G) Microtubule perturbations impair H3K9me3 redistribution during HSPC differentiation. Microtubule-modifying agents were added to culture medium between 48 and 72 hours. Cells were fixed and analyzed after 72 hours of culture. For each indicated treatment, one representative nucleus is presented. Inverted images of equatorial Z stacks of DAPI (left panel) and H3K9me3 (right panel) are shown. Scale bar: 5 µm. H) H3K9me3 signal dispersion significantly increases in non-treated cells between 48h (n=139/3 donors) and 72h (n=148/3 donors) of culture. At 72h, the dispersion is similar in non-treated and blebbistatin-treated cells (n=124/ 3 donors). By contrast, H3K9me3 signal dispersion is significantly reduced compared with non-treated cells after treatment with nocodazole and blebbistatin (n=55, 2donors), taxol (n= 109, 3 donors) and ciliobrevin-D (n=144, 3donors) to a level attained by non-treated cells at 48 hours, demonstrating that microtubules affect H3K9me3 redistribution during HSPC differentiation. Bars correspond to mean ± SD; ****:p<0.0001; n.s: non significant; Mann Whitney test. 