular levels of calcium during G1. We have demonstrated in vascular smooth muscle cells a mid-G1 decrease in ionized calcium concentration followed by a 2-fold rise at the G1/S interface (44 nM +/- 0.6 nM versus 98 nM +/- 1.1 nM, p < 0.01). The elevation of intracellular calcium is preceded by an increase in c-myb mRNA levels and is abolished with antisense but not missense c-myb oligonucleotides. Furthermore, cells stably transfected with c-myb show a similar 2-fold augmentation in intracellular calcium concentrations, as compared with untransfected cells, which is also abolished by antisense c-myb oligonucleotides. The c-myb-induced rise in intracellular calcium is dependent upon the presence of extracellular calcium and is not suppressed by L type calcium channel blockers. We conclude that c-myb induces an elevation in intracellular calcium levels of vascular smooth muscle cells at the G1/S interface which provides a novel role for this proto-oncogene as well as a potentially important control point for cell cycle regulation.
authors.affiliation: Department of Biology, Massachusetts Institute of Technology, Cambridge 02139.
authors.forename: M
authors.initials: M
authors.lastname: Simons
authors.forename: K G
authors.initials: KG
authors.lastname: Morgan
authors.forename: C
authors.initials: C
authors.lastname: Parker
authors.forename: E
authors.initials: E
authors.lastname: Collins
authors.forename: R D
authors.initials: RD
authors.lastname: Rosenberg
mesh_terms: D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D002118:Calcium / Q000378:metabolism*; D002453:Cell Cycle; D002460:Cell Line; D003470:Culture Media; D004268:DNA-Binding Proteins / Q000235:genetics; D005456:Fluorescent Dyes; D016257:Fura-2; D016193:G1 Phase / Q000502:physiology*; D006801:Humans; D007211:Indoles; D007700:Kinetics; D051379:Mice; D008969:Molecular Sequence Data; D016376:Oligonucleotides, Antisense / Q000494:pharmacology*; D009857:Oncogenes; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D020598:Proto-Oncogene Proteins c-myb; D011519:Proto-Oncogenes; D012091:Repetitive Sequences, Nucleic Acid; D014162:Transfection
chemical_list: D003470:Culture Media; D004268:DNA-Binding Proteins; D005456:Fluorescent Dyes; D007211:Indoles; C000715470:MAS1 protein, human; D016376:Oligonucleotides, Antisense; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins; D020598:Proto-Oncogene Proteins c-myb; C048960:indo-1; D002118:Calcium; D016257:Fura-2