Alexander S R, Kishimoto T K, Walcheck B
Center for Immunology, University of Minnesota, St. Paul 55108, USA.
J Leukoc Biol. 2000 Mar;67(3):415-22. doi: 10.1002/jlb.67.3.415.
The signaling factors that direct the rapid shedding of L-selectin from neutrophils upon chemoattractant stimulation are poorly understood. Protein kinase C (PKC) has been implicated, yet previous studies have relied on the use of phorbol esters and nonselective kinase inhibitors. We treated neutrophils with various selective kinase inhibitors to evaluate their effects on N-formyl-methionyl-leucyl-phenylalanine (fMLP)-induced L-selectin shedding. We found that three selective inhibitors of PKC, structurally related to staurosporine, largely blocked both fMLP- and phorbol 12-myristate 13-acetate (PMA)-induced L-selectin shedding; however, these inhibitors did not affect fMLP-induced up-regulation of Mac-1 (CD11b/CD18) expression, which has been shown not to involve PKC. Other selective serine, threonine, and tyrosine kinase inhibitors were found not to block fMLP-induced L-selectin shedding. These findings provide more definitive evidence for the role of PKC in chemoattractant-induced L-selectin proteolysis. It is interesting that certain highly selective PKC inhibitors, not structurally related to staurosporine, were found to directly induce L-selectin shedding from neutrophils.
趋化因子刺激中性粒细胞后，促使L-选择素迅速脱落的信号因子目前仍知之甚少。蛋白激酶C（PKC）被认为与之有关，但以往的研究依赖于佛波酯和非选择性激酶抑制剂的使用。我们用各种选择性激酶抑制剂处理中性粒细胞，以评估它们对N-甲酰甲硫氨酰-亮氨酰-苯丙氨酸（fMLP）诱导的L-选择素脱落的影响。我们发现，三种与星形孢菌素结构相关的PKC选择性抑制剂，在很大程度上阻断了fMLP和佛波醇12-肉豆蔻酸酯13-乙酸酯（PMA）诱导的L-选择素脱落；然而，这些抑制剂并未影响fMLP诱导的Mac-1（CD11b/CD18）表达上调，而这一过程已证明不涉及PKC。其他选择性丝氨酸、苏氨酸和酪氨酸激酶抑制剂未发现能阻断fMLP诱导的L-选择素脱落。这些发现为PKC在趋化因子诱导的L-选择素蛋白水解中的作用提供了更确凿的证据。有趣的是，某些与星形孢菌素结构无关的高度选择性PKC抑制剂，被发现可直接诱导中性粒细胞的L-选择素脱落。
