New role for cholesterol in regulating brain receptor!

New role for cholesterol in regulating brain receptor!
 

A study published in the journal Nature Communications, demonstrates that the cholesterol present in cell membranes can interfere with the function of an important brain membrane protein, through a previously unknown mode of interaction. Specifically, cholesterol is capable of regulating the activity of the adenosine receptor, by invading it and accessing the active site.

The adenosine receptor belongs to the GPCR family (G Protein-Coupled Receptors), a large group of proteins located in cell membranes, which are key in the transmission of signals and communication between cells. GPCRs are therefore involved in the majority of important physiological processes, including the interpretation of sensory stimuli such as vision, smell, and taste, the regulation of the immune and inflammatory system, and behaviour modulation.

"Cholesterol is an essential component of neuronal membranes, where GPCRs reside along with other proteins. Interestingly, the levels of cholesterol in the membrane are altered in diseases such as Alzheimer's, where GPCRs like the adenosine receptor play a key role", explains the senior auhtor. "This study has shown that cholesterol can exert direct action on this important family of proteins in neuronal membranes, the GPCRs, and establishes the basis for a hitherto unknown interaction pathway between the cell membrane and proteins", adds the researcher.

Up to now, it was thought that membrane cholesterol could regulate the activity of these proteins through two mechanisms: either by altering the physical properties of the membrane, or by binding to the surface of the protein. In both cases, it was thought that cholesterol could only exercise its modulatory action from outside the protein.

However, by using latest-generation molecular simulations the researchers were able to detect the fact that cholesterol can leave the neuronal membrane and get within the adenosine receptor, in particular accessing the receptor's active site. With this information authors designed an experimental protocol using cell assays to demonstrate that cholesterol is able to modulate the activity of this receptor by accessing its interior.

The results from this study represent a paradigm shift in the relationship between membrane cholesterol and GPCRs in the central nervous system, and open up new avenues of research in fields where the cholesterol-GPCR relationship is essential. It also appears that the cholesterol access pathway into the receptor is an evolutionary footprint. It is therefore necessary to discover whether the molecular mechanism described in this paper is present in other GPCRs and therefore potentially involved in a wide range of central nervous system diseases.

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