Lithium supports actin bundle formation

The in vitro influence of Li+ on the filament to filament interactions in polymeric actin samples was investigated. Actin filament bundling, induced by α-actinin, polyethylene glycol 6000 (PEG 6K) or ovalbumin, is enhanced in the presence of lithium ions. Light scattering, low shear viscosity and low speed centrifugation experiments showed that the complete as well as the partial replacement of KCl by LiCl in the assembly medium favours the formation of actin filament three-dimensional structures. We suggest that both Li+ nucleating activity on actin assembly and Li+ stabilizing effect on actin polymers could account for the obtained results. Since F-actin scaffoldings are relevant for cell functioning the influence of lithium ions on side to side actin filament interactions could represent a new further step of lithium's biological activity.