bims-mideyd 2025-04-13 papers

Autophagy. 2025 Apr 09.

MLST8 overexpression in RPE cells disrupts autophagy through novel mechanisms affecting AMD pathogenesis.

Sridhar Bammidi, Sayan Ghosh, Olivia Chowdhury, Vishnu Suresh Babu, Puja Dutta, Stacey Hose, Debasish Sinha.

Age-related macular degeneration (AMD) is a leading cause of blindness in the elderly, with dysfunction of the retinal pigment epithelium (RPE) central to disease pathogenesis. Using our uniquely developed MLST8 (MTOR associated protein, LST8 homolog) knock-in animal model with RPE-specific overexpression, which drives MTOR (mechanistic target of rapamycin kinase) upregulation, we demonstrate that increased MTOR complexes 1 and 2 in the RPE disrupts macroautophagy/autophagy by suppressing autophagosome formation genes and impairing MAP1LC3/LC3 processing. This leads to autophagosome accumulation and defective autolysosome formation, driving RPE dysfunction and AMD-like pathology, including subretinal debris build up and photoreceptor degeneration. Notably, MTOR inhibition with torin1 treatment or CRYBA1 overexpression rescues these defects, restoring autophagy and RPE integrity. Our findings reveal that autophagy disruption mediated by both MTORC1 and MTORC2 drives AMD-like pathology in our mouse model, establishing autophagy regulation as a promising avenue for therapeutic intervention in this vision-threatening disease.

Keywords: Age-related macular degeneration; MLST8; MTORC1; MTORC2; autophagy; retinal pigment epithelium

DOI: https://doi.org/10.1080/15548627.2025.2491097

Am J Pathol. 2025 Apr 07. pii: S0002-9440(25)00103-8. [Epub ahead of print]

Leucine-rich repeat kinase 2 promotes disintegration of retinal pigment epithelial cell: Implication in the pathogenesis of dry age-related macular degeneration.

Yuka Suimon, Moemi Nishimura, Miyuki Murata, Shiho Yoshida, Koichi Yokoi, Zhenyu Dong, Noriyuki Kuno, Shinobu Fujii, Zen-Ichi Tanei, Ichiro Yabe, Kousuke Noda, Susumu Ishida.

Recent epidemiological studies have shown that patients with age-related macular degeneration (AMD) have a considerably higher risk of developing Parkinson's disease (PD) later in life, suggesting a possible link between these diseases. However, the common mechanisms between these two diseases remain obscure, although the pathophysiology of each has been well investigated. In this study, we sought to explore the shared pathological features of AMD and PD by focusing on leucine-rich repeat kinase 2 (LRRK2) and α-synuclein, both of which play crucial roles in PD pathogenesis. Immunohistochemistry for LRRK2 and α-synuclein was performed on human eye specimens. The effect of LRRK2 on retinal pigment epithelium (RPE) cell function was investigated using the RPE cell line hTERT-RPE1. Retinal morphology and function were examined in LRRK2-G2019S transgenic mice, representing mutants with increased kinase activity of LRRK2. Immunohistochemistry revealed that LRRK2 and α-synuclein were present in the RPE layer of the human eye. Overexpression of LRRK2 in RPE cells increased α-synuclein and induced cell death. LRRK2 inhibited α-synuclein degradation via phosphorylation of RAB GTPases. LRRK2-G2019S transgenic mice exhibited apoptosis of RPE and photoreceptors, choroidal thinning, and reduced electroretinogram amplitude, on top of α-synuclein protein accumulation in the RPE cell layer. Taken together, the current study revealed that LRRK2 is one of the key molecules involved in the common pathological mechanisms of AMD and PD.

Keywords: G2019S; Leucine-rich repeat kinase 2; age-related macular degeneration; electroretinography; retinal pigment epithelium dysfunction; α-synuclein

DOI: https://doi.org/10.1016/j.ajpath.2025.03.002

bioRxiv. 2025 Mar 25. pii: 2025.03.21.644670. [Epub ahead of print]

Single-cell multiome and enhancer connectome of human retinal pigment epithelium and choroid nominate pathogenic variants in age-related macular degeneration.

Sean K Wang, Jiaying Li, Surag Nair, Reshma Korasaju, Yun Chen, Yuanyuan Zhang, Anshul Kundaje, Yuwen Liu, Ningli Wang, Howard Y Chang.

