Functional Expression of MT2 (Mel1b) Melatonin Receptors in Human PAZ6 Adipocytes

Brydon, Lena; Petit, Laurence; Delagrange, P; Strosberg, A. Donny; Jockers, Ralf

doi:10.1210/endo.142.10.8423

Cited by 135 publications

(70 citation statements)

References 40 publications

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“…1A). The screens were performed against a cDNA library of differentiated human brown adipocytes, a cellular context known to express functional melatonin receptors (31). Among the positive clones that interacted with the two baits containing the C-tail of MT 1 , we identified 14 sequences corresponding to the multi-PDZ protein MUPP1 (Fig.…”

Section: Resultsmentioning

confidence: 99%

The PDZ Protein Mupp1 Promotes Gi Coupling and Signaling of the Mt1 Melatonin Receptor

Guillaume

Daulat

Maurice

et al. 2008

Journal of Biological Chemistry

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The concept of organized networks has emerged in the field of cellular signaling in the last few years. Assembling the different partners in close proximity optimizes the spatial and temporal organization and the specificity of the cellular response. The assembly of these multimolecular complexes occurs through the interaction of modular domains recognizing their target counterparts. PDZ domains are widely spread modules exhibiting this function. Data bank exploration with SMART (1) identifies 584 PDZ domains in 328 different proteins in the human genome.G protein-coupled receptors (GPCRs) 5 constitute the largest family of membrane receptors, and many of the more than 750 members have been shown to interact with PDZ domain-containing proteins, either constitutively or upon agonist activation (2). Binding of PDZ proteins to GPCRs has been reported to primarily regulate subcellular localization, trafficking, and stability of receptors (3). For instance, binding of MUPP1 and syntrophins to the ␥-aminobutyric acid type B (GABA B ) receptor and the ␣ 1D -adrenergic receptor, respectively, significantly increases receptor stability (4, 5). In other cases, PDZ scaffolds determine the subcellular localization of GPCRs (6) and receptor endocytosis as shown for PSD-95 and the 5-HT 2A serotonin and ␤ 1 -adrenergic receptors (7,8). PDZ proteins, such as NHERF and hScrib, are also important for the recycling of receptors to the cell surface (9 -11).Binding of PDZ proteins to GPCRs also modulates receptor signaling by assembling proteins involved in signal transduction. NHERF family proteins are known to regulate the activity of the Na ϩ /H ϩ exchanger through association with NHERF-1 (12) and to form a ternary complex with phospholipase C␤3 and GPCRs, which enhances the signaling efficiency of the receptor-mediated activation of the phospholipase C␤/Ca 2ϩ pathway (13-15). Binding of GIPC (GAIP-interacting protein, COOH terminus) to the COOH terminus of the D3 dopamine and the ␤ 1 -adrenergic receptor (16) decreased G␣ i -mediated signaling of these receptors most likely through RGS19, which binds to GIPC (17). Further examples of PDZ scaffolds that regulate GPCR signaling include a ternary complex formation around the PDZ scaffold MAGI-3, which binds to the GPCR frizzled-4 and Ltap to regulate the JNK signaling cascade (18), as well as PDZ-domain-containing Rho guanine nucleotide exchange factors that interact with lysophosphatidic acid 1 and 2 receptors to activate RhoA (19).

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Section: Resultsmentioning

confidence: 99%

The PDZ Protein Mupp1 Promotes Gi Coupling and Signaling of the Mt1 Melatonin Receptor

Guillaume

Daulat

Maurice

et al. 2008

Journal of Biological Chemistry

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“…It lowers cortisol secretion (25) in the adrenal cortex, similar to the action shared with insulin (23). Moreover, human adipocytes, a major target tissue for insulin, express MT2 and have been shown to reduce expression of the insulin-dependent glucose transporter, Glut4, after melatonin stimulation (26). It also stimulates glucose uptake in muscle cells by phosphorylation of insulin receptor substrate-1 (IRS-1) through MT2 signaling (27).…”

Section: Melatonin and Its Functionmentioning

confidence: 95%

The role of melatonin in diabetes: therapeutic implications

Sharma

Singh

Ahmad

et al. 2015

Arch. Endocrinol. Metab.

