Dhx38 is required for the maintenance and differentiation of erythro-myeloid progenitors and hematopoietic stem cells by alternative splicing

Abstract

Mutations that occur in RNA splicing machinery may contribute to hematopoietic-related diseases. How splicing factor mutants perturb hematopoiesis, especially in the erythro-myeloid progenitors (EMP) process, remains elusive. Dhx38, a pre-mRNA splicing-related DEAH box RNA helicase, whose physiological function and splicing mechanisms during hematopoiesis currently remain unclear. Here we present that Dhx38 exerts a broad effect on definitive EMPs as well as the differentiation and maintenance of hematopoietic stem and progenitor cells (HSPCs). In dhx38 knockout zebrafish, EMPs and HSPCs are found arrested in mitotic prometaphase, accompanied by a ‘grape’ karyotype, due to the defects in chromosome alignment. Abnormal alternative spliced genes related to chromosome segregation, microtubule cytoskeleton, cell cycle kinase, and DNA damage are present in the dhx38 mutants. Subsequently, their EMPs and HSPCs undergo p53-dependent apoptosis. This study provides novel insights into alternative splicing regulated by Dhx38, a process that plays a critical role in proliferation and differentiation of fetal EMPs and HSPCs.

The splicing factor DHX38 enables retinal development through safeguarding genome integrity

“… 41 , 42 Our previous study reported that deletion Dhx38 in zebrafish hematopoietic tissues results in DNA damage and mitotic defects due to the abnormal alternative splicing of specific genes. 11 Here, we found that DNA damage caused by DHX38 deletion in human cells and zebrafish RPCs is mainly due to the replication stress caused by R-loop accumulation. Interestingly, we also found that the abnormal R-loop accumulation was not involved in mitotic defects, suggesting that there may be other mechanisms regulating mitosis.…”

“…Next, to determine whether dhx38 deletion has an impact on the development of the zebrafish retina, we explored this question with a zebrafish dhx38 loss-of-function mutant. 11 We found that dhx38 homozygous mutants showed pronounced developmental defects at 36 h postfertilization (hpf) and 48 hpf, including a smaller head, abnormal eye development, and a curled-tail ( Figures 1 A–1C), and died at 3–4 days post fertilization (dpf). The detailed retinal phenotypes of dhx38 knockout zebrafish were observed using immunofluorescence and WISH assays with the corresponding antibodies and probes.…”

“… 9 , 10 Our previous study has reported that DHX38 indirectly regulates mitosis by modulating the alternative splicing of cell cycle-related genes in zebrafish hematopoietic tissues. 11 Additionally, in vitro study has shown that DHX38 participates in chromosome segregation during mitosis in human cells independent of its splicing function. 12 However, in this regard, the physiological function of DHX38 in retinal tissue remains unclear.…”

Quantitative proteomics reveals the dynamic proteome landscape of zebrafish embryos during the maternal-to-zygotic transition

“…Dhx38 contributes to the differentiation of hematopoietic stem cells, which can develop into various types of blood cells. 70 One TF, Sall4, is also included in this cluster and it regulates genes that initiate hematopoiesis, contributing to the activation of the blood-specific program in zebrafish embryos. 71 Sall4 also modulates the development of pectoral fin and taste epithelia in zebrafish.…”

“…The seven upregulated RNA helicases including Hells, Ddx39a, Ddx19b, Dhx38, Ddx3, Ddx5, and Chd7, play essential roles in promoting transcription, cellular differentiation, and early organogenesis. 55 , 56 , 64 , 65 , 66 , 68 , 69 , 70 , 112 …”