Isolation and characterization of brain Y-box protein: developmentally regulated expression, polyribosomal association and dendritic localization.
Y-box proteins are DNA- and RNA-binding proteins and control specific gene expression at both transcriptional and translational levels. Particularly in germ cells, it has been reported that Y-box proteins bind to paternal or maternal mRNAs to form mRNPs, mask them from translation and control cell maturation. In this study, we cloned cDNA for a Y-box protein from rat brain. A deduced amino acid sequence of the protein was very similar to that of several other Y-box proteins, and we termed the protein rBYB1 (rat brain Y-box protein 1). rBYB1 was found to be considerably expressed in the cytoplasm of pre- and early postnatal brains, and then decreased to adult levels with brain development. Further, we found rBYB1 to be distributed in both polyribosomal and nonpolyribosomal (mRNP) fractions on a sucrose density gradient, and to be associated with polyribosomes via RNA in the higher-density fractions. Moreover, rBYB1 was localized in dendrites of the primary hippocampal neurons. We compared these sucrose gradient and intracellular rBYB1 localization results with those for fragile X mental retardation protein (FMRP), which is known to be an mRNA-binding and polyribosome-associating translational regulator distributed in neuronal dendrites. Our results suggest that in the brain of prenatal and newborn animals, rBYB1 may function in storage and/or translational regulation of mRNAs involved in the rapid progress of the postnatal brain, and in mature neurons, it may also participate in the control of protein synthesis in dendrites.
Funakoshi
Tomoko
T
Department of Biochemistry, College of Pharmacy, Nihon University, Narashinodai, Funabashi, Chiba 274-8555, Japan.
Kobayashi
Shunsuke
S
Ohashi
Sachiyo
S
Sato
Taka Aki
TA
Anzai
Kaijiro
K
D000595:Amino Acid Sequence / Q000235:genetics; D000818:Animals; D000831:Animals, Newborn; D001483:Base Sequence / Q000235:genetics; D001921:Brain / Q000254:growth & development / Q000378:metabolism*; D002454:Cell Differentiation / Q000235:genetics; D002478:Cells, Cultured; D018076:DNA, Complementary / Q000032:analysis / Q000235:genetics; D003712:Dendrites / Q000378:metabolism; D005333:Fetus; D051860:Fragile X Messenger Ribonucleoprotein 1; D018507:Gene Expression Regulation, Developmental / Q000235:genetics; D006624:Hippocampus / Q000254:growth & development / Q000378:metabolism; D007150:Immunohistochemistry; D051379:Mice; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D011132:Polyribosomes / Q000235:genetics / Q000378:metabolism*; D014176:Protein Biosynthesis / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000235:genetics / Q000302:isolation & purification*; D051381:Rats
D018076:DNA, Complementary; D051860:Fragile X Messenger Ribonucleoprotein 1; D009419:Nerve Tissue Proteins; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; C497684:Fmr1 protein, mouse; C497685:Fmr1 protein, rat; C481842:brain Y-box protein 1, rat