Molecular basis of thyroid evolution as revealed by the mechanism of the endostyle development in chordates

2023 Fiscal Year Final Research Report

• Project/Area Number: 20K07221
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 48010:Anatomy-related
• Research Institution: Chiba University
• Principal Investigator: Ogasawara Michio 千葉大学, 大学院理学研究院, 准教授 (00343088)
• Project Period (FY): 2020-04-01 – 2024-03-31
• Keywords: 甲状腺 / 内柱 / 脊索動物 / 進化発生 / 遺伝子発現 / 発現制御

Outline of Final Research Achievements

The thyroid in vertebrates is considered to originate from the endostyle of invertebrate chordates. From the point of view of functional and genetic aspects, several discrepancies are existed between the endostyle and the thyroid gland. In this study, we perturbed a gene expression of thyroid-related transcription factors, TTF-1/Nkx2-1 and TTF-2/FoxE, in two urochordates (larvacean Oikopleura dioica and ascidian Ciona intestinalis). TTF-1/Nkx2-1 perturbation eliminated the expression of thyroidal and glandular genes, e.g., TTF-2/FoxE, TPO, vWFL, and CiEnds1. On the other hand, TTF-2/FoxE perturbations did not affected the expressions of TTF-1/Nkx2-1 and vWFL, but eliminated the expressions of TPO and CiEnds1. These results provide insights into the evolution of the vertebrate thyroid as well as the urochordate endostyle.

Free Research Field

進化発生学

Academic Significance and Societal Importance of the Research Achievements

甲状腺は、我々ヒトを含む脊椎動物において新陳代謝の調節を担っている器官である。本研究で明らかにした「甲状腺転写因子TTF-1/Nkx2-1依存および非依存の遺伝子発現制御機構」と「TTF-1/Nkx2-1による分泌関連遺伝子の発現制御」の知見は、脊索動物門の内柱/甲状腺間で進化的に保守されたシステムの存在を明らかにし、脊椎動物が進化させたシステムを明確に区別するに至ったという意義を持つ。これらの知見は、今後の甲状腺機能の本質的理解や甲状腺機能障害への対応などへの寄与が期待できる。