Growth factor modulated calmodulin-binding protein stimulates nuclear DNA synthesis in hemopoietic progenitor cells.
A specific calmodulin-binding protein of 68 kDa (CaM-BP68) is modulated in response to growth factors that induce proliferative stimulation in a variety of hemopoietic progenitor cells. The nuclear localization of the CaM-BP68 coincided temporally with interleukin 3 (IL-3)-dependent progression of synchronized FDC-P1 cells from G1 to S phase [Reddy et al. (1992) Blood 79, 1946-1956]. To delineate the role of the CaM-BP68 in the onset of DNA synthesis (S phase), this protein was purified to an apparent homogeneity from FDC-P1 cells and its effects on DNA replication in permeabilized FDC-P1 cells were examined. Purified CaM-BP exhibited a single silver-stained protein band of 68 kDa on SDS-polyacrylamide gels. This purified protein, when incubated with permeabilized log-growing FDC-P1 cells, caused a 3-4-fold increase in the rate of [3H]dTTP incorporation into DNA as compared to the controls. There was a direct correlation between the increase in the rate of [3H]dTTP incorporation into DNA and the concentration of the added CaM-BP68 in the incubation mixture. These observations suggest that the CaM-BP68, whose nuclear localization is associated with growth factor dependent proliferative stimulation of myeloid progenitor cells, is involved in the regulation of nuclear DNA synthesis.
Reddy
G P
GP
Cancer Center, University of Massachusetts Medical Center, Worcester 01605.
Reed
W C
WC
Deacon
D H
DH
Quesenberry
P J
PJ
D002147:Calmodulin / Q000502:physiology; D002148:Calmodulin-Binding Proteins / Q000302:isolation & purification / Q000502:physiology*; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D002850:Chromatography, Gel; D004247:DNA / Q000096:biosynthesis*; D004591:Electrophoresis, Polyacrylamide Gel; D006133:Growth Substances / Q000502:physiology; D006412:Hematopoietic Stem Cells / Q000378:metabolism*; D006801:Humans; D007377:Interleukin-3 / Q000502:physiology
D002147:Calmodulin; D002148:Calmodulin-Binding Proteins; D006133:Growth Substances; D007377:Interleukin-3; D004247:DNA