Melanocortin GPCR Assays
Background of Melanocortin Receptors
Melanocortin receptors (MCRs) are members of the family of 7-transmembrane spanning G protein-coupled receptors (GPCR). Five different subtypes of MCRs have been successfully cloned, which were entitled MC1 receptor, MC2 receptor, MC3 receptor, MC4 receptor, and MC5 receptor, each with a different function. These receptors play an important role in many degenerative diseases.
Fig.1. Structure of the human MC4 receptor.
Distribution and Function of Melanocortin Receptors
MCRs can be found in most human organs and tissues. The regions in which MCRs can be found vary according to the member category. The MC1R mostly inhabits primarily in the skin, the MC2R primarily in the adrenal gland, the MC3R, and the MC4R in the brain and periphery, and the MC5R can be found throughout the human body. MCRs are involved in regulating many behaviors and functions in the human body, such as pigmentation genetics, childhood growth, puberty, early on-set obesity, fear flight, and others.
Subtypes and Mechanisms of Melanocortin Receptors
There are five members in the MCRs family. The main function of the MC1 receptor is to affect the pigmentation process, and its primary ligand would be the α-melanocyte stimulating hormone (α-MSH). MC2 receptor is also known as the adrenal corticotropic hormone (ACTH) receptor for its specificity for ACTH.
| Receptor | Gene | Mechanism | Agonists | Antagonists |
| MC1 receptor | MC1R |
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| MC2 receptor | MC2R |
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| MC3 receptor | MC3R |
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| MC4 receptor | MC4R |
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| MC5 receptor | MC5R |
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Assay List of Melanocortin Receptors
Creative Biolabs can provide a range of assays of melanocortin receptors. You can choose the assay in the list or contact us for more information:
| Assay No. | Assay Name | Host Cell | Assay Type | Datasheet |
|---|---|---|---|---|
| cAMP Assay | ||||
| S01YF-0722-KX131 | Magic™ Human MC1R In Vitro cAMP Assay & Reporter Assay, HEK293-CRE-Luc | HEK293-CRE-Luc | cAMP Assay; Reporter Assay | |
| Assay No. | Assay Name | Host Cell | Assay Type | Datasheet |
|---|---|---|---|---|
| cAMP Assay | ||||
| S01YF-0722-KX134 | Magic™ Human MC4R In Vitro cAMP Assay & Reporter Assay, HEK293-CRE-GFP | HEK293-CRE-GFP | cAMP Assay; Reporter Assay | |
Published Data
| Paper Title | Melanocortin receptor agonists MCR1-5 protect photoreceptors from high-glucose damage and restore antioxidant enzymes in primary retinal cell culture |
| Journal | Journal of Cellular and Molecular Medicine |
| Published | 2017 |
| Abstract | The retina is a complex layer of nerve cells that sits on the inner surface of the eye and is involved in processing visual stimuli. Previous studies have shown that photoreceptors on the retina are affected by high local glucose concentrations, making changes in photoreceptors and damage from oxidative stress a potentially important risk factor in the progression of diabetic retinopathy. Five subtypes of melanocortin receptors are expressed in multiple tissues including the retina, and MCRs protect RPE cells from oxidative stress through the MCR1-AKT-mTOR pathway. The data also demonstrate that MCR1 and MCR5 receptor agonists can modulate the expression patterns of cytokines and chemokines, thereby improving the pathological process of experimental diabetic retinopathy. Based on this, researchers tested whether the protective effects of these two receptors could be directed to specific structures during diabetes. Therefore, primary retinal photoreceptor cells were treated with agonists and antagonists of MCR1 and MCR5 under the condition of high concentration of glucose, and the protective effect of MCR agonists on photoreceptors was studied in depth through the expression of various cytokines. |
| Result |
In the experiment, primary retinal cells isolated from C57BL/6 mice were inoculated in a high-concentration glucose medium and treated with agonists and antagonists of MCR1 and MCR5, respectively. The integrity and degree of damage of cell membranes and photoreceptors are indicated by morphological observation and marker proteins (opsin and restorer protein). The experimental results showed that the photoreceptors of mouse primary cells exposed to high glucose medium were damaged to a certain extent, and agonists of MCR1 and MCR5 could effectively reduce this effect. Cell morphology analysis indicated that MCR1,5 agonists could effectively control the cytoplasmic swelling and abnormal cell morphology induced by high glucose, thereby exerting a protective response to photoreceptors. The results of biochemical analysis and immunocytochemistry showed that the participation of MCR1,5 agonist can effectively reduce the production of anti-inflammatory cytokines and chemokines, restore the levels of manganese superoxide dismutase and glutathione peroxidase that were damaged by high glucose, and alleviate the oxidative damage of primary retinal cells. Based on these findings, the researchers cautiously propose a protective role of MCR1,5 in the process of high glucose and oxidative stress-induced retinal photoreceptor damage, as well as a potential diabetic condition-modifying function.
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Fig.2. Retinal cells labeled with opsin, recoverin, and DAPI. (Maisto, 2017)
Reference
- Maisto, R.; et al. Melanocortin receptor agonists MCR1-5 protect photoreceptors from high-glucose damage and restore antioxidant enzymes in primary retinal cell culture. Journal of Cellular and Molecular Medicine. 2017, 21(5): 968-974.
