Cienciaes.com: Cholesterol, a cellular porter. We spoke with Mairena Martín López

2017-05-19 13:19:20

In recent years, cholesterol has gained a reputation that is, in some respects, undeserved. It is true that when its blood levels are excessively high, especially when it binds to certain proteins and forms LDL lipoproteins, the danger grows that its accumulation will block the flow of blood through the blood vessels and, as a consequence, the cells of those cells. organs that are affected by the lack of irrigation, die. This is how cholesterol is, on some occasions, the cause of a heart attack or stroke.

However, as our guest, Mairena Martín López, Professor of Biochemistry and Molecular Biology at UCLM and principal investigator of the Ciudad Real Neurochemistry Group (GNCR), comments today, cholesterol is good and necessary. To begin with, it is an essential component in the membranes of animal cells, to which it provides consistency and flexibility. We know that cell membranes are the outer border that separates, protects and communicates with the environment. In our bodies, and in the rest of the animals, this cell border must be flexible to allow movement. Without it, as in plant cells, the membranes would be more rigid and movements impossible.

Cholesterol is also the base substance that allows the synthesis of certain hormones and vitamins, such as vitamin D.

Although our cells can synthesize cholesterol, we must also consume it with foods such as cheese, eggs, meat, sausages, etc. Although, once again, you have to be restrained and not abuse these foods so as not to awaken the negative side of that molecule.

As you can see, there are many benefits of cholesterol, but there are still properties that scientists are trying to discover. One of these tasks is being investigated by the Ciudad Real Neurochemistry Group together with researchers from Pompeu Fabra University, whose results have been published in Nature Communications.

In a previous program, Mairena Martín had explained to us the basic concepts of the mechanism by which a cell receives an external stimulus, detects it and transmits information to the interior so that a reaction is produced according to it. Messages arrive from the outside in the form of certain molecules, such as adenosine, which bring information about a stimulus. The message reaches the surface of a cell and is picked up by a receptor located in the membrane, the receptor is a special molecule with a custom anchor system, into which the messenger is inserted. When the union occurs, the receptor is activated and sends a signal to the interior of the cell, where the message causes an adequate response to the perceived signal.

Cholesterol, being a very abundant component on the surface of the cell, it turns out that it is not a mere spectator in the process of delivery, reception and response, but can actively intervene in it. Cholesterol also finds active sites on adenosine receptors and binds to them. Thus, when an external molecule, carrying a message destined for the interior of the cell (a message that can be a movement of a muscle, a thought, etc.), reaches the cell surface and seeks the corresponding anchorage in the receptor of the membrane, to bind to it, it may happen that this anchor is already occupied by cholesterol and then delivery cannot be made. In this way, cholesterol acts as a “gatekeeper” that prevents, or facilitates, the passage of the stimulus and, therefore, the cell’s reaction. This change that can be good or bad, depending on the stimulus that arrives.

The result of the study is important in future research on degenerative diseases, such as Alzheimer’s. It has been proven that very early in Alzheimer’s disease, when symptoms are barely perceptible and the affected person has small memory lapses, to which he does not give importance, an alteration occurs in adenosine receptors. It is precisely these receptors that cholesterol binds to and blocks. This circumstance opens up possible avenues for research to find formulas for early diagnosis or new treatments for this disease.
I invite you to listen to Mairena Martín López, Professor of Biochemistry and Molecular Biology at UCLM and principal investigator of the Ciudad Real Neurochemistry Group (GNCR).

References.
Guixà-González R & José L. Albasanz, et al. Membrane cholesterol access into a G-protein-coupled receptor. born Commun. 8, 14505 doi: 10.1038/ncomms14505 (2017).