Two-Dimensional Kinetics Of Beta(2)-Integrin And Icam-1 Bindings Between Neutrophils And Melanoma Cells In A Shear Flow

Cell adhesion, mediated by specific receptor-ligand interactions, plays an important role in biological processes such as tumor metastasis and inflammatory cascade. For example, interactions between beta(2)-integrin ( lymphocyte function-associated antigen-1 and/or Mac-1) on polymorphonuclear neutrophils (PMNs) and ICAM-1 on melanoma cells initiate the bindings of melanoma cells to PMNs within the tumor microenvironment in blood flow, which in turn activate PMN-melanoma cell aggregation in a near-wall region of the vascular endothelium, therefore enhancing subsequent extravasation of melanoma cells in the microcirculations. Kinetics of integrin-ligand bindings in a shear flow is the determinant of such a process, which has not been well understood. In the present study, interactions of PMNs with WM9 melanoma cells were investigated to quantify the kinetics of beta(2)-integrin and ICAM-1 bindings using a cone-plate viscometer that generates a linear shear flow combined with a two-color flow cytometry technique. Aggregation fractions exhibited a transition phase where it first increased before 60 s and then decreased with shear durations. Melanoma-PMN aggregation was also found to be inversely correlated with the shear rate. A previously developed probabilistic model was modified to predict the time dependence of aggregation fractions at different shear rates and medium viscosities. Kinetic parameters of beta(2)-integrin and ICAM-1 bindings were obtained by individual or global fittings, which were comparable to respectively published values. These findings provide new quantitative understanding of the biophysical basis of leukocyte-tumor cell interactions mediated by specific receptor-ligand interactions under shear flow conditions.

β_2整合素-ICAM-1相互作用的动力学测试

<正>β_2-整合素α_Lβ_2(LFA-1)和α_Mβ_2(MAC-1)是白细胞表面的一类重要粘附分子,与其配体ICAM-1的相互作用在炎症反应和肿瘤转移过程中起着重要作用。在炎症反应发生时,β_2-整合素和ICAM-1的相互作用介导了白细胞与内皮细胞的稳态粘附,是选择素介导滚动粘附的后续反应,使白细胞渗出血管到达炎症部位。在肿瘤转移过程中,白细胞表面的β_2-整合素分别与黑色素瘤细胞及内皮细胞上的ICAM-1作用,使黑色素瘤细胞外渗进入组织,形成继发肿瘤。

不同长度β_2整合素_M亚基与ICAM-1的亲和性比较

国家自然科学基金项目(30730032/10702075)

整合素-ICAM-1相互作用的二维反应动力学研究

国家自然科学基金项目(30730032)

Interaction between single molecules of Mac-1 and ICAM-1 in living cells: An atomic force microscopy study

The interaction between integrin macrophage differentiation antigen associated with complement three receptor function (Mac-1) and intercellular adhesion molecule-1 (ICAM-1), which is controlled tightly by the ligand-binding activity of Mac-1, is central to the regulation of neutrophil adhesion in host defense. Several "inside-out" signals and extracellular metal ions or antibodies have been found to activate Mac-1, resulting in an increased adhesiveness of Mac-1 to its ligands. However, the molecular basis for Mac-1 activation is not well understood yet. In this work, we have carried out a single-molecule study of Mac-1/ICAM-1 interaction force in living cells by atomic force microscopy (AFM). Our results showed that the binding probability and adhesion force of Mac-1 with ICAM-1 increased upon Mac-1 activation. Moreover, by comparing the dynamic force spectra of different Mac-1 mutants, we expected that Mac-1 activation is governed by the downward movement of its alpha 7 helix. (c) 2007 Elsevier Inc. All rights reserved.

不同长度β_2整合素_M亚基与ICAM-1的亲和性比较

<正>整合素作为细胞表面糖蛋白受体,介导细胞-细胞、细胞-胞外基质以及细胞-病原体间粘附和信息传递,在免疫应答、凝血反应、炎症反应、肿瘤转移和创伤愈合等许多病理生理过程中起重要作用。整合素是由α、β两个亚基非共价结合而成的异源二聚体,其结构类似于两条近平行的腿部支撑着一个球形的头部。研究表明,β_2整合素_M亚基头部的.domain为与配体直接作用的结构域,并可通过"open"或"close"的构象变化

整合素-ICAM-1相互作用的二维反应动力学研究

<正>_2整合素(LFA-1和Mac-1)与其配体细胞间粘附分子-1(ICAM-1)的相互作用在诸如肿瘤转移、炎症反应等许多病理生理过程中起着重要的作用。研究表明,中性粒细胞(PMN)在特定环境下可通过_2整合素与ICAM-1的相互作用而增强黑色素瘤细胞的转移能力,但是其动力学调控机制还不清楚。受体-配体键结合和解离的二维反应动力学定量描述了分子结合的快慢和强弱,是回答_2整合素与ICAM-1相互作用如何调

