T. Brucei, Nup-1 Depletion

Organization of the genome into compacted chromatin is a eukaryotic innovation facilitating increased sophistication in transcriptional regulation. In metazoa coiled-coil lamin proteins are major components of the chromatin organizer at the nuclear periphery and maintain nuclear integrity. While identifiable lamin homologues are restricted to metazoans, morphologically analogous structures maintaining nuclear organization in other eukaryotic lineages are known, but the molecular constituents remain undefined. Trypanosoma brucei NUP-1 is a large coiled-coil protein associated with fibrils at the inner face of the nuclear envelope. Using transcriptome analysis in combination with RNA interference and various imaging techniques, we demonstrate that NUP-1 forms a stable immobile cage around the nucleus, is required for viability and nuclear structural integrity, directs the positional organization of nuclear pore complexes, and serves to organize chromatin and specifically repress genes located at the nuclear periphery involved in immune evasion. Based on architectural similarity and functionality, we propose that NUP-1 is a novel, highly divergent lamin The effect of Nup-1 depletion on the transcriptome was examined in three independent experiments (A, B, & C). T. brucei cultures were either treated with RNAi (plus) or left untreated (minus) and RNA was extracted from each sample at the indicated time point (0h, 6h, 12h, 24h, or 48h). Two color microarrays were performed comparing treated and untreated samples at each time point. Dye swaps were performed and are indicated. Replicates of t=12h and t=24h for sample B were also included.