Expression of 15‐Lipoxygenases in Hypoxic Pulmonary

Abstract

There are two isoforms of 15-lipoxygenases (15-LOXs), 15-LO-1 and 15-LO-2.We delineated the differential expression of the two isoenzymes in intrapulmonary arteries of normoxic and hypoxic rat, which were identified by immunohistochemical analysis, in situ hybridization, Western blot analysis, immunoelectron microscopy and reverse transcriptase PCR. Meanwhile, cell cultures of pulmonary arterial endothelium cells (PAECs) and smooth muscle cells (PASMCs) treated with hypoxia were also examined. Data showed that 15-LO-1 expressed in intrapulmonary arteries, PAECs and PASMCs in both normoxic and hypoxic rat models with high expression in PAECs. By contrast, 15-LO-2 couldn¡¯t be detected in normoxic group, but detected in hypoxic group with high expression in PASMCs. 15-LO-1 and 15-LO-2 proteins showed different subcellular expression during hypoxia. 15-LO-1 was expressed in cytoplasm whereas 15-LO-2 could hardly be detected during normoxia. Nevertheless, during hypoxia, 15-LO-2 was expressed and 15-LO-1 increased dramatically, which mainly distributed in plasma membrane. Both 15-LOXs mRNAs were detected by RT-PCR and in situ hybridization under both normoxic and hypoxic conditions. These results demonstrated that hypoxia induced expression in both isoforms of 15-LOXs; 15-LO-1 was the predominant isoform in normoxia and 15-LO-2 was a significant synergistic isoenzyme in hypoxia. This work was supported by the NNSFC(¡í.30370578; ¡í.30470752)