Distinct Molecular Signature of Murine Fetal Liver and Adult Hematopoietic Stem Cells Identify Novel Regulators of Hematopoietic Stem Cell Function

Abstract

During ontogeny, fetal liver (FL) acts as a major site for hematopoietic stem cell (HSC) maturation and expansion, whereas HSCs in the adult bone marrow (ABM) are largely quiescent. HSCs in the FL possess faster repopulation capacity as compared with ABM HSCs. However, the molecular mechanism regulating the greater self-renewal potential of FL HSCs has not yet extensively been assessed. Recently, we published RNA sequencing-based gene expression analysis on FL HSCs from 14.5-day mouse embryo (E14.5) in comparison to the ABM HSCs. We reanalyzed these data to identify key transcriptional regulators that play important roles in the expansion of HSCs during development. The comparison of FL E14.5 with ABM HSCs identified more than 1,400 differentially expressed genes. More than 200 genes were shortlisted based on the gene ontology (GO) annotation term "transcription." By morpholino-based knockdown studies in zebrafish, we assessed the function of 18 of these regulators, previously not associated with HSC proliferation. Our studies identified a previously unknown role for tdg, uhrf1, uchl5, and ncoa1 in the emergence of definitive hematopoiesis in zebrafish.In conclusion, we demonstrate that identification of genes involved in transcriptional regulation differentially expressed between expanding FL HSCs and quiescent ABM HSCs, uncovers novel regulators of HSC function.

In Utero Transfer of Adeno-Associated Viral Vectors Produces Long-Term Factor IX Levels in a Cynomolgus Macaque Model

“…Precedents have been set with the early treatment of severe combined immunodeficiencies in young children, in whom the substantial benefits of stem cell gene therapy outweigh the risk of leukemogenesis 39, 40. Integration occurred more frequently than we anticipated from adult animal data, likely due to the highly open structure of the fetal genome 41 . In the practical context, a decision for AAV-IUGT will require lifelong surveillance for vector-related complications, including liver cancer.…”

Nanog safeguards early embryogenesis against global activation of maternal β-catenin activity by interfering with TCF factors

“…The sequence of the MOs used is: nanog MO: 5′-CTGGCATCTTCCAGTCCGC CAT TTC-3′ (translation-blocking MO covering the translation initiation start, underlined). wnt8a MO1: 5′-ACGCAAAAATCTGGCAAGGGTTCAT-3′ [ 87 ], wnt8a MO2: 5′-GCCCAACGGAAGAAGTAAGCCATTA-3′ [ 87 ], tcf7l1a MO: 5′-CTCCGTTTAACTGAGGCATGTTGGC-3′ [ 64 ], ctnnb1 MO: 5′-ATCAAGTCAGACTGGGTAGCCATGA-3′ [ 88 ], ctnnb2 MO: 5′-CCTTTAGCCTGAGCGACTTCCAAAC-3’ [ 25 ], tle3b (gro1) MO: 5′-CGGCCCTGCGGATACATCTTGAATG-3′ [ 89 ], tle3a ( gro2 ) MO: 5′-ATGTATCCTTTATTTATTGGAGCTC-3′ [ 90 ], tle2a MO: 5′-CATGGTGAATAGCGTGGTTTGTTGC-3′[ 91 ]. For all experiments, MO or combinations of MOs were injected in more than 50 embryos and experiments were reproduced at least 3 times.…”

Frontline Science: Wnt/β-catenin pathway promotes early engraftment of fetal hematopoietic stem/progenitor cells

“…Canonical Wnt signaling is important for the emergence of the first functional HSCs but its role in FL HSC function has been largely unexplored. Although a number of studies have compared the transcriptomes from fetal and adult HSCs, they have not systematically explored Wnt signaling activity . To establish the potential differences between fetal and adult HSPCs, we first evaluated gene expression in both canonical and noncanonical arms of Wnt signaling by qRT‐PCR.…”

“…Although a number of studies have compared the transcriptomes from fetal and adult HSCs, they have not systematically explored Wnt signaling activity. 19,20 To establish the potential differences between fetal and adult HSPCs, we first evaluated gene expression in both canonical and noncanonical arms of Wnt signaling by lated from BM and FL as previously published by others 21 and described in Figure 1A. The in vitro functionality of sorted cells was determined by a long-term culture initiating cell (LTC-IC) assay, 17 and we found equivalent frequencies of LTC-ICs in both populations (95% confidence intervals 1/13-1/8 for BM, 1/10-1/5 for FL, P = 0.17; Figure 1B).…”