Cellular cholesterol involvement in Src, PKC, and p38/JNK transduction pathways by porins.
Biological membranes are described as a mosaic of different domains where interactions between membrane components induce the formation of subdomains with different characteristics and functions. Lipids play an important role in the formation of lipid-enriched microdomains where they dynamically associate to form platforms important for membrane protein sorting and construction of signaling complexes. Cholesterol confined in lipid domains is a crucial component required by microorganisms, directly or indirectly, to enter or exit the intracellular compartment. Cellular activation mediated by superficial bacterial component may be modified by local cholesterol depletion. Therefore, new perspectives for unconventional therapeutic intervention in Gram-negative infections may be envisaged. We tested this hypothesis by using methyl-beta-cyclodextrin (mbetaCD) as a cholesterol-complexing agent to alter the U937 plasma membrane cholesterol content. Our results demonstrate that cholesterol depletion of U937 cells inhibited Salmonella enterica serovar Typhimurium porins-mediated phosphorylation of Src kinase family, protein kinase C (PKC), JNK, and p38, while cholesterol repletion restored the phosphorylation. Lipopolysaccharide (LPS) extracted from the same bacterial strain has been used as a control. Our data demonstrate that the lack of activation of signal transduction pathway observed following cholesterol depletion differently modulates the release of interleukin-6 (IL-6) or tumor necrosis factor-alpha (TNF-alpha), suggesting that Src, associated to lipid domains, may represent an important pathway in Gram-negative-induced cellular signal.
Vitiello
Mariateresa
M
Department of Experimental Medicine, Section of Microbiology and Clinical Microbiology, Second University of Naples, Naples 80138, Italy.
Finamore
Emiliana
E
Raieta
Katia
K
Kampanaraki
Aikaterini
A
Mignogna
Eleonora
E
Galdiero
Emilia
E
Galdiero
Marilena
M
D002784:Cholesterol / Q000172:deficiency / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D015850:Interleukin-6 / Q000378:metabolism; D048031:JNK Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology; D010766:Phosphorylation; D018272:Porins / Q000378:metabolism*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D012485:Salmonella typhi / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000276:immunology; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors / Q000378:metabolism; D020298:U937 Cells; D047392:beta-Cyclodextrins / Q000494:pharmacology; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D019061:src-Family Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000093242:Interleukin-6 Inhibitors
D002784:Cholesterol; D004791:Enzyme Inhibitors; D015850:Interleukin-6; D048031:JNK Mitogen-Activated Protein Kinases; D007770:L-Lactate Dehydrogenase; D008070:Lipopolysaccharides; D018272:Porins; D011493:Protein Kinase C; D014409:Tumor Necrosis Factor-alpha; D047392:beta-Cyclodextrins; D048051:p38 Mitogen-Activated Protein Kinases; D019061:src-Family Kinases; D000093242:Interleukin-6 Inhibitors; C508600:IL6 protein, human; C108732:methyl-beta-cyclodextrin