1. Diphosphoryl lipid A from Rhodobacter sphaeroides blocks the binding and internalization of lipopolysaccharide in RAW 264.7 cells.
- Author
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Kutuzova GD, Albrecht RM, Erickson CM, and Qureshi N
- Subjects
- Animals, Binding Sites, Cell Line drug effects, Cell Line metabolism, Cell Line ultrastructure, Escherichia coli chemistry, Escherichia coli drug effects, Escherichia coli physiology, Gold Colloid metabolism, Lipid A analogs & derivatives, Lipid A metabolism, Lipid A pharmacology, Lipopolysaccharides toxicity, Lipopolysaccharides ultrastructure, Macrophages drug effects, Macrophages metabolism, Macrophages ultrastructure, Mice, Lipid A physiology, Lipopolysaccharides antagonists & inhibitors, Lipopolysaccharides metabolism, Rhodobacter sphaeroides physiology
- Abstract
Diphosphoryl lipid A derived from the nontoxic LPS of Rhodobacter sphaeroides (RsDPLA) has been shown to be a powerful LPS antagonist in both human and murine cell lines. In addition, RsDPLA also can protect mice against the lethal effects of toxic LPS. In this study, we complexed both the deep rough LPS from Escherichia coli D31 m4 (ReLPS) and RsDPLA with 5- and 30-nm colloidal gold and compared their binding to the RAW 264.7 cell line by electron microscopy. Both ReLPS and RsDPLA bound to the cells with the following observations. First, binding studies revealed that pretreatment with RsDPLA completely blocked the binding and thus internalization of ReLPS-gold conjugates to these cells at both 37 degrees C and 4 degrees C. Second, ReLPS was internalized via micropinocytosis (noncoated plasma membrane invaginations) involving formation of caveolae-like structures and leading to the formation of micropinocytotic vesicles, macropinocytosis (or phagocytosis), formation of clathrin-coated pits (receptor mediated), and penetration through plasma membrane into cytoplasm. Third, in contrast, RsDPLA was internalized predominantly via macropinocytosis. These studies show for the first time that RsDPLA blocks the binding and thus internalization of LPS as observed by scanning and transmission electron microscopy.
- Published
- 2001
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