Role of adhesion in arthropod immune recognition

Abstract

The recognition and inactivation of toxins and pathogens are mediated by a combination of cell-free and cellular mechanisms. A number of soluble and membrane-bound pattern recognition molecules interact with elicitors to become involved in both cell-free inactivation as well as cellular uptake reactions. Here we describe the possible recognition and effector function of key arthropod immune proteins, such as peroxinectin, hemolin, and hemomucin, as an outcome of changes in adhesiveness, which drive self-assembly reactions leading to cell-free coagulation and cellular uptake reactions. The fact that some of these proteins are essential for immune and developmental functions in some species, but are not found in closely related species, may point to the existence of multiprotein assemblies, which are conserved at the mechanistic level and can function with more than one combination of protein constituents. Acronyms and Definitions CP: clotting protein Elicitor: a substance that induces the defense response in an organism GPI: glycosylphosphatidylinositol LPS: lipopolysaccharide Macropinocytosis: a cellular uptake reaction of extracellular fluids, creating large translucent vacuoles Opsonin: a surface coating of objects that interact with cell surface proteins to mediate a response Pattern recognition: identification process based on the evolution of unique recognition proteins that identify typical structures that may potentially damage the organism Procoagulant: a plasma or membrane component involved in coagulation reactions by the activation of regulatory cascades proPO: prophenoloxidase PRP: pattern recognition protein SOD: superoxide dismutase Velcro-like mechanism: cellular uptake reaction in which the membrane is wrapped around objects by adhesive forces; also called zipper mechanism