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- Hellsten Caron, Murielle
(author)
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Effects of ethanol on muscarinic acetylcholine receptors in nerve cells
- 2002
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Doctoral thesis (other academic/artistic)abstract
- This thesis focused on the mechanisms involved in the effects of long-term ethanol treatment on mAChRs and their coupled-signal transduction pathway in human neuroblastoma SH-SY5Y cells. All 5 subtypes of mAChRs were expressed in these cells. Acute ethanol exposure induced a minor and transient decrease in the number of cell surface mAChRs, which could not account for the previously described pronounced and long-lasting inhibition of receptor-stimulated IP3 formation. Both mAChR number and stimulated PLC activity were increased after long-term ethanol treatment. Up-regulation of mAChRs was paralleled by a subtype-specific increase in mRNA levels of M1, M2, M4 and M5 mAChR subtypes, and a decrease in mRNA levels of the M3 mAChR subtype. Levels of M2 and M4 mRNA were most sensitive to the effects of ethanol. Together with the finding that up-regulated mAChRs after short ethanol exposure times were not capable of stimulating PLC, it is conceivable that these receptors may be M2 and/or M4 subtypes, with appearance of PLC-coupled mAChRs at the cell surface, first after prolonged ethanol exposure times. Our results also show that the ethanol-induced up-regulation of mAChR number can be blocked by both PKC and an NO-donor, and reproduced by PKC- and nNOS-inhibition. Furthermore, long-term ethanol treatment of the cells resulted in decreased levels of NO. Thus, PKC- and/or NO-dependent mechanisms may be involved in the long-term ethanol-induced up-regulation of mAChRs. On the other hand, the mechanisms involved in the ethanol-induced potentiation of mAChR-stimulated PLC activity were not PKC-sensitive, suggesting that at least 2 kinds of mechanisms are responsible for the effects of ethanol on mAChR number and PLC activity, a PKC-sensitive and a PKC-insensitive, respectively.
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| 2. |
- Lenhart, P.M., et al.
(author)
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G-protein-coupled receptor 30 interacts with receptor activity-modifying protein 3 and confers sex-dependent cardioprotection
- 2013
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In: Journal of Molecular Endocrinology. - 1479-6813. ; 51:1, s. 191-202
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Journal article (peer-reviewed)abstract
- Abstract Receptor activity-modifying protein 3 (RAMP3) is a single-pass transmembrane protein known to interact with and affect the trafficking of several G-protein-coupled receptors (GPCRs). We sought to determine whether RAMP3 interacts with GPR30, also known as G-protein-coupled estrogen receptor 1. GPR30 is a GPCR that binds estradiol and has important roles in cardiovascular and endocrine physiology. Using bioluminescence resonance energy transfer titration studies, co-immunoprecipitation, and confocal microscopy, we show that GPR30 and RAMP3 interact. Furthermore, the presence of GPR30 leads to increased expression of RAMP3 at the plasma membrane in HEK293 cells. In vivo, there are marked sex differences in the subcellular localization of GPR30 in cardiac cells, and the hearts of Ramp3(-/-) mice also show signs of GPR30 mislocalization. To determine whether this interaction might play a role in cardiovascular disease, we treated Ramp3(+)(/)(+) and Ramp3(-/-) mice on a heart disease-prone genetic background with G-1, a specific agonist for GPR30. Importantly, this in vivo activation of GPR30 resulted in a significant reduction in cardiac hypertrophy and perivascular fibrosis that is both RAMP3 and sex dependent. Our results demonstrate that GPR30-RAMP3 interaction has functional consequences on the localization of these proteins both in vitro and in vivo and that RAMP3 is required for GPR30-mediated cardioprotection.
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