Effect of cell membrane tension on the lifetime and size of mature clathrin-coated pits and their spatial distribution

Clathrin-mediated endocytosis is the most characterized pathway for cells to internalize diverse receptor-bound cargo, such as proteins, nanoparticles, and viruses. However, the effect of membrane tension on clathrin-coated pit (CCP) maturation remains inadequately characterized. This study aimed to determine the effect of membrane tension on CCP maturation both spatially and temporarily, which remains a controversial and elusive issue. We obtained the sizes and spatial distributions of CCPs by the structured illumination microscopy of fixed cells and observed CCP lifetimes in live cells by total internal reflection fluorescence microscopy. The processes of CCP maturation and abortion were reproduced numerically through Monte Carlo simulation. The results showed that the growth time of CCP was more reasonably proportional to its volume rather than its surface area. We further investigated the spatial distribution of the membrane tension and size of CCPs, finding a significant positive correlation between the membrane tension and the size of mature CCPs spatially. This indicates that the CCPs tend to enrich in the highest-tension region, especially the mature ones. These results agreed with our numerical prediction that the CCP structure grew larger to overcome a higher energy barrier caused by higher background cell membrane tension. Our findings enhance the understanding of CCP maturation dynamics and underscore the importance of membrane tension in regulating CCP development.