リンパ球の系列分岐・運命分岐を決定するシグナル伝達機構

• Project/Area Number: 12051219
• Research Category: Grant-in-Aid for Scientific Research on Priority Areas
• Allocation Type: Single-year Grants
• Review Section: Biological Sciences
• Research Institution: Tokyo Medical and Dental University (2002); Kyoto University (2000-2001)
• Principal Investigator: 桂 義元 東京医科歯科大学, 大学院・医歯学総合研究科, 客員教授 (90027095)
• Co-Investigator(Kenkyū-buntansha): 高浜 洋介 徳島大学, ゲノム機能研究センター, 教授 (20183858)
• Project Period (FY): 2000 – 2002
• Project Status: Completed (Fiscal Year 2002)
• Budget Amount: ¥78,300,000 (Direct Cost: ¥78,300,000); Fiscal Year 2002: ¥26,400,000 (Direct Cost: ¥26,400,000); Fiscal Year 2001: ¥27,000,000 (Direct Cost: ¥27,000,000); Fiscal Year 2000: ¥24,900,000 (Direct Cost: ¥24,900,000)
• Keywords: 胸腺 / T細胞 / 分化 / 系列決定 / 正・負の選択 / ケモカイン / ケモカインレセプター / 移出 / αβT細胞 / γσT細胞 / 胸線 / 前駆細胞 / 遺伝子再構成 / γδT細胞

Research Abstract

胎仔肝臓中のT前駆細胞(p-T)とp-Bを細胞表面マーカーの1つpaired immunoglobulin-like receptor (PIR)を用いて分離精製することに成功した.このことによって,従来はMLPアッセイによる検出だけで定義していたp-T, p-B, p-M(これはすでにFcR^+分画に分離されていた)などの存在が確定的となった.とくに,最近では胸腺へ移行するのは共通リンパ球前駆細胞(CLPまたはp-TB)であると主張する発表があいついでいたのであるが,PIRによる分離の成功でp-Tの存在とp-Tの胸腺移行を実証することができた.一連の研究において,胸腺移行前のp-TはすべてNKおよびDCへの分化能を保存しているのに対して,p-Bはいずれへの分化能も持たない事も示された.さらに,胸腺へ移行したp-TはCD44^+CD25^<low>段階からCD44^<low>CD25^+の段階へ至る過程でNKへの分化能とDC産生能を失う事が明らかとなった.
Tリンパ球の分化と選択に伴う細胞の移動機構を解析するため,胸腺器官内Tリンパ球移動を顕微鏡下で直接タイムラプス追跡する新規解析法を開発した.その結果,ケモカインのひとつCCL19が成熟Tリンパ球の胎仔胸腺移出をひきおこすことを見いだした.一方,CCL19受容体CCR7のノックアウトマウスでは,新生仔期の末梢T細胞供給数は著明に少なかった.しかし,成体CCR7ノックアウトマウスでの脾臓T細胞数は正常マウスを上回り,CCR7非依存性胸腺移出機構の存在も示された.また,正常マウス胸腺内でのCCL19は主に髄質内の血管内皮細胞や血管周囲間充織細胞に局在していた.以上の結果から,CCR7シグナルは新生仔胸腺からの成熟Tリンパ球の移出に必須であることが示された.また,CCR7リガンドは髄質の血管周辺に成熟Tリンパ球を誘引することで胸腺移出に関与することが示唆された.加えて,CCR7非依存性の胸腺移出機構の存在も示された.

