Screening of factors required for uptake of vitamin A into hepatic stellate cells

2019 Fiscal Year Final Research Report

• Project/Area Number: 16K00872
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Eating habits
• Research Institution: Jikei University School of Medicine
• Principal Investigator: Mezaki Yoshihiro 東京慈恵会医科大学, 医学部, 講師 (40431621)
• Co-Investigator(Kenkyū-buntansha): 松浦 知和 東京慈恵会医科大学, 医学部, 教授 (30199749) ; 岩本 武夫 東京慈恵会医科大学, 医学部, 教授 (90568891)
• Project Period (FY): 2016-04-01 – 2020-03-31
• Keywords: ビタミンA / 肝臓 / 星細胞 / 北極圏 / 放射能

Outline of Final Research Achievements

Vitamin A is a fat-soluble vitamin required for many physiological functions, however, excess intake of vitamin A causes hypervitaminosis A. Polar bears, the top predators in the Arctic, take a large amount of vitamin A but they do not suffer from hypervitaminosis A. We analyzed vitamin A-esterifying enzyme, LRAT, and revealed that LRAT activities of liver microsome fractions from polar bears were considerably lower than those obtained from rats. LRAT and cellular retinol-binding protein (CRBP) I were well co-localized. The CRBP I effectively conveys retinol to the LRAT, thereby alleviating the low enzymatic activity of LRAT in polar bear livers.

Free Research Field

生物学

Academic Significance and Societal Importance of the Research Achievements

分厚い脂肪に覆われたアザラシなどを捕食するホッキョクグマは、必然的に高濃度のビタミンAを摂取することになり、ビタミンA過剰症の危機にさらされたが、進化の過程で効率的なビタミンA貯蔵能力を獲得することで、その地位を維持することが可能になったと考えられる。本研究で得られたビタミンA貯蔵に関する知見は、ヒトにおけるビタミンA過剰症や欠乏症の解決にも役立つと思われる。