Role of Tspan18 in the intracellular trafficking of VEGF receptor

• Project/Area Number: 19K07389
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 49010:Pathological biochemistry-related
• Research Institution: Keio University
• Principal Investigator: Tai Ikue 慶應義塾大学, 医学部(信濃町), 講師 (90749508)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Project Status: Completed (Fiscal Year 2021)
• Budget Amount: ¥4,420,000 (Direct Cost: ¥3,400,000、Indirect Cost: ¥1,020,000); Fiscal Year 2021: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000); Fiscal Year 2020: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000); Fiscal Year 2019: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
• Keywords: 血管新生 / 血管形成 / リンパ管新生 / tetraspanin / Tspan18 / Folliculin / Tetraspanin18 / shedding / VEGFR2 / リンパ管内皮 / 血管内皮 / 静脈内皮 / リン酸化VEGFR2 / VEGFR2切断断片 / Tspan / Tetraspanin / angiogenesis / VEGFシグナル

Outline of Research at the Start

血管形成に重要な受容体であるVEGFR2はタンパク質分解を受けて細胞膜結合型の2種類の断片が多量に産生されるがその意義や機能はよくわかっていない。Tspan18欠損マウスでは血管形成の抑制が起こり、VEGFシグナルが減弱していると推定されるが、Tspan18はVEGFR2の上記断片と特異的に結合し、全長のVEGFR2とは結合しない。このことから、Tspan18はVEGFR2の断片産生に何らかの形で関わり、それにより血管新生を正常に保っているものと推定される。このため、研究が期待通り進捗すれば、これまでほとんど解析されてこなかったVEGFR2の分解を伴う制御機構を初めて解明できると期待される。

Outline of Final Research Achievements

We are analyzing effects of Tspan18, a membrane protein with four transmembrane regions, on shedding of VEGFR2, as a mechanism by which Tspan18 contributes to normal retinal vascular development and development of tumor blood vessels. Though nuclear localization of VEGFR2 fragments was not detected, we have shown that Tspan18 increases the amount of VEGFR2 fragments and phosphorylation of full length VEGFR2 by overexpression and knockdown experiments using HUVECs. The amount of VEGFR2 fragments were normal in the postnatal retina, lung and mesentery endothelial cells of endothelial-cell-specific Tspan18 KO mice, but phosphorylation of full-length VEGFR2 was suppressed in those mice. We additionally identified a novel gene important for development of blood vessels and lymphatic vessels, and developed and analyzed its knockout mice.

Academic Significance and Societal Importance of the Research Achievements

より効果的で副作用の少ない、抗腫瘍血管新生療法の新たな分子標的を探索するため、VEGFシグナルの詳細を基礎研究により徹底的に見直そうという機運が世界的に高まっている。その中で、Tetraspaninというまだ知見の乏しいタンパク質によるVEGF受容体のtruncationという切り口はユニークと言える。特に、ノックアウトマウスの解析からTspan18のin vivoでの重要性は既に示されていることから、上記のVEGFシグナルの詳細の解明、次世代の抗腫瘍血管新生療法の開拓へ本研究が寄与するところは大きいと考えられる。

Research Products

• [Journal Article] Tumor-specific inter-endothelial adhesion mediated by FLRT2 facilitates cancer aggressiveness (2022)
  • Author(s): Ando T, Tai-Nagara I, Sugiura Y, Kusumoto D, Okabayashi K, Kido Y, Sato Kohji, Saya H, Navankasattusas S, Li DY, Suematsu M, Kitagawa Y, Seiradake E, Yamagishi S, *Kubota Y.
  • Journal Title: J Clin Invest Volume: 132 Issue: 6 Pages: 153626-153626
  • DOI: 10.1172/jci153626
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Coupling of angiogenesis and odontogenesis orchestrates tooth mineralization in mice (2022)
  • Author(s): Matsubara T, Iga T, Sugiura Y, Kusumoto D, Sanosaka T, Tai-Nagara I, Takeda N, Fong GH, Ito K, Ema M, Okano H, Kohyama J, Suematsu M, *Kubota Y.
  • Journal Title: J Exp Med Volume: 219 Issue: 4
  • DOI: 10.1084/jem.20211789
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Genetic Deletion of Vascular Endothelial Growth Factor Receptor 2 in Endothelial Cells Leads to Immediate Disruption of Tumor Vessels and Aggravation of Hypoxia. (2021)
  • Author(s): Kido Y, Ando T, Iga T, Ema M, *Kubota Y, *Tai-Nagara I.
  • Journal Title: Am J Pathol. Volume: 9440 Issue: 2 Pages: 00511-3
  • DOI: 10.1016/j.ajpath.2021.11.003
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Neuron-derived VEGF contributes to cortical and hippocampal development independently of VEGFR1/2-mediated neurotrophism. (2020)
  • Author(s): Okabe K, Fukada H, Tai-Nagara I, Ando T, Honda T, Nakajima K, Takeda N, Fong GH, Ema M, Kubota Y.
  • Journal Title: Dev Biol. Volume: 459(2) Issue: 2 Pages: 65-71
  • DOI: 10.1016/j.ydbio.2019.11.016
  • Peer Reviewed / Open Access / Int'l Joint Research