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To provide a multi-omics resource and investigate transcriptional regulatory mechanisms, we profile the transcriptome, chromatin accessibility, and methylation status of over 70,000 single nuclei (sn) from adult mouse pituitaries. Paired snRNAseq and snATACseq datasets from individual animals highlight a continuum between developmental epigenetically-encoded cell types and transcriptionally-determined transient cell states. Co-accessibility analysis-based identification of a putative Fshb cis-regulatory domain that overlaps the fertility-linked rs11031006 human polymorphism, followed by experimental validation illustrate the use of this resource for hypothesis generation. We also identify transcriptional and chromatin accessibility programs distinguishing each major cell type. Regulons, which are co-regulated gene sets sharing binding sites for a common transcription factor driver, recapitulate cell type clustering. We identify both cell type-specific and sex-specific regulons that are highly correlated with promoter accessibility, but not with methylation state, supporting the centrality of chromatin accessibility in shaping cell-defining transcriptional programs. The sn multi-omics atlas is accessible at snpituitaryatlas.princeton.edu.

Muscle inflammation and fibrosis underlie disuse‐related complications and may contribute to impaired muscle recovery in aging. Cellular senescence is an emerging link between inflammation, extracellular matrix (ECM) remodeling and poor muscle recovery after disuse. In rodents, metformin has been shown to prevent cellular senescence/senescent associated secretory phenotype (SASP), inflammation, and fibrosis making it a potentially practical therapeutic solution. Thus, the purpose of this study was to determine in older adults if metformin monotherapy during bed rest could reduce muscle fibrosis and cellular senescence/SASP during the re‐ambulation period. A two‐arm controlled trial was utilized in healthy male and female older adults (n = 20; BMI: <30, age: 60 years+) randomized into either placebo or metformin treatment during a two‐week run‐in and 5 days of bedrest followed by metformin withdrawal during 7 days of recovery. We found that metformin‐treated individuals had less type‐I myofiber atrophy during disuse, reduced pro‐inflammatory transcriptional profiles, and lower muscle collagen deposition during recovery. Collagen content and myofiber size corresponded to reduced whole muscle cellular senescence and SASP markers. Moreover, metformin treatment reduced primary muscle resident fibro‐adipogenic progenitors (FAPs) senescent markers and promoted a shift in fibroblast fate to be less myofibroblast‐like. Together, these results suggest that metformin pre‐treatment improved ECM remodeling after disuse in older adults by possibly altering cellular senescence and SASP in skeletal muscle and in FAPs. [ABSTRACT FROM AUTHOR]

Context: A genetic etiology accounts for the majority of unexplained primary ovarian insufficiency (POI). Objective: We hypothesized a genetic cause of POI for a sister pair with primary amenorrhea. Design: The study was an observational study. Subjects were recruited at an academic institution. Subjects: Subjects were sisters with primary amenorrhea caused by POI and their parents. Additional subjects included women with POI analyzed previously (n = 291). Controls were recruited for health in old age or were from the 1000 Genomes Project (total n = 233). Intervention: We performed whole exome sequencing, and data were analyzed using the Pedigree Variant Annotation, Analysis and Search Tool, which identifies genes harboring pathogenic variants in families. We performed functional studies in a Drosophila melanogaster model. Main Outcome: Genes with rare pathogenic variants were identified. Results: The sisters carried compound heterozygous variants in DIS3. The sisters did not carry additional rare variants that were absent in publicly available datasets. DIS3 knockdown in the ovary of D. melanogaster resulted in lack of oocyte production and severe infertility. Conclusions: Compound heterozygous variants in highly conserved amino acids in DIS3 and failure of oocyte production in a functional model suggest that mutations in DIS3 cause POI. DIS3 is a 3' to 5' exoribonuclease that is the catalytic subunit of the exosome involved in RNA degradation and metabolism in the nucleus. The findings provide further evidence that mutations in genes important for transcription and translation are associated with POI. [ABSTRACT FROM AUTHOR]

In this prospective, interventional study of 8 women with hypothalamic amenorrhea, leptin administration led to normalization of levels of reproductive hormones, follicular development, and menstrual cyclicity. Leptin administration for the relative leptin deficiency in women with hypothalamic amenorrhea appears to improve reproductive, thyroid, and growth hormone axes and markers of bone formation.

Context: A genetic etiology likely accounts for the majority of unexplained primary ovarian insufficiency (POI). Objective: We hypothesized that heterozygous rare variants and variants in enhanced categories are associated with POI. Design: The study was an observational study. Setting: Subjects were recruited at academic institutions. Patients: Subjects from Boston (n = 98), the National Institutes of Health and Washington University (n = 98), Pittsburgh (n = 20), Italy (n = 43), and France (n = 32) were diagnosed with POI (amenorrhea with an elevated follicle-stimulating hormone level). Controls were recruited for health in old age or were from the 1000 Genomes Project (total n = 233). Intervention: We performed whole exome sequencing (WES), and data were analyzed using a rare variant scoring method and a Bayes factor-based framework for identifying genes harboring pathogenic variants. We performed functional studies on identified genes that were not previously implicated in POI in a D. melanogaster model. Main Outcome: Genes with rare pathogenic variants and gene sets with increased burden of deleterious variants were identified. Results: Candidate heterozygous variants were identified in known genes and genes with functional evidence. Gene sets with increased burden of deleterious alleles included the categories transcription and translation, DNA damage and repair, meiosis and cell division. Variants were found in novel genes from the enhanced categories. Functional evidence supported 7 new risk genes for POI (USP36, VCP, WDR33, PIWIL3, NPM2, LLGL1, and BOD1L1). Conclusions: Candidate causative variants were identified through WES in women with POI. Aggregating clinical data and genetic risk with a categorical approach may expand the genetic architecture of heterozygous rare gene variants causing risk for POI. [ABSTRACT FROM AUTHOR]