Formins and Arp2/3 Reciprocally Regulate Contact Guidance on Aligned Collagen Fibrils.

Motivation: Directed cell migration is essential in many biological processes and is driven by a variety of directional cues, including aligned fibrils in the extracellular matrix (ECM), a phenomenon known as contact guidance. How different cells respond to aligned fibrils and how internal regulators like formins and Arp2/3 control contact guidance is unknown. Methods: In this study, a unique system to assemble aligned collagen fibrils on mica and to transfer them onto controllable substrates is used to probe contact guidance. Results: This fibril alignment system reveals that cytoskeletal regulation through myosin contractility and not receptor expression drives contact guidance ability. Highly contractile cells exhibit high-fidelity contact guidance, weakly contractile cells ignore cues and moderately contractile cells use a mixture of both parallel and perpendicular migration strategies on aligned collagen fibrils. In addition to myosin contractility, formins and Arp2/3 control contact guidance in a reciprocal manner across a variety of cell types. Formins, mediators of linear F-actin structures, enhance contact guidance and Arp2/3, a mediator of branched F-actin structures, diminishes contact guidance. Conclusion: This controlled materials system reveals the importance of both myosin-mediated contractility as well as the antagonistic action of formins and Arp2/3 on contact guidance, providing potential targets to tune contact guidance. Supplementary Information: The online version contains supplementary material available at 10.1007/s12195-025-00868-9.