ROLE OF BETA-2 INTEGRINS IN LEUKOCYTE ADHESION AND SIGNALING

白细胞被吸引到炎症部位是一个重要的因素， 稳态反应 不适当的吸引和髓样激活 然而，白细胞是多种疾病的潜在机制 以明显的炎症为特征。 精确调节 招聘过程是必要的，既要作出适当的反应， 防止过度的组织损伤。 许多细胞和分子 已经描述了这一反应所涉及的事件。 Beta2 整联蛋白是PMN表面上的粘附蛋白家族， 巨噬细胞在支持正常的炎症反应中至关重要， 反应 例如，患有这些遗传性缺陷的患者 蛋白质遭受反复的生命强化感染， 伤口愈合 相反，阻断粘附功能的抗体 β 2整联蛋白的表达改善了一些动物模型中的组织损伤， 炎症 β 2整联蛋白是由共同的β 2 链和三条阿尔法链之一。 虽然它们的主要结构 是已知的，并且许多功能性反应已经被表征， 不清楚每个异二聚体是否对 粘附和信号传导。 我们建议从HL 60细胞中建立永久性细胞系， 可以在体外分化为PMN或巨噬细胞白血病细胞系， 就像细胞一样 每个品系将具有一个亚基的缺陷（即， β，或α之一）通过靶向基因破坏产生， 同源重组 我们将创造纯合品系， 为了确定每个异二聚体对粘附的贡献 其他细胞和细胞外的候选反受体 矩阵 我们将使用相同的细胞来评估每种整合素的作用 在配体诱导的反应中，包括细胞内钙的变化， 浓度、氧化剂爆发、脂质介质的合成和基因 表情 拟议的研究将剖析Beta2的功能， 整合素在分子水平上，并将提供永久性的试剂， 白细胞功能、整合素和炎症的研究。

The attraction of leukocytes to a site of inflammation is an essential homeostatic response. Inappropriate attraction and activation of myeloid leukocytes, however, is a mechanism underlying a variety of diseases characterized by marked inflammation. Precise regulation of the recruitment process is necessary both to respond appropriately and to prevent excessive tissue damage. Many of the cellular and molecular events involved in this response have been described. The Beta2 integrins are a family of adhesion proteins on the surface of PMNs and macrophages that are crucial in supporting a normal inflammatory response. For example, patients with an inherited deficiency of these proteins suffer recurrent life-strengthening infections and have poor wound healing. Conversely, antibodies that block the adhesive function of Beta2 integrins ameliorate the tissue damage in some animal models of inflammation. The Beta2 integrins are dimers comprised of a common Beta chain and one of three alpha chains. Although their primary structures are known and many functional responses have been characterized, it is not clear whether each of the heterodimers makes unique contributions to adhesion and signaling. We propose to make permanent cell lines from HL60 cells, a promyelocytic leukemia line that can be differentiated in vitro to PMN- or macrophage- like cells. Each line will have a deficiency of one subunit (i.e. the Beta, or one of the alpha's) created by targeted gene disruption through homologous recombination. We will create homozygous lines and use them to determine the contribution of each individual heterodimer to adhesion to candidate counter-receptors on other cells and in extracellular matrix. We will use the same cells to assess the role of each integrin in ligand-induced responses including changes in intra cellular calcium concentration, the oxidant burst, synthesis of lipid mediators, and gene expression. The proposed studies will dissect the functions of the Beta2 integrins at the molecular level, and will provide permanent reagents for studies of leukocyte function, integrins, and inflammation.