Poster abstracts
Poster number 49 submitted by Jon Fritz
Annexin A2 mediates plasma membrane repair post-injury in lung epithelial cells
Jonathan R. Fritz (Interdisciplinary Biophysics Program), Sanjana Suresh (Division of Pulmonary, Critical Care and Sleep Medicine, Department of Internal Medicine), Ian D. Bentley (Division of Pulmonary, Critical Care and Sleep Medicine, Department of Internal Medicine), Samir N. Ghadiali (Department of Biomedical Engineering), Noah L. Weisleder (Department of Physiology & Cell Biology), Joshua A. Englert (Division of Pulmonary, Critical Care and Sleep Medicine, Department of Internal Medicine)
Abstract:
Physical forces generated during mechanical ventilation can damage the plasma membranes of alveolar epithelial cells and trigger active plasma membrane (PM) repair to reseal membrane disruptions and prevent cell death. In many mammalian cell types, calcium influx through injury-induced membrane disruptions initiates active PM repair mechanisms. One such repair mechanism involves Annexin A2 (AnxA2) translocation to PM injury sites to mediate vesicle delivery, patch formation, and membrane bending. Recently, we have shown that global AnxA2-knockout mice have increased injury following ventilator-induced lung injury (VILI) compared to wild-type mice. However, the mechanisms by which AnxA2 mediates PM repair in lung cells are not well understood. In this study, we transiently transfected primary human alveolar type I (ATI) cells with GFP-tagged AnxA2 to visualize single-cell AnxA2 organization and translocation after laser ablation injury. As expected, absent extracellular calcium injury dampens AnxA2-GFP fluorescence at the site of PM injury. To demonstrate that AnxA2 is essential for PM repair in alveolar epithelial cells post-injury, we isolated primary alveolar type II (AT2) cells from AnxA2 wild-type (WT) and knockout (KO) mouse. Using a dye entry assay, we show that isolated AnxA2 KO cells exhibit greater membrane injury compared to WT cells. Furthermore, by using a global injury model such as microparticle bombardment, we show greater membrane injury in AnxA2 KO cells vs. WT cells at a multicellular level. AnxA2 is a promising therapeutic target for mitigating plasma membrane damage and lung injury during MV.
Keywords: lung, repair, annexin