Gene Expression
The ultimate output of cell-cell signaling is changes in gene expression. Transcriptional activation and repression require not only sequence-specific transcription factors, but also more general complexes that alter chromatin structure or recruit the basal transcriptional machinery. We have found that some subunits of such complexes act as adaptors that allow them to contribute to transcriptional regulation by specific signaling pathways (Collns and Treisman, Genes Dev. 2000; Treisman, Development 2001; Janody et al., Development 2003; Janody et al., Genetics 2004; Carrera et al., PNAS 2008; Carrera et al., Mol. Cell. Biol. 2008).

Gene expression can also be regulated post-transcriptionally. We showed that a specific subset of transcripts, including MAP kinase, which codes for a critical signal transduction component, are spliced by a novel mechanism that requires the exon junction complex (Roignant and Treisman, Cell 2010). Many of the genes regulated by this mechanism are located in heterochromatin, raising the intriguing possibility of a connection between chromatin structure and splicing. The exon junction complex also regulates mRNA translation, localization and degradation. We are investigating the different functions and targets of individual subunits of the complex (Roignant et al., in preparation).