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Wheat germ agglutinin (WGA) reduces ADH‐induced water flow and induces cell surface changes in epithelial cells of frog urinary bladder
Author(s) -
Favard Pierre,
Favard Nina,
Zhu Qian Long,
Bourguet Jacques,
Lechaire JeanPierre,
Maillard Maryvonne
Publication year - 1989
Publication title -
biology of the cell
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.543
H-Index - 85
eISSN - 1768-322X
pISSN - 0248-4900
DOI - 10.1111/j.1768-322x.1989.tb00852.x
Subject(s) - wheat germ agglutinin , cytoskeleton , biology , microbiology and biotechnology , agglutinin , apical membrane , cytoplasm , microfilament , biophysics , lectin , anatomy , membrane , biochemistry , cell
The functional and structural changes induced by apical wheat germ agglutinin (WGA) 100 μg/ml exposure on frog urinary bladder have been investigated and the possible correlation between these effects discussed. Bladders, apically exposed to WGA for 30 min to 3 hr exhibit a marked reduction of their response to antidiuretic hormone (ADH) challenge and of their hydrosmotic reactivity. Structural changes triggered by WGA trreatmentare: 1. apical invaginations of the plasma membrane, interpreted as endocytotic in nature, taking into account the results of carbohydrate cytochemical detection and horseradish peroxidase (HRP) exposure: 2. cytoskeleton disorganization and microvilli collapse. These phenomena do not interfere with cortical granule traffic and are independent of ADH challenge: they occur in ADH‐stimulated bladders as well as in bladders at rest. These findings could be interpreted as follows: binding of the divalent lectin WGA to its coat specific receptors would induce changes in the apical membrane structure which in turn could provoke disorganization and disruption of apical cytoskeletal elements associated with plasma membrane. Reduction of bladder response to ADH challenge could result from a reduced recyling of aggrephores, as they are associated with cytoskeletal elements in the subapical cytoplasm. Collapse of microvilli and endocytotic events also could result from apical cytoskeleton disruption, as microvilli are sustained by bundles of actin filaments interconnected with apical cytoskeleton filaments and as plasma membrane is associated with apical cytoskeleton. However, these two last events evidently occur in ADH‐challenged or non‐challenged bladders.