TY - JOUR TI - Centering and symmetry breaking in confined contracting actomyosin networks AU - Ierushalmi, Niv AU - Malik-Garbi, Maya AU - Manhart, Angelika AU - Abu Shah, Enas AU - Goode, Bruce L AU - Mogilner, Alex AU - Keren, Kinneret A2 - Pfeffer, Suzanne R VL - 9 PY - 2020 DA - 2020/04/21 SP - e55368 C1 - eLife 2020;9:e55368 DO - 10.7554/eLife.55368 UR - https://doi.org/10.7554/eLife.55368 AB - Centering and decentering of cellular components is essential for internal organization of cells and their ability to perform basic cellular functions such as division and motility. How cells achieve proper localization of their organelles is still not well-understood, especially in large cells such as oocytes. Here, we study actin-based positioning mechanisms in artificial cells with persistently contracting actomyosin networks, generated by encapsulating cytoplasmic Xenopus egg extracts into cell-sized ‘water-in-oil’ droplets. We observe size-dependent localization of the contraction center, with a symmetric configuration in larger cells and a polar one in smaller cells. Centering is achieved via a hydrodynamic mechanism based on Darcy friction between the contracting network and the surrounding cytoplasm. During symmetry breaking, transient attachments to the cell boundary drive the contraction center to a polar location. The centering mechanism is cell-cycle dependent and weakens considerably during interphase. Our findings demonstrate a robust, yet tunable, mechanism for subcellular localization. KW - actomyosin contraction KW - artificial cell KW - subcellular localization KW - centering KW - symmetry breaking JF - eLife SN - 2050-084X PB - eLife Sciences Publications, Ltd ER -