Elucidation of retinoid acid-dependent mechanism of organogenesis and its evolution in chordates

2015 Fiscal Year Final Research Report

• Project/Area Number: 25440192
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Evolutionary biology
• Research Institution: Kochi University
• Principal Investigator: Fujiwara Shigeki 高知大学, 教育研究部自然科学系理学部門, 教授 (40229068)
• Co-Investigator(Renkei-kenkyūsha): SASAKURA Yasunori 筑波大学, 生命環境系, 教授 (10400649) ; NISHINO Atsuo 弘前大学, 農学生命科学部, 准教授 (50343116)
• Project Period (FY): 2013-04-01 – 2016-03-31
• Keywords: レチノイン酸 / ホヤ / 脊索動物 / 進化 / Hox1 / レチノイン酸合成酵素Raldh2 / レチノイン酸分解酵素Cyp26 / 転写調節

Outline of Final Research Achievements

Retinoic acid is a signaling molecule important for the chordate development. This study identified region-specific enhancer elements of the genes encoding retinoic acid-synthesizing and degrading enzymes (Raldh2 and Cyp26 respectively) in ascidians. Dominant negative experiments suggested that the transcription factor Mesp activates the Raldh2 enhancer.
Although the body plan of larvaceans is similar to that of ascidians, they completely lack biological pathways to synthesize retinoic acid. Retinoic acid is required for transactivation of Hox1 gene in ascidians but not in larvaceans. The present study revealed that an enhancer of larvacean Hox1 can be activated in ascidian embryos. The results suggest that a retinoic acid-independent mechanism of transactivation of Hox1 has been equipped in the common ancestor of ascidians and larvaceans. This mechanism may have enabled the larvaceans to survive the loss of retinoic acid-synthesizing pathways during their evolution.

Free Research Field

進化発生学