Fat is important for the human body not only as a way to store energy, but also as an essential building block. That is because the membranes that surround each of our cells, and their internal organelles, are composed primarily of fat.
However, not all fats are the same. Saturated fats, which are abundant in animal fats, tend to form “rigid” cell membranes. Conversely, unsaturated fats, such as those found in vegetable oils, tend to form “fluid” membranes. For the cells to function properly, membranes must have just the right degree of fluidity to allow proteins to move within the membranes, interact with each other and generally function properly.
The fats that make up the membranes are obtained primarily via the diet. This leads to the following challenge: how to regulate membrane composition to compensate for dietary variations? Researchers at the University of Gothenburg (Sweden), led by Prof. Marc Pilon, have discovered that the small nematode C. elegans, a popular model organism used for research throughout the world, have a special protein that is specifically required to deal with dietary saturated fats. C. elegans worms that express this protein, called PAQR-2, can thrive on diets rich in saturated fats. In contrast, feeding saturated fats to mutant worms lacking PAQR-2 causes their membranes to become too rigid, which is accompanied by growth arrest then death. In other words: the protein PAQR-2 is essential to survive on a diet containing saturated fats.
The next step in their research was to investigate whether humans also have a protein that does the same job. Sequence comparisons show that the worm PAQR-2 is very similar to two human proteins called AdipoR1 and AdipoR2, which are often described in the scientific literature as proteins that protect against diabetes but for which the precise cellular functions has remained elusive since their discovery.
Using cell lines, the scientists found that AdipoR2 is also essential for human cells to prevent membrane rigidification by saturated fats. The authors conclude that the human AdipoR2 and the worm PAQR-2 are evolutionarily conserved proteins essential to prevent toxic membrane rigidification by saturated fats. Think about that next time you spread butter on your toasts!
An early version of this work appeared online in the journal PLoS Genetics on Sept. 8, 2017. The final version of the article appeared on Sept. 14, 2017. Here is the link: https://doi.org/10.1371/journal.pgen.1007004
BY: CARINA ELIASSON