The reduced GM-CSF priming of ROS production in granulocytes from patients with myelodysplasia is associated with an impaired lipid raft formation.
Patients with myelodysplasia (MDS) show an impaired reactive oxygen species (ROS) production in response to fMLP stimulation of GM-CSF-primed neutrophils. In this study, we investigated the involvement of lipid rafts in this process and showed that treatment of neutrophils with the lipid raft-disrupting agent methyl-beta-cyclodextrin abrogates fMLP-induced ROS production and activation of ERK1/2 and protein kinase B/Akt, two signal transduction pathways involved in ROS production in unprimed and GM-CSF-primed neutrophils. We subsequently showed that there was a decreased presence of Lyn, gp91(phox), and p22(phox) in lipid raft fractions from neutrophils of MDS. Furthermore, the plasma membrane expression of the lipid raft marker GM1, which increases upon stimulation of GM-CSF-primed cells with fMLP, was reduced significantly in MDS patients. By electron microscopy, we showed that the fMLP-induced increase in GM1 expression in GM-CSF-primed cells was a result of de novo synthesis, which was less efficient in MDS neutrophils. Taken together, these data indicate an involvement of lipid rafts in activation of signal transduction pathways leading to ROS production and show that in MDS neutrophils, an impaired lipid raft formation in GM-CSF-primed cells results in an impaired ROS production.
Fuhler
Gwenny M
GM
Division of Hematology, Department of Medicine, University Medical Center Groningen, Hanzeplein 1, 9713 GZ Groningen, The Netherlands.
Blom
Nel R
NR
Coffer
Paul J
PJ
Drayer
A Lyndsay
AL
Vellenga
Edo
E
D005677:G(M1) Ganglioside / Q000096:biosynthesis; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000187:drug effects / Q000276:immunology*; D006098:Granulocytes / Q000187:drug effects / Q000276:immunology*; D006801:Humans; D021962:Membrane Microdomains / Q000378:metabolism*; D019950:Mitogen-Activated Protein Kinase 1 / Q000187:drug effects / Q000276:immunology; D048052:Mitogen-Activated Protein Kinase 3 / Q000187:drug effects / Q000276:immunology; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D009436:Neural Tube Defects / Q000276:immunology*; D009504:Neutrophils / Q000187:drug effects / Q000276:immunology; D051057:Proto-Oncogene Proteins c-akt / Q000187:drug effects / Q000276:immunology; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013329:Structure-Activity Relationship; D047392:beta-Cyclodextrins / Q000494:pharmacology
D017382:Reactive Oxygen Species; D047392:beta-Cyclodextrins; C108732:methyl-beta-cyclodextrin; D005677:G(M1) Ganglioside; D009240:N-Formylmethionine Leucyl-Phenylalanine; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D051057:Proto-Oncogene Proteins c-akt; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3