Activation of the canonical Wnt pathway leads to loss of hematopoietic stem cell repopulation and multilineage differentiation block

Abstract

Wnt signaling increases hematopoietic stem cell self-renewal and is activated in both myeloid and lymphoid malignancies, indicating involvement in both normal and malignant hematopoiesis. We report here activated canonical Wnt signaling in the hematopoietic system through conditional expression of a stable form of beta-catenin. This enforced expression led to hematopoietic failure associated with loss of myeloid lineage commitment at the granulocyte-macrophage progenitor stage; blocked erythrocyte differentiation; disruption of lymphoid development; and loss of repopulating stem cell activity. Loss of hematopoietic stem cell function was associated with decreased expression of Cdkn1a (encoding the cell cycle inhibitor p21(cdk)), Sfpi1, Hoxb4 and Bmi1 (encoding the transcription factors PU.1, HoxB4 and Bmi-1, respectively) and altered integrin expression in Lin(-)Sca-1(+)c-Kit(+) cells, whereas PU.1 was upregulated in erythroid progenitors. Constitutive activation of canonical Wnt signaling therefore causes multilineage differentiation block and compromised hematopoietic stem cell maintenance.

miR-99a/100∼125b tricistrons regulate hematopoietic stem and progenitor cell homeostasis by shifting the balance between TGFβ and Wnt signaling

“…Cold Spring Harbor Laboratory Press on May 12, 2018 -Published by genesdev.cshlp.org Downloaded from defects (Kirstetter et al 2006). The deregulation of Wnt signaling as a causative factor in leukemogenesis has become more and more apparent (Klaus and Birchmeier 2008).…”

The emerging role of Wnt signaling in the pathogenesis of acute myeloid leukemia

“…73,89 The Wnt and Notch pathway have both been implicated in self-renewal of HSCs 75,89,90 and cooperation between Wnt and Notch in HSCs has recently been suggested by Duncan et al 89 Recent studies have demonstrated that the Wnt/b-catenin pathway must be well controlled to assure normal hematopoiesis, because constitutive activation of Wnt signaling results in multilineage differentiation block and compromised HSC maintenance. 91,92 Taken together, Wnt signaling mediates stimulation of self-renewal and enhanced proliferation of HSCs, as well as reduced differentiation. These are features, which might contribute to leukemogenesis.…”

Ablation of Wntless in endosteal niches impairs lymphopoiesis rather than HSCs maintenance

“…β-Catenin is the key and obligatory mediator of canonical Wnt signaling. Stabilized β-catenin expression expands the pool of HSCs and leads to deficiency in HSCs repopulation capacity [12,13]. Conversely, deletion of β-catenin or Wnt3a leads to defective HSCs long-term maintenance [14,15].…”