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 4

Wnt5a from LepR+CXCL12+ cells regulates hematopoietic recovery and HSC regeneration after irradiation.

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Wnt5a from LepR+CXCL12+ cells regulates hematopoietic recovery and HSC r...
(A) Wnt5a expression in LepR+ cells at 24 hours after 500 cGy TBI (n = 6). (B) Wnt5a protein levels in the BM supernatants of the indicated mice at 24 hours after TBI (n = 6). (C) Mouse PB parameters at day 22 after TBI. Mice were administered 500 cGy TBI and treated i.p. with rWnt5a (50 μg/kg) or vehicle (saline). WT, vehicle: n = 7; WT rWnt5a: n = 9; Fanca–/–, vehicle: n = 6; Fanca–/– rWnt5a: n = 6. (D) Total BM cells (left) and SLAM cells (right) in mice described in C. WT, vehicle: n = 7; WT rWnt5a: n = 9; Fanca–/–, vehicle: n = 6; Fanca–/– rWnt5a: n = 6. (E) First (n = 8) and second (n = 10) BMT with cells from mice described in C (first, 8; second, 10). (F) Effect of anti-Wnt5a neutralization on HSC expansion. WT SLAM cells were subjected to 300 cGy irradiation and cocultured with WT LepR+ cells and anti-Wnt5a (2 μg/mL) or control IgG for 5 days (IgG: n = 9; α-Wnt5a: n = 6). (G) Neutralization of Wnt5a dampens the repopulation capacity of the irradiated WT HSCs. 1000 progeny cells from the cocultures described in F were subjected to serial BMT (n = 9). (H) Deletion of Wnt5a delays PB recovery after irradiation. WT: n = 9; Wnt5a–/–, 0: n = 7; Wnt5a–/–, 5, 10, 15: n = 6. (I) Mean total BM cells (left) and SLAM cells (right) for the mice described in H at day 15 after TBI. WT: n = 9; Wnt5a–/–: n = 6. (J) Deletion of Wnt5a dampens HSC repopulation after irradiation. BM SLAM cells from the mice described in H were subjected to BMT (n = 9). Statistics were performed in the indicated groups: 2-tailed, paired t test (parametric). *P < 0.05; **P < 0.01.