title: Deletion of tetraspanin CD9 diminishes lymphangiogenesis in vivo and in vitro.
abstract: 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 wild-type 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 (α5 and α9). 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.
authors.affiliation: Department of Respiratory Medicine, Allergy and Rheumatic Diseases, Osaka University Graduate School of Medicine, Suita, Osaka 565-0871, Japan.
authors.forename: Takeo
authors.initials: T
authors.lastname: Iwasaki
authors.forename: Yoshito
authors.initials: Y
authors.lastname: Takeda
authors.forename: Kazuichi
authors.initials: K
authors.lastname: Maruyama
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Yokosaki
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Tsujino
authors.forename: Satoshi
authors.initials: S
authors.lastname: Tetsumoto
authors.forename: Hanako
authors.initials: H
authors.lastname: Kuhara
authors.forename: Kaori
authors.initials: K
authors.lastname: Nakanishi
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Otani
authors.forename: Yingji
authors.initials: Y
authors.lastname: Jin
authors.forename: Satoshi
authors.initials: S
authors.lastname: Kohmo
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Hirata
authors.forename: Ryo
authors.initials: R
authors.lastname: Takahashi
authors.forename: Mayumi
authors.initials: M
authors.lastname: Suzuki
authors.forename: Koji
authors.initials: K
authors.lastname: Inoue
authors.forename: Izumi
authors.initials: I
authors.lastname: Nagatomo
authors.forename: Sho
authors.initials: S
authors.lastname: Goya
authors.forename: Takashi
authors.initials: T
authors.lastname: Kijima
authors.forename: Toru
authors.initials: T
authors.lastname: Kumagai
authors.forename: Isao
authors.initials: I
authors.lastname: Tachibana
authors.forename: Ichiro
authors.initials: I
authors.lastname: Kawase
authors.forename: Atsushi
authors.initials: A
authors.lastname: Kumanogoh
mesh_terms: D000818:Animals; D002465:Cell Movement; D049109:Cell Proliferation; D002478:Cells, Cultured; D018450:Disease Progression; D042783:Endothelial Cells / Q000166:cytology; D061307:Human Umbilical Vein Endothelial Cells; D006801:Humans; D047468:Immunoprecipitation; D066298:In Vitro Techniques; D007249:Inflammation; D042583:Lymphangiogenesis / Q000235:genetics*; D051379:Mice; D018345:Mice, Knockout; D009362:Neoplasm Metastasis; D009369:Neoplasms / Q000378:metabolism; D009389:Neovascularization, Pathologic; D060225:Tetraspanin 28 / Q000235:genetics / Q000378:metabolism; D060245:Tetraspanin 29 / Q000235:genetics* / Q000502:physiology; D059470:Tetraspanins / Q000737:chemistry*
chemical_list: D060225:Tetraspanin 28; D060245:Tetraspanin 29; D059470:Tetraspanins