Hypoxia alters biophysical properties of endothelial cells via p38 MAPK- and Rho kinase-dependent pathways.
Hypoxia alters the barrier function of the endothelial cells that line the pulmonary vasculature, but underlying biophysical mechanisms remain unclear. Using rat pulmonary microvascular endothelial cells (RPMEC) in culture, we report herein changes in biophysical properties, both in space and in time, that occur in response to hypoxia. We address also the molecular basis of these changes. At the level of the single cell, we measured cell stiffness, the distribution of traction forces exerted by the cell on its substrate, and spontaneous nanoscale motions of microbeads tightly bound to the cytoskeleton (CSK). Hypoxia increased cell stiffness and traction forces by a mechanism that was dependent on the activation of Rho kinase. These changes were followed by p38-mediated decreases in spontaneous bead motions, indicating stabilization of local cellular-extracellular matrix (ECM) tethering interactions. Cells overexpressing phospho-mimicking small heat shock protein (HSP27-PM), a downstream effector of p38, exhibited decreases in spontaneous bead motions that correlated with increases in actin polymerization in these cells. Together, these findings suggest that hypoxia differentially regulates endothelial cell contraction and cellular-ECM adhesion.
An
Steven S
SS
Physiology Program, Department of Environmental Health, Harvard School of Public Health, Boston, MA, USA.
Pennella
Corin M
CM
Gonnabathula
Achuta
A
Chen
Jianxin
J
Wang
Ning
N
Gaestel
Matthias
M
Hassoun
Paul M
PM
Fredberg
Jeffrey J
JJ
Kayyali
Usamah S
US
D000818:Animals; D001692:Biological Transport / Q000502:physiology; D055592:Biophysical Phenomena; D001703:Biophysics; D002448:Cell Adhesion / Q000502:physiology; D002478:Cells, Cultured; D003599:Cytoskeleton / Q000378:metabolism; D005109:Extracellular Matrix / Q000378:metabolism; D055551:HSP27 Heat-Shock Proteins; D006360:Heat-Shock Proteins / Q000378:metabolism; D000860:Hypoxia / Q000378:metabolism*; D047908:Intracellular Signaling Peptides and Proteins; D008863:Microspheres; D009363:Neoplasm Proteins / Q000378:metabolism; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D051381:Rats; D020545:Respiratory Mucosa / Q000166:cytology / Q000378:metabolism*; D013718:Tensile Strength / Q000502:physiology*; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*; D054460:rho-Associated Kinases
D055551:HSP27 Heat-Shock Proteins; D006360:Heat-Shock Proteins; C486114:Hspb1 protein, rat; D047908:Intracellular Signaling Peptides and Proteins; D009363:Neoplasm Proteins; D017346:Protein Serine-Threonine Kinases; D054460:rho-Associated Kinases; D048051:p38 Mitogen-Activated Protein Kinases