Age-related macular degeneration (AMD) is a leading cause of vision loss worldwide. Genome-wide association studies (GWAS) of AMD have identified dozens of risk loci that may house disease targets. However, variants at these loci are largely noncoding, making it difficult to assess their function and whether they are causal. Here, we present a single-cell gene expression and chromatin accessibility atlas of human retinal pigment epithelium (RPE) and choroid to systematically analyze both coding and noncoding variants implicated in AMD. We employ HiChIP and Activity-by-Contact modeling to map enhancers in these tissues and predict cell and gene targets of risk variants. We further perform allele-specific self-transcribing active regulatory region sequencing (STARR-seq) to functionally test variant activity in RPE cells, including in the context of complement activation. Our work nominates new pathogenic variants and mechanisms in AMD and offers a rich and accessible resource for studying diseases of the RPE and choroid.

DOI: https://doi.org/10.1101/2025.03.21.644670

Cytotechnology. 2025 Jun;77(3): 84

Metformin inhibits subretinal fibrosis by activating Klotho by miR-126-5p.

Zhijuan Hua, Qin Zhu, Jingfei Yang, Yuxiang Zheng, Wenchang Yang, Dongli Li, Yixin Cui, Lu Shen, Lingna Rao, Xiaofan Zhang, Ling Yuan.

Subretinal fibrosis is a main cause of visual loss in patients with neovascular age-related macular degeneration (nAMD), for whom there has been a lack of effective medication. Metformin can improve inflammation and angiogenesis in eye diseases. This study aimed to investigate the mechanism by which metformin inhibits subretinal fibrosis. A subretinal fibrosis cell model was induced by treating human retinal pigment epithelial cells (ARPE-19) with TGF-β1, a subretinal fibrosis mouse model was induced by a laser, and both cells and mice were treated with metformin. Cell proliferation, migration, and invasion were detected by CCK-8, scratch, and Transwell assays. Western blotting and immunofluorescence were used to evaluate protein expression levels, and RT‒qPCR was used to detect gene expression levels. HE and Masson staining were used to observe the morphological changes in retinal and choroidal tissues. Metformin treatment inhibited the TGF-β1-induced proliferation, migration, invasion and epithelial‒mesenchymal transition (EMT) of ARPE-19 cells and effectively ameliorated laser-induced subretinal fibrosis in mice. Mechanistically, metformin inhibits the expression of miR-126-5p, promotes Klotho synthesis, slows the progression of subretinal fibrosis, and miR-126-5p targets and negatively regulates Klotho. Metformin activates Klotho by inhibiting miR-126-5p, thereby reversing TGF-β1-induced ARPE-19 cell EMT and improving laser-induced subretinal fibrosis in mice.

Keywords: Klotho; Metformin; Subretinal fibrosis; miR-126-5p

DOI: https://doi.org/10.1007/s10616-025-00744-4

Sci Rep. 2025 Apr 11. 15(1): 12516

CaMK2A/CREB pathway activation is associated with enhanced mitophagy and neuronal apoptosis in diabetic retinopathy.

Xiaochun Yang, Yuxin Zhang, Yikun Zhou, Mingzhi Liu, Haiyan Zhao, Yang Yang, Jianyun Su.

Diabetic retinopathy (DR) is a common complication of diabetes mellitus, characterized by progressive neurodegeneration and vision impairment. The Ca2+/calmodulin-dependent protein kinase II alpha (CaMK2A) and cAMP response element-binding protein (CREB) signaling pathway has been implicated in various neurological disorders. However, its role in DR pathogenesis remains elusive. We established a DR mouse model by streptozotocin administration and performed histological, biochemical, and molecular analyses to investigate the involvement of CaMK2A/CREB signaling and its interplay with mitophagy. Additionally, we employed in vitro high-glucose (HG) treatment in primary mouse retinal ganglion cells to dissect the underlying mechanisms. Pharmacological and genetic modulations were utilized to target CaMK2A/CREB pathway and mitophagy. In the DR model, we observed retinal degeneration, increased apoptosis, and reduced neurotransmitter production, accompanied by enhanced mitophagy and activation of the CaMK2A/CREB pathway. HG induction in retinal ganglion cells recapitulated these findings, and autophagy inhibition partially rescued cell death but failed to suppress CaMK2A/CREB activation, suggesting mitophagy as a downstream consequence. CaMK2A knockdown or CREB phosphorylation inhibition attenuated HG-induced mitophagy, apoptosis, and neurotransmitter depletion, while CREB activation exacerbated these effects. CaMK2A silencing mitigated DR progression, oxidative stress, inflammation, and neuronal loss, akin to dopamine/carbidopa administration in DR mouse model. Our findings reveal the involvement of CaMK2A/CREB signaling activation and enhanced mitophagy in DR, suggesting these pathways may be therapeutically relevant targets for DR management.

Keywords: CREB; CaMK2A; Diabetic retinopathy; Mitophagy; Neurodegeneration

DOI: https://doi.org/10.1038/s41598-025-97371-y