Project description:Nuclear lamin B1 constitutes one of the major structural proteins in the lamina mesh. We silenced the expression of lamin B1 by RNA interference in the colon cancer cell line DLD-1 and showed a dramatic redistribution of H3K27me3 from the periphery to a more homogeneous nuclear dispersion; in addition we observed an increased frequency of micronuclei and nuclear blebs. By 3D-FISH analyses, we demonstrate that the volume and surface of chromosome territories were significantly larger in LMNB1-depleted cells, suggesting that lamin B1 is required to maintain chromatin condensation in interphase nuclei. These changes led to a prolonged S-phase due to activation of Chk1 and telomere attrition. Finally, silencing of LMNB1 resulted in extensive changes in alternative splicing of multiple genes and in a higher number of enlarged nuclear speckles. Taken together, our results suggest a mechanistic role of the nuclear lamina in the organization of chromosome territories, maintenance of genome integrity and proper gene splicing. This dataset includes the comparison of gene transcripts between cells with silenced lamin B1 and empty vector negative control transfected cells. Single cell clones were generated after transfection of DLD-1 cells with shRNA against LMNB1. Two different constructs were used. For clone number 2, three replicates of the the same clone were included in the analysis. The rest of the clones correspond to biological replicates. As control, we used three different cones transfected with an empty vector control as well as wild type cells.