We have updated our privacy policy. If you have any question, contact us at privacy@scicrunch.org. Dismiss and don't show again

Searching across hundreds of databases

Our searching services are busy right now. Your search will reload in five seconds.

Forgot Password

If you have forgotten your password you can enter your email here and get a temporary password sent to your email.

Hypoxia-inducible factor 1alpha is regulated by the mammalian target of rapamycin (mTOR) via an mTOR signaling motif.

Tumors that form as a result of heightened mammalian target of rapamycin (mTOR) signaling are highly vascularized. This process of angiogenesis is regulated through hypoxia-inducible factor (HIF)-mediated transcription of angiogenic factors. It is recognized that inhibition of mTOR with rapamycin can diminish the process of angiogenesis. Our work shows that activation of mTOR by Ras homologue enriched in brain (Rheb) overexpression potently enhances the activity of HIF1alpha and vascular endothelial growth factor (VEGF)-A secretion during hypoxia, which is reversed with rapamycin. Mutants of Rheb, which do not bind guanine nucleotide (D60K, D60V, N119I, and D122N) and are unable to activate mTOR, inhibit the activity of HIF when overexpressed. We show that regulatory associated protein of mTOR (Raptor) interacts with HIF1alpha and requires an mTOR signaling (TOS) motif located in the N terminus of HIF1alpha. Furthermore, a mutant of HIF1alpha lacking this TOS motif dominantly impaired HIF activity during hypoxia and was unable to bind to the co-activator CBP/p300. Rapamycin treatments do not affect the stability of HIF1alpha and modulate HIF activity via a Von Hippel-Lindau (VHL)-independent mechanism. We demonstrate that the high levels of HIF activity in cells devoid of TSC2 can be reversed by treatments with rapamycin or the readdition of TSC2. Our work explains why human cancers with aberrant mTOR signaling are prone to angiogenesis and suggests that inhibition of mTOR with rapamycin might be a suitable therapeutic strategy.

Pubmed ID: 17502379 RIS Download

Mesh terms: Amino Acid Motifs | Animals | Antibiotics, Antineoplastic | Cell Hypoxia | Cell Line, Tumor | Guanine Nucleotides | Humans | Hypoxia-Inducible Factor 1, alpha Subunit | Mice | Monomeric GTP-Binding Proteins | Mutation, Missense | Neoplasms | Neovascularization, Pathologic | Neuropeptides | Protein Binding | Protein Kinases | Protein Structure, Tertiary | Signal Transduction | Sirolimus | TOR Serine-Threonine Kinases | Tumor Suppressor Proteins | Vascular Endothelial Growth Factor A | Von Hippel-Lindau Tumor Suppressor Protein | p300-CBP Transcription Factors

Publication data is provided by the National Library of Medicine ® and PubMed ®. Data is retrieved from PubMed ® on a weekly schedule. For terms and conditions see the National Library of Medicine Terms and Conditions.

We have not found any resources mentioned in this publication.