Deletion of Tetraspanin CD9 Diminishes Lymphangiogenesis in Vivo and in Vitro
Deletion of Tetraspanin CD9 Diminishes Lymphangiogenesis in Vivo and in Vitro
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DOI：
10.1074/jbc.m112.424291
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发表时间：
2013-01-25
影响因子：
4.8
通讯作者：
Kumanogoh, Atsushi
中科院分区：
文献类型：
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作者：
Iwasaki, Takeo;Takeda, Yoshito;Kumanogoh, Atsushi
四跨膜蛋白已成为恶性肿瘤和炎症性疾病的关键参与者，但很少有人知道他们在血管生成中的作用，也没有什么是知道他们参与淋巴管生成。我们发现四跨膜蛋白在人淋巴管内皮细胞（LEC）中大量表达。胸内肿瘤植入后，tetraspanin CD 9-KO小鼠的淋巴结转移减少，并伴有血管生成和淋巴管生成减少。此外，与野生型小鼠相比，在CD 9-KO小鼠中诱导的淋巴管瘤不太明显，淋巴管生成减少。虽然从CD 9-KO小鼠分离的小鼠LEC显示正常粘附，但在体外和离体淋巴环测定中的几种测定（迁移、增殖和缆形成）中淋巴管生成显著受损。与小鼠LEC中的这些发现一致，敲低人LEC中的CD 9也产生了降低的迁移、增殖和缆线形成。免疫沉淀分析表明，LEC中CD 9的缺失减少了VEGF受体-3和整合素（α 5和α 9）之间功能复合物的形成。因此，敲低LEC中的CD 9减弱了VEGF受体-3信号传导，以及下游信号传导，如VEGF-C刺激后的Erk和p38。最后，在小鼠中，CD 9/CD 81的双缺失引起气管和隔膜中淋巴管系统的异常发育，这表明CD 9和密切相关的四跨膜蛋白CD 81协调地在生理性淋巴管生成中发挥重要作用。总之，四跨膜蛋白CD 9调节LEC中整合素的分子组织，从而支持淋巴管生成所需的几种功能。
Tetraspanins have emerged as key players in malignancy and inflammatory diseases, yet little is known about their roles in angiogenesis, and nothing is known about their involvement in lymphangiogenesis. We found here that tetraspanins are abundantly expressed in human lymphatic endothelial cells (LEC). After intrathoracic tumor implantation, metastasis to lymph nodes was diminished and accompanied by decreased angiogenesis and lymphangiogenesis in tetraspanin CD9-KO mice. Moreover, lymphangiomas induced in CD9-KO mice were less pronounced with decreased lymphangiogenesis compared with those in wildtype mice. Although mouse LEC isolated from CD9-KO mice showed normal adhesion, lymphangiogenesis was markedly impaired in several assays (migration, proliferation, and cable formation) in vitro and in the lymphatic ring assay ex vivo. Consistent with these findings in mouse LEC, knocking down CD9 in human LEC also produced decreased migration, proliferation, and cable formation. Immunoprecipitation analysis demonstrated that deletion of CD9 in LEC diminished formation of functional complexes between VEGF receptor-3 and integrins (alpha 5 and alpha 9). Therefore, knocking down CD9 in LEC attenuated VEGF receptor-3 signaling, as well as downstream signaling such as Erk and p38 upon VEGF-C stimulation. Finally, double deletion of CD9/CD81 in mice caused abnormal development of lymphatic vasculature in the trachea and diaphragm, suggesting that CD9 and a closely related tetraspanin CD81 coordinately play an essential role in physiological lymphangiogenesis. In conclusion, tetraspanin CD9 modulates molecular organization of integrins in LEC, thereby supporting several functions required for lymphangiogenesis.