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.

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 > School 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: https://theses.gla.ac.uk/id/eprint/2421