you are here... Home | Staff | A - Z
Nuclear structure and RNA processing
We are studying the functional organisation of the cell nucleus and the mechanism of pre-mRNA splicing in mammalian cells. The importance of understanding nuclear organisation is underlined by recent evidence showing that multiple human diseases, including inherited genetic disorders, malignancies and viral infections, modify or disrupt subnuclear bodies (see ref. 1). Our aim is to understand how subnuclear structures assemble, how splicing factors and other proteins are targeted to them and how factors traffic in the nucleoplasm between separate structures. In parallel, we are carrying out detailed functional studies on novel human spliceosome proteins we have identified (ref. 2). We aim to characterise their respective roles in the splicing mechanism and their interactions with other nuclear factors. In many cases we are able to use the reagents generated in the biochemical studies of splicing factors to help our in vivo analyses of nuclear structure.
The major subunits of spliceosomes are the RNA-protein complexes called snRNPs. In vivo, snRNPs show a complex and dynamic localisation pattern (see ref. 1). We have shown recently that newly assembled splicing snRNPs accumulate in coiled bodies prior to speckles when they are first imported into the nucleus (ref. 3). The data indicate a specific pathway whereby snRNPs interact with separate nuclear structures in a defined temporal sequence. We are studying the dynamic behaviour of snRNPs and other nuclear proteins by expressing genes fused to fluorescent protein tags and performing time lapse microscopy on living cells. We have developedprotocols allowing the isolation of intact subnuclear bodies from human cells, including nucleoli and coiled bodies (see figure). We are currently using mass spectrometry to characterise the protein components of these isolated nuclear bodies (in collaboration with Matthias Mann and co-workers).