Expression of 15-lipoxygenases in pulmonary arteries after hypoxia.

OBJECTIVE

We have previously reported that subacute hypoxia upregulates and activates the steady state expression of pulmonary artery 15-lipoxygenase (15-LOX). However, there are two 15-LOX isoenzymes, 15-LOX-1 and 15-LOX-2, which are expressed in pulmonary arteries that have not been previously studied. In the present study, we identified the differential expression of the two isoenzymes in normoxic or hypoxic intrapulmonary arteries of rats, pulmonary artery endothelial cells (PAECs) and pulmonary artery smooth muscle cells (PASMCs) from the main branches of pulmonary artery of neonatal bovines.

METHODS

Immunohistochemistry, in situ hybridisation, RT-PCR, and Western blotting were employed to identify the differential expression of the two isoenzymes.

RESULTS

15-LOX-1 was expressed in both normoxic and hypoxic rat arteries. In contrast, 15-LOX-2 was hardly detectable in normoxic vessels by immunohistochemistry and Western blotting, but it was detected in hypoxic arteries. In cultured bovine pulmonary artery cells, 15-LOX-1 and 15-LOX-2 were found to be different in cellular distribution. The expression of 15-LOX-1 was stronger in PAECs than in PASMCs, whereas, 15-LOX-2 was weaker in PAECs than in PASMCs. Moreover, the expressions of both 15-LOX isoenzymes increased dramatically after hypoxia.

CONCLUSIONS

These results suggest that both isoenzymes of 15-LOXs are upregulated after hypoxia.