bims-mideyd 2023-12-17 papers

Issue of 2023‒12‒17
four papers selected by
Rajalekshmy “Raji” Shyam, Indiana University Bloomington

Front Biosci (Landmark Ed). 2023 Nov 29. 28(11): 319

PEDF Prevents Mitochondrial Function Decay and ER Stress Induced by Rotenone in Aging RPE Cells.

Ruixue Zhang, Zhi Ji, Zhuoya Quan, Yao Lu, Yuan Ren, Yuan He.

BACKGROUND: Neurodegenerative diseases, including age-related macular degeneration (AMD), may be linked to mitochondrial dysfunction and endoplasmic reticulum (ER) stress. We examined whether Pigment epithelium-derived factor (PEDF) could prevent changes in the structure and function of these organelles by accelerating by rotenone (ROT), a mitochondrial inhibitor, in human retinal pigment epithelium (RPE) cells of chronological age.METHODS: RPE cells from 9-20, 50-55, 60-70, and >70-year-old donors were isolated, grown as primary cultures, harvested, and treated with ROT and PEDF for electron microscope (EM), western blot analysis, and polymerase chain reaction (PCR). Reactive oxygen species (ROS) and cytoplasmic calcium [Ca2+]c and mitochondrial calcium [Ca2+]m levels were measured by flow cytometry using 2',7'-dichlorodihydrofluorescin diacetate (H2-DCF-DA), fluo-3/AM, and Rhod-2/AM, and ATP levels were measured using a luciferin/luciferase-based assay. Mitochondrial membrane potential (ΔΨm) was detected using 5,5',6,6'-tetrachloro1,1',3,3'-tetraethylbenzimid azolocarbocyanine iodide (JC-1), and susceptibility of the cells to ROT toxicity and PEDF-protective effect was determined by propidium iodide (PI) staining and lactate dehydrogenase (LDH) assay. The expression of ER stress-related genes was detected using real-time (RT)-PCR.
RESULTS: We observed decay in the mitochondria of aged RPE cells, including matrix abnormalities, elongation, loss of cristae, and disruption of membrane integrity after ROT treatment. We also observed lower [Ca2+]c, higher ROS and [Ca2+]m levels, decreased ΔΨm after ROT treatment, and greater susceptibility to ROT toxicity in aged RPE cells. PEDF can protect the cristae and integrity of the mitochondrial membrane, increase ATP levels and ΔΨm, and lower ROS, [Ca2+]c, and [Ca2+]m in aged RPE cells induced by ROT. In addition, there was an increase in RDH expression in RPE cells with increasing age after PEDF treatment. Similarly, PEDF decreased the expression of ROT-induced ER stress-related genes.
CONCLUSIONS: Our study provides evidence that PEDF can reduce bioenergetic deficiencies, mitochondrial decay, and ER stress in aging RPE, a condition that may trigger the onset of retinal diseases such as AMD.

Keywords: Ca2+; PEDF; ROS; RPE cells; mitochondria; rotenone

DOI: https://doi.org/10.31083/j.fbl2811319

Int J Mol Sci. 2023 Nov 27. pii: 16801. [Epub ahead of print]24(23):

Alteration in Melanin Content in Retinal Pigment Epithelial Cells upon Hydroquinone Exposure.

Takeyuki Nishiyama, Hiroki Tsujinaka, Tetsuo Ueda, Nahoko Ogata.

Abnormal pigmentation or depigmentation of the retinal pigment epithelium (RPE) is a precursor to neovascular age-related macular degeneration (nAMD). In this study, we evaluated the effects of hydroquinone (HQ), the most potent reductant in cigarette smoke, on the melanin production in RPE cells. Induced pluripotent stem cell (iPS)-derived RPE and adult retinal pigment epithelial (ARPE-19) cells were cultured with HQ. Real-time reverse transcription polymerase chain reaction revealed that the expression of melanin-related genes decreased due to the addition of HQ for 1 day. Enzyme-linked immunosorbent immunoassay showed that the concentration of melanin significantly decreased due to the addition of HQ for 24 h. A suspension of RPE cells with HQ for 24 h was prepared, and the absorbance was measured. The absorbance decreased particularly under blue light, suggesting that blue light may reach the choroid and cause choroidal inflammation. Additionally, melanin levels significantly decreased due to the addition of HQ for 1 week. After blue light irradiation on the RPE with HQ for 1 week, the vascular endothelial growth factor in the medium was significantly higher in the HQ group than in the control group. HQ-induced changes in melanin production may be responsible for the uneven pigmentation of the RPE, and these changes may cause nAMD.

