J Cell Sci 2016 : doi: 10.1242/jcs.175745
Eukaryotic chromosomes undergo movements involved in the regulation of functional processes such as DNA repair. To better understand the origin of these movements, we use fluorescence microscopy, image analysis and chromosome conformation capture to quantify actin contribution to chromosome movements and interactions in budding yeast. We show that both the cytoskeletal and nuclear actin drive local chromosome movements, independently of Csm4, a putative LINC protein. Inhibition of actin polymerization reduces subtelomeres dynamics, resulting in more confined territories and enrichment in subtelomeric contacts. Artificial tethering of actin to nuclear pores increases both NPC and subtelomere motion. Chromosome loci located away from telomere exhibit reduced motion in the presence of an actin polymerization inhibitor, but were unaffected by the lack of Csm4. We further show that actin is required for locus mobility induced by targeting chromatin remodeler protein Ino80. Correlated to this, DNA repair by homologous recombination is less efficient. Overall, interphase chromosome dynamics is modulated by the additive effects of cytoskeletal actin through forces mediated by the nuclear envelope, and nuclear actin probably through its function in chromatin remodelers.