β_2整合素-ICAM-1配体相互作用的生物力学与生物物理

<正>细胞粘附在诸如炎症反应、肿瘤转移、血栓形成等病理生理过程中起着至关重要的作用。在血流作用下,表达于细胞表面的特异性粘附分子(如整合素、ICAM-1配体)间如何介导细胞粘附、怎样定量描述受体-配体相互作用及其反应动力学、外力如何调控受体-配体键强度和寿命、分子键结合与解离的结构基础是什么等,均是亟待认识的基本科学问题。

突然扩张流槽中血管内皮细胞表面粘附蛋白表达的研究

动脉粥样硬化的非随机分布与当地的血流动力环境有关，为了研究复杂的流体动力学条件对血和皮细胞生理功能的影响，构建了平行板式平直流槽和突然扩张流槽，通过数值模拟分析了流型的特征，并探讨流型改变对人脐静脉血管内皮细胞表面粘附蛋白表达的影响，发现突然扩张流槽中流动的空间变化使得总体细胞表面粘附蛋白ICAM-1的表达显著高于平直流槽中的均匀定常剪切作用，表明局部流动空间变化的性质可以影响血管内皮细胞的功能。

Migration of mouse antibody-secreting hybridoma cells from blood to genital tract and its regulation by sex hormones are associated with the differential expression patterns of adhesion molecules and chemokines in the tract rather than in the antibody-secreting cells

To understand better the molecular mechanisms of differential migration of antibody-secreting cells (ASCs) into mouse genital tracts, and regulation by sex hormones, surface markers, hormone receptors and adhesion molecules in mouse SG2 and PA4 hybridoma cells, respectively, secreting IgG2b and polymeric IgA antibody were detected by flow cytometry or RT-PCR. Semiquantitative RT-PCR was also used for measuring mRNA expression of adhesion molecules and chemokines (VCAM-1, ICAM-1, P-selectin, JAM-1 and CXCL12) in genital tracts of various adult mouse groups. The mRNAs of androgen receptor, estrogen receptor beta and CXCR4 were expressed in the ASCs. Sex hormones had no effect on expression of these molecules in ASCs. Except for VCAM-1, mRNA of all examined genes was expressed in normal mouse genital tracts. The mean of relative amounts of ICAM-1 and CXCL12 mRNA in all examined organs of females were higher (2.1- and 1.9-fold) than those in males. After orchiectomy or ovariectomy, the expression of ICAM-1, CXCL12 and P-selectin mRNA in the examined organs increased, except JAM-1 in male and CXCL12 in female. Sex hormone treatment recovered the changes to normal levels of mRNA expression in many examined genital tissues. In combination with our previous work, preferential migration of ASCs into female genital tract and regulation of migration by sex hormones are associated with expression patterns of adhesion molecules and chemokines in genital tract rather than in ASCs. (C) 2006 Elsevier Ireland Ltd. All rights reserved.

Staphylococcus aureus lipoproteins trigger human corneal epithelial innate response through toll-like receptor-2

Bacterial lipoproteins (LP) are a family of cell wall components found in a wide variety of bacteria. In this study, we characterized the response of HUCL, a telomerase-immortalized human corneal epithelial cell (HCEC) line, to LP isolated from Staphylococcus (S) aureus. S. aureus LP (saLP) prepared by Triton X-114 extraction stimulated the activation of NF-kappa B, JNK, and P38 signaling pathways in HUCL cells. The extracts failed to stimulate NF-kappa B activation in HUCL cells after lipoprotein lipase treatment and in cell lines expressing TLR4 or TLR9, but not TLR2, indicating lipoprotein nature of the extracts. saLP induced the up-regulation of a variety of inflammatory cytokines and chemokines (IL-6, IL-8, ICAM-1). antimicrobial molecules (hBD-2, LL-37, and iNOS), and homeostasis genes (Mn-SOD) at both the mRNA level and protein level. Similar inflammatory response to saLP was also observed in primarily cultured HCECs using the production of IL-6 as readout. Moreover, TLR2 neutralizing antibody blocked the saLP-induced secretion of IL-6, IL-8 and hBD2 in HUCL cells. Our findings suggest that saLP activates TLR2 and triggers innate immune response in the cornea to S. aureus infection via production of proinflammatory cytokines and defense molecules. (C) 2007 Elsevier Ltd. All rights reserved.