bims-mideyd 2024-11-17 papers

Issue of 2024‒11‒17
five papers selected by
Rajalekshmy “Raji” Shyam, Indiana University Bloomington

Heliyon. 2024 Nov 15. 10(21): e39100

Protective effect of zinc against A2E-induced toxicity in ARPE-19 cells: Possible involvement of lysosomal acidification.

Jeong A Choi, Bo-Ra Seo, Jae-Young Koh, Young Hee Yoon.

A key pathogenic mechanism of dry age-related macular degeneration (AMD) is lysosomal dysfunction in retinal pigment epithelium (RPE) cells, which results in the accumulation of lipofuscins such as A2E (N-retinylidene-N-retinylethanolamine) that further compromises lysosomal function. This vicious cycle leads to cell death and poor visual acuity. Here, we established an in vitro model of AMD by treating a human RPE cell line (ARPE-19) with A2E and examined whether raising zinc levels confers protective effects against lysosomal dysfunction and cytotoxicity. MTT assay showed that A2E induced apoptosis in ARPE-19 cells. pHrodo™ Red fluorescence staining showed that lysosomal pH increased in A2E-treated ARPE-19 cells. Treatment with a zinc ionophore (clioquinol) reduced A2E accumulation, restored lysosomal pH to the acidic range, and reduced A2E-induced cell death, all of which were reversed by the addition of a zinc chelator (TPEN). Consistent with the in vitro results, subretinal injections of A2E in mouse eyes resulted in the death of RPE cells as well as lysosomal dysfunction, all of which were reversed by co-treatment with clioquinol. Our results suggest that restoring the levels of intracellular zinc, especially in lysosomes, would be helpful in mitigating A2E-induced cytotoxic changes including lysosomal dysfunction in RPE cells in the pathogenesis of AMD.

Keywords: Age-related macular degeneration; Lysosome dysfunction; Retinal pigment epithelium; Zinc

DOI: https://doi.org/10.1016/j.heliyon.2024.e39100

Int J Mol Sci. 2024 Oct 24. pii: 11414. [Epub ahead of print]25(21):

Ginsenoside Rg3 Improved Age-Related Macular Degeneration Through Inhibiting ROS-Mediated Mitochondrion-Dependent Apoptosis In Vivo and In Vitro.

Rui-Yi Hu, Si-Min Qi, Ya-Jun Wang, Wen-Lin Li, Wan-Chen Zou, Zi Wang, Shen Ren, Wei Li.

Age-related macular degeneration (AMD) is marked by a progressive loss of central vision and is the third leading cause of irreversible blindness worldwide. The exact mechanisms driving the progression of this macular degenerative condition remain elusive, and as of now, there are no available preventative measures for dry AMD. According to ancient records, ginseng affects the eyes by brightening them and enhancing wisdom. Modern pharmacological research shows that the active ingredients in ginseng, ginsenosides, may be used to prevent or improve eye diseases that threaten vision. Some articles have reported that ginsenoside Rg3 can treat diabetic retinopathy in mice, but no reports exist on its effects and mechanisms in AMD. Therefore, the role and mechanism of ginsenoside Rg3 in AMD warrant further study. This study aims to investigate the effects of Rg3 on AMD and its underlying molecular mechanisms. We established a mouse model of AMD to examine the impact of ginsenoside Rg3 on NaIO3-induced apoptosis in the retina and to explore the related intrinsic mechanisms. The in vivo results indicated that ginsenoside Rg3 prevents NaIO3-induced apoptosis in retinal pigment epithelial cells by inhibiting reactive oxygen species production and preventing the reduction in mitochondrial membrane potential. Additionally, we assessed the levels of protein expression within the apoptosis pathway. Ginsenoside Rg3 decreased the expression of Bax, cleaved caspase-3, and cleaved caspase-9 proteins. Additionally, it increased the expression of Bcl-2 by decreasing P-JNK levels. Moreover, our in vivo results showed that ginsenoside Rg3 enhanced retinal structure, increased the relative thickness of the retina, and decreased the extent of disorganization in both the inner and outer nuclear layers. Ginsenoside Rg3 may safeguard the retina against NaIO3-induced cell apoptosis by attenuating reactive-oxygen-species-mediated mitochondrial dysfunction, in which the JNK signaling pathway is also involved. These findings suggest that ginsenoside Rg3 has the potential to prevent or attenuate the progression of AMD and other retinal pathologies associated with NaIO3-mediated apoptosis.

Keywords: age-related macular degeneration; apoptosis; ginsenoside Rg3; retinal pigment epithelium; sodium iodate

DOI: https://doi.org/10.3390/ijms252111414

Int J Clin Exp Pathol. 2024 ;17(10): 371-380

PCSK7, a potential target for the treatment of age-related macular degeneration: inhibition of retinal epithelial cell death.

Xiaolong Zhang, Xin Zhao, Xiangyang Xin.

