Biomaterial Database

Lipopolysaccharide modulates chemotactic peptide-induced actin polymerization in neutrophils. 1990

T H Howard, and D Wang, and R L Berkow

Department of Pediatrics, School of Medicine, University of Alabama, Birmingham.

To study the effect of endotoxin (LPS) on the basal and chemotactic peptide, formyl-methionyl-leucyl-phenylalanine (fMLP)-induced alterations in neutrophil cytoskeleton, we purified (greater than 98%) LPS-free neutrophils (LPS- less than 10 pg/ml LPS), compared their cytoskeletal organization to that of circulating neutrophils, and examined the effect of LPS exposure on the basal and fMLP-induced change in the cytoskeleton as reflected by F-actin content and distribution. Shape, F-actin content and distribution were monitored by FACS analysis and fluorescence microscopy of NBDphallicidin-stained cells. The F-actin content of basal and fMLP-activated, purified LPS- cells is similar to that of circulating neutrophils (defined as cells drawn in LPS- buffers at 37 degrees C and analyzed after less than 10 seconds of ex vivo manipulation). LPS- cells are round with a diffuse F-actin distribution. Exposure of LPS- cells to LPS causes cell polarization and F-actin redistribution without net gain in F-actin content. Peptide activation of the LPS- cell causes actin polymerization, which is preceded by a brief lag time. Exposure of LPS- cells to LPS (LPS+) enhances fMLP-induced actin polymerization by: 1) increasing the maximal extent of polymerization; 2) shortening the lag time preceding polymerization and increasing the rate of polymerization; and 3) lowering fMLP dose required for half maximal F-actin response. The enhancement depends on LPS dose, duration of exposure, and temperature. To examine the mechanism whereby LPS enhances fMLP-induced actin polymerization, we determined the predominant end for filament growth in LPS- and LPS+ cells, the number of actin nuclei generated in LPS- and LPS+ by fMLP activation, and the number and affinity of fMLP receptors on LPS- and LPS+ cells by 3[H]fMLP binding. Actin polymerization in both LPS- and LPS+ occurs predominantly by monomer addition to the barbed ends of nuclei, and the number of actin nuclei in basal and fMLP-activated LPS- and LPS+ cells is similar. LPS+ cells express three times more fMLP receptors than LPS- cells. The results show that LPS- cells are similar in cytoskeletal organization to circulating neutrophils, LPS causes shape change without change in F-actin content, and LPS enhances fMLP-induced actin polymerization response in neutrophils. The results suggest that LPS enhancement of actin polymerization response is associated with an increase in the number of fMLP receptors expressed on the cell surface.

