Saturday, August 09, 2014

Polyunsaturated Lipids Boost the Brain


New research, published in the August 8, 2014 issue of Science, helps explain the mechanisms through which polyunsaturated fats improve brain health and function. We have known for years that omega-3 fats, in particular, are good for the brain (better memory, lower risk of stroke, and so on), but this study provides new information into these fats improve brain function.

Lipids boost the brain, study finds

Date: August 8, 2014
Source: CNRS (Délégation Paris Michel-Ange)

Summary:
Consuming oils with high polyunsaturated fatty acid content, in particular those containing omega-3s, is beneficial for the health. But the mechanisms underlying this phenomenon are poorly known. Researchers have investigated the effect of lipids bearing polyunsaturated chains when they are integrated into cell membranes. Their work shows that the presence of these lipids makes the membranes more malleable and therefore more sensitive to deformation and fission by proteins.


Membranes containing monounsaturated (left) and polyunsaturated (right) lipids after adding dynamin and endophilin. In a few seconds membranes rich in polyunsaturated lipids undergo many fissions. Credit: © Copyright : Mathieu Pinot

Consuming oils with high polyunsaturated fatty acid content, in particular those containing omega-3s, is beneficial for the health. But the mechanisms underlying this phenomenon are poorly known. Researchers at the Institut de Pharmacologie Moléculaire et Cellulaire (CNRS/Université Nice Sophia Antipolis), the Unité Compartimentation et Dynamique Cellulaires (CNRS/Institut Curie/UPMC), the INSERM and the Université de Poitiers investigated the effect of lipids bearing polyunsaturated chains when they are integrated into cell membranes. Their work shows that the presence of these lipids makes the membranes more malleable and therefore more sensitive to deformation and fission by proteins. These results, published on August 8, 2014 in Science, could help explain the extraordinary efficacy of endocytosis in neuron cells.

Consuming polyunsaturated fatty acids (such as omega-3 fatty acids) is good for the health. The effects range from neuronal differentiation to protection against cerebral ischemia. However the molecular mechanisms underlying these effects are poorly understood, prompting researchers to focus on the role of these fatty acids in cell membrane function.

For a cell to function properly, the membrane must be able to deform and divide into small vesicles. This phenomenon is called endocytosis. Generally, these vesicles allow the cells to encapsulate molecules and transport them.. In neurons, these synaptic vesicles will act as a transmission pathway to the synapse for nerve messages. They are formed inside the cell, then they move to its exterior and fuse with its membrane, to transmit the neurotransmitters that they contain. Then they reform in less than a tenth of a second: this is synaptic recycling.

In the work published in Science, the researchers show that cell- or artificial membranes rich in polyunsaturated lipids are much more sensitive to the action of two proteins, dynamin and endophilin, which facilitate membrane deformation and fission. Other measurements in the study and in simulations suggest that these lipids also make the membranes more malleable. By facilitating the deformation and scission necessary for endocytosis, the presence of polyunsaturated lipids could explain rapid synaptic vesicle recycling.. The abundance of these lipids in the brain could then represent a major advantage for cognitive function.

This work partially sheds light on the mode of action of omega-3. Considering that the body cannot synthesize them and that they can only be supplied by a suitable diet (rich in oily fish, etc.), it seems important to continue this work to understand the link between the functions performed by these lipids in the neuronal membrane and their health benefits.


Story Source:
The above story is based on materials provided by CNRS (Délégation Paris Michel-Ange). Note: Materials may be edited for content and length.


Journal Reference:
M. Pinot, S. Vanni, S. Pagnotta, S. Lacas-Gervais, L.-A. Payet, T. Ferreira, R. Gautier, B. Goud, B. Antonny, H. Barelli. (2014, Aug 8). Polyunsaturated phospholipids facilitate membrane deformation and fission by endocytic proteins. Science; 345(6197): 693. DOI: 10.1126/science.1255288
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The full article is behind a paywall, so here is the abstract.

Polyunsaturated phospholipids facilitate membrane deformation and fission by endocytic proteins


Mathieu Pinot, Stefano Vanni, Sophie Pagnotta, Sandra Lacas-Gervais, Laurie-Anne Payet, Thierry Ferreira, Romain Gautier, Bruno Goud, Bruno Antonny, Hélène Barelli

Editor's Summary:


Bending the benefits of polyunsaturates

We have often heard that it is beneficial to eat polyunsaturated fatty acids. We also know that some organelles such as synaptic vesicles are extremely rich in polyunsaturated lipids. However, what polyunsaturated lipids do in our body is unclear. Using cell biology, biochemical reconstitutions, and molecular dynamics, Pinot et al. show that polyunsaturated phospholipids can change the response of membranes to proteins involved in membrane curvature sensing, membrane shaping, and membrane fission. Polyunsaturated phospholipids make the plasma membrane more amenable to deformation; facilitate endocytosis; and, in reconstitution experiments, increased membrane fission by the dynamin-endophilin complex.

Science, this issue p. 693

Abstract:

Phospholipids (PLs) with polyunsaturated acyl chains are extremely abundant in a few specialized cellular organelles such as synaptic vesicles and photoreceptor discs, but their effect on membrane properties is poorly understood. Here, we found that polyunsaturated PLs increased the ability of dynamin and endophilin to deform and vesiculate synthetic membranes. When cells incorporated polyunsaturated fatty acids into PLs, the plasma membrane became more amenable to deformation by a pulling force and the rate of endocytosis was accelerated, in particular, under conditions in which cholesterol was limiting. Molecular dynamics simulations and biochemical measurements indicated that polyunsaturated PLs adapted their conformation to membrane curvature. Thus, by reducing the energetic cost of membrane bending and fission, polyunsaturated PLs may help to support rapid endocytosis.

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