Research Products

• [Publications] Lu, M., Katsura, Y.: "The common myelolymphoid progenitor : A key intermediate stage in hemopoiesis generating T and B cells"J. Immunol. 169. 3519-3525 (2002)
• [Publications] Kawamoto, H., Katsura, Y.: "Extensive proliferation of T cell lineage restricted progenitors in the thymus : An essential process for clonal expression of diverse T cell receptor β chains"Eur. J. Immunol.. 33. 606-615 (2003)
• [Publications] Ueno, T., Takahama, Y.: "Role for CCR7 ligands in the emigration of newly generated T lymphocytes from the neonatal thymus"Immunity. 16. 205-218 (2002)
• [Publications] Akamatsu, Y., Takahama, Y.: "Deletion of the RAG2 C-terminus leads to impaired lymphoid development in mice"Proc. Natl. Acad. Sci. USA.. 100. 1209-1214 (2003)
• [Publications] Ueno, T., Takahama, Y.: "Advanced methods of fetal thymus organ cultures"Methods in Mol. Biol.. (In press).
• [Publications] Katsura, Y.: "Developmental Hematopoiesis (ed. By Margaret H. Baron) A new clonal assay system for lymphoid and myeloid lineages"Humana Press (In press).
• [Publications] Ohmura, K. et al.: "Immature multipotent hematopoietic progenitors lacking long-term bone marrow-reco-nstituting activity in the aorta-gonad-mesonephros region of murine day 10 fetuses"Journal of Immunology. 166. 3290-3296 (2001)
• [Publications] Ikawa, T. et al.: "Commitment to natural killer clels requires the helix-loop-helix inhitibor Id2"Proceedings of the National Academy of Sciences of the USA. 98. 5164-5169 (2001)
• [Publications] Katsura, Y. et al.: "Stepwise lineage restriction of progenitors in lympho-myelopoiesis"International Review of Immunology. 20. 1-20 (2001)
• [Publications] Egawa, T. et al.: "The earliest stages of B cell development require a chemokine stormal cell-derived factor/pre-B cell growth-stimulating fcator"Immunity. 15. 1-20 (2001)
• [Publications] Yoshida, H. et al.: "Expression of a4b7 intergrn defines a distinct pathway of lymphoid progenitors committed to T cells, fetal intestinal lymphotoxin producer, NK, and dendritic cells"Journal of Immunology. 167. 2511-2521 (2001)
• [Publications] Itoi, M et al.: "Two distinct steps of immigration of hematopoietic progenitors into the early thymus anlage"International Immunology. 13. 1203-1211 (2001)
• [Publications] Katsura, Y.: "Redefiniation of lymphoid progenitors"Nature Reviews Immunology. 2. 127-131 (2002)
• [Publications] Masuyama, N. et al.: "Akt inhibits the orphan nuclear receptor Nur77 and T cell apoptosis"J.Biol.Chem.. 276. 32799-32805 (2001)
• [Publications] Sano, S. et al.: "Stat3 in thymic epithelial cells is essential for postnatal maintenance of thymic architecture and thymocyte survial"Immunity. 15. 261-273 (2001)
• [Publications] Tada, M. et al.: "Nuclear reprogramming of somatic cells by in vitro hybridization with ES cells"Current Biology. 11. 1553-1558 (2001)
• [Publications] Yoh, K.et al.: "Transgenic overexpression of MafK suppressor T cel proliferaiton and fullciton in vivo"Genes to Cells. 6. 1055-1066 (2001)
• [Publications] Ueno, T. et al.: "Role for CCR7 ligands in the emigration of newly generated T lymphocytes from the neonatal thymus"Immunity. 16. 205-218 (2002)
• [Publications] Kawamoto,H. et al.: "T cellprogenitors emerge earlier than B cell progenitors in the murine fetal liver."Immunity. 12. 441-450 (2000)
• [Publications] Ohmura,K. et al.: "Immature multipotent hematopoietic progenitors lacking long-term bone marrow-recostituting activity in the aorta-gonad-mesonephros region of murine day 10 fetuses. "Journal of Immunology. 166. 3290-3296 (2001)
• [Publications] Ikawa,T. et al.: "Commitment to natural killer clels requires the helix-loop-helix inhitibor Id2."Proc.Natl.Acad.Sci.USA. (in press). (2001)
• [Publications] Kaneda,M. et al.: "A role for Pref-1 and HES-1 in thymocyte development."Journal of Immunology. 164. 256-264 (2000)
• [Publications] Sheard,M.A. et al.: "Synchronous deletion of Mtv-superantigen-reactive thymocytes in the CD3medium/high CD4^+ CD8^+ subset."Scand.J.Immunol.. 52. 550-554 (2000)
• [Publications] Hayashi,K. et a.: "Diminution of the AML1 transcription factor function causes differential effects on the fates of CD4 and CD8 single positive T cells."Journal of Immunology. 165. 6816-6824 (2000)
• [Publications] van Evijk,W. et al.: "Current Topics in Microbiology and Immunology"Springer,Germany. 210 (2000)