While chromosomes fill the nuclear space as decondensed chromosome territories during interphase, they are dramatically re-structured into compact rod-shaped rigid bodies during mitosis. The aim of my work is to elucidate the molecular mechanisms underlying this cell cycle-dependent chromosome reorganization. Unlike previous studies, I plan to focus on a yet poorly characterized chromosomal domain defined as ‘chromosome periphery’. I first plan to establish a detailed map of the proteins that target to the chromosome periphery in human cells, applying both high-resolution three-dimensional microscopy and superresolution fluorescence imaging techniques as well as molecular biology techniques, including chromatin immunoprecipitation combined with next generation sequencing (ChIP-seq) analysis. The combination of these approaches will provide me with information on different scales, first at the cell biological level and second at the DNA sequence level, to obtain a complete picture of the localization of the proteins that may organize the chromosome periphery. I will then investigate the functional relevance of chromosome periphery components in mitotic chromosome morphogenesis by RNAi screening in tissue culture cells. I expect that this work will provide insight into how a protein network sets up a chromosomal domain and how such a domain can contribute to the formation of mitotic chromosomes.