Influence of methionine on the ubiquitination of mouse liver cytosolic proteins”

YEVES, ALEJANDRA M.; RONCHI, VIRGINIA P; CHISARI, ANDREA; SANLLORENTI, PEDRO M.; CONDE, RUBÉN D.

Pinamar, BsAs, Argentina

Congreso; ¨10th Congress Panamerican Association for Biochemistry and Molecular Biology. SAIB 41th Annual Meeting; 2005

Sociedad Argentina de Investigacion Bioquimica y Biologia Molecular (SAIB)

INFLUENCE OF DIETARY METHIONINE ON THE UBIQUITINATION OF MOUSE LIVERCYTOSOLIC PROTEINS.Yeves1, Alejandra M.; Ronchi1, Virginia P.; Chisari2, Andrea;Sanllorenti1, Pedro M.; Conde1, Rubén D.1Instituto de Investigaciones Biológicas (UNMdP). 2Instituto deInvestigaciones Biológicas (UNMdP) and Facultad de Ciencias Exactas(UNLP). Argentina. E-mail: achisari@mdp.edu.ar Protein content decreases 50% in the liver of mice fed with a protein freediet. The ubiquitin–dependent system is responsible for the degradation ofshort-lived and abnormal proteins in eukaryotic cells. This work wasdesigned to examine the effect of diets on the ubiquitination of cytosolicproteins in vivo and in isolated hepatocytes. Balb-c female mice were fedduring 5 days with normal (23% of casein), protein free, and protein freecontaining Met, respectively. The isolated hepatocytes were incubated for4h with a complete medium, minimal medium, and minimal medium supplementedwith Met. The ubiquitin conjugates were analyzed by Western blot withpolyclonal antibodies. The results indicated that: a) the total proteincontent of undernourished hepatocytes decreases as observed in vivo; b)the main size range of ubiquitinated proteins in vivo and in vitro was89000-18000 and 73000-34000, respectively; c) the level of someubiquitinated proteins was modified by diets (while some increased others decreased); e) supplementation with Met caused a pattern of ubiquitinated proteins similar to that of controls. Then dietary Met can increase in both systems the stability of some proteins. Supported by CONICET, UNLP and UNMdP.