Ernst S, Zobiack N, Boecker K, Gerke V, Rescher U
Center for Molecular Biology of Inflammation, Institute for Medical Biochemistry, von Esmarch-Str. 56, 48149 Münster, Germany.
Cell Mol Life Sci. 2004 Jul;61(13):1684-92. doi: 10.1007/s00018-004-4116-x.
The formyl peptide-like receptor FPRL1 is a member of the chemoattractant subfamily of G protein- coupled receptors involved in regulating leukocyte migration in inflammation. To elucidate mechanisms underlying the internalization of ligand-bound FPRL1 and possible receptor recycling, we characterized the endocytic itinerary of FPRL1. We show that agonist-triggered internalization from the plasma membrane into intracellular compartments is prevented by perturbation of clathrin-mediated endocytosis, such as expression of the dominant-negative clathrin Hub mutant, siRNA-mediated depletion of cellular clathrin and expression of a dominant-negative mutant of the large GTPase dynamin. Internalized FPRL1 co-localized with endocytosed transferrin and the small GTPases Rab4 and Rab11 in vesicular structures most resembling recycling endosomes. Recycling of FPRL1 was significantly reduced by pretreatment with PI3-kinase inhibitors. Thus, ligand-bound FPRL1 undergoes primarily clathrin-mediated and dynamin-dependent endocytosis and the receptor recycles via a rapid PI3-kinase-sensitive route as well as pathways involving perinuclear recycling endosomes.
甲酰肽样受体FPRL1是G蛋白偶联受体趋化因子亚家族的成员，参与调节炎症中白细胞的迁移。为了阐明配体结合的FPRL1内化的机制以及可能的受体再循环，我们对FPRL1的内吞途径进行了表征。我们发现，网格蛋白介导的内吞作用的扰动可阻止激动剂触发的从质膜到细胞内区室的内化，例如显性负性网格蛋白Hub突变体的表达、siRNA介导的细胞网格蛋白的消耗以及大GTP酶发动蛋白的显性负性突变体的表达。内化的FPRL1与内吞的转铁蛋白以及小GTP酶Rab4和Rab11在最类似于再循环内体的囊泡结构中共定位。用PI3激酶抑制剂预处理可显著减少FPRL1的再循环。因此，配体结合的FPRL1主要经历网格蛋白介导的和发动蛋白依赖性的内吞作用，并且受体通过快速的PI3激酶敏感途径以及涉及核周再循环内体的途径进行再循环。
