Molecular characterization of the putative oncogene myeov

The myeov gene was identified using the tumorigenicity assay with DNA from a patient suffering a gastric carcinoma. The Myeov gene is localized at chromosome band 11q13, a frequent site for chromosomal rearrangements in various carcinomas and B-cell neoplasms. The gene was shown to be involved in cases of multiple myeloma harboring the t(11;14)(q13;q32). In addition, myeov is coamplified with cyclin D1 and overexpressed in carcinomas of the breast, lung, bladder, esophageal squamous cell carcinomas and oral squamous cell carcinomas. Myeov DNA amplification and overexpression was detected in several carcinoma cell lines, however, hardly any MYEOV protein could be detected using specific antibodies in Western blot analysis. The 5 untranslated region (5UTR) of the myeov gene is long, encompasses four upstream AUG codons (uAUGs) and is predicted to fold in a strong secondary structure. These features are common among mRNAs regulated by their 5UTR and suggest that MYEOV protein synthesis might be regulated at a posttranscriptional level. These findings prompted us to investigate the possible role of the myeov 5UTR in controlling its protein level, and the possibility of MYEOV protein synthesis to be mediated by an internal ribosome entry site (IRES). Here we show that initial experiments using mono- and bicistronic reporter constructs supported this view. However, further examination by in vitro transcription/translation assays, Northern blot analysis and the application of promoterless constructs revealed promoter activity in the myeov 5UTR. Despite this strong promoter activity, we did not find any translation products. Our experiments showed that this was due to the presence of uAUGs codons present in the myeov 5UTR. DNA and RNA transfection of the wild type and mutated 5UTR, where the uAUGs were mutated to AAG, confirmed that these uAUGs abrogate translation of the reporter gene as well as the myeov gene. Alternative splicing mechanisms in specific cell types and/or developmental stages may be a way to evade this translation control.

Level thesis:degree_level

thesis.doctoral

Grantor dc:publisher

Universität Heidelberg

Year

2005

Author dc:creator

• Alves de Almeida, Rogério

Contributors dc:contributor

• Buselmaier, Werner

Repository record source_url

http://www.ub.uni-heidelberg.de/archiv/5285

OAI identifier oai:identifier

oai:archiv.ub.uni-heidelberg.de:5285