Hypoxic induction of adrenomedullin in cultured human umbilical vein endothelial cells.
OBJECTIVE
The current study evaluated the hypoxic induction of adrenomedullin gene expression and secretion, and its mechanism in cultured human umbilical vein endothelial cells (HUVEC).


METHODS
HUVEC were exposed to hypoxia or normoxia as controls for 1 to 24 h. Using Northern blot analysis and a radioimmunoassay, we evaluated adrenomedullin expression in HUVEC. The transcriptional component of adrenomedullin gene regulation was assessed by nuclear run-off experiments, and adrenomedullin mRNA half-life was measured by actinomycin D experiments.


RESULTS
We found that hypoxic conditions (1-3% oxygen) significantly increased adrenomedullin mRNA and protein in HUVEC. This increase was inversely proportional to oxygen tension and was reversible upon re-exposure to a 21% oxygen environment Nuclear run-off experiments revealed the enhanced transcriptional rate of adrenomedullin gene. Next, actinomycin D experiments revealed the enhanced adrenomedullin mRNA stability.


CONCLUSIONS
These results indicate that hypoxia increases adrenomedullin gene expression and secretion in HUVEC by transcriptional and post-transcriptional mechanisms. Hypoxic induction of adrenomedullin may play a pathophysiological role in the vascular systems.
Ogita
T
T
Department of Internal Medicine, School of Medicine, University of Tokyo, Japan. ogita-tky@umin.ac.jp
Hashimoto
E
E
Yamasaki
M
M
Nakaoka
T
T
Matsuoka
R
R
Kira
Y
Y
Fujita
T
T
D053607:Adrenomedullin; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D000860:Hypoxia / Q000235:genetics / Q000378:metabolism*; D010455:Peptides / Q000235:genetics / Q000378:metabolism*; D020871:RNA Stability; D012333:RNA, Messenger / Q000378:metabolism; D011863:Radioimmunoassay; D014158:Transcription, Genetic; D014471:Umbilical Veins / Q000378:metabolism* / Q000473:pathology
D010455:Peptides; D012333:RNA, Messenger; D053607:Adrenomedullin