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Reyes-Resina I, Awad Alkozi H, del Ser-Badia A, Sánchez-Naves J, Lillo J, Jiménez J, Pintor J, Navarro G, Franco R. Expression of Melatonin and Dopamine D 3 Receptor Heteromers in Eye Ciliary Body Epithelial Cells and Negative Correlation with Ocular Hypertension. Cells 2020; 9:cells9010152. [PMID: 31936298 PMCID: PMC7016594 DOI: 10.3390/cells9010152] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Revised: 12/23/2019] [Accepted: 01/02/2020] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Experiments in the late nineties showed an inverse relationship in the eye levels of melatonin and dopamine, thereby constituting an example of eye parameters that are prone to circadian variations. The underlying mechanisms are not known but these relevant molecules act via specific cell surface dopamine and melatonin receptors. This study investigated whether these receptors formed heteromers whose function impact on eye physiology. We performed biophysical assays to identify interactions in heterologous systems. Particular heteromer functionality was detected using Gi coupling, MAPK activation, and label-free assays. The expression of the heteroreceptor complexes was assessed using proximity ligation assays in cells producing the aqueous humor and human eye samples. Dopamine D3 receptors (D3Rs) were identified in eye ciliary body epithelial cells. We discovered heteromers formed by D3R and either MT1 (MT1R) or MT2 (MT2R) melatonin receptors. Heteromerization led to the blockade of D3R-Gi coupling and regulation of signaling to the MAPK pathway. Heteromer expression was negatively correlated with intraocular hypertension. CONCLUSIONS Heteromers likely mediate melatonin and dopamine actions in structures regulating intraocular pressure. Significant expression of D3R-MT1R and D3R-MT1R was associated with normotensive conditions, whereas expression diminished in a cell model of hypertension. A clear trend of expression reduction was observed in samples from glaucoma cases. The trend was marked but no statistical analysis was possible as the number of available eyes was 2.
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Affiliation(s)
- Irene Reyes-Resina
- Department of Biochemistry and Molecular Biomedicine, School of Biology, Universitat de Barcelona, 08028 Barcelona, Spain;
- Neuroplasticity Research Group, Leibniz Institute for Neurobiology, 39118 Magdeburg, Germany
- Centro de Investigación en Red, Enfermedades Neurodegenerativas, CiberNed, Instituto de Salud Carlos III, 28029 Madrid, Spain; (A.d.S.-B.); (J.J.)
- Correspondence: (I.R.-R.); (G.N.); or (R.F.); Tel.: +34-934021208 (I.R.-R. & G.N.)
| | - Hanan Awad Alkozi
- Department of Biochemistry and Molecular Biology, Faculty of Optics and Optometry, University Complutense of Madrid, 28037 Madrid, Spain; (H.A.A.); (J.P.)
| | - Anna del Ser-Badia
- Centro de Investigación en Red, Enfermedades Neurodegenerativas, CiberNed, Instituto de Salud Carlos III, 28029 Madrid, Spain; (A.d.S.-B.); (J.J.)
- Department de Bioquímica i Biologia Molecular, Institut de Neurociències, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, 08193 Barcelona, Spain
| | - Juan Sánchez-Naves
- Department of Ophthalmology, Balearic Islands Institute of Ophthalmology, 07013 Palma de Mallorca, Mallorca, Spain;
| | - Jaume Lillo
- Department of Biochemistry and Molecular Biomedicine, School of Biology, Universitat de Barcelona, 08028 Barcelona, Spain;
- Centro de Investigación en Red, Enfermedades Neurodegenerativas, CiberNed, Instituto de Salud Carlos III, 28029 Madrid, Spain; (A.d.S.-B.); (J.J.)
| | - Jasmina Jiménez
- Centro de Investigación en Red, Enfermedades Neurodegenerativas, CiberNed, Instituto de Salud Carlos III, 28029 Madrid, Spain; (A.d.S.-B.); (J.J.)
| | - Jesús Pintor
- Department of Biochemistry and Molecular Biology, Faculty of Optics and Optometry, University Complutense of Madrid, 28037 Madrid, Spain; (H.A.A.); (J.P.)
| | - Gemma Navarro
- Centro de Investigación en Red, Enfermedades Neurodegenerativas, CiberNed, Instituto de Salud Carlos III, 28029 Madrid, Spain; (A.d.S.-B.); (J.J.)
- Department of Biochemistry and Physiology, School of Pharmacy and Food Sciences, Universitat de Barcelona, 08027 Barcelona, Spain
- Correspondence: (I.R.-R.); (G.N.); or (R.F.); Tel.: +34-934021208 (I.R.-R. & G.N.)
| | - Rafael Franco
- Centro de Investigación en Red, Enfermedades Neurodegenerativas, CiberNed, Instituto de Salud Carlos III, 28029 Madrid, Spain; (A.d.S.-B.); (J.J.)
- School of Chemistry, Universitat de Barcelona, 08028 Barcelona, Spain
- Correspondence: (I.R.-R.); (G.N.); or (R.F.); Tel.: +34-934021208 (I.R.-R. & G.N.)
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