Differential behavior of sPLA₂-V and sPLA₂-X in human neutrophils

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• 作者：I. Solodkin-Szaingurten ; R. Levy ; N. Hadad
• 关键词：Neutrophils ; PLB-985 cells ; Granulocyte-like PLB cell ; Secreted PLA₂
• 刊名：Biochimica et Biophysica Acta (BBA)/Molecular and Cell Biology of Lipids
• 出版年：2007
• 期刊代码：18_13881981
• 类别：bio
• 出版时间：February 2007
• 卷：1771
• 期：2
• 页码：155-163
• 文件大小：662 K

摘要

Neutrophils and differentiated PLB-985 cells contain various types of PLA₂s including the 85 kDa cytosolic PLA₂ (cPLA₂), Ca²⁺-independent PLA₂ (iPLA₂) and secreted PLA₂s (sPLA₂s). The present study focuses on the behavior of sPLA₂s in neutrophils and PLB cells and their relationship to cPLA₂α. The results of the present research show that the two types of sPLA₂ present in neutrophils, sPLA₂-V and sPLA₂-X, which are located in the azurophil granules, are differentially affected by physiological stimuli. While sPLA₂-V is secreted to the extacellular milieu, sPLA₂-X is detected on the plasma membranes after stimulation. Stimulation of neutrophils with formyl-Met–Leu–Phe (fMLP), opsonized zymosan (OZ) or A23187 resulted in a different kinetics of sPLA₂ secretion as detected by its activity in the neutrophil supernatants. Neutrophil priming by inflammatory cytokines or LPS enhanced sPLA₂ activity detected in the supernatant after stimulation by fMLP. This increased activity was due to increased secretion of sPLA₂-V to the supernatant and not to release of sPLA₂-X. sPLA₂ in granulocyte-like PLB cells exhibit identical characteristics to neutrophil sPLA₂, with similar activity and optimal pH of 7.5. Granulocyte-like cPLA₂α-deficient PLB cells serve as a good model to study whether sPLA₂ activity is regulated by cPLA₂α. Secretion and activity of sPLA₂ were found to be similar in granulocyte-like PLB cells expressing or lacking cPLA₂α, indicating that they are not under cPLA₂α regulation.