Characterisation of multiple regulatory domains spanning the major transcriptional start site of the FUS gene, a candidate gene for motor neurone disease.

Fused-In-Sarcoma (FUS) is a candidate gene for neurological disorders including motor neurone disease and Parkinson׳s disease in addition to various types of cancer. Recently it has been reported that over expression of FUS causes motor neurone disease in mouse models hence mutations leading to changes in gene expression may contribute to the development of neurodegenerative disease. Genome evolutionary conservation was used to predict important cis-acting DNA regulators of the FUS gene promoter that direct transcription. The putative regulators identified were analysed in reporter gene assays in cells and in chick embryos. Our analysis indicated in addition to regulatory domains 5' of the transcriptional start site an important regulatory domain resides in intron 1 of the gene itself. This intronic domain functioned both in cell lines and in vivo in the neural tube of the chick embryo including developing motor neurones. Our data suggest the interaction of multiple domains including intronic domains are involved in expression of FUS. A better understanding of the regulation of expression of FUS may give insight into how its stimulus inducible expression may be associated with neurological disorders.

An evaluation of a SVA retrotransposon in the FUS promoter as a transcriptional regulator and its association to ALS.

Genetic mutations of FUS have been linked to many diseases including Amyotrophic Lateral Sclerosis (ALS) and Frontotemporal Lobar Degeneration. A primate specific and polymorphic retrotransposon of the SINE-VNTR-Alu (SVA) family is present upstream of the FUS gene. Here we have demonstrated that this retrotransposon can act as a classical transcriptional regulatory domain in the context of a reporter gene construct both in vitro in the human SK-N-AS neuroblastoma cell line and in vivo in a chick embryo model. We have also demonstrated that the SVA is composed of multiple distinct regulatory domains, one of which is a variable number tandem repeat (VNTR). The ability of the SVA and its component parts to direct reporter gene expression supported a hypothesis that this region could direct differential FUS expression in vivo. The SVA may therefore contribute to the modulation of FUS expression exhibited in and associated with neurological disorders including ALS where FUS regulation may be an important parameter in progression of the disease. As VNTRs are often clinical associates for disease progression we determined the extent of polymorphism within the SVA. In total 2 variants of the SVA were identified based within a central VNTR. Preliminary analysis addressed the association of these SVA variants within a small sporadic ALS cohort but did not reach statistical significance, although we did not include other parameters such as SNPs within the SVA or an environmental factor in this analysis. The latter may be particularly important as the transcriptional and epigenetic properties of the SVA are likely to be directed by the environment of the cell.