Colchicine down-regulates lipopolysaccharide-induced granulocyte-macrophage colony-stimulating factor production in murine macrophages.
Activation of macrophages by LPS and taxol results in production of IL-1, IL-6, TNF-alpha, and granulocyte-macrophage CSF (GM-CSF), which are involved in regulating hemopoiesis, inflammation, and immune responses. Microtubules are proposed as a target site for LPS interaction(s), based on similarities between the effects of the tubulin-binding drug taxol and LPS. To clarify the role of microtubules in LPS-induced GM-CSF expression in macrophages, we examined whether microtubule depolymerizing agents affect GM-CSF production in macrophages. Pretreatment with colchicine impaired LPS induction of GM-CSF in RAW 264 cells, and studies using stable transfectants revealed that colchicine impaired the transcriptional responsiveness of a reporter gene driven by a GM-CSF promoter sequence. Colchicine inhibition of the GM-CSF response correlated with decreases in the mRNA levels of beta-tubulin; maximal inhibition of both events was observed 4 h after addition of colchicine. Microtubule agents inhibited LPS induction of IL-6 and TNF-alpha, while the induction of both IL-1beta and inducible nitric oxide synthase was unaltered, suggesting that LPS activates microtubule-dependent and -independent pathways. Interestingly, LPS stimulation of macrophages down-regulated levels of beta-tubulin transcripts, implying that LPS interacts with an element(s) of the microtubule network in vivo, activating pathways regulating transcription of beta-tubulin. The ability of both colchicine and LPS to modulate transcription of beta-tubulin suggests that this event does not per se underlie the inhibitory effect of colchicine on LPS-induced GM-CSF expression. These data led us to conclude that colchicine inhibits LPS induction of GM-CSF by affecting microtubule-dependent costimulatory signaling pathways that synergize with primary LPS-triggered responses.
Rao
P
P
Division of Hematologic Products, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, MD 20892, USA.
Falk
L A
LA
Dougherty
S F
SF
Sawada
T
T
Pluznik
D H
DH
D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000187:drug effects / Q000378:metabolism; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D003078:Colchicine / Q000494:pharmacology*; D015536:Down-Regulation / Q000187:drug effects* / Q000276:immunology*; D005786:Gene Expression Regulation / Q000187:drug effects / Q000276:immunology; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000235:genetics; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008264:Macrophages / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D051379:Mice; D008870:Microtubules / Q000187:drug effects / Q000276:immunology; D016328:NF-kappa B / Q000187:drug effects / Q000378:metabolism; D017239:Paclitaxel / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D011401:Promoter Regions, Genetic / Q000187:drug effects / Q000276:immunology; D012333:RNA, Messenger / Q000096:biosynthesis / Q000187:drug effects / Q000276:immunology; D013997:Time Factors; D014158:Transcription, Genetic / Q000187:drug effects / Q000276:immunology; D014404:Tubulin / Q000187:drug effects / Q000235:genetics; D014443:Tyrosine / Q000378:metabolism
D008070:Lipopolysaccharides; D016328:NF-kappa B; D012333:RNA, Messenger; D014404:Tubulin; D014443:Tyrosine; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D017239:Paclitaxel; D003078:Colchicine