In vivo structure/function and expression analysis of the CX3C chemokine fractalkine
In vivo structure/function and expression analysis of the CX3C chemokine fractalkine
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DOI：
10.1182/blood-2011-04-348946
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发表时间：
2011-11-24
期刊：
影响因子：
20.3
通讯作者：
Jung, Steffen
中科院分区：
文献类型：
--
作者：
Kim, Ki-Wook;Vallon-Eberhard, Alexandra;Jung, Steffen
CX3C 趋化因子家族仅由一个成员 CX(3)CL1 组成，也称为 fractalkine，在小鼠中是 G 蛋白偶联 7 次跨膜受体 CX(3)CR1 的唯一配体。与经典的小肽趋化因子不同，CX(3)CL1 是作为膜锚定蛋白合成的，可以促进不依赖于整合素的粘附。随后金属蛋白酶的裂解（无论是组成型还是诱导型）可以产生可能具有化学吸引活性的脱落的 CX(3)CL1 实体。为了研究活体动物组织中的CX3C界面，我们生成了转基因小鼠（CX（3）CL1（樱桃）：CX（3）CR1（gfp）），其在CX（3）CL1和CX（3）CR1启动子的分别控制下表达红色和绿色荧光报告基因。此外，我们进行了结构/功能分析，通过比较膜束缚与脱落的 CX(3)CL1 部分各自纠正巨噬细胞功能和 CX(3)CL1 缺陷小鼠中白细胞存活缺陷的能力，区分它们的体内功能。具体而言，CX(3)CL1(105 Delta)（一种必需的可溶性CX(3)CL1亚型）的表达重建了肠道巨噬细胞跨上皮树突的形成，但没有挽救CX(3)CR1(gfp/gfp)小鼠中循环的Ly6C(lo)CX(3)CR1(hi)血单核细胞。相反，单核细胞的存活需要全长膜锚定的 CX(3)CL1，这表明束缚和脱落的 CX(3)CL1 实体的活性存在差异。 （血。2011；118(22)：e156-e167）
The CX3C chemokine family is composed of only one member, CX(3)CL1, also known as fractalkine, which in mice is the sole ligand of the G protein-coupled, 7-transmembrane receptor CX(3)CR1. Unlike classic small peptide chemokines, CX(3)CL1 is synthesized as a membrane-anchored protein that can promote integrin-independent adhesion. Subsequent cleavage by metalloproteases, either constitutive or induced, can generate shed CX(3)CL1 entities that potentially have chemoattractive activity. To study the CX3C interface in tissues of live animals, we generated transgenic mice (CX(3)CL1(cherry): CX(3)CR1(gfp)), which express red and green fluorescent reporter genes under the respective control of the CX(3)CL1 and CX(3)CR1 promoters. Furthermore, we performed a structure/function analysis to differentiate the in vivo functions of membrane-tethered versus shed CX(3)CL1 moieties by comparing their respective ability to correct established defects in macrophage function and leukocyte survival in CX(3)CL1-deficient mice. Specifically, expression of CX(3)CL1(105 Delta), an obligatory soluble CX(3)CL1 isoform, reconstituted the formation of transepithelial dendrites by intestinal macrophages but did not rescue circulating Ly6C(lo) CX(3)CR1(hi) blood monocytes in CX(3)CR1(gfp/gfp) mice. Instead, monocyte survival required the full-length membrane-anchored CX(3)CL1, suggesting differential activities of tethered and shed CX(3)CL1 entities. (Blood. 2011; 118(22): e156-e167)