A small molecule probe which can be stealthily deployed to activate a hypoxic response has been identified by University of Dundee scientists. Hypoxic response is a process which can help to fight a range of conditions including stroke, angina, colitis and brain injuries.

The Dundee team, led by Professor Alessio Ciulli in the School of Life Sciences, used cutting-edge techniques to develop the chemical probe, called VH298. It offers highly targeted access to the parts of the cell which regulate hypoxia, known as the hypoxic signalling pathway.

“Using a small molecule like this offers a highly targeted option to control the hypoxic pathway, and one which can sneak in under the cell’s natural defences to perform its work, a bit like a molecular commando,"

said Professor Ciulli.

Active Hypoxic Signalling

Active hypoxic signalling can be both good and bad, depending on context. In diseases like cancer it can be a bad thing as it can help tumor cells to survive and prosper.

On the other hand, a hypoxic response can provide therapeutic benefits in conditions such as ischaemic injuries to the brain or heart, including stroke, and anemia due to chronic kidney disease or chemotherapy.

Being able to control the hypoxic signalling pathway offers the prospect of finding new drugs which could be deployed in those cases. Existing methods include genetic knockouts which affect the entire pathway and chemical tools which interfere with multiple processes, and until now it had been hard to be more selective in picking a single target.

“The difficulty with some of the existing methods of tackling this pathway are that they affect stages which are also involved in other processes, meaning you are potentially triggering side effects, which makes it harder to control the overall outcomes,” said Professor Ciulli.

“We have identified a stage of the pathway that is very specific and doesn’t have this broad range of activity. By targeting it we can be much more specific in the actions we are triggering in the cell.

This is important as a chemical probe because it means we can make better measurements of cause and effect and build more information about how hypoxia works and how we may be able to control it. It also offers a potentially drug target in itself.

The difference in approach between for example gene knockouts and our small molecule method is a bit like between blowing up the whole factory or sneaking someone in to take out the little bit that you want to."

The use of small molecules like this is a growing area of drug development, offering the prospect of highly specific treatments for many conditions. Successfully identifying and developing suitable small molecules, however, is extremely complex.

Julianty Frost et al. Potent and selective chemical probe of hypoxic signalling downstream of HIF-α hydroxylation via VHL inhibition Nature Communications (2016). DOI: 10.1038/ncomms13312

Image: University of Dundee

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