Rheological behavior of actin stress fibers in myoblasts after nanodissection: Effectsofoxidative stress.

Abstract

Cytoskeletal stress fibers (SFs) play important roles in cell rheology. Oxidative stress, as caused by excessive hydrogen peroxide (H2O2) or other reactive oxygen species, can cause cell damages via multiple pathways. Stress fiber mechanics in an oxidative environment is important for the understanding of such pathological challenges. This investigation aimed to assess the effects of oxidative stress on the mechanical conditions of single stress fibers in living cells. Utilizing a femtosecond (fs) laser to sever single SFs inside living C2C12 myoblasts, we investigated the retraction rheology of the severed single SFs to probe the mechanical conditions of the cells and the effect of H2O2 on them. The equilibration time of the retraction of the severed SFs became longer in the H2O2-treated myoblasts compared to the control. The initial gap between the two severed ends of the SF immediately after fs laser severing was larger in the H2O2-treated groups. This suggested that H2O2 exposure could promote the pre-stress in individual SFs in-situ. Oxidative stress could significantly affect the mechanical conditions of cytoskeletal SFs in myoblasts. The results were consistent with cell stiffness measured on single myoblasts under oxidative stress.