Targeting Ras palmitoylation for the treatment of cancer

Lay summary: Proteins can be thought of as molecular machines that carry out work within cells. Protein activity can be regulated through the reversible attachment of certain chemical groups to specific amino acids within proteins. Protein palmitoylation is one such modification and has been shown to control both the activity and location of proteins within mammalian cells. Protein palmitoylation regulates a wide range of processes within the body including how cells grow and divide. 20-30% of all cancers are caused by changes in the amino acid sequence of a protein called Ras. These changes cause Ras to be permanently active, which drives unregulated cell growth. To function correctly in the cell, Ras must be palmitoylated. Therefore, small molecule drugs that block Ras palmitoylation will likely be useful for treating cancer as they will block excess Ras activity preventing cells from growing and dividing. This Ph.D. is concerned with understanding the way that Ras is palmitoylated with a view to developing new drugs for the treatment of cancer.

Scientific summary: In humans, the genes HRAS, NRAS and KRAS encode three closely related proteins frequently mutated in cancer promoting unregulated cell growth. Ras proteins function as molecular switches transmitting signals from cell surface growth factor receptors to intracellular effector proteins cycling between inactive (GDP bound) and active (GTP) states. Oncogenic Ras activity requires the protein to be localised to the inner face of the plasma membrane suggesting strategies that cause Ras to be mistargeted within the cell may be effective in treating cancer. Ras membrane association is facilitated by two lipid post-translational modifications – farnesylation (all Ras isoforms) followed by palmitoylation (H-Ras, N-Ras and K-Ras4A only) – at specific cysteine residues located at the protein’s C-terminus. Ras is palmitoylated in the Golgi by an enzymatic complex consisting of zDHHC9 and GOLGA7. Molecules that bind to the surface of Ras and prevent it from interacting with the zDHHC9-GOLGA7 complex would be expected to selectively block Ras palmitoylation. In recent years, several groups have identified small molecules, peptides and Affimers that bind to shallow pockets on the surface of Ras blocking its activity. Yet, their effect on Ras palmitoylation has not been determined. In this Ph.D., the student will investigate the molecular basis of Ras palmitoylation using a range of biochemical, biophysical and pharmacological techniques. The novel, fundamental insights into Ras biology that will be gained are expected to open new drug discovery opportunities for the treatment of cancer.

Techniques: The student will gain experience of mammalian cell culture, molecular biology techniques (including PCR and site-directed mutagenesis), pharmacology, acyl-RAC (assay for determining protein palmitoylation levels), co-immunoprecipitation and pulldown experiments, SDS-PAGE and Western blotting, protein expression (bacteria, yeast) and purification as well as Hydrogen-Deuterium Exchange (HDX) mass spectrometry.

Supervisors: Dr. Fraser is an experienced biochemist whose research is concerned with understanding how molecular events at the cell membrane are regulated by palmitoylation [e.g. 1-4]. Dr. Masson is a world-leading expert in the field of Hydrogen-Deuterium Exchange (HDX) mass spectrometry and is interested in dynamic protein-protein interactions [e.g. 5-8].

For informal enquiries about the project, contact Dr. Niall Fraser, [Email Address Removed]

For general enquiries about the University of Dundee, contact [Email Address Removed]

Our research community thrives on the diversity of students and staff which helps to make the University of Dundee a UK university of choice for postgraduate research. We welcome applications from all talented individuals and are committed to widening access to those who have the ability and potential to benefit from higher education.

QUALIFICATIONS

Applicants must have obtained, or expect to obtain, a UK honours degree at 2.1 or above (or equivalent for non-UK qualifications), and/or a Masters degree in a relevant discipline. For international qualifications, please see equivalent entry requirements here: www.dundee.ac.uk/study/international/country/.

English language requirement: IELTS (Academic) overall score must be at least 6.5 (with not less than 5.5 in reading, listening, speaking and 6.0 in writing). The University of Dundee accepts a variety of equivalent qualifications and alternative ways to demonstrate language proficiency; please see full details of the University’s English language requirements here: www.dundee.ac.uk/guides/english-language-requirements.

APPLICATION PROCESS

Step 1: Email Dr. Niall Fraser, [Email Address Removed] to (1) send a copy of your CV and (2) discuss your potential application and any practicalities (e.g. suitable start date).

Step 2: After discussion with Dr Fraser, formal applications can be made via our direct application system. When applying, please follow the instructions below:

Candidates must apply for the Doctor of Philosophy (PhD) degree in Medicine (3 year) using our direct application system: apply for a PhD in Medicine.

Please select the study mode (full-time/part-time) and start date agreed with the lead supervisor.

In the Research Proposal section, please:

-         Enter the lead supervisor’s name in the ‘proposed supervisor’ box

-         Enter the project title listed at the top of this page in the ‘proposed project title’ box

In the ‘personal statement’ section, please outline your suitability for the project selected.