Lamins and other nuclear architectural proteins: emerging roles in the spatial organization of nuclear events

Eukaryotic nuclei have discrete compartments or domains enriched for specific proteins involved in specialised functions such as DNA replication, transcription and RNA splicing. Chromosomes are also organised into defined domains or territories in the nucleus. A major issue concerning nuclear organisation is the identity of the underlying structure or nucleoskeleton and the extent to which the components of this structure are involved in nuclear functions. Important advances have been made in the past few years in understanding the functions of the major architectural proteins in the nucleus. The lamins play essential roles in DNA replication and transcription. Other structural proteins such as nuclear actin are components of chromatin remodelling complexes and mRNA processing complexes. These recent findings open up the exciting possibility that lamins and actin might act to modulate the organisation and functions of nuclear activities