BCAS2 is essential for hematopoietic stem and progenitor cell maintenance during zebrafish embryogenesis

Abstract

Hematopoietic stem and progenitor cells (HSPCs) originate from the hemogenic endothelium via the endothelial-to-hematopoietic transition, are self-renewing, and replenish all lineages of blood cells throughout life. BCAS2 (breast carcinoma amplified sequence 2) is a component of the spliceosome and is involved in multiple biological processes. However, its role in hematopoiesis remains unknown. We established a bcas2 knockout zebrafish model by using transcription activator–like effector nucleases. The bcas2−/− zebrafish showed severe impairment of HSPCs and their derivatives during definitive hematopoiesis. We also observed significant signs of HSPC apoptosis in the caudal hematopoietic tissue of bcas2−/− zebrafish, which may be rescued by suppression of p53. Furthermore, we show that the bcas2 deletion induces an abnormal alternative splicing of Mdm4 that predisposes cells to undergo p53-mediated apoptosis, which provides a mechanistic explanation of the deficiency observed in HSPCs. Our findings revealed a novel and vital role for BCAS2 during HSPC maintenance in zebrafish.

The spliceosome factor sart3 regulates hematopoietic stem/progenitor cell development in zebrafish through the p53 pathway

“…The sart3 smu471 mutant exhibited a transcriptome-wide RNA splicing defect. Several reports suggest that p53 activation may be a consequence of a spliceosome defect [ 60 – 62 ], with our results providing new evidence supporting this hypothesis. It is known that MDM4 could inhibit the transcription of p53 and stimulate the MDM2-mediated protein degradation of p53 [ 53 , 54 ].…”

“…Mdm4 expression was changed by sart3 mutation, which is consistent with a report demonstrating reduced mdm4 expression to interfere with the spliceosome [ 60 ]. Zebrafish AS of mdm4 in which exon 6 is skipped in the sart3 smu471 mutant is similar to another HSPC deficient zebrafish spliceosome mutant, bcas2 −/− [ 62 ] and to the skipping of exon 6 in human or exon 7 in mouse [ 63 , 64 ]. A truncated transcript termed mdm4-S was previously identified [ 52 ].…”

A splicing factor switch controls hematopoietic lineage specification of pluripotent stem cells

“…In addition, distinct Lamin B1 (Wong et al , 2013) and NFIB isoforms (Chen et al , 2014) uniquely influence granulocytic and megakaryocytic differentiation, respectively. Furthermore, AS of MDM4 (Yu et al , 2019), RUNX1 (Komeno et al , 2014), and HMGA2 (Cesana et al , 2018) regulates HSC maintenance, homeostasis, and developmental stage‐specific transcriptional programs, respectively. Mutations of genes encoding core spliceosome proteins and auxiliary regulatory splicing factors, such as SF3B1 , SRSF2 , U2AF1 , and ZRSR2 , are frequently detected in patients with myelodysplastic syndrome, leukemia, and clonal hematopoiesis (Yoshida et al , 2011; Saez et al , 2017; Sperling et al , 2017; Hodson et al , 2019).…”

Rod-genesis driven by mafba in an nrl knockout zebrafish model with altered photoreceptor compositions and progressive retinal degeneration

“…The T7 promoter was added to the 5’ and 3’ ends to synthesize the sense and anti-sense probes using the DIG RNA Labeling Kit (Roche, Cat# 11175025910). In situ hybridization was performed as previously described [65,66] with minor modifications. The signals were detected and developed by the Anti-Digoxigenin-AP antibody (Roche, Cat# 11093274910) and NBT/BCIP solution (Roche, Cat# 11681451001) following the manuals.…”