Page 136 - Haematologica Vol. 109 - July 2024

ARTICLE - Ppm1b regulates HSC homeostasis
Z. Lu et al.
significantly reduced in HN252-treated mice BM upon the challenge of 5-FU (Figure 4E). These findings phenocopied the defect of the HSC pool and B-cell differentiation in Ppm1bCKO mice. To avoid the off-target effect of HN252, we performed experiments to confirm the specificity of HN252 on Ppm1b. There were no significant changes in WBC and lymphocytes in PB observed in Ppm1b deficient mice with or without HN252 treatment after 5-FU injection (Online Supplementary Figure S4B), as well as the cell number of B220+ cells and the proportion of LSK cells in the BM
A
B
(Online Supplementary Figure S4C, D). In addition, HN252 treatment showed no notable effect on the relative mean fluorescence intensity of CFSE in Ppm1b-deficient LSK (Online Supplementary Figure S4E). These results indicate that HN252 affects the HSC pool and B-cell differentiation in adult hematopoiesis mainly via targeting Ppm1b.
Transcriptome profiling of Ppm1b-deficient hematopoietic stem cells reveals altered stem cell property
To explore the basis of abnormal hematopoiesis upon Ppm1b
CDE
Figure 4. Ppm1b regulates hematopoietic stem cell pool and B-cell differentiation in stressed hematopoiesis. (A) Experimental design for HN252-treated mice in response to 5-FU-induced emergency hematopoiesis. Long blue arrow indicates HN252 or Ve- hicle injection every 2 days. Black arrow indicates the time point for 5-FU injection. Red arrows indicates the bleeding for blood assays. (B) Quantification of white blood cells (WBC) and lymphocytes in peripheral blood at indicated time points during HN252 injection (N=6). (C) The mice were treated with HN252 as in (A), and the ratio of B cells in peripheral blood was analyzed by flow cytometry (N=6). (D and E) The number of B cells (D) and the percentage of Lin−Sca-1+c-Kit+ (LSK) cells (E) from indicated mice in (C) were measured by flow cytometry (N=6). Data are presented as mean ± Standard Deviation. All P values were determined by unpaired two-tailed Student t test. See also Online Supplementary Figure S4. BM: bone marrow; GO: gene ontology; PBMC: peripheral blood mononuclear cells.
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