IL-3 increases surface proteoglycan synthesis in haemopoietic progenitors and their adhesiveness to the heparin-binding domain of fibronectin.
Haemopoietic progenitor cells (HPC) synthesize and accumulate a single type of membrane-associated chondroitin sulphate proteoglycan (MA-PG), which participates in HPC adhesiveness to fibronectin by interacting with its heparin-binding domain. Shortly after incubating cells with IL-3, we observed an increase in MA-PG synthesis in the multipotent (FDCP-mix) but not in the bipotent (FDCP-1) progenitor cell line. The charge density, hydrodynamic size, nature of the glycosaminoglycan (GAG) chains and stability of MA-PG from IL-3-treated and non-treated FDCP-mix cells were the same, suggesting that IL-3 affects the amount of MA-PG. The latter was evaluated by flow cytometry using monoclonal antibodies to the core protein and GAG residues. In all cases the mean fluorescence intensities were higher for IL-3-treated than for untreated cells. Cell adhesion studies to dishes coated with the fibronectin 40 kD fragment, containing the heparin-binding domain, demonstrated that adhesiveness of IL-3-treated cells was higher than that of untreated cells. These results suggest that in multipotent haemopoietic cells IL-3 regulates the amount of membrane-associated proteoglycans, which in turn modify the adhesive interactions of cells with the heparin-binding domain of fibronectin.
Conget
P
P
Unidad de Biología Celular, INTA, Universidad de Chile, Santiago.
Minguell
J J
JJ
D000818:Animals; D002448:Cell Adhesion / Q000502:physiology; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D011508:Chondroitin Sulfate Proteoglycans / Q000096:biosynthesis*; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D017077:Culture Media, Conditioned / Q000494:pharmacology; D005353:Fibronectins / Q000378:metabolism*; D006412:Hematopoietic Stem Cells / Q000378:metabolism / Q000502:physiology*; D006493:Heparin / Q000378:metabolism*; D007377:Interleukin-3 / Q000494:pharmacology / Q000502:physiology*; D051379:Mice; D011994:Recombinant Proteins / Q000494:pharmacology
D011508:Chondroitin Sulfate Proteoglycans; D017077:Culture Media, Conditioned; D005353:Fibronectins; D007377:Interleukin-3; D011994:Recombinant Proteins; D006493:Heparin