Rapid adaptation of endocytosis, exocytosis and eisosomes after an acute increase in membrane tension in yeast cells

Abstract

During clathrin-mediated endocytosis in eukaryotes, actin assembly is required to overcome large membrane tension and turgor pressure. However, the molecular mechanisms by which the actin machinery adapts to varying membrane tension remain unknown. In addition, how cells reduce their membrane tension when they are challenged by hypotonic shocks remains unclear. We used quantitative microscopy to demonstrate that cells rapidly reduce their membrane tension using three parallel mechanisms. In addition to using their cell wall for mechanical protection, yeast cells disassemble eisosomes to buffer moderate changes in membrane tension on a minute time scale. Meanwhile, a temporary reduction of the rate of endocytosis for 2 to 6 minutes, and an increase in the rate of exocytosis for at least 5 minutes allow cells to add large pools of membrane to the plasma membrane. We built on these results to submit the cells to abrupt increases in membrane tension and determine that the endocytic actin machinery of fission yeast cells rapidly adapts to perform clathrin-mediated endocytosis. Our study sheds light on the tight connection between membrane tension regulation, endocytosis and exocytosis.