Journal of Proteomics & Bioinformatics
Open Access
ISSN: 0974-276X
+44 1223 790975
ISSN: 0974-276X
+44 1223 790975
Manuela A A Ayee and Irena Levitan
University of Illinois at Chicago, USA
Scientific Tracks Abstracts: J Proteomics Bioinform
Cell volume regulation is a fundamental property of all mammalian cells. Numerous signaling pathways are known to be activated by cell swelling and to contribute to cell volume homeostasis. Cellular biomechanics and membrane tension have long been proposed to couple cell swelling to signaling pathways; however, the impact of swelling on these parameters has yet to be fully elucidated. In this study, we utilize atomic force microscopy (AFM) under isotonic and hypotonic conditions to measure the mechanical properties of human aortic endothelial membranes. From AFM force/displacement curves, we obtain estimates of membrane elastic modulus, which reflects the stiffness of the sub-membrane cytoskeleton complex and the force required for membrane tether formation, reflecting membrane tension and membrane cytoskeleton attachment. We find that hypotonic swelling results in significant stiffening of the membrane region of endothelial cells, without a corresponding change in membrane tension or membrane-cytoskeleton attachment. Furthermore, depolymerization of F-actin in the cytoskeleton, which as expected results in a dramatic decrease in the cellular elastic modulus of both the membrane and the deeper cytoskeleton, indicating a collapse of the cytoskeleton scaffold, does not abrogate swelling-induced stiffening of the membrane, instead this stiffening is enhanced. We propose that the hypotonically induced membrane stiffening should be attributed to an increase in hydrostatic pressure that results from an influx of solutes and water into the cells. Most importantly, our results suggest that increased hydrostatic pressure, rather than changes in membrane tension, could be responsible for activating volume sensitive mechanisms in hypotonically swollen cells. Recent Publications 1. Ayee M A A, LeMaster E, Teng T, Lee J and Levitan I (2018) Hypotonic challenge of endothelial cells increases membrane stiffness with no effect on tether force. Biophysical Journal 114(4):929-938. 2. Barbera N, Ayee M A A, Akpa B S and Levitan I (2017) Differential effects of sterols on ion channels: stereospecific binding vs. stereospecific response. Current Topics in Membranes 80:25-50. 3. Ayee M A A, LeMaster E, Shentu T P, Singh D K, Barbera N, Soni D, Tiruppathi C, Subbaiah P V, Berdyshev E, Bronova I, Cho M, Akpa B S and Levitan I (2017) Molecular-scale biophysical modulation of an endothelial membrane by oxidized phospholipids. Biophysical Journal 112(24):325-338. 4. Ayee M A A and Levitan I (2016) Paradoxical impact of cholesterol on lipid packing and cell stiffness. Frontiers in Bioscience, Landmark Edition 21:1245-59. 5. Ayee M A A, Roth C and Akpa B S (2016) Structural perturbation of a dipalmitoylphosphatidylcholine (DPPC) bilayer by warfarin and its bolaamphiphilic analogue: A molecular dynamics study. Journal of Colloid and Interface Science 468:227-237.