J. Biol. Chem., Vol. 265, Issue 14, 7729-7732, May, 1990
Thrombin binds to murine bone marrow-derived macrophages and enhances colony-stimulating factor-1-driven mitogenesis
DR Clohisy, JM Erdmann and GD Wilner
Department of Pathology, Jewish Hospital, Washington University Medical Center, St. Louis, Missouri 63110.
The binding and mitogenic properties of thrombin have been established in
various transformed cell lines. In such systems, thrombin induces cell
division in the absence of exogenous growth factors, and the enzyme is
considered to act directly as a mitogen. This study explores thrombin's
interaction with nontransformed, growth factor-dependent cells. Binding of
125I-alpha-thrombin to colony-stimulating factor (CSF)-1-dependent bone
marrow-derived macrophages is saturable, time- dependent, and displaceable
by both unlabeled alpha-thrombin, and esterolytically inactive thrombin.
Both dissociation studies of pre- bound radio-labeled thrombin and
Scatchard analysis assisted by the program "Ligand" suggest adherence of
thrombin-binding data to a multi- site model. There are an estimated 2 x
10(4) high affinity sites (Kd = 7 x 10(-9)M) and 2 x 10(6) low affinity
sites (Kd = 9 x 10(-7)M) per cell. Quiescent bone marrow-derived
macrophages were cultured with either 10(-8)M thrombin, 1000 units of
CSF-1/ml, or both and [3H]thymidine incorporation was determined. Thrombin
alone did not induce mitogenesis. CSF-1 induced mitogenesis with peak [3H]
thymidine incorporation occurring 24 h after addition of the mitogen. This
CSF-1- dependent mitogenic influence was enhanced greater than 2-fold by
treatment with thrombin.