Mócsai A, Jakus Z, Vántus T, Berton G, Lowell C A, Ligeti E
Department of Physiology, Semmelweis University of Medicine, Budapest, Hungary.
J Immunol. 2000 Apr 15;164(8):4321-31. doi: 10.4049/jimmunol.164.8.4321.
The aim of the present study was to investigate the role of tyrosine phosphorylation pathways in fMLP-induced exocytosis of the different secretory compartments (primary and secondary granules, as well as secretory vesicles) of neutrophils. Genistein, a broad specificity tyrosine kinase inhibitor, blocked the exocytosis of primary and secondary granules, but had only a marginal effect on the release of secretory vesicles. Genistein also inhibited the phosphorylation of extracellular signal-regulated kinase (ERK) and p38 mitogen-activated protein kinases (MAPK), raising the possibility that inhibition of ERK and/or p38 MAPK might be responsible for the effect of the drug on the degranulation response. Indeed, SB203580, an inhibitor of p38 MAPK, decreased the release of primary and secondary granules, but not that of secretory vesicles. However, blocking the ERK pathway with PD98059 had no effect on any of the exocytic responses tested. PP1, an inhibitor of Src family kinases, also attenuated the release of primary and secondary granules, and neutrophils from mice deficient in the Src family kinases Hck, Fgr, and Lyn were also defective in secondary granule release. Furthermore, activation of p38 MAPK was blocked by both PP1 and the hck-/-fgr-/-lyn-/- mutation. Taken together, our data indicate that fMLP-induced degranulation of primary and secondary granules of neutrophils is mediated by p38 MAPK activated via Src family tyrosine kinases. Although piceatannol, a reportedly selective inhibitor of Syk, also prevented degranulation and activation of p38 MAPK, no fMLP-induced phosphorylation of Syk could be observed, raising doubts about the specificity of the inhibitor.
本研究的目的是探讨酪氨酸磷酸化途径在甲酰甲硫氨酸-亮氨酸-苯丙氨酸（fMLP）诱导的中性粒细胞不同分泌小室（初级和次级颗粒以及分泌囊泡）胞吐作用中的作用。染料木黄酮是一种具有广泛特异性的酪氨酸激酶抑制剂，它可阻断初级和次级颗粒的胞吐作用，但对分泌囊泡的释放仅有轻微影响。染料木黄酮还抑制细胞外信号调节激酶（ERK）和p38丝裂原活化蛋白激酶（MAPK）的磷酸化，这增加了ERK和/或p38 MAPK的抑制可能是该药物对脱颗粒反应产生作用的原因的可能性。事实上，p38 MAPK抑制剂SB203580可减少初级和次级颗粒的释放，但不影响分泌囊泡的释放。然而，用PD98059阻断ERK途径对所测试的任何胞吐反应均无影响。PP1是Src家族激酶的抑制剂，它也减弱了初级和次级颗粒的释放，并且来自缺乏Src家族激酶Hck、Fgr和Lyn的小鼠的中性粒细胞在次级颗粒释放方面也存在缺陷。此外，PP1和hck-/-fgr-/-lyn-/-突变均阻断了p38 MAPK的激活。综上所述，我们的数据表明，fMLP诱导的中性粒细胞初级和次级颗粒的脱颗粒作用是由经由Src家族酪氨酸激酶激活的p38 MAPK介导的。尽管据报道，白藜芦醇是一种选择性的Syk抑制剂，它也可阻止脱颗粒作用和p38 MAPK的激活，但未观察到fMLP诱导的Syk磷酸化，这引发了对该抑制剂特异性的质疑。
