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HIF prolyl hydroxylase-3 regulates actin polymerisation and hypoxia-induced motility and invasion

Heiserich, Lisa (2011) HIF prolyl hydroxylase-3 regulates actin polymerisation and hypoxia-induced motility and invasion. PhD thesis, University of Glasgow.

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Abstract

Limited oxygen availability (hypoxia) influences cell migration and invasion, but the underlying mechanisms are poorly understood. Much of the cellular response to hypoxia is regulated by a family of Hypoxia Inducible Factor (HIF) prolyl hydroxylases (PHD1-3), each of which is thought to regulate specific pathways.Their activity is dependent on the availability of oxygen and alpha-ketoglutarate but despite intensive studies their activity in vivo and their substrates are poorly defined. In this study we performed a quantitative proteomic screen to identify new substrates of PHDs. Co-immunoprecipitations using FLAG-tagged PHDs were performed under hypoxia to trap the enzyme-substrate interactions, and binding partners were identified by mass spectrometry. Actin was identified to interact with PHD3 specifically under hypoxia. Subsequently two defined prolyl residues in beta-actin were shown to be hydroxylated. Hypoxia-induced rearrangement of the actin cytoskeleton was shown to be dependent on PHD3 activity as a knockdown of PHD3 was sufficient to increase the intracellular G- to F-actin ratio. An increase in cell migration and invasion was also found to be dependent on PHD3 activity. Mutation of both hydroxylated prolyl residues led to a similar phenotype regarding actin rearrangement and cell migration. Using constantly active HIF-mutants, we could show that these PHD3-dependent pathways are independent of HIF. All together, this study shows a pro-invasive pathway linking HIF-independent oxygen-sensing pathways and actin signalling. However, the mechanism of how hypoxia-induced actin rearrangement leads to increased migration and invasion remains to be elucidated.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Keywords: hypoxia, prolyl hydroxylases, actin cytoskeleton, migration
Subjects: R Medicine > RC Internal medicine > RC0254 Neoplasms. Tumors. Oncology (including Cancer)
Colleges/Schools: College of Medical Veterinary and Life Sciences > Institute of Cancer Sciences
Supervisor's Name: Gottlieb, Dr. Eyal
Date of Award: 2011
Depositing User: Lisa Heiserich
Unique ID: glathesis:2011-2421
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 15 Mar 2011
Last Modified: 10 Dec 2012 13:55
URI: http://theses.gla.ac.uk/id/eprint/2421

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