Department of Biomedical Engineering, Cornell University, Ithaca, NY 14853, USA.
Blood Cells Mol Dis. 2011 Mar 15;46(3):246-51. doi: 10.1016/j.bcmd.2010.12.010. Epub 2011 Feb 1.
L-selectin is a key molecule that participates in neutrophil tethering and subsequent rolling. It is cleaved from the surface of neutrophils activated in the presence of lipopolysaccharides, N-formyl-methionine-leucine-phenylalanine (fMLP), or Interleukin-8 (IL-8). We previously showed that L-selectin is also shed from the neutrophil surface during rolling on sialyl Lewis-x coated surfaces in a force-, ADAM-17 sheddase-, and p38 MAP kinase-dependent manner under flow. c-Abl tyrosine kinase is phosphorylated when L-selectin on the surface of neutrophils is cross-linked with anti-L-selectin antibodies. Here, we study the effect of c-Abl inhibition on L-selectin shedding from primary human neutrophils in static conditions following exposure to fMLP, IL-8, and hypotonic buffer and under flow through sialyl Lewis-x coated microtubes. Results indicate that c-Abl inhibition by STI571 significantly affects neutrophil adhesion via L-selectin, by decreasing the average rolling velocity and increasing the flux of rolling cells. The change in surface receptor expression was verified by flow cytometry. Interestingly, other forms of L-selectin shedding induced by fMLP, IL-8 or osmotic swelling were unaffected by STI571 treatment. These findings implicate the c-Abl signaling molecule in regulating L-selectin mechanical shedding in response to shear stress, setting this type of signaling apart from those triggered by the presence of a hypotonic environment, fMLP, or IL-8. This study sheds light on the role of c-Abl in neutrophil adhesion not previously reported in the literature.
L-选择素是一种参与中性粒细胞连接和随后滚动的关键分子。它在脂多糖、N-甲酰基-甲硫氨酸-亮氨酸-苯丙氨酸（fMLP）或白细胞介素-8（IL-8）存在的情况下从激活的中性粒细胞表面被切割。我们之前表明，L-选择素也在中性粒细胞在唾液酸化 Lewis-x 涂层表面上滚动时通过力、ADAM-17 脱落酶和 p38 MAP 激酶依赖的方式从中性粒细胞表面脱落，在流动条件下。当表面的 L-选择素与抗 L-选择素抗体交联时，c-Abl 酪氨酸激酶被磷酸化。在这里，我们研究了 c-Abl 抑制对 fMLP、IL-8 和低渗缓冲液暴露后以及通过唾液酸化 Lewis-x 涂层微管流动时原发性人中性粒细胞中 L-选择素脱落的影响。结果表明，STI571 通过 c-Abl 抑制通过 L-选择素显著影响中性粒细胞粘附，降低平均滚动速度并增加滚动细胞的通量。通过流式细胞术验证了表面受体表达的变化。有趣的是，fMLP、IL-8 或渗透肿胀诱导的其他形式的 L-选择素脱落不受 STI571 处理的影响。这些发现表明 c-Abl 信号分子在调节 L-选择素机械脱落以响应剪切应力方面起作用，这种类型的信号与低渗环境、fMLP 或 IL-8 存在触发的信号分开。这项研究揭示了 c-Abl 在中性粒细胞粘附中的作用，这在以前的文献中尚未报道。