UI	MeSH Term	Description	Entries
D008070	Lipopolysaccharides	Lipid-containing polysaccharides which are endotoxins and important group-specific antigens. They are often derived from the cell wall of gram-negative bacteria and induce immunoglobulin secretion. The lipopolysaccharide molecule consists of three parts: LIPID A, core polysaccharide, and O-specific chains (O ANTIGENS). When derived from Escherichia coli, lipopolysaccharides serve as polyclonal B-cell mitogens commonly used in laboratory immunology. (From Dorland, 28th ed)	Lipopolysaccharide,Lipoglycans
D009240	N-Formylmethionine Leucyl-Phenylalanine	A formylated tripeptide originally isolated from bacterial filtrates that is positively chemotactic to polymorphonuclear leucocytes, and causes them to release lysosomal enzymes and become metabolically activated.	F-Met-Leu-Phe,N-Formyl-Methionyl-Leucyl-Phenylalanine,Formylmet-Leu-Phe,Formylmethionyl Peptide,Formylmethionyl-Leucyl-Phenylalanine,Formylmethionylleucylphenylalanine,N-Formylated Peptide,N-formylmethionyl-leucyl-phenylalanine,fMet-Leu-Phe,F Met Leu Phe,Formylmet Leu Phe,Formylmethionyl Leucyl Phenylalanine,Leucyl-Phenylalanine, N-Formylmethionine,N Formyl Methionyl Leucyl Phenylalanine,N Formylated Peptide,N Formylmethionine Leucyl Phenylalanine,N formylmethionyl leucyl phenylalanine,Peptide, Formylmethionyl,Peptide, N-Formylated,fMet Leu Phe
D009504	Neutrophils	Granular leukocytes having a nucleus with three to five lobes connected by slender threads of chromatin, and cytoplasm containing fine inconspicuous granules and stainable by neutral dyes.	LE Cells,Leukocytes, Polymorphonuclear,Polymorphonuclear Leukocytes,Polymorphonuclear Neutrophils,Neutrophil Band Cells,Band Cell, Neutrophil,Cell, LE,LE Cell,Leukocyte, Polymorphonuclear,Neutrophil,Neutrophil Band Cell,Neutrophil, Polymorphonuclear,Polymorphonuclear Leukocyte,Polymorphonuclear Neutrophil
D011108	Polymers	Compounds formed by the joining of smaller, usually repeating, units linked by covalent bonds. These compounds often form large macromolecules (e.g., BIOPOLYMERS; PLASTICS).	Polymer
D011971	Receptors, Immunologic	Cell surface molecules on cells of the immune system that specifically bind surface molecules or messenger molecules and trigger changes in the behavior of cells. Although these receptors were first identified in the immune system, many have important functions elsewhere.	Immunologic Receptors,Immunologic Receptor,Immunological Receptors,Receptor, Immunologic,Receptors, Immunological
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000199	Actins	Filamentous proteins that are the main constituent of the thin filaments of muscle fibers. The filaments (known also as filamentous or F-actin) can be dissociated into their globular subunits; each subunit is composed of a single polypeptide 375 amino acids long. This is known as globular or G-actin. In conjunction with MYOSINS, actin is responsible for the contraction and relaxation of muscle.	F-Actin,G-Actin,Actin,Isoactin,N-Actin,alpha-Actin,alpha-Isoactin,beta-Actin,gamma-Actin,F Actin,G Actin,N Actin,alpha Actin,alpha Isoactin,beta Actin,gamma Actin
D044042	Receptors, Formyl Peptide	A family of G-protein-coupled receptors that was originally identified by its ability to bind N-formyl peptides such as N-FORMYLMETHIONINE LEUCYL-PHENYLALANINE. Since N-formyl peptides are found in MITOCHONDRIA and BACTERIA, this class of receptors is believed to play a role in mediating cellular responses to cellular damage and bacterial invasion. However, non-formylated peptide ligands have also been found for this receptor class.	Chemotactic Peptide Receptor,Chemoattractant Receptor,F-Chemotactic Peptide Receptor,FMLP Receptor,Formyl Peptide Receptor,N-Formylmethionyl Peptide Receptor,N-formyl Hexapeptide Receptor,Receptor, Chemotactic Peptide,fMet-Leu-Phe Receptor,F Chemotactic Peptide Receptor,Formyl Peptide Receptors,Hexapeptide Receptor, N-formyl,N Formylmethionyl Peptide Receptor,N formyl Hexapeptide Receptor,Peptide Receptor, Chemotactic,Peptide Receptor, N-Formylmethionyl,Peptide Receptors, Formyl,Receptor, Chemoattractant,Receptor, F-Chemotactic Peptide,Receptor, FMLP,Receptor, Formyl Peptide,Receptor, N-Formylmethionyl Peptide,Receptor, N-formyl Hexapeptide,Receptor, fMet-Leu-Phe,fMet Leu Phe Receptor
D066298	In Vitro Techniques	Methods to study reactions or processes taking place in an artificial environment outside the living organism.	In Vitro Test,In Vitro Testing,In Vitro Tests,In Vitro as Topic,In Vitro,In Vitro Technique,In Vitro Testings,Technique, In Vitro,Techniques, In Vitro,Test, In Vitro,Testing, In Vitro,Testings, In Vitro,Tests, In Vitro,Vitro Testing, In