Effect of plant lectins on low density lipoprotein metabolism in adipocytes

The effect of plant lectins on low density lipoprotein metabolism was studied in isolated human adipocytes. Concanavalin A (0.1 mg X mL-1) resulted in 3-5 fold increase in [125I]-low density lipoprotein uptake in isolated human adipocytes but [125I]-low density lipoprotein degradation was not significantly affected. Adipocytes pre-incubated with alpha-methyl-D-mannopyranoside showed normal amount of [125I]-low density lipoprotein uptake. Wheat germ agglutinin and ricin both showed significant increase in [125]I-low density lipoprotein uptake in adipocytes. The effects of wheat germ agglutinin and ricin are likely mediated through their specific interactions with plasma membrane glycoprotein since the respective free saccharides can abolish the increased uptake. Lectin from Lotus tetragonolobus (10-30 micrograms . mL-1) resulted in reduction of [125I]-low density lipoprotein uptake but enhanced its uptake at 80 micrograms . mL-1. The effect of Lotus tetragonolobus lectin seems to be unrelated to interaction with L-fucosyl residue on the adipocyte membrane.