Hematopoietic stem cell regeneration through paracrine regulation of the Wnt5a/Prox1 signaling axis
Qiqi Lin, … , Jonathan Joseph, Wei Du
Qiqi Lin, … , Jonathan Joseph, Wei Du
Published June 15, 2022
Citation Information: J Clin Invest. 2022;132(12):e155914. https://doi.org/10.1172/JCI155914.
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Research Article Cell biology Hematology

Hematopoietic stem cell regeneration through paracrine regulation of the Wnt5a/Prox1 signaling axis

Abstract

The crosstalk between the BM microenvironment (niche) and hematopoietic stem cells (HSCs) is critical for HSC regeneration. Here, we show that in mice, deletion of the Fanconi anemia (FA) genes Fanca and Fancc dampened HSC regeneration through direct effects on HSCs and indirect effects on BM niche cells. FA HSCs showed persistent upregulation of the Wnt target Prox1 in response to total body irradiation (TBI). Accordingly, lineage-specific deletion of Prox1 improved long-term repopulation of the irradiated FA HSCs. Forced expression of Prox1 in WT HSCs mimicked the defective repopulation phenotype of FA HSCs. WT mice but not FA mice showed significant induction by TBI of BM stromal Wnt5a protein. Mechanistically, FA proteins regulated stromal Wnt5a expression, possibly through modulating the Wnt5a transcription activator Pax2. Wnt5a treatment of irradiated FA mice enhanced HSC regeneration. Conversely, Wnt5a neutralization inhibited HSC regeneration after TBI. Wnt5a secreted by LepR+CXCL12+ BM stromal cells inhibited β-catenin accumulation, thereby repressing Prox1 transcription in irradiated HSCs. The detrimental effect of deregulated Wnt5a/Prox1 signaling on HSC regeneration was also observed in patients with FA and aged mice. Irradiation induced upregulation of Prox1 in the HSCs of aged mice, and deletion of Prox1 in aged HSCs improved HSC regeneration. Treatment of aged mice with Wnt5a enhanced hematopoietic repopulation. Collectively, these findings identified the paracrine Wnt5a/Prox1 signaling axis as a regulator of HSC regeneration under conditions of injury and aging.

Authors

Qiqi Lin, Limei Wu, Srinivas Chatla, Fabliha A. Chowdhury, Neha Atale, Jonathan Joseph, Wei Du

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Figure 6

Effect of Wnt5a/Prox1 signaling on HSC regeneration and hematopoietic recovery in aged mice.

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Effect of Wnt5a/Prox1 signaling on HSC regeneration and hematopoietic re...
(A) Deletion of Prox1 improves CFC recovery in aged mice after irradiation. Mean numbers of BM CFCs in nonirradiated and irradiated (15 days after 500 cGy TBI) young and old Prox1fl/fl or Prox1fl/flVav1-Cre mice (n = 6). (B) Deletion of Prox1 improves BM and HSC recovery in aged mice after irradiation. Mean numbers of total BM cells (left) and BM SLAM cells (right) in nonirradiated and radiated young and old mice (n = 6). (C) Ablation of Prox1 increases survival of irradiated aged mice (young Prox1fl/fl: n = 15; young Prox1fl/flVav1-Cre: n = 15; old Prox1fl/fl: n = 14; old Prox1fl/flVav1-Cre: n = 15). Old Prox1fl/fl versus Prox1fl/flVav1-Cre mice: P = 0.0174. (D) Wnt5a improves regeneration of aged HSCs after irradiation. SLAM cells from young and old mice were irradiated at 300 cGy and cultured in the presence of rWnt5a (100 ng/mL) or vehicle (saline) for 5 days. 500 progeny cells from the cultures were transplanted into BoyJ recipients (n = 12). (E) Mean levels of donor CD45.2+ cell engraftment in secondary recipients at 16 weeks following transplantation with BM cells from the primary mice in D (old vehicle: n = 10; others: n = 12). (F) Systemic administration of rWnt5a improves hematopoietic recovery in aged mice after irradiation. Total BM cells (left) and SLAM cells (right) in young and old mice on day 22 after 500 cGy TBI. Mice were subjected to 500 cGy TBI and treated i.p. with rWnt5a (50 μg/kg) or vehicle (saline) (old vehicle: n = 10; others: n = 12). Statistics were performed in the indicated groups: 2-tailed, paired t test (parametric). *P < 0.05; **P < 0.01.