Effect of Actin Filament on Deformation-Induced Ca²⁺ Response in Osteoblast-Like Cells

Abstract

Under the influence of mechanical environment, bone structure is formed and maintained by adaptive remodeling that involves osteoclastic resorption and osteoblastic formation. In the mechanotransduction system in osteoblasts, it is believed that intracellular calcium plays a fundamental role and cytoskeletal actin filament is a crucial component for the signal transduction process. To clarify the role of actin filament in deformation-induced Ca²⁺ signaling, osteoblast-like cells (MC3T3-E1) with different actin filament densities controlled by cytochalasin D were subjected to tensile strain in vitro. The change in intracellular Ca²⁺ concentration labeled by fluo-3 was observed using a confocal laser-scanning microscope. As a result, the disruption of the actin filament was found to significantly suppress the deformation-induced Ca²⁺ response that was regulated according to the degree of actin filament organization. This result indicates that the actin filament is indispensable for the quantitative regulation of Ca²⁺ signaling in response to a mechanical stimulus in osteoblasts.