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.
View: Text | PDF
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

×

Figure 7

Dysregulated paracrine WNT5a/PROX1 axis in patients with FA.

Options: View larger image (or click on image) Download as PowerPoint
Dysregulated paracrine WNT5a/PROX1 axis in patients with FA. (A) MSCs fr...
(A) MSCs from healthy donors (HDs) but not patients with FA show significant induction of Wnt5a in response to irradiation. MSCs from HDs or patients with FA were cultured in MSC culture medium. The levels of mRNA (left) and protein (right) of WNT5a were measured by qPCR and ELISA, respectively (n = 6). (B) Schematic presentation of experimental design. Healthy BM hCD34+ cells cocultured with irradiated MSCs from HDs or patients with FA followed by β-catenin staining, qPCR analysis, or BMT. (C) Recombinant WNT5a reduces β-catenin accumulation in cocultured human HSPCs. Healthy hCD34+ cells and MSCs from HDs were subjected to 300 cGy irradiation and then cocultured for 5 days in the presence of rWNT5a or vehicle control; β-catenin levels were determined in the suspension cells by flow cytometry analysis. MFI of β-catenin shown (HD vehicle: n = 8; HD WNT5a: n = 6; FA vehicle: n = 8; FA WNT5a: n = 6). (D) rWNT5a represses PROX1 expression in hCD34+ cells cocultured on FA MSCs. Healthy hCD34+ cells and MSCs cells from HDs or patients with FA were subjected to 300 cGy irradiation followed by coculture for 5 days in the presence of recombinant WNT5a or vehicle control. Suspension cells were collected for RNA extract and qPCR analysis for PROX1 expression (HD vehicle: n = 8; HD WNT5a: n = 8; FA vehicle: n = 6; FA WNT5a: n = 7). (E) rWNT5a improves repopulating capacity of the progenies of hCD34+ cells cocultured on FA MSC in NSGS recipients. Ten thousand progeny cells after coculture in the presence of recombinant WNT5a or vehicle control for 5 days were transplanted into sublethally irradiated NSGS mice. Human engraftment at 16 weeks after BMT were determined by flow cytometry. Statistics were performed in the indicated groups: 2-tailed, paired t test (parametric). *P < 0.05; **P < 0.01.