Reassignment of the EPB4 center dot 1 gene to 1p36 and assessment of its involvement in neuroblastomas

Objectives EPB4.1 has been previously mapped to human chromosome 1p33-p34.2 . In contradiction to this chromosomal location, we have mapped EPB4.1-1p36 by using fluorescence in situ hybridization and radiation hybrid mapping. In neuroblastomas, deletions of the telomeric end of chromosome 1 (1p36) ar e the most common genetic aberration. Methods We investigated whether genetic aberrations of EPB4.1 can be detect ed in some neuroblastomas by analyzing 72 tumours for EPB4.1 mutation, expr ession, and alternative splicing pattern. Furthermore, EPB4.1 protein from a neuroblastoma cell line was studied for its subcellular localization. Results Sequence changes could be detected in 14 out of 72 neuroblastomas, including missense, silent, and intronic changes. Duplex RT-PCR analysis re vealed a subset of 11 tumours expressing significantly low levels of EPB4.1 . Significant EPB4.1 sequence changes that were detected included an exon 4 G/A missense mutation (amino acid: V/I) that was shown to be associated wi th absence of wild-type EPB4.1 expression (3 tumours), an exon 8 G/A missen se mutation (V/M) (1 tumour), and an intronic sequence change that was show n to be associated with the presence of an aberrant transcript (1 tumour). Splicing pattern analysis revealed that all EPB4.1 transcripts from tumours exclude exon 3, a splicing pattern for generating the 135 kDa isoform. EPB 4.1 cDNA cloned from a neuroblastoma cell line produced a 135-kDa protein w ith a cytoplasm/membrane localization. Conclusions Out of 72 neuroblastomas we have identified 11 tumours with imp aired EPB4.1 expression and 5 tumours with significant sequence changes. We also found that the 135 kDa isoform is the main EPB4.1 product in neurobla stoma. EPB4.1 cDNA from a neuroblastoma cell line produced a 135-kDa protei n and displayed a cytoplasm/membrane localization in transfected cells.