Résumé
Changes in gene expression in response to external signals provide a key mechanisms for the regulation of higher eukaryotic cell functions. The importance of transcriptional control in the response of cells to growth factors and cytokines has been extensively documented, but gene expression has also been shown to be controlled at other levels, such as the stability of mRNA in the cytoplasm, its localization and translation. By contrast to transcriptional control, little is known of the contribution of pre-mRNA nuclear processing to the regulation of gene expression, as most of our knowledge of pre-mRNA processing in vivo is indirect, being inferred from comparisons of transcription rates and levels of mRNA accumulation.