Biology subjects

Dion, W.

Publications and source records attributed to Dion, W..

5 recordsLinked to original sources

bioRxiv2025

Beige fat appearance during lipoatrophy reveals trade-offs between metabolic homeostasis and female fertility

White adipose tissue (WAT) meets the energetic demands required for estrous cycle regularity, ovulation, and reproductive success in women. Here, we report WAT loss and subsequent female-specific compensatory beige fat recruitment impact metabolic and reproductive outcomes in mice. Female mice that undergo progressive lipoatrophy ( fat-less) displayed disrupted estrous cycles, reduced ovarian reserve, and subfertility. These effects were attributable to an accumulation of thermogenic beige fat cells in residual subcutaneous WAT depots and greater energy expenditure. Conversely, high-fat diet lowered energy expenditure and rescued estrous cycle regularity among fat-less mice compared to littermate controls, despite profound insulin resistance and metabolic dysfunction. Together, these findings provide evidence of trade-offs between the maintenance of metabolic homeostasis and reproduction, where increased energy expenditure and beige fat cell emergence compensate for fat loss but occur at the expense of fecundity in female mice.

cell biology↗

bioRxiv2024

Epigenetic regulation of global proteostasis dynamics by RBBP5 ensures mammalian organismal health

Proteostasis is vital for cellular health, with disruptions leading to aging, neurodegeneration and metabolic disorders. Traditionally, proteotoxic stress responses were studied as acute reactions to various noxious factors; however, recent evidence reveals that many proteostasis genes exhibit [~]12h ultradian rhythms under physiological conditions in mammals, driven by an XBP1s-dependent 12h oscillator. By examining the chromatin landscape of this oscillator, we identified RBBP5 as an essential epigenetic regulator of global proteostasis dynamics. Mechanistically, as the core subunit of the SET1/COMPASS complex, RBBP5 co-activates XBP1s to facilitate dynamic proteostasis gene expression by marking promoter-proximal H3K4me3, which further recruits the Integrator Complex and SWI/SNF chromatin remodelers. Functionally, RBBP5 is indispensable for regulating both the 12h oscillator and acute transcriptional response to various proteotoxic stresses, including ER stress and nutrient deprivation. RBBP5 ablation causes increased susceptibility to proteotoxic stress, chronic inflammation, and hepatic steatosis in mice, along with impaired autophagy and reduced cell survival in vitro. In humans, lower RBBP5 expression is associated with reduced adaptive stress-response gene expression and hepatic steatosis. Our findings not only highlight a previously unrecognized epigenetic timing mechanism distinct from circadian regulation but also establish RBBP5 as a central regulator of proteostasis, essential for cellular resilience and organismal health. One sentence summaryRBBP5 regulates global mammalian proteostasis.

cell biology↗

bioRxiv2024

Nuclear speckle rejuvenation alleviates proteinopathies at the expense of YAP1

Current treatments targeting individual protein quality control pathways have limited efficacy in alleviating proteinopathies, highlighting the prerequisite for a common druggable target capable of global proteostasis modulation. Building upon our prior research establishing nuclear speckles as pivotal membrane-less organelles for transcriptional control of proteostasis, we aim to alleviate proteinopathies through nuclear speckle rehabilitation. We identified pyrvinium pamoate as a nuclear speckle rehabilitator that enhances protein quality control gene expression and suppresses YAP1 transcriptional activity via decreasing the surface/interfacial tension of nuclear speckle condensates through interaction with the intrinsically disordered region of nuclear speckle scaffold protein SON. In pre-clinical models, nanomolar pyrvinium pamoate protected against retinal degeneration and tauopathy mainly by promoting autophagy and ubiquitin-proteasome activity in a SON-dependent manner without causing stress. Aberrant nuclear speckle morphology, reduced protein quality control and increased YAP1 activity were observed in human tauopathies. Our study provides proof-of-principle of targeting nuclear speckles to ameliorate proteinopathies.

cell biology↗

bioRxiv2023

LEF1 isoforms regulate cellular senescence and aging

BackgroundThe study of aging and its mechanisms, such as cellular senescence, has provided valuable insights into age-related pathologies, thus contributing to their prevention and treatment. The current abundance of high throughput data combined with the surge of robust analysis algorithms has facilitated novel ways of identifying underlying pathways that may drive these pathologies. MethodsWith the focus on identifying key regulators of lung aging, we performed comparative analyses of transcriptional profiles of aged versus young human subjects and mice, focusing on the common age-related changes in the transcriptional regulation in lung macrophages, T cells, and B immune cells. Importantly, we validated our findings in cell culture assays and human lung samples. ResultsWe identified Lymphoid Enhancer Binding Factor 1 (LEF1) as an important age-associated regulator of gene expression in all three cell types across different tissues and species. Follow-up experiments showed that the differential expression of long and short LEF1 isoforms is a key regulatory mechanism of cellular senescence. Further examination of lung tissue from patients with Idiopathic Pulmonary Fibrosis (IPF), an age-related disease with strong ties to cellular senescence, we demonstrated a stark dysregulation of LEF1. ConclusionsCollectively, our results suggest that the LEF1 is a key factor of aging, and its differential regulation is associated with human and murine cellular senescence.

genomics↗

bioRxiv2023

Evidence for conservation of a primordial 12-hour ultradian gene program in humans

While circadian rhythms are entrained to the once daily light-dark cycle of the sun, many marine organisms exhibit [~]12h ultradian rhythms corresponding to the twice daily movement of the tides. Although human ancestors emerged from circatidal environment millions of years ago, direct evidence of [~]12h ultradian rhythms in humans is lacking. Here, we performed prospective, temporal transcriptome profiling of peripheral white blood cells and identified robust [~]12h transcriptional rhythms from three healthy participants. Pathway analysis implicated [~]12h rhythms in RNA and protein metabolism, with strong homology to the circatidal gene programs previously identified in Cnidarian marine species. We further observed [~]12h rhythms of intron retention events of genes involved in MHC class I antigen presentation, synchronized to expression of mRNA splicing genes in all three participants. Gene regulatory network inference revealed XBP1, and GABP and KLF transcription factor family members as potential transcriptional regulators of human [~]12h rhythms. These results suggest that human [~]12h biological rhythms have a primordial evolutionary origin with important implications for human health and disease.

systems biology↗