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Feedback regulation between ALKBH3-mediated glycolysis and histone lactylation promotes age-related macular degeneration

ABSTRACT: Age-related macular degeneration (AMD) is a leading cause of blindness among the elderly. Using clinical samples and knockout mice, we reported that the m1A eraser ALKBH3 reshaped retinal metabolism to promote AMD. In retinal pigment epithelium (RPE), the dm1ACRISPR system demonstrated that ALKBH3 demethylated the glycolytic enzyme HK2 to activate anaerobic glycolysis, producing excessive lactate. The lactate promoted histone lactylation at H3K18, which in turn bound to ALKBH3 to amplify its transcription, establishing a positive feedback loop. The ALKBH3 inhibitor HUHS015 disrupted this loop, effectively mitigating RPE degeneration. Furthermore, ALKBH3 directly targeted the pro-angiogenic factor VEGFA to modulate the metabolic cross-talk between RPE and choroidal capillaries, thus promoting choroidal neovascularization (CNV). HUHS015 inhibited CNV synergistically with the anti-VEGF drug Aflibercept. Our study provides critical insights into the molecular mechanisms and metabolic events facilitating the progression from RPE degeneration to CNV in AMD, laying the groundwork for new treatments of AMD.

ORGANISM(S): Homo sapiens

PROVIDER: GSE274399 | GEO | 2024/08/14

REPOSITORIES: GEO

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Project description:Background: Age-related macular degeneration (AMD) is caused by the degeneration of the macular photoreceptors. This is preceded by development of subretinal protein aggregates (drusen) and degeneration of the macular retinal pigment epithelium (RPE). The underlying pathogenesis remains unknown, but the immune system is suspected to play a key role in it. Aging of the immune system, immunosenescence, includes changes in T cell sub-populations and results in low-level chronic inflammation. Because AMD exclusively occurs in patients over 55 years of age, we hypothesize that aging of the T cell compartment may be implicated in AMD pathogenesis. Methodology and principal findings: Using an in vitro co-culture system, we investigated the effects of activated T cells on a human RPE cell line (ARPE-19). Differential gene expression in the RPE cells of complement factor genes was identified using microarrays, and selected gene transcripts from the alternative complement pathway were validated by q-RT-PCR. Protein expression was determined by ELISA and immunoblotting. Co-culture with activated T cells increased RPE mRNA and protein expression of complement component C3, factors B, H, H-like 1, CD46, CD59, and clusterin, in a dose-dependent manner. Conclusions: RPE cells responded to inflammatory assault caused by exposure to T cell-derived cytokines by upregulating expression of many complement factors from the alternative pathway. This may have implications for RPE ability to deal with complement attack, and opsonization and removal of debris from the RPE-choroidal interface. We speculate that regulation of the complement system in response to inflammatory assault may play a vital role in RPE pathology and drusen biogenesis. Experiment Overall Design: 10 samples investigating variations of co-cultures of RPE cells and T-cells. Variable parameters include the cell type, the co-culturing of the counter-part cell type and the orientation of the system (apical vs basolateral).

Project description:Purpose: Age-related degeneration (AMD) is a major cause of blindness in developed countries. The molecular pathogenesis of early events in AMD is poorly understood. We investigated differential gene expression in samples of human retinal pigment epithelium (RPE)/choroid from early AMD and control maculas using exon-based arrays. Methods: Gene expression levels in nine early AMD and nine control human donor eyes were assessed using Affymetrix Human Exon ST 1.0 arrays. Two controls did not pass quality control and were removed. Differentially expressed genes were annotated using DAVID, and gene set enrichment analysis (GSEA) was performed on RPE-specific and endothelium-associated gene sets. CFH genotype was also assessed and differential expression was analyzed with respect to high AMD risk (YH/HH) and low AMD risk (YY) genotypes. Results: Seventy-five genes were identified as differentially expressed (raw p-value < 0.01; >50% fold change, mean log2 expression level in AMD or control M-bM-^IM-% median of all average gene expression values); however, no genes were significant (adj. p-value < 0.01) after correction for multiple hypothesis testing. Of 52 genes with decreased expression in AMD (fold change < 0.5; raw p-value < 0.01), 18 genes were identified by DAVID analysis as associated with vision or neurological processes. GSEA of RPE-associated and endothelium-associated genes revealed a significant decrease in genes typically expressed by endothelial cells in the early AMD group compared to controls, consistent with previous histologic and proteomic studies. Analysis with respect to CFH genotype indicated decreased expression of ADAMTS9 in eyes with high-risk genotypes (fold change = -2.61; raw p-value = 0.0008). Conclusions: GSEA results suggest that RPE transcripts are preserved or elevated in early AMD, concomitant with loss of endothelial cell marker expression. These results are consistent with the notion that choroidal endothelial cell dropout occurs early in the pathogenesis of AMD. Using AltAnalyze (ver. 2.0.7 beta), we analyzed nine early AMD and nine control eyes using Affymetrix Human Exon ST 1.0 arrays. Following initial processing in AltAnalyze, two control arrays were identified as potential outliers by tests implement in arrayQualityMetrics, a package for R.

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Feedback regulation between ALKBH3-mediated glycolysis and histone lactylation promotes age-related macular degeneration

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