Scientists know that lipids, a group of naturally-occurring molecules that includes fats, regulate how well the body uses energy from food. The body stores excess energy in the form of fat within lipid droplets in cells, and releases lipids from the droplets when cells are running low on energy.

However, scientists do not clearly understand how lipid droplets interact with other parts of the cell. This is because traditional, animal-based methods of studying these interactions only look at their effects and not at what happens while they take place.

Abdou Rachid Thiam, an EU-funded researcher with France’s Centre National de la Recherche Scientifique (National Center of Scientific Research), has developed a way to study directly how proteins interact with the fats in lipid droplets to consume them or store them better. His research has revealed information that could help prevent serious health conditions and virus-based diseases.

He says: “Lipid metabolism is at the core of body energy regulation. Its impairment has dramatic consequences for health, influencing obesity, cardio-vascular diseases and diabetes.” 

In addition, there is a class of virus that develops around the body using lipid droplets, which includes the viruses that cause hepatitis C and dengue. So his work could also help scientists prevent these diseases taking hold in people infected with the viruses, he adds.

His research has shown how cells restrict the reactions between lipids and proteins to regulate energy use and storage, and what mechanisms the reactions use to control transport of proteins within a cell to store or release more lipids.

Focusing on the roles of individual cell proteins, Thiam looked at proteins that are part of the mechanism for transporting other proteins in and around cells.

He discovered that these proteins change the very thin barrier between the fat in the lipid droplet and the watery fluid inside the rest of the cell.

The change allows a cell’s enzymes – which trigger the body’s chemical reactions – to access the fat in the lipid droplets to obtain the energy they need to operate, influencing how much fat the body stores, and how much it releases for energy. 

Through the microscope

Thiam’s innovation in studying protein-lipid droplet reactions was to use microfluid-based emulsions. These are mixtures of oil and water in very small quantities, which gives them special properties that help scientists see more clearly how molecules behave.

“Lipids are fats suspended in body fluids, so it seemed obvious to use this approach,” Thiam says.

His innovation sprang from his work with Nobel Laureate James E. Rothman – who discovered how cells transport the material inside them – and lipid droplet specialist Tobias C. Walther, and his own interest in emulsion science. “We bridged different research communities – emulsion science and cell research – for a simple solution to studying cell properties,” he explains.

The emulsion-based approach breaks down the lipid processing and studies each part of it, bit by bit. “The new system allows scientists to isolate part of the reaction to look at the process in detail. It is more precise, more detailed and gives more control of the mechanisms of lipid-protein interaction,” Thiam says.

Thiam’s research has had a strong impact on understanding key steps in regulating lipid droplets in cells, he says. He adds that researchers are beginning to recognise the value of his emulsion-based approach, calling it “an unrivalled mechanism for creating a well-controlled interface” and predicting that it could improve the accuracy of other types of research on the body’s cell reactions.

He has been already offered the opportunity to create his own laboratory to continue with his research at the end of his EU grant. “This is fundamental research,” he says, “It is creating new knowledge that is a springboard to develop practical applications.”