Melatonin Modulates Prohibitin and Cytoskeleton in the Retinal Pigment Epithelium

Abstract

The retinal pigment epithelium (RPE) plays imperative roles in normal retinal function by photoreceptor protection from light and phagocytosis of rod and cone outer segments during disc shedding. Melatonin is the free radical scavenger and circadian determinant to protect the RPE and retina from oxidative stress and regulate the circadian clock. The current study tested the hypothesis whether melatonin could affect cytoskeletal structure within RPE. Our Western blot analysis demonstrated that melatonin treatment up-regulated prohibitin 3-fold compared to control. β-tubulin levels were also up-regulated by melatonin but to a lesser extent. Initial cell shape of ARPE-19 is epitheloid, however, after 30-minute treatment with melatonin, RPE cells undergo a morphological change to a fusiform shape with spindle outgrowth. Cells return to epitheloid shape after 12 hours in untreated medium. Melatonin treated cells showed increased and dissimilar distribution of prohibitin and β-tubulin compared to non-treated cells, thus altered cytoskeletal and mitochondrial structure in the RPE. Our data implies that melatonin may play a protective role under oxidative stress, which is shown by the marker prohibitin in terms of increased expression and nuclear distribution. During the protective process, cells change their morphology. Our results suggest that melatonin treatment could be beneficial to protect mitochondria under oxidative stress and treat certain ocular diseases, including age-related macular degeneration.

Effects of melatonin on protecting against lung injury (Review)

“…Rho belongs to the Ras superfamily of low molecular weight GTPases, which have a key role in the formation of the alveolar epithelial cell cytoskeleton, as well as Rho-associated coiled-coil forming protein kinase (110). Sripathi et al (111) reported that MT treatment could be beneficial in protecting mitochondria under oxidative stress and maintaining the structure of the cytoskeleton in the retinal pigment epithelium. Moreover, p120 serves as an essential protein in the regulation of cell junctions and protects against VILI by regulating both adherens and tight junctions by reducing the degradation of occludin via the inhibition of RhoA activity (112).…”

Dual Switch Mechanism of Erythropoietin as an Antiapoptotic and Pro-Angiogenic Determinant in the Retina

“…We have investigated the therapeutic applications of retinal degeneration by focusing on antiapoptotic and neuroprotective mechanisms using a functional proteomics approach. − Previously, we demonstrated that the retinal expression of erythropoietin (EPO), the visual cycle, and the subsequent kinase phosphorylations are interconnected to the circadian clock in anticipation of daily light onset . Our data demonstrated that the EPO is a neuroprotective molecule involved in the inhibition of the apoptotic pathway, including BCL-xL and caspase-9.…”

Mechanistic Dissection of Macular Degeneration Using the Phosphorylation Interactome

“…Cells were grown on sterile glass cover slips using DMEM/F12 medium with 10% FBS and 1% penicillin/streptomycin (Hyclone) in 5% CO 2 incubator at 37°C. Cells were treated under oxidative stress or intense light as previously reported [9][10][11][18][19][20]. Cells were washed with PBS and incubated with MitoTracker Orange CMTMRos (100 nM, Molecular Probes, Carlsbad, CA) in serum-free culture medium (30 min, 37°C), followed by washing (PBS) and fixing (10% formaldehyde, 30 min, room temperature).…”