BACKGROUND: Age-related macular degeneration (AMD) is a complex disease with a pathophysiology that remains incompletely understood. PCSK7 is closely related to the normal development of ocular tissues; however, the roles and mechanisms of PCSK7 in AMD have yet to be elucidated. Therefore, the purpose of this study was to investigate the specific manifestations of PCSK7 in AMD.METHODS: An AMD cell model was established by using hydrogen peroxide (H2O2)-treated ARPE-19 cells. The efficiency of PCSK7 overexpression was analyzed by western blotting (WB) and quantitative reverse transcription PCR (RT-qPCR). Subsequently, a Cell Counting Kit 8 (CCK-8) assay was employed to assess the proliferation of ARPE-19 cells, while flow cytometry and immunofluorescence were utilized to examine apoptosis. Iron accumulation and glutathione (GSH) levels in cells were measured using Enzyme-linked immunosorbent assay (ELISA), and WB was conducted to evaluate the expression of anti-ferroptosis protein. Finally, JC-1 staining was performed to assess mitochondrial membrane potential.
RESULTS: Overexpressing of PCSK7 enhanced the proliferation and inhibited the apoptosis of ARPE-19 cells treated with H2O2. Additionally, increased PCSK7 expression suppressed intracellular iron levels and GSH content, thereby inhibiting the ferroptosis process. Furthermore, overexpression of PCSK7 restored mitochondrial membrane potential, alleviating H2O2-induced mitochondrial damage.
CONCLUSIONS: PCSK7 might be one of the targets for the treatment of AMD through the regulation of retinal epithelial cell death.

Keywords: ARPE-19; PCSK7; age-related macular degeneration; ferroptosis; mitochondrial damage

DOI: https://doi.org/10.62347/LEHU9944

PLoS One. 2024 ;19(11): e0313446

RTA408 alleviates retinal ganglion cells damage in mouse glaucoma by inhibiting excessive autophagy.

Hongmei Qian, Wei Chen, Guomei Yuan, Man Luo, Li Zhang, Biao Wu, Hanshi Huang, Jiahao Xu, Qiong Wang, Mengyun Li.

BACKGROUND: Glaucoma, characterized by a high incidence and significant ocular harm, has been elucidated through various mechanisms. Excessive autophagy leading to the loss of retinal ganglion cells (RGCs) is suggested as one potential cause for visual impairment in glaucoma.METHODS: A glaucoma model was established through anterior chamber injection of silicone oil in mice. RTA408 and the positive control tafluprost were administered for intervention. The efficacy was preliminarily assessed by intraocular pressure measurement. HE staining and fluorescent staining were used to assess RGC loss, while fluorescent staining and western blot were employed to evaluate the expression of Nrf2. The role of autophagy in the pathogenesis of glaucoma was investigated by artificially modulating autophagy levels.
RESULTS: In glaucomatous mice, RTA408 significantly reduces the apoptosis levels of RGCs and decreases RGC loss. Further investigations reveal a notable upregulation of autophagy levels in glaucomatous mice, with RGC loss being associated with autophagy. RTA408 promotes the expression of Nrf2 and downstream antioxidant molecules, enhancing the antioxidant system while downregulating mitochondrial autophagy levels. This reduces RGC apoptosis and loss, demonstrating a protective effect against glaucoma.
CONCLUSION: Autophagy mediates the occurrence of glaucoma in mice, promoting RGC apoptosis. RTA408 alleviates RGCs damage by inhibiting excessive autophagy in the context of glaucoma.

DOI: https://doi.org/10.1371/journal.pone.0313446

Cells. 2024 Oct 24. pii: 1761. [Epub ahead of print]13(21):

Prominin-1 Knockdown Causes RPE Degeneration in a Mouse Model.

Sujoy Bhattacharya, Tzushan Sharon Yang, Bretton P Nabit, Evan S Krystofiak, Tonia S Rex, Edward Chaum.

There are currently no effective treatments for retinal pigment epithelial (RPE) cell loss in atrophic AMD (aAMD). However, our research on Prominin-1 (Prom1), a known structural protein in photoreceptors (PRs), has revealed its distinct role in RPE and offers promising insights. While pathogenic Prom1 mutations have been linked to macular diseases with RPE atrophy, the broader physiological impact of dysfunctional Prom1 in RPE loss is unclear. We have shown that Prom1 plays a crucial role in regulating autophagy and cellular homeostasis in human and mouse RPE (mRPE) cells in vitro. Nevertheless, a comprehensive understanding of its in vivo expression and function in mRPE remains to be elucidated. To characterize Prom1 expression in RPE in situ, we used RNAscope assays and immunogold electron microscopy (EM). Our use of chromogenic and fluorescent RNAscope assays in albino and C57BL/6J mouse retinal sections has revealed Prom1 mRNA expression in perinuclear regions in mRPE in situ. Immunogold EM imaging showed Prom1 expression in RPE cytoplasm and mitochondria. To confirm Prom1 expression in RPE, we interrogated human RPE single-cell RNA-sequencing datasets using an online resource, Spectacle. Our analysis showed Prom1 expression in human RPE. To investigate Prom1's function in RPE homeostasis, we performed RPE-specific Prom1 knockdown (KD) using subretinal injections of AAV2/1.CMV.saCas9.U6.Prom1gRNA in male and female mice. Our data show that RPE-specific Prom1-KD in vivo resulted in abnormal RPE morphology, subretinal fluid accumulation, and secondary PR loss. These changes were associated with patchy RPE cell death and reduced a-wave amplitude, indicating retinal degeneration. Our findings underscore the central role of Prom1 in cell-autonomous mRPE homeostasis. The implications of Prom1-KD causing aAMD-like RPE defects and retinal degeneration in a mouse model are significant and could lead to novel treatments for aAMD.

Keywords: adeno-associated virus (AAV2/1); atrophic age-related macular degeneration; geographic atrophy; lysosomal pathways; microglia; mitochondria

DOI: https://doi.org/10.3390/cells13211761