Premium
α 2 ‐macroglobulin stimulation of protein tyrosine phosphorylation in macrophages via the mannose receptor for Fcγ receptor‐mediated phagocytosis activation
Author(s) -
MURAI M.,
ARAMAKI Y.,
TSUCHIYA S.
Publication year - 1996
Publication title -
immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.297
H-Index - 133
eISSN - 1365-2567
pISSN - 0019-2805
DOI - 10.1046/j.1365-2567.1996.d01-765.x
Subject(s) - mannose , tyrosine phosphorylation , mannose receptor , receptor , biochemistry , phosphorylation , tyrosine , tyrosine kinase , biology , receptor tyrosine kinase , microbiology and biotechnology , macrophage , in vitro
Macrophage phagocytic activity has previously been shown to be increased by binding of modified α 2 ‐macroglobulin (α 2 M) with mannose residues at termini of sugar chains to mannose receptors on macrophages, with a subsequent increase in the number of Fcγ receptors at the cell surface. In the present study, an examination was made of the association of protein tyrosine kinase with the increase in number of Fcγ receptors following binding of modified α 2 M to mannose receptors. The phagocytosis of IgG‐opsonized sheep red blood cells through the action of the Fcγ receptor by modified α 2 M was inhibited by mannose and herbimycin A and slightly so by genistein. The mannose receptor would thus appear to be associated with tyrosine kinase activity. By Western blotting, tyrosine phosphorylated proteins with molecular weights of 32 000, 34 000, 36 000, 65 000, 85 000 and 110 000 appeared or increased upon treating macrophages with modified α 2 M. The degree of tyrosine phosphorylated proteins was the same for control macrophages following incubation in the presence of mannose and herbimycin A. Genistein treatment affected only tyrosine phosphorylated proteins of 65 000 and 110 000. The binding of modified α 2 M to mannose receptors was demonstrated by the inducement of tyrosine kinase activation that was sensitive to herbimycin A, followed by an increase in Fcγ receptors and consequently greater phagocytosis.