Keywords: blue light; hydroquinone; melanin production; neovascular age-related macular degeneration; vascular endothelial growth factor

DOI: https://doi.org/10.3390/ijms242316801

bioRxiv. 2023 Dec 01. pii: 2023.11.30.569464. [Epub ahead of print]

Modeling aging and retinal degeneration with mitochondrial DNA mutation burden.

John Sturgis, Rupesh Singh, Quinn Caron, Ivy S Samuels, Thomas Micheal Shiju, Aditi Mukkara, Paul Freedman, Vera L Bonilha.

Somatic mitochondrial DNA (mtDNA) mutation accumulation has been observed in individuals with retinal degenerative disorders. To study the effects of aging and mtDNA mutation accumulation in the retina, a Polymerase gamma (POLG) deficiency model, the POLG D257A mutator mice (PolgD257A), was used. POLG is an enzyme responsible for regulating mtDNA replication and repair. Retinas of young and older mice with this mutation were analyzed in vivo and ex vivo to provide new insights into the contribution of age-related mitochondrial dysfunction due to mtDNA damage. Optical coherence tomography (OCT) image analysis revealed a decrease in retinal and photoreceptor thickness starting at 6 months of age in mice with the POLG D257A mutation compared to wild-type (WT) mice. Electroretinography (ERG) testing showed a significant decrease in all recorded responses at 6 months of age. Sections labeled with markers of different types of retinal cells, including cones, rods, and bipolar cells, exhibited decreased labeling starting at 6 months. However, electron microscopy analysis revealed differences in retinal pigment epithelium (RPE) mitochondria morphology beginning at 3 months. Interestingly, there was no increase in oxidative stress observed in the retina or RPE of POLGD257A mice. Additionally, POLGD257A RPE exhibited an accelerated rate of autofluorescence cytoplasmic granule formation and accumulation. Mitochondrial markers displayed decreased abundance in protein lysates obtained from retina and RPE samples. These findings suggest that the accumulation of mitochondrial DNA mutations leads to impaired mitochondrial function and accelerated aging, resulting in retinal degeneration.

DOI: https://doi.org/10.1101/2023.11.30.569464

Redox Biol. 2023 Dec 06. pii: S2213-2317(23)00387-7. [Epub ahead of print]69 102986

Estrogen genotoxicity causes preferential development of Fuchs endothelial corneal dystrophy in females.

Varun Kumar, Neha Deshpande, Mohit Parekh, Raymond Wong, Shazia Ashraf, Muhammad Zahid, Hanna Hui, Annie Miall, Sylvie Kimpton, Marianne O Price, Francis W Price, Frank J Gonzalez, Eleanor Rogan, Ula V Jurkunas.

Fuchs endothelial corneal dystrophy (FECD) is a genetically complex, age-related, female-predominant disorder characterized by loss of post-mitotic corneal endothelial cells (CEnCs). Ultraviolet-A (UVA) light has been shown to recapitulate the morphological and molecular changes seen in FECD to a greater extent in females than males, by triggering CYP1B1 upregulation in females. Herein, we investigated the mechanism of greater CEnC susceptibility to UVA in females by studying estrogen metabolism in response to UVA in the cornea. Loss of NAD(P)H quinone oxidoreductase 1 (NQO1) resulted in increased production of estrogen metabolites and mitochondrial-DNA adducts, with a higher CEnC loss in Nqo1-/- female compared to wild-type male and female mice. The CYP1B1 inhibitors, trans-2,3',4,5'-tetramethoxystilbene (TMS) and berberine, rescued CEnC loss. Injection of wild-type male mice with estrogen (E2; 17β-estradiol) increased CEnC loss, followed by increased production of estrogen metabolites and mitochondrial DNA (mtDNA) damage, not seen in E2-treated Cyp1b1-/-male mice. This study demonstrates that the endo-degenerative phenotype is driven by estrogen metabolite-dependent CEnC loss that is exacerbated in the absence of NQO1; thus, explaining the mechanism accounting for the higher incidence of FECD in females. The mitigation of estrogen-adduct production by CYP1B1 inhibitors could serve as a novel therapeutic strategy for FECD.

Keywords: Berberine; CYP1B1; Catechol estrogen; Estrogen metabolism; Estrogen-DNA adducts; Fuchs endothelial corneal dystrophy; Mitochondrial DNA damage; NQO1; Oxidized estrogen; TMS; Ultraviolet-A

DOI: https://doi.org/10.1016/j.redox.2023.102986