How does CLIC-1 insert into lipid membranes in healthy and tumour cells?

Cancer is a leading cause of disease worldwide. In 2012 approximately 14 million new cases were diagnosed, and there were 8.2 million cancer related deaths, with the number of new cases expected to rise about 70% over the next two 20 years.
The main challenge in cancer treatment is how to design selective drugs targeting exclusively tumour cells. Ion channels, and chloride channels in particular, are key target for potential drugs, but specificity towards tumour cells still remains a problem.

CLIC-1 has emerged as a promising candidate because it localises to the plasma membrane only in tumour cells. In healthy cells it can exist as both cytoplasmic soluble protein or integral membrane embedded intracellular ion channel. This unusual equilibrium is regulated by reactive oxidative species (ROS) and pH changes, common features of tumour cells. Two members of this family, CLIC1 and CLIC4, have been directly implicated in tumour development and identified as novel therapeutic targets.

The goal of this project is to understand the mechanism of CLIC1 insertion into lipid membranes and membrane mimetic systems using solution Nuclear Magnetic Resonance (NMR) in combination with Circular Dichroism and other biophysical tools. Initially, different protein constructs will be screened for favourable in vitro lipid insertion using biochemical assays. State-of-the-art NMR methods will be applied to characterize with atomic detail the soluble and membrane bound states of CLIC1, as well as the mechanism of insertion.

A second part of the project aims to understand the chloride transport function of CLIC-1 and its modulation by drugs. We intend to do use a multidisciplinary approach that integrates X-ray crystallography, solution NMR, electron microscopy and in-cell fluorescence microscopy.

Any mechanistic information obtained for CLIC1 will be of great interest for the development of conformation-specific pharmacological inhibitors and regulators of CLIC1 that could lead to new avenues for cancer treatment.