Project description:Mito-nuclear crosstalk underlying ovarian aging remains elusive. Single-cell transcriptomics of aged ovaries identified senescent signatures including dysregulated mitochondrial metabolism, disturbed histone modification and enriched SASP. We demonstrated that impaired SIRT5-mediated desuccinylation drives ovarian aging. As a major substrate of SIRT5 in the TCA cycle, SUCLG2 is regulated by desuccinylation at K93 and K101, which enhances its stability and activity to rescue mitochondrial dysfunction. Conversely, SUCLG2 hypersuccinylation leads to acetyl-CoA accumulation, increases nuclear H4K8ac and upregulates metabolic genes to compensate for energy deficiency. In vivo experiments showed excess acetyl-CoA accelerates ovarian aging, while a SUCLG2 desuccinylation mutant alleviates this defect. This study reveals the molecular basis of ovarian aging and highlights the SIRT5-SUCLG2 axis as a promising therapeutic target.
Project description:The study aimed to identify miRNAs expression profiles associated with growth and regression of dominant-size follicles in bovine. Follicles were collected from abattoir ovaries and their status (healthy/atretic) was assessed by measuring steroid levels and aromatase expression. Corpora lutea (CL) were collected from ovarian pairs correponding to days 1 to 4 of the oestrus cycle. Total RNA was isolated from whole follicles at different developmental stages and from CL. An heterologous microarray (Exiqon, Denmark) approach followed by RT-qPCR validation (Qiagen, UK) was used to identify and compare miRNA profiles between large healthy follicles (diameter, 13–16 mm, n=6) and each of small (4–8 mm, n=6 pools of follicles), large atretic folllicles (13-16 mm, n=6) and CL (n=6). RNA from the above groups was hybridized to the miRCURY LNA™ microRNA Hi-Power Labeling Kit,Hy3™/Hy5™ (Exiqon) and hybridized on the miRCURY LNA™ microRNA Array (6th gen). A total of 17 and 57 microRNAs were differentially expressed (> 2 fold, adj. P-value < 0.05) between Large Healthy and each of Small and Large Atretic follicles, respectively, a fraction of which corresponded to registered bovine miRNA sequences. A subset of 5 bovine miRNAs (miR-144, miR-202,vmiR-451, miR-652, miR-873) were confirmed by qPCR to be upregulated in Large Healthy follicles, were enriched in mural granulosa cells and their predicted targets mapped to genes involved in follicular cell proliferation and differentiation, suggesting an involvemet of this subset of microRNAs in ovarian follicle development. In addition, the miR-183-96-183 cluster was identified as upregulated in CL and was shown to be involved in luteal survival and progesterone production.
Project description:Mito-nuclear crosstalk underlying ovarian aging remains elusive. Single-cell transcriptomics of aged ovaries identified senescent signatures including dysregulated mitochondrial metabolism, disturbed histone modification and enriched SASP. We demonstrated that impaired SIRT5-mediated desuccinylation drives ovarian aging. As a major substrate of SIRT5 in the TCA cycle, SUCLG2 is regulated by desuccinylation at K93 and K101, which enhances its stability and activity to rescue mitochondrial dysfunction. Conversely, SUCLG2 hypersuccinylation leads to acetyl-CoA accumulation, increases nuclear H4K8ac and upregulates metabolic genes to compensate for energy deficiency. In vivo experiments showed excess acetyl-CoA accelerates ovarian aging, while a SUCLG2 desuccinylation mutant alleviates this defect. This study reveals the molecular basis of ovarian aging and highlights the SIRT5-SUCLG2 axis as a promising therapeutic target.