Effects of Colchicine, Cytochalasin B, and 2-Deoxyglucose on the Topographical Organization of Surface-Bound Concanavalin a in Normal and Transformed Fibroblasts

Abstract

The distribution of surface-bound concanavalin A on the membranes of 3T3, and simian virus 40-transformed 3T3 cultured mouse fibroblasts was examined using a shadow-cast replica technique with a hemocyanin marker. When cells were prefixed in paraformaldehyde, the binding site distribution was always random on both cell types. On the other hand, labeling of transformed cells with concanavalin A (Con A) and hemocyanin at 37°C resulted in the organization of Con A binding sites (CABS) into clusters (primary organization) which were not present on the pseudopodia and other peripheral areas of the membrane (secondary organization). Treatment of transformed cells with colchicine, cytochalasin B, or 2-deoxyglucose did not alter the inherent random distribution of binding sites as determined by fixation before labeling. However, these drugs produced marked changes in the secondary (but not the primary) organization of CABS on transformed cells labeled at 37°C. Colchicine treatment resulted in the formation of a caplike aggregation of binding site clusters near the center of the cell, whereas cytochalasin B and 2-deoxyglucose led to the formation of patches of CABS over the entire membrane, eliminating the inward displacement of patches observed on untreated cells. The distribution of bound Con A on normal cells (3T3) at 37°C was always random, in both control and drug-treated preparations. Pretreatment of cells with Con A enhanced the effect of colchicine on cell morphology, but inhibited the morphological effects of cytochalasin B. The mechanisms that determine receptor movement and disposition are discussed.

Dislocation of Sialic Acid on Erythrocytes Membrane by nesthetics and its Blocking by SH-reagents, Colchicine r Cytochalasin B

“…That there was no effects caused by pretreatment with both cytochalasin B and colchicine is an apparent but reproducible paradox. Impairment of membrane peripheral proteins sensitive to colchicine and cytochalasin B by local anesthetics has been suggested (16), and the mechanism of the regulation of the lection receptor mobility by Ca2+ and peripheral proteins with different roles has been envisaged (5,17,26). The results of our experiment suggest that not only the lateral movement of lection receptros but also the conformation of sialoproteins are regulated by colchicine and cytochalasin-sensitive proteins, and are changed by anesthetics.…”

Effects of antitubulins on the redistribution of crosslinked receptors on the surface of fibroblasts and epithelial cells

“…Certain alterations described in the previous papers may be similar to those seen in our experiments. In particular, this may be true for the clearing of the whole cell perimeter of the colchicine-treated simian virus 40-transformed 3T3 cells observed after incubation with Con A by Ukena et al (18). However, the results in most published papers show that alterations of surface components produced by antitubulins were not correlated with the alterations of the sites of pseudopodial activity.…”

Factors Affecting the Redistribution of Surface-Bound Concanavalin a on Human Polymorphonuclear Leukocytes

“…This contrasts with recent work by Ukena et al . (29) in which, using the surface replica technique, it was shown that colchicine enhances capping of Con A on simian virus 40-transformed 3T3 cultured mouse fibroblasts .…”