Receptors for maleylated proteins regulate secretion of neutral proteases by murine macrophages.
Receptors for maleylated or acetylated proteins as well as for alpha-2-macroglobulin-protease complexes on macrophages serve as scavengers by mediating the uptake of macromolecules from the extracellular compartment. Described in this report is a novel function of these receptors on macrophages: regulation of neutral protease secretion. The binding of maleylated bovine serum albumin to macrophages triggered secretion of three neutral proteases: neutral caseinases, plasminogen activator, and cytolytic proteinase. Release of acid phosphatase, however, was not induced. An important biological consequence of protease secretion by macrophages, tumor-cytolysis, was also triggered by engagement of the receptor for maleylated bovine serum albumin. By contrast, the binding of alpha-2-macroglobulin-protease complexes to the macrophages suppressed secretion of all three proteases. Thus two receptors heretofore believed to serve principally as scavengers also regulate secretory functions of macrophages.
Johnson, WJ; Pizzo, SV; Imber, MJ; Adams, DO
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