Qu, Y.-F. | bioRxiv Science

bioRxiv2026

M6A-modified circEZH2 Protects Endothelial Cells from Senescence and Suppresses Atherosclerosis by Stabilizing ZNF326

BACKGROUNDEndothelial cell senescence induces endothelial dysfunction, thereby contributing to atherosclerosis progression. Circular RNAs (circRNAs) play diverse roles in multiple physiological and pathological processes. N6-methyladenosine (m6A) is the most abundant internal RNA modification in eukaryotic RNAs and dynamically regulates RNA fate and function. However, the functions and therapeutic potential of m6A-modified circRNAs in endothelial cell senescence remain unknown. METHODSm6A-modified circRNAs associated with endothelial cell senescence were screened by circRNA expression and m6A-circRNA microarray profiling of endothelial cells and mouse aortic intima. circEZH2 expression was validated in endothelial cells, vascular tissues, and human atherosclerotic plaques by RT-qPCR, and RNA fluorescence in situ hybridization. The role of circEZH2 in endothelial senescence and atherosclerosis was assessed in vitro and in vivo. RNA pull-down, mass spectrometry, RNA immunoprecipitation, co-immunoprecipitation, ubiquitination assays, and rescue experiments were used to define the underlying mechanism. RESULTSWe identified A novel m6A-modified circRNA, circEZH2, that was downregulated in the aged aortic intima and advanced plaques. CircEZH2 was stabilized by m6A reader IGF2BP2. Endothelial cell-specific overexpression of circEZH2 delayed senescence and suppressed atherosclerosis progression. At the cellular level, circEZH2 overexpression delayed senescence, decreased p53/p21 levels and increased angiogenic activity of endothelial cells, while circEZH2 knockdown exhibited the opposite effect. Mechanistically, circEZH2 functions as a scaffold to promote USP37-mediated deubiquitination, thereby stabilizing ZNF326. Moreover, endothelial cell-specific knockdown of ZNF326 counteracts the anti-senescent and anti-atherosclerotic effects mediated by circEZH2 overexpression. CONCLUSIONSIn summary, the present study identifies circEZH2 as a novel suppressor of endothelial cell senescence, highlighting its potential as a therapeutic target for age-related atherosclerosis. GRAPHIC ABSTRACTA graphic abstract is available for this article. O_FIG O_LINKSMALLFIG WIDTH=177 HEIGHT=200 SRC="FIGDIR/small/730538v1_ufig1.gif" ALT="Figure 1"> View larger version (78K): org.highwire.dtl.DTLVardef@d3a586org.highwire.dtl.DTLVardef@1180c1forg.highwire.dtl.DTLVardef@1c3d832org.highwire.dtl.DTLVardef@a6d424_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOGraphic abstract.C_FLOATNO Schematic model of m6A-modified circEZH2 regulation in endothelial cell senescence and atherosclerosis. In young endothelial cells, IGF2BP2 is highly expressed and recognizes m6A-modified circEZH2, thereby maintaining its RNA stability. CircEZH2 stabilizes ZNF326 protein through USP37-mediated deubiquitination, which leads to suppression of p21 and p53, delays endothelial cell senescence, ameliorates endothelial dysfunction, and ultimately suppresses the progression of atherosclerosis. C_FIG What Are the Clinical Implications?This study identifies circEZH2 as a novel m6A-modified circular RNA that is reduced in the aged aortic intima and in endothelial cells within advanced atherosclerotic plaques. Endothelial circEZH2 overexpression delays endothelial cell senescence, preserves endothelial function, and suppresses atherosclerotic lesion formation, supporting an important role for circEZH2 in vascular aging-associated atherosclerosis. Mechanistically, circEZH2 acts as a scaffold to enhance USP37-mediated deubiquitination and stabilization of ZNF326, while endothelial ZNF326 knockdown counteracts the anti-senescent and anti-atherosclerotic effects of circEZH2. These findings reveal the circEZH2-ZNF326 axis as a previously unrecognized mechanism regulating endothelial senescence and atherosclerosis progression. Our work supports the potential of circEZH2-based gene therapy as a novel therapeutic approach for atherosclerosis.

cell biology↗

bioRxiv2022

Gut Microbiome Contributes to Cold-climate Adaptation in Lizards

The metabolic cold-climate adaption hypothesis predicts that animals from cold environments have relatively high metabolic rates compared with their warm-climate counterparts. However, studies testing this hypothesis are sparse. Here, we compared gut microbes between two cold-climate lizard species of the genus Phrynocephalus to test the hypothesis that gut microbiota can help lizards adapt to cold environments by promoting metabolism and absorption efficiency. We kept lizards at 24{degrees}C and 30{degrees}C for 25 d, and then collected their fecal samples to analyze and compare the microbiota based on 16S rRNA gene sequencing technology. The gut microbiota was mainly composed of Proteobacteria, Firmicutes, Bacteroidetes, and Verrucomicrobia at the phylum level in both species (Proteobacteria > Firmicutes > Verrucomicrobiota in P. erythrurus, and Bacteroidota > Proteobacteria > Firmicutes in P. przewalskii). Further analysis revealed that the gut microbiota contributed to the hosts cold adaptation, but with differences in the relative abundance of these contributory bacteria between the two species. KEGG analysis revealed that the gut microbiota primarily played roles in metabolism, genetic information processing, cellular processes, and environmental information processing in both species. Furthermore, genes related to metabolism were more abundant in P. erythrurus at 24 {degrees}C than in other species x temperature combinations, indicating the role of gut microbiota in long-term cold-climate adaptation. Our finding that gut microbiome contributes to cold-climate adaptation in both species but more evidently in P. erythrurus using colder habitats than P. przewalskii throughout a year confirms the gut microbiotas role in the cold-climate adaptation in lizards. IMPORTANCEThis study proves that temperature affects the composition and relative abundance of the gut microbiota in two Phrynocephalus lizards in a species-specific manner. Both species harbor specific gut microbiota with significant roles in cold-climate adaptation. Specifically, P. erythrurus has a higher Proteobacteria ratio and relative abundance of metabolism-related microbial genes in the gut than P. przewalskii. Given that P. erythrurus uses colder habitats than P. przewalskii throughout a year, these results suggest that gut microbiota contributes to cold-climate adaptation in both species lizards but more evidently in P. erythrurus. This study provides evidence linking gut microbiome with cold adaptation. The co-evolution mechanism between gut microbiota and their hosts in extreme environments will provide new insights into animal adaptation.

ecology↗