The down-regulation of the mitogenic fibrinogen receptor (MFR) in serum-containing medium does not occur in defined medium.
Normal human hemopoietic cells such as early bone marrow progenitors, or lymphoma-derived cell lines such as Raji or JM cells, possess a low-affinity receptor specific for fibrinogen. This receptor triggers a mitogenic effect. It differs from the glycoprotein IIb-IIIa which is involved in fibrinogen-induced platelet aggregation. We demonstrate here that this mitogenic fibrinogen receptor (MFR) can be internalized or reexpressed, depending on culture conditions. Internalization was temperature-dependent. At 37 degrees C in the presence of cycloheximide or actinomycin D, the half-life of cell surface MFRs was 2 h, independent of receptor occupancy. Binding of fibrinogen to the MFR resulted in a down-regulation which was fibrinogen dose-dependent. This occurred in serum-supplemented medium but not in defined medium supplemented with fatty acids. Reexpression of MFRs could be induced in 28 to 42 h by serum removal. The down-regulation of mitogenic receptors in plasma or serum could explain why normal cells do not proliferate in the peripheral blood.
Levesque
J P
JP
Laboratoire de Biologie Cellulaire et Moléculaire des Facteurs de Croissance, C.N.R.S., Hôpital Paul Brousse, Villejuif, France.
Hatzfeld
A
A
Domart
I
I
Hatzfeld
J
J
D001769:Blood; D002455:Cell Division; D002478:Cells, Cultured; D003470:Culture Media; D003513:Cycloheximide / Q000494:pharmacology; D003609:Dactinomycin / Q000494:pharmacology; D015536:Down-Regulation; D005340:Fibrinogen / Q000378:metabolism / Q000494:pharmacology*; D006207:Half-Life; D006412:Hematopoietic Stem Cells / Q000378:metabolism; D006801:Humans; D007163:Immunosorbent Techniques; D007700:Kinetics; D008223:Lymphoma / Q000378:metabolism; D010980:Platelet Membrane Glycoproteins / Q000378:metabolism*; D014407:Tumor Cells, Cultured
D003470:Culture Media; D010980:Platelet Membrane Glycoproteins; D003609:Dactinomycin; D005340:Fibrinogen; D003513:Cycloheximide