I. Mechanisms of Plasma Membrane Repair
II. Ca2+-Dependent Lysosomal Exocytosis Mediates Endocytosis and Wound Healing
Part I: Mechanisms of Plasma Membrane Repair
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Dr. Norma Andrews overviews the mechanisms of cellular plasma membrane repair. As she describes, a lesion is followed by a Ca2+-dependent movement of vesicles to the plasma membrane. By studying how the Trypanosoma cruzi parasite enters the cell, Andrews’ laboratory discovered that an increase of intracellular calcium was triggering lysosomal fusion to the plasma membrane. This unexpected observation allowed them to conclude that upon an injury to the plasma membrane, a Ca2+ influx induces lysosomal exocytosis mediated repair. This research demonstrates that lysosomes are not only responsible for the degradation of material that comes inside the cell through endocytosis, but also have an important role in plasma membrane repair.
In her second talk, Andrews further explains how Ca2+-dependent exocytosis of lysosomes aids membrane repair. Her laboratory showed that after lysosomal exocytosis, an injury to the plasma membrane would also trigger a Ca2+-dependent endocytosis that is required for the repair mechanism. Andrews laboratory showed that lysosomes release the enzyme acid sphingomyelinase (ASM) which induce the endocytosis required for plasma membrane repair.
Dr. Norma Andrews is a professor at the University of Maryland, College Park. She obtained her PhD degree from the University of Sao Paulo, Brazil in 1983, and continued her postdoctoral training at New York University. In 1990, Andrews joined the faculty at Yale University and in 2009 her laboratory moved to the University of Maryland, where she was chair of the Molecular Genetics Department from 2009 to 2014. Her laboratory studies the cell biology of intracellular parasites and the mechanism of plasma membrane repair. While studying the molecular mechanisms of Trypanosoma cruzi infection, her laboratory discovered the Ca2+-dependent exocytosis of lysosomes that followed an injury to the plasma membrane.
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Andrews, N.W, et al. (2015) Above the fray: Surface remodeling by secreted lysosomal enzymes leads to endocytosis-mediated plasma membrane repair. Seminars in Cell and Developmental Biology, 45:10-7