Alpha 2-Adrenergic Receptor Agonist Brimonidine Stimulates ERK1/2 and AKT Signaling via Transactivation of EGF Receptors in the Human MIO-M1 Müller Cell Line.
Curr Eye Res
; 44(1): 34-45, 2019 01.
Article
en En
| MEDLINE
| ID: mdl-30198788
ABSTRACT
PURPOSE:
Alpha 2-adrenergic receptor (α2-ADR) agonists are used clinically for a range of indications including reducing elevated intraocular pressure in patients with open-angle glaucoma or ocular hypertension. Animal experiments show that α2-ADR agonists attenuate the injury-induced Müller cell dedifferentiation by a mechanism that involves activation and regulation of extracellular signal-regulated kinase (ERK) 1/2 leading to transactivation of epidermal growth factor receptors (EGFRs). The purpose of this study was to study and corroborate the activation of this system in human cells. MATERIAL ANDMETHODS:
The human Müller cell line MIO-M1 was treated with the α2A-ADR agonist brimonidine in combination with inhibitors for Src-kinase, EGFR-kinase, matrix metalloproteinase (MMP) as well as small interfering RNAs (siRNAs) for the EGFR. The cells were analyzed using immunocytochemistry, quantitative PCR and western blot techniques.RESULTS:
Our results show that human MIO-M1 cells express α2A-ADRs and that stimulation of these receptors caused a robust increase of ERK1/2 and protein kinase B (PKB/AKT) (Thr-308) phosphorylation in MIO-M1 cells. P-ERK1/2 and P-AKT (Thr-308) signaling was mediated by Src-kinase and associated with phosphorylation of tyrosine residue of epidermal growth factor receptor (P-EGFR Y1173). In addition, the agonist caused activation of MMPs. These effects could be blocked by Src-kinase inhibitors (PP1, PP2), EGFR-kinase inhibitor (AG1478), EGFR-siRNA and a MMP inhibitor (GM6001).CONCLUSION:
The results confirm that this human Müller cell line responds to ADR stimulation with phosphorylation of ERK and AKT, which suggests that it is possible to pharmacologically target ADR to modulate the early events in human Müller cell dedifferentiation in a similar fashion as been shown for chicken Müller cells. ABBREVIATIONS CRALBP cellular retinaldehyde binding protein; EGFR epidermal growth factor receptor; ERK1/2 extracellular signal-regulated kinase 1/2; GS glutamine synthetase; GPCR G protein-coupled receptor; IR immunoreactivity; MAPK mitogen-activated protein kinase; MMP matrix metalloproteinase; P-ERK1/2 phospho-ERK1/2; qRT-PCR quantitative reverse transcriptase PCR.Palabras clave
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Bases de datos:
MEDLINE
Asunto principal:
Sistema de Señalización de MAP Quinasas
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Agonistas de Receptores Adrenérgicos alfa 2
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Tartrato de Brimonidina
Límite:
Humans
Idioma:
En
Revista:
Curr Eye Res
Año:
2019
Tipo del documento:
Article
País de afiliación:
Suecia