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A HIF1α Regulatory Loop Links Hypoxia and Mitochondrial Signals in Pheochromocytomas
Jul 25, 2005, 17:13, Reviewed by: Dr.
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The authors found that loss of two genes that cause two distinct pheochromocytoma syndromes (the genes SDHB and SDHD, which encode the subunits B and D of succinate dehydrogenase, a component enzyme of the energy and respiratory system in mitochondria) also triggers a HIF1α response.
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By PLoS Genetics,
Pheochromocytomas (also known as paragangliomas) are highly vascular tumors that arise from mutations in a diverse and apparently unrelated group of tumor suppressor genes and oncogenes. The authors show here that three of the genes that cause hereditary pheochromocytomas have a common function. Specifically, these genes, VHL, SDHB, and SDHD, encode proteins that regulate a transcription factor known as hypoxia-inducible factor 1 subunit α (HIF1α), which helps cells adapt to hypoxia (low oxygen levels).
VHL is named after its role in von Hippel-Lindau disease (VHL), an inherited disorder that predisposes individuals to pheochromocytomas and other tumors. Previous studies showed that when cells lack VHL, HIF1α is not degraded, resulting in a signal that resembles hypoxia.
The authors found that loss of two genes that cause two distinct pheochromocytoma syndromes (the genes SDHB and SDHD, which encode the subunits B and D of succinate dehydrogenase, a component enzyme of the energy and respiratory system in mitochondria) also triggers a HIF1α response.
The researchers further discovered that high H1F1α levels can suppress SDHB. This suggests a regulatory loop that further enhances the �hypoxia� profile of tumors. This finding provides a rational explanation for the shared features of these distinct syndromes and may be relevant for other cancers with a prominent hypoxic pattern. 
- Dahia PL, Ross KN, Wright ME, Hayashida C, Santagata S, et al. (2005) A HIF1α Regulatory Loop Links Hypoxia and Mitochondrial Signals in Pheochromocytomas. PLoS Genet 1(1): e8
PDF of Article
DOI: 10.1371/journal.pgen.0010008
Copyright: � 2005 Dahia et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License.
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