Winston, C. L. | Search bioRxiv

bioRxiv2026

Sexual dimorphism in adult zebrafish marrows regulates blood cell composition and immune response

Hematopoiesis sustains lifelong blood production and immunity and is strongly influenced by biological sex. Males and females differ in their hematopoietic composition and susceptibility to infection and hematologic disease. Because current models cannot readily disentangle the independent contributions of sex chromosomes versus hormones, the mechanisms underlying sexual dimorphism remain poorly understood. Zebrafish have proven to be a powerful, translatable system for studying hematopoiesis, and offer a unique opportunity to isolate hormonal contributions due to their absence of sex chromosomes. However, whether sex is regulated in the zebrafish hematopoietic system remained unknown. Here, we discovered pronounced sexual dimorphism in the adult zebrafish marrow, with compositional differences peaking at reproductive age. Transcriptome analysis of marrows revealed conservation of sex-specific programs between zebrafish and human datasets. Upon immune challenge with lipopolysaccharide, all major blood lineages exhibited sex-biased changes in their composition and transcriptomes with the largest responses in erythroid and myeloid cell types. Among these sex differences was an unexpected immunoregulation of the erythroid lineage across maturation states. These findings establish biological sex as a major regulator of zebrafish hematopoiesis and immunity, paralleling humans, and lay the groundwork necessary for future mechanistic studies on sexual dimorphism in hematologic health and disease.

immunology↗

bioRxiv2023

Chronic metabolic stress drives developmental programs and loss of tissue functions in non-transformed liver that mirror tumor states and stratify survival

Under chronic stress, cells must balance competing demands between cellular survival and tissue function. In metabolic dysfunction-associated steatotic liver disease (MASLD, formerly NAFLD/NASH), hepatocytes cooperate with structural and immune cells to perform crucial metabolic, synthetic, and detoxification functions despite nutrient imbalances. While prior work has emphasized stress-induced drivers of cell death, the dynamic adaptations of surviving cells and their functional repercussions remain unclear. Namely, we do not know which pathways and programs define cellular responses, what regulatory factors mediate (mal)adaptations, and how this aberrant activity connects to tissue-scale dysfunction and long-term disease outcomes. Here, by applying longitudinal single-cell multi-omics to a mouse model of chronic metabolic stress and extending to human cohorts, we show that stress drives survival-linked tradeoffs and metabolic rewiring, manifesting as shifts towards development-associated states in non-transformed hepatocytes with accompanying decreases in their professional functionality. Diet-induced adaptations occur significantly prior to tumorigenesis but parallel tumorigenesis-induced phenotypes and predict worsened human cancer survival. Through the development of a multi-omic computational gene regulatory inference framework and human in vitro and mouse in vivo genetic perturbations, we validate transcriptional (RELB, SOX4) and metabolic (HMGCS2) mediators that co-regulate and couple the balance between developmental state and hepatocyte functional identity programming. Our work defines cellular features of liver adaptation to chronic stress as well as their links to long-term disease outcomes and cancer hallmarks, unifying diverse axes of cellular dysfunction around core causal mechanisms.

systems biology↗