Membrane Microviscosity Modulates μ‐Opioid Receptor Conformational Transitions and Agonist Efficacy

Emmerson, Paul J.; Clark, Mary Jo; Medzihradsky, Fedor; Remmers, Ann E.

doi:10.1046/j.1471-4159.1999.0730289.x

Cited by 26 publications

(24 citation statements)

References 45 publications

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“…The receptor, however, is less tightly coupled to G proteins (47) and may depend on cholesterol to aid in this coupling even in non-raft regions of the plasma membrane. This is supported by evidence that cholesterol alone can stabilize receptors in a high affinity state (23), and increasing membrane viscosity with a cholesterol analog has been shown to improve the potency of the -opioid receptor agonist DAMGO to stimulate [ 35 S]GTP␥S binding (22). The heterogeneous distribution of -opioid receptors in caveolin-enriched and caveolin-poor fractions may explain the rather small effect of cholesterol depletion on acute -opioid signaling (either [ 35 S]GTP␥S binding or adenylyl cyclase inhibition).…”

Section: Discussionmentioning

confidence: 89%

“…Receptor expression in HEK FLAG-␦ cells (8.4 Ϯ 1.5 pmol/mg protein; n ϭ 5) and HEK FLAG-cells (9.7 Ϯ 1.3 pmol/mg protein; n ϭ 5) was similar (p Ͼ 0.05). Receptor expression was measured by saturation binding of the opioid antagonist [ 3 H]diprenorphine as described previously (22). SH-SY5Y cells were grown as above but without geneticin.…”

Section: Materials-snc80 ((ϩ)-4-[(␣r)-␣-((2smentioning

confidence: 99%

“…For example, an increase in plasma membrane microviscosity by addition of cholesteryl hemisuccinate to SH-SY5Y cell membranes increased -opioid receptor coupling to G proteins (22). Conversely, removal of membrane cholesterol from Chinese hamster ovary cells has been shown to either decrease (23) or increase (24) the coupling of -opioid receptors to G proteins, as measured by [ 35 …”

mentioning

confidence: 99%

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Differential Effect of Membrane Cholesterol Removal on μ- and δ-Opioid Receptors

Levitt¹,

Clark²,

Jenkins³

et al. 2009

Journal of Biological Chemistry

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According to the lipid raft theory, the plasma membrane contains small domains enriched in cholesterol and sphingolipid, which may serve as platforms to organize membrane proteins. -ol]enkephalin responses back to control values, and were confirmed in SH-SY5Y cells endogenously expressing -opioid receptors. The effects of M␤CD may be due to uncoupling of the receptor from G proteins but were not because of decreases in receptor number and were not mimicked by cytoskeleton disruption. In contrast to the results in HEK FLAG-cells, M␤CD treatment of HEK FLAG-␦ cells had no effect on acute inhibition or sensitization of adenylyl cyclase by ␦-opioid agonists. The differential responses of -and ␦-opioid agonists to cholesterol depletion suggest that -opioid receptors are more dependent on cholesterol for efficient signaling than ␦ receptors and can be partly explained by localization of -but not ␦-opioid receptors in cholesterol-and caveolin-enriched membrane domains.

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Section: Discussionmentioning

confidence: 89%

Section: Materials-snc80 ((ϩ)-4-[(␣r)-␣-((2smentioning

confidence: 99%

mentioning

confidence: 99%

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Differential Effect of Membrane Cholesterol Removal on μ- and δ-Opioid Receptors

Levitt¹,

Clark²,

Jenkins³

et al. 2009

Journal of Biological Chemistry

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“…Several investigations have suggested the importance of lipid membrane composition and organization in determining the activity of transmembrane proteins (7)(8)(9)(10)(11). Reports also emphasized the large diversity of lipid species found from one cell type to another (12,13).…”

mentioning

confidence: 99%

Role of Sterols in Modulating the Human μ-Opioid Receptor Function in Saccharomyces cerevisiae

