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Spatial Dynamics of Clathrin-Mediated Endocytosis

Allen Liu (University of Michigan), Xinyu Tan (University of Michigan)

Mechanics and Physics of Biological Cells

Tue 10:45 - 12:15

Barus-Holley 141

Clathrin-mediated endocytosis (CME) represents the primary pathway for cells to regulate signaling receptors and to internalize nutrient receptors. This process occurs continuously on the plasma membrane and the fundamental functional unit of CME is a clathrin-coated pit (CCP). The combination of live cell imaging by total internal reflection fluorescence microscopy and computational image analysis has revealed heterogeneous dynamics of CCPs, but whether CCP dynamics varies spatially is unclear. In order to examine the spatial dynamics, we have employed microcontact printing of extracellular matrix proteins to constrain cell adhesion area and cell shape. By using asymmetric shapes that introduce cell polarity, we found that CCP lifetimes are slower in the front of the cell versus the trailing edge. Interestingly, we found CCPs are enriched at the front and trailing edges of polarized cells. However, such spatially regulated dynamics is not observed on symmetric patterns. Furthermore, on a square pattern, there is a distinct difference in the CCP lifetimes between the peripheral CCPs versus those in the middle of the cells. This radial pattern of CCP dynamics is abolished when cells are treated with a low dose of actin depolymerization drug latrunculin A. Together, we have revealed CME as a spatially regulated cellular process and the dynamics of CCPs depends on the underlying actin cytoskeleton.