title: The role of increased calcium influx rate in receptor mediated function of differentiating HL-60 cells.
abstract: In this study we have investigated the link between increased Ca2+ influx rate, acquired upon the differentiation of HL-60 cells, to changes in cytosolic free Ca2+ ([Ca2+]i], evoked by the chemotactic peptide-FMLP and the mitogen Con-A. Although differentiating and undifferentiated HL-60 cells exhibited similar steady-state levels of [Ca2+]i, cells induced to differentiate by dibutyryl-cAMP, at 48 h, exhibited enhanced Ca2+ influx rate, measured by non-steady state 45Ca2+ uptake, and augmentation of FMLP-stimulated Ca2+ influx. At 120 h the above cells responded to FMLP but not to Con-A, by a marked augmentation of Ca2+ influx, and elevated levels of [Ca2+]i. On the other hand HL-60 cells induced to differentiate by retinoic acid responded, as described above, to Con-A but not to FMLP. HL-60 cells grown in the presence of cholera-toxin, were reported to express high levels of FMLP-receptors without expressing cell differentiation. We have demonstrated that, in these cells the Ca2+ influx rate was unchanged, moreover, FMLP-stimulated Ca2+ influx and [Ca2+]i rise were low. These findings strongly suggest that the presence of receptor is not sufficient for FMLP-mediated changes in [Ca2+]i. A link between increased Ca2+ influx rate, acquired upon induction of differentiation, and receptor mediated response in these cells is proposed.
authors.affiliation: Hematology Division, Beilinson Medical Center, Petach-Tikva, Israel.
authors.forename: A
authors.initials: A
authors.lastname: Aviram
authors.forename: A
authors.initials: A
authors.lastname: Rephaeli
authors.forename: M
authors.initials: M
authors.lastname: Shaklai
mesh_terms: D003994:Bucladesine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002454:Cell Differentiation; D002772:Cholera Toxin / Q000494:pharmacology; D003208:Concanavalin A / Q000494:pharmacology*; D006801:Humans; D007700:Kinetics; D015473:Leukemia, Promyelocytic, Acute / Q000378:metabolism* / Q000473:pathology; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology*; D044042:Receptors, Formyl Peptide; D011971:Receptors, Immunologic / Q000378:metabolism*; D014212:Tretinoin / Q000494:pharmacology; D014407:Tumor Cells, Cultured
chemical_list: D044042:Receptors, Formyl Peptide; D011971:Receptors, Immunologic; D003208:Concanavalin A; D014212:Tretinoin; D009240:N-Formylmethionine Leucyl-Phenylalanine; D003994:Bucladesine; D002772:Cholera Toxin; D002118:Calcium