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Austad, S. N.

Publications and source records attributed to Austad, S. N..

2 recordsLinked to original sources

A Fourfold Male-Specific Lifespan Extension via Canonical Insulin/IGF-1 Signaling

Aging is a universal biological process driven by conserved genetic networks that balance somatic maintenance with growth and reproduction. The insulin/insulin-like growth factor I signaling pathway is a central architect of this balance, and inhibiting its activity has long been established as a primary mechanism to extend lifespan across diverse species. However, our understanding of this pathways limits has been constrained by a historical focus on hermaphroditic models, which inherently link longevity extensions to a rigid trade-off involving immense reproductive costs and restricted somatic growth. Here we show that the latent potential of this canonical aging pathway is profoundly amplified by male-specific biology. We demonstrate that a classic insulin receptor mutation extends male survival to an unprecedented extreme, vastly surpassing the established benchmarks of the field. We reveal that this extraordinary lifespan expansion remains strictly dependent on the canonical FOXO transcription factor, yet it fuels a male-specific metabolic reprogramming that uncouples aging from stunted growth--massively accumulating neutral lipids to support sustained somatic preservation. These findings establish biological sex as a primary determinant of longevity potential and provide a new framework for identifying hidden, sex-specific mechanisms capable of promoting extreme healthy longevity.

physiology↗

Differential regulation of mouse hippocampal gene expression sex differences by chromosomal content and gonadal sex

Common neurological disorders, like Alzheimers disease (AD), multiple sclerosis (MS), and autism, display profound sex differences in prevalence and clinical presentation. However, sex differences in the brain with health and disease are often overlooked in experimental models. Sex effects originate, either directly or indirectly, from hormonal or sex chromosomal mechanisms. To delineate the contributions of genetic sex (XX v. XY) versus gonadal sex (ovaries v. testes) to the epigenomic regulation of hippocampal sex differences, we use the Four Core Genotypes (FCG) mouse model to uncouple chromosomal and gonadal sex. Transcriptomic and epigenomic analyses of [~]12-month-old FCG mice hippocampi, revealed genomic context-specific regulatory effects of genotypic and gonadal sex on X- and autosome-encoded gene expression and DNA modification patterns. X-chromosomal epigenomic patterns, classically associated with X-inactivation, were established almost entirely by genotypic sex, independent of gonadal sex. Differences in X-chromosome methylation were primarily localized to gene regulatory regions including promoters, CpG islands, CTCF binding sites, and active/poised chromatin, with an inverse relationship between methylation and gene expression. Whereas, autosomal gene expression demonstrated regulation by both genotypic and gonadal sex, particularly in immune processes. These data demonstrate an important regulatory role of sex chromosomes, independent of gonadal sex, on sex-biased hippocampal transcriptomic and epigenomic profiles. Future studies will need to further interrogate specific CNS cell types, identify the mechanisms by which sex chromosomes regulate autosomes, and differentiate organizational from activational hormonal effects.

genomics↗