High resolution Hi-C analysis in S. pombe reveals fundamental elements of genome architecture [Expression Array]

Eukaryotic genomes are folded into three-dimensional structures that govern diverse hromosomal procsses. Studeis in Drosophila and mammals have revealed large self-associating tomological domains whose borders are enriched in cohesin/CTCF factors that are required for long-range intrations. However, mechanisms governing higher-order folding of chromatin fivbers and the exact function of cohesin in this process remain poor understood. Here we perform Hi-C to explore the organization of the Schizosaccharomyces pombe genome at high-resolution, which despite its small size comprises fundamental features found in higher eukaryotes. Our analyses reveal that in addition to determinants of Rabl-like chromosome architecture, smaller locally interacting regions of chromatin, referred to as globules, are a distinctive features of S. pombe chromosome organization. This feature of chromatin architecture requires a function of cohesin distinct from its role in sister chromatid cohesion. Cohesin is enriched at globule boundaries and its loss causes disruption of local globule structure and global chromosome territories. Heterochromatin, which selectively loads cohesin at specific loci including pericentromric and subtelomeric domains, is dispensable for globule formation but uniquely impacts genome organization through chromatin compaction by enforcing Rabl configuration. Agilent 60mer oligonucleotide custom array containing probes spanning large portion of chromosome 2 at 50bp resolution was used to profile expression levels in mutant cells and to compare them to levels in wild type cells.