26 April 2018

Sugar Control Cell Absorption of Bad Cholesterol

Basic Research

Sugar or carbohydrates affect cells’ ability to absorb and remove bad cholesterol – LDL in the blood. This new knowledge is the result of research conducted at the University of Copenhagen, which for the first time at cell level has established that carbohydrates on proteins increase cells’ ability to absorb cholesterol by up to five times.

When we eat fatty food, we increase the level of bad cholesterol – also known as LDL – in the body. Bad cholesterol is related to fat deposits in the blood vessels, and therefore the body attempts to remove the bad cholesterol by absorbing it into the cells.

A receptor in the body thus creates a passage for the bad cholesterol into the cell. Now Danish researchers have arrived at the surprising discovery that carbohydrates increase the function of this receptor.

‘We knew that the cell’s receptor affects the amount of cholesterol a cell is able to absorb. But it is completely new to us that the carbohydrates attached to the receptor hold a vital function. Without the carbohydrates the cell’s ability to absorb cholesterol decreases. We have thus outlined the importance of sugar to an important mechanism in our physiology, which in the long run can increase our understanding of the processes that lead to high cholesterol levels and, for example, kidney diseases and neurodegenerative diseases’, says Assistant Professor Katrine Schjoldager from the Copenhagen Center for Glycomics at the Department of Cellular and Molecular Medicine.

Advanced Techniques Generate Vital New Knowledge
Using advanced techniques such as the gene-editing tool CRISPR and mass spectrometry for protein sequencing, the researchers first identified the gene that determines whether carbohydrates attach to a cell’s receptor.

They then removed the gene, ensuring that no carbohydrates were attached to the receptor. This enabled the researchers to compare the reaction of the receptor to cholesterol with and without carbohydrates, respectively. The study showed that the receptors with carbohydrates attached were up to five times as good at absorbing bad cholesterol than the receptors with no carbohydrates attached.

‘At the Copenhagen Center for Glycomics we do fundamental research, which in particular focusses on generating knowledge on how carbohyrates affect the health of the body. First and foremost, this study has provided us with the insight that carbohydrates play a far greater role in cholesterol absorption than previously assumed. In addition, the study stresses the importance of research into carbohydrates, as it affects virtually all the molecular and physiological processes in the body’, says Katrine Schjoldager and stresses that the tests described here were made in cell cultures and therefore cannot be compared directly to cholesterol in the human body.

The study results have just been published in the scientific Journal of Biological Chemistry. It was conducted in cooperation with researchers from Rigshospitalet, Aarhus University and researchers from Spain. With funding from the Alfred Benzon Foundation the Copenhagen Center for Glycomics is inviting leading experts from all over the world to a symposium (27-30 August 2018) on carbohydrates and medicine at SUND. Here the researchers will discuss how new discoveries like these can be used in further research.

The project is funded by the Lundbeck Foundation, and last year Katrine Schjoldager received DKK 5 million from the Novo Nordisk Foundation (Excellence Project for Young Researchers) for pursuing the importance of carbohydrates in metabolism.

The scientific journal will be published 18 may. Read the article online.

Assistant Professor Katrine Schjoldager, email: schjoldager@sund.ku.dk, phone: 35 33 55 41
Press Officer Kristine Snedker, email: kristine.snedker@sund.ku.dk, phone: 23 64 88 42