京都大学 / 新制・課程博士 / 博士(医学) / 甲第24517号 / 医博第4959号 / 新制||医||1065(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 妹尾 浩, 教授 松田 道行, 教授 小濱 和貴 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

Chloramphenicol has been used to study mitochondrial biogenesis in mammalian cells by examining its effect on: the incorporation of radioactive amino acids into protein by isolated mitochondria, the growth of L cells, the level of representative enzymes and cytochromes in the mitochondria and cytoplasm and the structure of mitochondria and L cells. A reversible inhibition of synthesis of cytochrome c oxidase was obtained by treating cells with D-threo-chloramphenicol for 90 hr. Recovery of cytochrome c oxidase activity was inhibited by cycloheximide, an inhibitor of cytoplasmic protein synthesis. Cycloheximide also reversibly inhibited cytochrome c oxidase formation in cells which were not treated with D-chloramphenicol. It is suggested that the mitochondria and the nucleus have a joint control in the formation of a functionally active cytochrome c oxidase enzyme. / Thesis / Doctor of Philosophy (PhD)

Glucagon-like peptide-1 (GLP-1) is an anti-diabetic intestinal L cell hormone. The monounsaturated fatty acid, oleic acid (OA), is an effective GLP-1 secretagogue that crosses the cell membrane by an unknown mechanism. Immunoblotting demonstrated the presence of fatty acid transport proteins (CD36 and FATP1, 3 and 4) in the murine GLUTag L cell model. The cells demonstrated specific 3H-OA uptake, which was dose-dependently inhibited by unlabeled-OA. Phloretin and SSO, inhibitors of carrier-mediated transport and CD36, respectively, also significantly decreased 3H-OA uptake, as did knocking down FATP4 by transfection of siRNA. OA dose-dependently increased GLP-1 secretion in GLUTag cells, while phloretin and FATP4 knockdown, but not SSO, decreased this response. OA injected directly into the ileum of wild-type mice increased plasma GLP-1 levels; in contrast, preliminary findings suggest decreased GLP-1 levels in FATP4 null mice at 60 min. Collectively, these findings indicate a role for FATP4 in OA-induced GLP-1 secretion.

Glucagon-like peptide-1 (GLP-1) is an anti-diabetic intestinal L cell hormone. The monounsaturated fatty acid, oleic acid (OA), is an effective GLP-1 secretagogue that crosses the cell membrane by an unknown mechanism. Immunoblotting demonstrated the presence of fatty acid transport proteins (CD36 and FATP1, 3 and 4) in the murine GLUTag L cell model. The cells demonstrated specific 3H-OA uptake, which was dose-dependently inhibited by unlabeled-OA. Phloretin and SSO, inhibitors of carrier-mediated transport and CD36, respectively, also significantly decreased 3H-OA uptake, as did knocking down FATP4 by transfection of siRNA. OA dose-dependently increased GLP-1 secretion in GLUTag cells, while phloretin and FATP4 knockdown, but not SSO, decreased this response. OA injected directly into the ileum of wild-type mice increased plasma GLP-1 levels; in contrast, preliminary findings suggest decreased GLP-1 levels in FATP4 null mice at 60 min. Collectively, these findings indicate a role for FATP4 in OA-induced GLP-1 secretion.