Biology subjects

Kholod, O.

Publications and source records attributed to Kholod, O..

4 recordsLinked to original sources

bioRxiv2025

Multiomic analysis reveals that polyamines alter G. vaginalis-induced cervicovaginal epithelial cell dysfunction

An anaerobe-dominant, Lactobacillus-deplete cervicovaginal microbiome is associated with adverse reproductive outcomes. Gardnerella vaginalis, a cervicovaginal anaerobe, alters cervicovaginal epithelial cell function, resulting in immune activation and barrier breakdown. Host-microbial mechanisms inducing this epithelial dysfunction remain unknown. We show microbe-specific alterations in cervicovaginal epithelial cell metabolite profiles where G. vaginalis, but not Lactobacillus crispatus, increases polyamine biosynthesis. Pretreatment with polyamines (putrescine, spermidine and spermine) globally shifts G. vaginalis-induced transcriptomic profiles. Alterations in enzyme transcripts responsible for polyamine synthesis and catabolism provide evidence that G. vaginalis modifies polyamine biosynthesis. Polyamine-mediated transcriptomic changes include genes related to bacterial defense, inflammation, and epigenetic processes. Polyamines mitigate G. vaginalis-induced inflammatory responses through reduction of cytokines/chemokines and matrix metalloproteinases. In vitro transcriptional signatures positively correlated to existing human datasets. The ability of cervicovaginal metabolites to alter microbe-mediated changes in epithelial cell function suggests that metabolite-microbe interactions are critical mediators of epithelial defense against a Lactobacillus-deplete microbiota.

microbiology↗

bioRxiv2025

A pre-menopausal single-cell atlas for ovarian drug discovery

Multi-tissue single-cell atlas efforts have transformed our understanding of cellular diversity across the human body and led to the creation of harmonized resources to advance research and therapeutic development. Ovarian biology, however, often remains underrepresented in these resources and is rarely analyzed with menopausal status as a biological variable. Here, we present the Menopause Cell Map (MenoMap), an integrated single-cell resource comprising more than 2 million cells from 13 healthy human tissues, including the ovary, from pre- and post-menopausal age donors. This harmonized atlas leverages curated samples from healthy female donors and enables transcriptomic comparisons across cell types, tissues, and organs while preserving menopausal status based on age as an interpretable variable. Using this resource, we show that menopause-associated gene expression changes are highly context dependent, with prominent remodeling in ovarian stromal, endothelial, immune, and reproductive cell populations. Within the ovary, post-menopausal remodeling rewired intercellular communication and shifted reproductive and steroidogenic programs toward collagen-integrin signaling, endothelial-to-mesenchymal transition, and senescence concentrated in the endothelial and stromal compartments. Cross-species comparison with young and aged mouse ovarian single-cell data showed these endothelial and stromal changes were conserved with age, most prominently in tumor necrosis factor-nuclear factor-kappa-beta signaling. Finally, we apply Human Protein Atlas-inspired specificity rules and fertility phenotype annotations to evaluate how menopausal age status affects tissue- and cell-type-specific gene classification and to prioritize ovary-enriched genes for downstream biological and translational investigation. Through this analysis, we find that the tissue specificity classification of several genes involved in reproductive-specific programs change in the pre- to post-menopausal transition, highlighting the need for age-aware and healthy donors in multi-tissue single-cell atlas efforts. Together, the MenoMap provides a human single-cell framework that leverages existing and standardized single-cell datasets curated for studying ovarian biology across reproductive aging, evaluating the influence of menopausal status on gene expression and tissue specificity, and nominating candidate genes for future investigation in reproductive biology, fertility, and target discovery.

bioinformatics↗

bioRxiv2025

Disrupted MOS signaling alters meiotic cell cycle regulation and the egg transcriptome

Mammalian female meiosis is tightly regulated to produce a developmentally competent egg. Oocytes enter meiosis in the fetal ovary and then arrest at prophase I until sexual maturation. Upon hormonal stimulation, a subset of oocytes resumes meiosis at which time, new transcription is halted. Oocytes then complete meiosis I, enter metaphase II, and arrest until fertilization, a process essential for egg competency and fertility. The MOS kinase is a key regulator of the metaphase II arrest, activating the MAPK signaling cascade. Loss of MOS in female mice disrupts the maintenance of the metaphase II arrest, leading some eggs to extrude two polar bodies and some to divide beyond anaphase II. To investigate the consequences of the Mos deletion, we performed live imaging and found that mos-/- eggs exhibit transient chromosome separation events in meiosis I, suggesting a role for MOS in coordinating the timing of meiotic divisions. Further analysis showed that new transcription is required for mos-/- eggs to undergo additional divisions but not for second polar body extrusion. Surprisingly, single-egg sequencing revealed extensive differences in gene expression between wildtype and mos-/-eggs, including those with only one polar body. Many of the differentially expressed genes were involved in cell cycle regulation, including Aurka, Bub3, and Cdk7. Other upregulated pathways included metabolism of RNA, transcription, and neddylation. Furthermore, the gene expression profile of mos-/- eggs was markedly different from that of wildtype eggs chemically activated to undergo embryo-like divisions. Our findings demonstrate that MOS plays a crucial role in meiotic cell cycle regulation and helps ensure that the egg maintains the proper transcriptome necessary for developmental competence.

cell biology↗

bioRxiv2025

Transcriptomic analysis of whole staged ovarian follicles reveals stage-specific folliculogenesis signatures in mice

Activation and maturation of ovarian follicles are essential for female reproduction, yet the underlying molecular and transcriptional mechanisms that govern these processes remain poorly understood. In this study, we used single follicle RNA-sequencing (RNA-seq) to identify transcriptional signatures of staged ovarian follicles, from primordial to secondary stages, to uncover the genes and pathways involved in early folliculogenesis. Our findings demonstrate that primordial follicles are transcriptionally distinct from growing follicles, with enrichment in DNA integrity and RNA processing pathways, which may play a role in preserving oocyte genomic stability and cell state during dormancy. Additionally, our analysis reveals minimal transcriptomic differences between primary and secondary follicles using traditional differential expression analysis. To better distinguish growing follicle stages, we introduce unsupervised approaches, including discrete-variable predictors of follicle stage and weighted gene co-expression analysis. We identified pathways involved in DNA integrity, meiotic arrest, and cellular metabolism that drive the transition from dormant to active follicle states, as well as pathways related to cellular growth, ECM organization, and biosynthesis in growing follicle stages. Our study offers novel insights into the molecular mechanisms governing early follicle activation and growth, providing a foundation for future research with applications in reproductive biology, contraception, and fertility preservation. Author SummaryThe development of ovarian follicles is essential for female fertility, but the molecular signals that control their growth remain unclear. In this study, we used advanced gene sequencing techniques to analyze the genetic activity of individual ovarian follicles at different stages of early development. We found that dormant follicles have unique gene expression patterns that help protect the genetic material of the egg and maintain their inactive state. In contrast, follicles that have begun to grow show increased activity in genes related to cell growth, communication, and structural changes. Interestingly, we observed that early growing follicles are more similar to each other than previously thought, prompting us to apply new analytical methods to better distinguish their developmental stages. Our findings highlight key biological pathways that regulate the transition from dormant to active follicles and uncover new genes that may play a role in this process. Understanding these mechanisms provides valuable insights into ovarian biology and could inform future research on fertility treatments, contraception, and reproductive health.

bioinformatics↗