107

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Melatonin referred as the hormone of darkness is mainly secreted by pineal gland, its levels being elevated during night and low during the day. The effects of melatonin on insulin secretion are mediated through the melatonin receptors (MT1 and MT2). It decreases insulin secretion by inhibiting cAMP and cGMP pathways but activates the phospholipaseC/IP3 pathway, which mobilizes Ca 2+ from organelles and, consequently increases insulin secretion. Both in vivo and in vitro, insulin secretion by the pancreatic islets in a circadian manner, is due to the melatonin action on the melatonin receptors inducing a phase shift in the cells. Melatonin may be involved in the genesis of diabetes as a reduction in melatonin levels and a functional interrelationship between melatonin and insulin was observed in diabetic patients. Evidences from experimental studies proved that melatonin induces production of insulin growth factor and promotes insulin receptor tyrosine phosphorylation. The disturbance of internal circadian system induces glucose intolerance and insulin resistance, which could be restored by melatonin supplementation. Therefore, the presence of melatonin receptors on human pancreatic islets may have an impact on pharmacotherapy of type 2 diabetes. Arch Endocrinol Metab.2015;59(5):391-9

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“…These results suggest that the binding site of the MT2 receptor to Akt may locate at its C-terminal, the most important region in a GPCR for interaction with GPCR-interacting proteins (GIPs), and a region of posttranslational modification and coupling with G proteins. 36 MT2 receptor activation also changed the ratio of cAMP/cGMP, 37 of which the local and long-range reciprocal regulation in axon-dendrite differentiation have been reported recently. 38 We also demonstrated that the PH domain of Akt is essential for the interaction with the MT2 receptor at the C-terminal.…”

Section: Discussionmentioning

confidence: 68%

The MT2 receptor stimulates axonogenesis and enhances synaptic transmission by activating Akt signaling

Man

et al. 2014

Cell Death Differ

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The MT2 receptor is a principal type of G protein-coupled receptor that mainly mediates the effects of melatonin. Deficits of melatonin/MT2 signaling have been found in many neurological disorders, including Alzheimer's disease, the most common cause of dementia in the elderly, suggesting that preservation of the MT2 receptor may be beneficial to these neurological disorders. However, direct evidence linking the MT2 receptor to cognition-related synaptic plasticity remains to be established. Here, we report that the MT2 receptor, but not the MT1 receptor, is essential for axonogenesis both in vitro and in vivo. We find that axon formation is retarded in MT2 receptor knockout mice, MT2-shRNA electroporated brain slices or primary neurons treated with an MT2 receptor selective antagonist. Activation of the MT2 receptor promotes axonogenesis that is associated with an enhancement in excitatory synaptic transmission in central neurons. The signaling components downstream of the MT2 receptor consist of the Akt/GSK-3β/CRMP-2 cascade. The MT2 receptor C-terminal motif binds to Akt directly. Either inhibition of the MT2 receptor or disruption of MT2 receptor-Akt binding reduces axonogenesis and synaptic transmission. Our data suggest that the MT2 receptor activates Akt/GSK-3β/CRMP-2 signaling and is necessary and sufficient to mediate functional axonogenesis and synaptic formation in central neurons. Synaptic circuits are established at the sites of axon-dendritic, axon-somatic or axon-axonal contact, in which functional axonogenesis is a critical step. 1 Axonogenesis can be regulated by many intracellular signals that involve cytoskeletal rearrangements, 2 local protein degradation, 3 as well as diffusional barriers. 4 Additionally, several extracellular neurotrophic factors and hormones have also been shown to have a role in axon guidance and synaptic formation in central neurons. 5,6 To date, the role of melatonin and its receptors in axonogenesis remains unclear. Most of the biological functions of melatonin are mediated by its two receptors, MT1 and MT2 receptors, both of them belong to the G protein-coupled receptor (GPCR) subfamily and are widely expressed throughout the central nervous system (CNS). 7 Activation of the MT2 receptor in response to melatonin is critical for controlling circadian rhythms 7 and regulation of slow wave sleep. 8,9 Early studies have shown that activation of the MT2 receptor in the retina reduces the release of dopamine, while dopamine inhibits growth cone motility and neurite outgrowth during embryonic development, 10,11 suggesting the involvement of the MT2 receptor in functional axonogenesis. In mutant mice with deficient expression of the MT2 gene, the induction of long-term potentiation (LTP) of excitatory synaptic transmission is impaired, and this impairment is closely related to deficits in learning. 12 In the hippocampus, the MT2 receptor inhibits GABA A receptor-mediated current, 13 which is implicated in the synaptic transmission. In Alzheimer's disease, expression of the MT...

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Functional Expression of MT2 (Mel1b) Melatonin Receptors in Human PAZ6 Adipocytes

Cited by 135 publications

References 40 publications

The PDZ Protein Mupp1 Promotes Gi Coupling and Signaling of the Mt1 Melatonin Receptor

The PDZ Protein Mupp1 Promotes Gi Coupling and Signaling of the Mt1 Melatonin Receptor

The role of melatonin in diabetes: therapeutic implications

The MT2 receptor stimulates axonogenesis and enhances synaptic transmission by activating Akt signaling

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