The role of lamin Bl for the maintenance of nuclear structure and function

Abstract

Lamins constitute an integral struc-tural component of the nuclear lamina. However, their impact on the structure and stability of chromosome territories, and on the regulation of gene expression is explored to a lesser extent. By 3D-FISH, Camps and colleagues showed that lamin Bl (LMNBl) is required for proper chromosome conden-sation in interphase nuclei, and defi-ciency of LMNBl triggers the relocation of the epigenetic mark of facultative het-erochromatin, H3K27me3, toward the interior of the nucleus. Additionally, LMNBl repression slowed cellular growth due to S-phase delays and increased genomic instability. Finally, silencing of LMNBl resulted in enlarged nuclear speckles and in extensive changes in alternative splicing of multiple genes. Altogether, the data suggest a central role of LMNBl for the condensation of chro-mosome territories, for the distribution of heterochromatin, and for the regula-tion of gene expression and splicing.