Lagane¹,

Gaibelet²,

Meilhoc³

et al. 2000

Journal of Biological Chemistry

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This study provides evidence that the differences in membrane composition found from one cell type to another can represent a limiting factor to recovering the functionality of transmembrane proteins when expressed in heterologous systems. Restoring the properties of the human -opioid receptor in yeast (Saccharomyces cerevisiae), similar to those observed in native cells, was achieved by replacing ergosterol from yeast by cholesterol, which is normally found in mammalian plasma membranes. The results suggest that these two sterols have opposite effects with respect to the ligand binding function of the receptor. Ergosterol was found to constrain the -opioid receptor in an inactive state in yeast plasma membranes and cannot replace cholesterol in activating it. These data differ from previous works dealing with the function of related G-protein-coupled receptors (GPCR) in ergosterol-enriched membranes. This suggests that structural requirements of GPCR with respect to their modulation by lipid components differ from one protein to another. As a consequence, we assume that the presence of appropriate lipids around transmembrane proteins determines their function. This highlights the functional significance of lateral heterogeneities of membrane components within biological membranes.To perform functional and structural studies of mammalian G-protein-coupled receptors (GPCR), 1 heterologous expression has long been a tool of choice (1). Unfortunately, although exceptions have been reported (2), these recombinant GPCR often fail to retain pharmacological properties similar to their native counterpart. Previous studies from our laboratory have focused on the expression of the human -opioid receptor in Saccharomyces cerevisiae (3). We found that the affinities of the antagonists were in the same range with yeast spheroplasts as in reference tissues. However those of agonists were shown to be lower. Assuming a lack of effective receptor coupling to endogenous G-protein ␣-subunits (i.e. GPA1 proteins (4, 5)), we were able to restore agonist binding upon addition of purified mammalian G-proteins (3). However, this approach requires high G-protein to receptor molar ratios and is not compatible with in vivo exploration of receptor functionality in heterologous systems. Finally, recent co-expressions of yeast/mammalian G-protein ␣-subunit chimeras with mammalian receptors have provided an alternative means to increase functional coupling (2, 6). According to this study and to restore human -opioid receptor activity in S. cerevisiae, we have co-expressed a G␣ i2 -GPA1 chimera protein with the receptor. Unfortunately, as further shown below, this approach failed to restore the ligand binding function of the -opioid receptor.Several investigations have suggested the importance of lipid membrane composition and organization in determining the activity of transmembrane proteins (7-11). Reports also emphasized the large diversity of lipid species found from one cell type to another (12, 13). Membrane composition and organization ...

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“…The fluidity of a cell membrane which is caused by the existence of PUFAs (n-3 and n-6) is essential for normal functions of neurons and other cell types in the tissues of human organs. These functions include cell growth, solute transport, signal transduction and membrane-associated enzyme activities [52,134,170]. Membrane fluidity optimizes the metabolic rate within the cells, and by doing so contributes to the prevention of metabolic syndrome and mental diseases via the so called "membrane-pacemaker" theory of metabolism [82].…”

Section: Membrane Fluiditymentioning

confidence: 99%

An intercalation mechanism as a mode of action exerted by psychotropic drugs: results of altered phospholipid substrate availabilities in membranes?

et al. 2010

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Patients respond differently to psychotropic drugs, and this is currently a controversial theme among psychiatrists. The effects of 16 psychotropics on cell membrane parameters have been reported. These drugs belong to three major groups used in therapeutic psychiatry: antipsychotics, antidepressants, and anxiolytic/hypnotics. Human platelets, lacking dopamine (D 2 ) receptors (proposed targets of most psychotropics), have been used as a cell model. Here we discuss the effects of these drugs on three metabolic phenomena and also results from Langmuir experiments. Diazepam, in contrast to the remaining drugs, had negligible effects on metabolic phenomena and had no effects in Langmuir experiments. Psychotropic drugs may work through intercalation in membrane phospholipids. It is possible that the fluidity of membranes, rich in essential fatty acids, the content being influenced by diet, could be a contributing factor to the action of psychotropics. This might in turn explain the observed major differences in therapeutic response among patients.

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Membrane Microviscosity Modulates μ‐Opioid Receptor Conformational Transitions and Agonist Efficacy

Cited by 26 publications

References 45 publications

Differential Effect of Membrane Cholesterol Removal on μ- and δ-Opioid Receptors

Differential Effect of Membrane Cholesterol Removal on μ- and δ-Opioid Receptors

Role of Sterols in Modulating the Human μ-Opioid Receptor Function in Saccharomyces cerevisiae

An intercalation mechanism as a mode of action exerted by psychotropic drugs: results of altered phospholipid substrate availabilities in membranes?

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