tailieunhanh - Báo cáo khoa học: Two splicing isoforms of the Y-box protein ctYB-1 appear on the same mRNA molecule

Y-box proteins constitute an evolutionarily conserved family of DNA- and RNA-binding proteins involved in the regulation of transcription and translation. In the dipteran Chironomus tentans, a homologue to the verte-brate Y-box protein YB-1 was recently characterized and designated ctYB-1. It is transferred from nucleus to cytoplasm bound to mRNA and is likely to affect translation. | ễFEBS Journal Two splicing isoforms of the Y-box protein ctYB-1 appear on the same mRNA molecule Dmitry Nashchekin Sergej Masich Teresa Soop Alexander Kukalev Elizaveta Kovrigina Oxana Nashchekina and Bertil Daneholt Department of Celland Molecular Biology MedicalNobellnstitute Karolinska Institutet Stockholm Sweden Keywords mRNA transport mRNP protein isoforms YB-1 Y-box proteins Correspondence B. Daneholt Department of Cell and Molecular Biology MedicalNobelInstitute Karolinska Institutet S-171 77 Stockholm Sweden Fax 46 8 313529 Tel 46 8 524 87370 E-mail Received 31 August 2006 revised 2 November 2006 accepted 7 November 2006 doi Y-box proteins constitute an evolutionarily conserved family of DNA- and RNA-binding proteins involved in the regulation of transcription and translation. In the dipteran Chironomus tentans a homologue to the vertebrate Y-box protein YB-1 was recently characterized and designated ctYB-1. It is transferred from nucleus to cytoplasm bound to mRNA and is likely to affect translation. It appears in two size variants p40 and p50. We further analysed the two size variants and their interaction with mRNA. Southern blot analysis in situ hybridization and RT-PCR analysis suggested that there is just one YB-1 gene and that the two size variants represent splicing isoforms. In a C. tentans epithelial cell line only p40 is present whereas both variants appear together in eight tissues from fourthinstar larvae although in somewhat different proportions. Furthermore the appearance of the two isoforms was studied in relation to a specific 3540 kb mRNA transcript in the salivary glands the Balbiani ring mRNA. Because of their exceptional size Balbiani ring messenger ribonucleoprotein particles in nucleoplasm and Balbiani ring polysomes in cytoplasm could be identified and selectively studied. We were able to establish that both isoforms are associated with both nuclear and cytoplasmic Balbiani ring