cell-specific-paired-interrogation-mouse-ovarian-epigenome

Cell-Specific Paired Interrogation of the Mouse Ovarian Epigenome and Transcriptome

Assessing cell-type-specific epigenomic and transcriptomic changes are key to understanding ovarian aging. To this end, the optimization of the ...

oklahoma medical research foundation

Decline in ovarian reserve with advancing age is associated with reduced fertility and the emergence of metabolic disturbances, osteoporosis, and neurodegeneration. Recent studies have provided insight into connections between ovarian insufficiency and systemic aging, although the basic mechanisms that promote ovarian reserve depletion remain unknown. Here, we sought to determine if chronological age is linked to changes in ovarian cellular senescence, transcriptomic, and epigenetic mechanisms in a mouse model. Histological assessments and transcriptional analyses revealed the accumulation of lipofuscin aggresomes and senescence-related transcripts (Cdkn1a, Cdkn2a, Pai-1 and Hmgb1) significantly increased with advancing age. Transcriptomic profiling and pathway analyses following RNA sequencing, revealed an upregulation of genes related to pro-inflammatory stress and cell-cycle inhibition, whereas genes involved in cell-cycle progression were downregulated; which could be indicative of senescent cell accumulation. The emergence of these senescence-related markers preceded the dramatic decline in primordial follicle reserve observed. Whole Genome Oxidative Bisulfite Sequencing (WGoxBS) found no genome-wide or genomic context-specific DNA methylation and hydroxymethylation changes with advancing age. These findings suggest that cellular senescence may contribute to ovarian aging, and thus, declines in ovarian follicular reserve. Cell-type-specific analyses across the reproductive lifespan are needed to fully elucidate the mechanisms that promote ovarian insufficiency.

Cellular hallmarks of aging emerge in the ovary prior to primordial follicle depletion.

Estrogen signaling is protective against chronic liver diseases, although men and a subset of women are contraindicated for chronic treatment with 17β-estradiol (17β-E2) or combination hormone replacement therapies. We sought to determine if 17α-estradiol (17α-E2), a naturally occurring diastereomer of 17β-E2, could attenuate liver fibrosis. We evaluated the effects of 17α-E2 treatment on collagen synthesis and degradation rates using tracer-based labeling approaches in male mice subjected to carbon tetrachloride (CCl)-induced liver fibrosis. We also assessed the effects of 17α-E2 on markers of hepatic stellate cell (HSC) activation, collagen cross-linking, collagen degradation, and liver macrophage content and polarity. We found that 17α-E2 significantly reduced collagen synthesis rates and increased collagen degradation rates, which was mirrored by declines in transforming growth factor β1 (TGF-β1) and lysyl oxidase-like 2 (LOXL2) protein content in liver. These improvements were associated with increased matrix metalloproteinase 2 (MMP2) activity and suppressed stearoyl-coenzyme A desaturase 1 (SCD1) protein levels, the latter of which has been linked to the resolution of liver fibrosis. We also found that 17α-E2 increased liver fetuin-A protein, a strong inhibitor of TGF-β1 signaling, and reduced proinflammatory macrophage activation and cytokines expression in the liver. We conclude that 17α-E2 reduces fibrotic burden by suppressing HSC activation and enhancing collagen degradation mechanisms. Future studies will be needed to determine if 17α-E2 acts directly in hepatocytes, HSCs, and/or immune cells to elicit these benefits.

Tatiana D. Saccon

Aging and Metabolism Research Program

oklahoma medical research foundation

Cell-Specific Paired Interrogation of the Mouse Ovarian Epigenome and Transcriptome

Tatiana D. Saccon

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oklahoma medical research foundation

Cell-Specific Paired Interrogation of the Mouse Ovarian Epigenome and Transcriptome

Aging and Metabolism Research Program