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The morphology and composition of cholesterol-rich micellar nanostructures determine transmembrane protein (GPCR) activity.

ABSTRACT: We examined model mixed micelles consisting of the nonionic surfactant n-dodecyl-?-D-maltoside, 3-(3-cholamidopropyl)-dimethylammoniopropane sulfonate, and the cholesterol derivative cholesteryl hemisuccinate (CHS) to identify micellar properties that are correlated with the in vitro conformational stability and activity of the human adenosine A?a receptor, a G-protein coupled receptor. Small-angle neutron scattering was used to determine micellar structure and composition as a function of concentration of the various components, and radioligand binding was used as a sensitive probe for receptor activity. Micelles adopted an oblate ellipsoidal morphology and exhibited a reduction in size and change in curvature upon addition of CHS. Our results show a strong correlation between the number of CHS monomers per micelle and the activity of the receptor reconstituted in those micelles. Micelles that yield optimal human adenosine A?a receptor stability closely mimic the cholesterol composition and thickness of mammalian membranes. Thus, successful reconstitution of the receptor is dependent on both specific lipid-protein interactions and the geometry of the micelle environment.

SUBMITTER: O'Malley MA

PROVIDER: S-EPMC3021673 | biostudies-literature | 2011 Jan

REPOSITORIES: biostudies-literature

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The morphology and composition of cholesterol-rich micellar nanostructures determine transmembrane protein (GPCR) activity.

O'Malley Michelle A MA Helgeson Matthew E ME Wagner Norman J NJ Robinson Anne S AS

Biophysical journal 20110101 2

We examined model mixed micelles consisting of the nonionic surfactant n-dodecyl-β-D-maltoside, 3-(3-cholamidopropyl)-dimethylammoniopropane sulfonate, and the cholesterol derivative cholesteryl hemisuccinate (CHS) to identify micellar properties that are correlated with the in vitro conformational stability and activity of the human adenosine A₂a receptor, a G-protein coupled receptor. Small-angle neutron scattering was used to determine micellar structure and composition as a function of conce ...[more]

PMID: 21244820

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Project description:ObjectivePlatelet-rich plasma (PRP) therapy is increasingly popular to treat musculoskeletal diseases, including tendinopathies and osteoarthritis (OA). To date, it remains unclear to which extent PRP compositions are determined by the immune cell and cytokine profile of individuals or by the preparation method. To investigate this, we compared leukocyte and cytokine distributions of different PRP products to donor blood samples and assessed the effect of pro-inflammatory cytokines on chondrocytes.DesignFor each of three PRP preparations (ACP®, Angel™, and nSTRIDE® APS), products were derived using whole blood samples from twelve healthy donors. The cellular composition of PRP products was analyzed by flow cytometry using DURAClone antibody panels (DURAClone IM Phenotyping Basic and DURAClone IM T Cell Subsets). The MESO QuickPlex SQ 120 system was used to assess cytokine profiles (V-PLEX Proinflammatory Panel 1 Human Kit, Meso Scale Discovery). Primary human chondrocyte 2D and 3D in vitro cultures were exposed to recombinant IFN-γ and TNF-α. Proliferation and chondrogenic differentiation were quantitatively assessed.ResultsAll three PRP products showed elevated portions of leukocytes compared to baseline levels in donor blood. Furthermore, the pro-inflammatory cytokines IFN-γ and TNF-α were significantly increased in nSTRIDE® APS samples compared to donor blood and other PRP products. The characteristics of all other cytokines and immune cells from the donor blood, including pro-inflammatory T cell subsets, were maintained in all PRP products. Chondrocyte proliferation was impaired by IFN-γ and enhanced by TNF-α treatment. Differentiation and cartilage formation were compromised upon treatment with both cytokines, resulting in altered messenger ribonucleic acid (mRNA) expression of collagen type 1A1 (COL1A1), COL2A1, and aggrecan (ACAN) as well as reduced proteoglycan content.ConclusionsIndividuals with elevated levels of cells with pro-inflammatory properties maintain these in the final PRP products. The concentration of pro-inflammatory cytokines strongly varies between PRP products. These observations may help to unravel the previously described heterogeneous response to PRP in OA therapy, especially as IFN-γ and TNF-α impacted primary chondrocyte proliferation and their characteristic gene expression profile. Both the individual's immune profile and the concentration method appear to impact the final PRP product.Trial registrationThis study was prospectively registered in the Deutsches Register Klinischer Studien (DRKS) on 4 November 2021 (registration number DRKS00026175).

Dataset Information

The morphology and composition of cholesterol-rich micellar nanostructures determine transmembrane protein (GPCR) activity.

Publications

The morphology and composition of cholesterol-rich micellar nanostructures determine transmembrane protein (GPCR) activity.

Similar Datasets

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