Plectin-mediated mitochondrial fusion is necessary for hepatocellular carcinoma cell migration promoted by higher matrix stiffness.

Increased matrix stiffness is a key physical signal affecting the migration of hepatocellular carcinoma (HCC) cells, and mitochondrial dynamics and function also play important roles in cell migration. Plectin may influence mitochondrial dynamics and function through its cytoskeletal cross-linking function. However, the relationship between these two factors remains unclear. HCC cells were seeded on hydrogels with stiffness of 7 kPa and 53 kPa, respectively, to investigate the effects of matrix stiffness on plectin expression, mitochondrial dynamics and function, and cell migration. Moreover, plectin was knocked down to further assess its specific impacts on mitochondrial dynamics and function, as well as cell migration under different matrix stiffness. Compared with 7 kPa, high matrix stiffness (53 kPa) promotes HCC cell migration by upregulating plectin expression, promoting mitochondrial fusion, and enhancing mitochondrial function. Under high matrix stiffness, plectin knockdown weakens mitochondrial fusion capacity and function, reducing cell migration. Subsequently, we treated cells with carbonyl cyanide 3-chlorophenylhydrazone (CCCP) to inhibit mitochondrial function. This treatment significantly suppressed cell migration on high- matrix stiffness. Then, when mitochondrial dynamics were disrupted by the mitochondrial fusion inhibitor 8 (MFI8), mitochondrial function was compromised, and cell migration decreased. High matrix stiffness enhances mitochondrial function by driving mitochondrial fusion through increasing plectin expression, thereby promoting the migration of HCC cells. It provides new insights into the mechanobiological mechanisms underlying matrix stiffness affected HCC cell migration.