Polypyrimidine tract-binding protein is involved in regulation of albumin synthesis in response to food intake

• Published in: Journal of Nutritional Science and Vitaminology Vol. 54; no. 2; pp. 142 - 147
• Main Authors: Kuwahata, M.(Tokushima Univ. (Japan)), Kuramoto, Y, Sawai, Y, Amano, S, Tomoe, Y, Segawa, H, Tatsumi, S, Ito, M, Kobayashi, Y, Kido, Y, Oka, T, Miyamoto, K
• Format: Journal Article
• Language: English
• Published: Tokyo Center for Academic Publications Japan 01.04.2008
• Subjects: albumin synthesis; ALBUMINAS; ALBUMINE; ALBUMINS; Animals; ARN MENSAJERO; ARN MESSAGER; BINDING PROTEINS; Biological and medical sciences; Blotting, Northern - methods; Blotting, Western - methods; CITOPLASMA; CYTOPLASM; Cytoplasm - metabolism; CYTOPLASME; Diet; Eating; Fasting; Feeding. Feeding behavior; FOOD INTAKE; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation - drug effects; Gene Expression Regulation - physiology; HIPO ALIMENTACION; INGESTION DE ALIMENTOS; Insulin - blood; Liver - drug effects; Liver - metabolism; Male; mammalian target of rapamycin; MESSENGER RNA; Phosphorylation - drug effects; PIRIMIDINAS; POLIMEROS; POLYMERE; POLYMERS; polypyrimidine tract-binding protein; Polypyrimidine Tract-Binding Protein - metabolism; Polyribosomes - metabolism; PRISE ALIMENTAIRE (HOMME); PROTEIN SYNTHESIS; PROTEINAS AGLUTINANTES; PROTEINE DE LIAISON; PYRIMIDINE; PYRIMIDINES; Rats; Rats, Sprague-Dawley; Ribosomal Protein S6 - drug effects; Ribosomal Protein S6 - metabolism; RNA, Messenger - drug effects; RNA, Messenger - metabolism; Serum Albumin - biosynthesis; Serum Albumin - genetics; SINTESIS DE PROTEINAS; Sirolimus - pharmacology; SOUS-ALIMENTATION; SYNTHESE PROTEIQUE; UNDERFEEDING; Vertebrates: anatomy and physiology, studies on body, several organs or systems; polypyrimidine tract-binding protein; Rat; Rodentia; Albumin; Biosynthesis; Feeding; Binding protein; Vertebrata; Regulation(control); Mammalia; Food intake; Animal; Mammalian target of rapamycin; albumin synthesis; rats; Mechanism of action; Fast
• ISSN: 0301-4800; 1881-7742
• DOI: 10.3177/jnsv.54.142

Our recent study demonstrates that polypyrimidine tract-binding protein (PTB), which is a sequence specific RNA-binding protein, attenuates albumin synthesis in a cell-free translation system. In this study, the effects of food intake on regulation of albumin synthesis through binding of PTB to albumin messenger RNA (mRNA) were investigated. Rats were divided into 1 of 3 groups: fed; fasted for 36 h; or fasted for 36 h and then refed for 24 h. No significant differences in albumin mRNA levels were found among fed, fasted and refed rats. However, a decrease in the proportion of albumin mRNA associated with polysomes was identified in fasted rats. Furthermore, UV-cross linking analysis demonstrated that levels of albumin mRNA-PTB complex were increased in liver extracts from fasted rats. No significant differences in PTB levels in liver homogenate were found among the experimental groups. However, PTB level in the cytoplasmic fraction was higher in fasted rats than in fed rats. In refed rats, PTB level in the cytoplasmic fraction returned to a level comparable to that in fed rats, but was inhibited by treatment with rapamycin, a mammalian target of rapamycin (mTOR) inhibitor. These results suggest that localization of PTB is regulated by food intake through mTOR signaling, and alterations in level of albumin mRNA-PTB complex play a role in mediating the effects of food intake on albumin synthesis in the rat liver.