Coordinated Arp2/3-mediated actin branching and myosin-dependent force generation in membrane-cytoskeleton remodeling.

The Arp2/3 (Actin-Related Protein 2/3) complex nucleates branched actin networks, while myosin motors generate force and reorganize actin through ATP-dependent motor activity. Their coordination is central to membrane remodeling, but the underlying mechanisms differ substantially among cellular processes and organisms. In this review, we distinguish direct molecular coupling from indirect mechanical coupling and signaling cross-talk. We also separate mechanisms established in fungal systems from those supported in mammalian cells. Across endocytosis, migration, secretion, membrane repair, and membrane fusion, Arp2/3 primarily determines where and how branched networks are nucleated, whereas polymerizing actin filaments generate protrusive or invaginating force. Distinct myosin isoforms then contribute membrane anchoring, contractile tension, network remodeling, or cargo transport. We further discuss membrane and cortical tension, retrograde flow, actin turnover, mTOR and Rho signaling, disease relevance, and unresolved questions. This mechanistic framework clarifies which aspects of Arp2/3-myosin coordination are experimentally demonstrated and which remain context-dependent models.