Biomolecular condensation driven by liquid–liquid phase separation (LLPS) is key to assembly of membraneless organelles in numerous crucial pathways. It is largely unknown how cellular structures or components spatiotemporally regulate LLPS and condensate formation. Here we reveal that cytoskeletal dynamics can control the condensation of p62 bodies comprising the autophagic adaptor p62/SQSTM1 and poly-ubiquitinated cargos. Branched actin networks are associated with p62 bodies and are required for their condensation. Myosin 1D, a branched actin-associated motor protein, drives coalescence of small nanoscale p62 bodies into large micron-scale condensates along the branched actin network. Impairment of actin cytoskeletal networks compromises the condensation of p62 bodies and retards substrate degradation by autophagy in both cellular models and Myosin 1D knockout mice. Coupling of LLPS scaffold to cytoskeleton systems may represent a general mechanism by which cells exert spatiotemporal control over phase condensation processes.

由液-液相分离（LLPS）驱动的生物分子缩合是许多关键途径中无膜细胞器组装的关键。目前尚不清楚细胞结构或成分如何时空调节 LLPS 和冷凝物形成。在这里，我们揭示了细胞骨架动力学可以控制包含自噬接头 p62/SQSTM1 和多聚泛素化货物的 p62 体的凝结。分支肌动蛋白网络与 p62 体相关，并且是其缩合所必需的。肌球蛋白 1D 是一种分支肌动蛋白相关运动蛋白，可沿着分支肌动蛋白网络驱动小型纳米级 p62 体聚结成大型微米级凝聚物。在细胞模型和肌球蛋白 1D 敲除小鼠中，肌动蛋白细胞骨架网络的损伤会损害 p62 体的凝结并延缓自噬引起的底物降解。LLPS支架与细胞骨架系统的耦合可能代表细胞对相凝结过程施加时空控制的一般机制。