RRM
2008 Rustbelt RNA Meeting
RRM
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Poster abstracts
Abstract:
In mammalian cells, pre-mRNA splicing factors and other pre-mRNA processing factors are stored in nuclear bodies called nuclear speckles. Proteomic analysis of nuclear speckles reflected enrichment of splicing factors in nuclear speckles and revealed 33 novel speckle proteins including Son1. Son is a large protein (2564 amino acid length) that contains six types of repetitive sequences that cover approximately one-third of its sequence and that are not found in any other protein. This study aims to determine nuclear functions for Son in pre-mRNA transcription and splicing as well as in structural organization of speckles.
We have recently generated rabbit polyclonal antibodies against both the amino- and the carboxy-termini of Son. Immunofluorescence localization of endogenous Son with these antibodies shows colocalization of Son with splicing factor 2/alternative splicing factor (SF2/ASF) in nuclear speckles. In addition, we fused Son with yellow fluorescent protein (YFP) and stably expressed YFP-Son in Hela cells where it also co-localizes with SF2/ASF in nuclear speckles. Interestingly, Hela cells that are treated with Son siRNA oligos show a complete reorganization of nuclear speckle components (including SR proteins and snRNP proteins) from their typical irregular shape into a donut-like shape. Son depleted cells also show a hampered cell growth pattern and an accumulation in G2/M phase of the cell cycle. The altered organization of nuclear speckles and an impeded cell growth pattern observed after Son depletion implicates Son in a novel and essential role in the structural maintenance of nuclear speckles and in cell cycle progression.
References:
1. Saitoh, N., C. S. Spahr, S. Patterson, P. Bubulya, A. F. Neuwald and D. L. Spector. 2004. Proteomic analysis of interchromatin granule clusters. Mol. Biol. Cell. 15:3876-3890
Keywords: nuclear speckles, cell cycle
