Cholesterol is associated with an increased risk of heart attack or stroke when it is present in our blood at high levels.
But cholesterol also plays a positive role in our health. The molecule sits at the outer layer of our cells, known as the cell membrane, and contributes to important biological processes like cell communication.
A team led by Dr Shanshan Kou, Professor Adam Mechler, Professor Brian Abbey and Dr Arif Siddiquee have used a new scientific technique to examine the composition of synthetic cell membranes at the nanoscale.
Their findings have identified where cholesterol is found in synthetic cell membranes, and why.
“Scientists have been unable to determine where cholesterol resided in the cell membrane, or how it influenced membrane structure and function,” explains Dr Kou. “And, because it is a small molecule, it has been challenging to investigate its role without affecting its function.”
The research team used a technique called spectroscopic scanning near-field optical microscopy to image the synthetic membranes without disrupting them. This type of microscopy captures three-dimensional images of materials at the nanoscale, along with new chemical data.
“By examining cholesterol in this way, we discovered that it is not evenly distributed in the synthetic membrane, but instead forms localized, cholesterol-rich islands. Islands like these form in cell membranes, and play a role in natural and pathogenic membrane processes,” says Dr Kou.
The team also identified molecular-scale interactions between cholesterol and the main membrane components, which offer insight into how the islands form in synthetic membranes. “The islands form spontaneously, which indicates that such processes are key to membrane development in biological cells,” says Dr Kou.
“Cholesterol is important to our health, so it is vital that we understand its role in our body. Our findings point towards a better understanding of how cell membranes function and the biochemical machinery of life.”
Read the paper.