title: Expression and polysome association of YB-1 in various tissues at different stages in the lifespan of mice.
abstract: Tissue-specific translational regulation is important for gene expression. YB-1 binds to mRNAs to form mRNPs and affects translation. In this study we investigated expression and polysome association of YB-1 in various tissues at different stages in the lifespan of mice. YB-1 levels decreased markedly with growth in brain, heart and muscle, but increased in the spleen. In lung, kidney and testis, the levels of YB-1 diminished with aging. In liver, no significant change in the level of YB-1 was observed throughout life. We further showed that the distribution pattern of YB-1 on a sucrose gradient differed according to tissue. Moreover, the distribution pattern of YB-1 changed drastically with growth in the liver. In 5-day-old liver, YB-1 was distributed almost exclusively in nonpolysomal fractions, whereas in 4-week-old liver, it was associated with heavy-sedimenting polysomes, as was the case in 5-day-old brain. Immunohistochemical analysis revealed that YB-1 is mainly a cytoplasmic protein in these tissues. Our results indicate that the expression and polysome association of YB-1 are regulated with growth or aging in a tissue-specific manner, presumably to control gene expression at the translational level in each tissue.
authors.affiliation: Department of Biochemistry, College of Pharmacy, Nihon University, Narashinodai, Funabashi, Chiba 274-8555, Japan.
authors.forename: Arisa
authors.initials: A
authors.lastname: Miwa
authors.forename: Takashi
authors.initials: T
authors.lastname: Higuchi
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Kobayashi
mesh_terms: D000818:Animals; D001921:Brain / Q000254:growth & development / Q000378:metabolism; D005786:Gene Expression Regulation; D008099:Liver / Q000254:growth & development / Q000378:metabolism; D008168:Lung / Q000254:growth & development / Q000378:metabolism; D051379:Mice; D009928:Organ Specificity; D011132:Polyribosomes / Q000378:metabolism*; D051840:Y-Box-Binding Protein 1 / Q000378:metabolism*
chemical_list: D051840:Y-Box-Binding Protein 1