Cohesin rad21 mutation dysregulates erythropoiesis and granulopoiesis output within the whole kidney marrow of adult zebrafish.

Cohesin complex is essential for cell division and regulating cell type-specific gene expression programs. Mutations in genes encoding the cohesin subunits are associated with hematological malignancies, preleukemia, and clonal hematopoiesis of indeterminate potential. In this study, we examined how cohesin mutation impacts hematopoiesis using adult zebrafish that carry heterozygous germline nonsense mutation in the cohesin subunit, rad21 (rad21^+/-) that is orthologous to human RAD21. Single-cell RNA sequencing analyses showed that adult zebrafish harboring rad21^+/- mutation exhibit significant transcriptional dysregulation within the whole kidney marrow and have altered erythroid and granulocyte output. Erythroid progenitors were expanded in rad21^+/- and erythroid differentiation was altered. The expression profile of several erythroid genes, including gata1a, was dysregulated in rad21^+/- erythroid cells. Mature granulocyte population declined in rad21^+/-, and the transcriptional program of granulocytes was impaired but granulocytic maturation was maintained. Granulocytes from rad21^+/- showed upregulation of stress hematopoiesis factor, cebpb. These findings show that normal rad21 is required to maintain steady erythropoiesis and granulopoiesis in the adult zebrafish marrow.NEW & NOTEWORTHY Mutations in cohesin subunit genes are early events in leukemogenesis. This study characterizes the hematopoietic compartment of adult zebrafish that carry germline heterozygous mutation in cohesin subunit, rad21. Our results show that despite normal appearance, rad21 mutant adult zebrafish exhibit transcriptional dysregulation and altered erythroid and granulocyte output. No obvious morphological dysplasia was observed in the rad21 mutant hematopoietic cells. These results suggest that rad21 mutation can cause underlying hematopoietic disturbances.