HYPEROXIA-RESPONSIVE PROTEINS IN RAT PULMONARY MICROVASCULAR ENDOTHELIAL-CELLS

Exposure to high partial pressures of oxygen are toxic to the lung, an d much of the damage observed is related to injury of the pulmonary mi crovasculature. In this study, ave evaluated the response of the pulmo nary microvascular endothelial cell to high oxygen concentrations, usi ng two-dimensional protein gel electrophoresis as a direct molecular a ssay of differences between cells exposed to room air or hyperoxia. We observed a differential expression of five specific proteins within 2 4 h of a hyperoxic insult that we termed hyperoxia-responsive proteins . After 4 h of hyperoxia there was a decrease in two of the proteins. From 8 to 24 h we observed a repression of a third and an induction of the other two proteins. One of the induced proteins was also increase d by heat shock and hydrogen peroxide and has characteristics similar to heat shock protein (HSP) 32 (hemeoxygenase 1). Western analysis usi ng an antibody specific to rat heme oxygenase 1 verified that this oxy gen-responsive protein is heme oxygenase 1. The response of the other four hyperoxia-responsive proteins appears to be specific to oxygen an d not a general stress response, since they were not changed in respon se to heat shock or hydrogen peroxide. Based on RNA inhibitor and puls e chase experiments, these changes may result from transcriptional/pos ttranscriptional mechanisms or hyperoxia-dependent protein turnover.