Hypoxia inducible factor (HIF)-2 alpha is required for the development of the catecholaminergic phenotype of sympathoadrenal cells.
The basic helix-loop-helix transcription factor, hypoxia inducible factor (HIF)-2alpha has been implicated in the development of the catecholaminergic phenotype in cells of the sympathoadrenal (SA) lineage; however, the underlying mechanisms and HIF-2alpha targets remain unclear. Using an immortalized rat adrenomedullary chromaffin cell line (MAH cells) derived from a fetal SA progenitor, we examined the role of HIF-2alpha in catecholamine biosynthesis. Chronic hypoxia (2% O(2), 24 h) induced HIF-2alpha in MAH cells but expression of the rate-limiting enzyme, tyrosine hydroxylase (TH) and catecholamine levels were unaltered. Interestingly, HIF-2alpha depleted MAH cells showed dramatically lower (5-12 times) levels of dopamine and noradrenaline compared with wild-type and scrambled controls, even in normoxia (21% O(2)). This was correlated with a marked reduction in the expression of DOPA decarboxylase (DDC) and dopamine beta hydroxylase (DbetaH) but not TH. Chromatin immunoprecipitation assays revealed that HIF-2alpha was bound to the DDC gene promoter which contains two putative hypoxia response elements. These data suggest that a basal level of HIF-2alpha function is required for the normal developmental expression of DDC and DbetaH in SA progenitor cells, and that loss of this function leads to impaired catecholamine biosynthesis.
Brown
Stephen T
ST
Department of Biology, McMaster University, Hamilton, Ontario, Canada. brownst@mcmaster.ca
Kelly
Kevin F
KF
Daniel
Juliet M
JM
Nurse
Colin A
CA
D000313:Adrenal Medulla / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D002395:Catecholamines / Q000096:biosynthesis / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D002461:Cell Line, Transformed; D019439:Chromaffin Cells / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D000860:Hypoxia / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D010641:Phenotype; D051381:Rats; D013564:Sympathetic Nervous System / Q000166:cytology / Q000473:pathology / Q000502:physiology*; D014446:Tyrosine 3-Monooxygenase / Q000096:biosynthesis; D000099162:Endothelial PAS Domain-Containing Protein 1
D051792:Basic Helix-Loop-Helix Proteins; D002395:Catecholamines; D014446:Tyrosine 3-Monooxygenase; D000099162:Endothelial PAS Domain-Containing Protein 1