Persistent DNA damage–induced NLRP12 improves hematopoietic stem cell function
Qiqi Lin, Limei Wu, Zhilin Ma, Fabliha Ahmed Chowdhury,1, Habibul Hasan Mazumder, Wei Du
Qiqi Lin, Limei Wu, Zhilin Ma, Fabliha Ahmed Chowdhury,1, Habibul Hasan Mazumder, Wei Du
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Research Article Aging Hematology

Persistent DNA damage–induced NLRP12 improves hematopoietic stem cell function

Abstract

NOD-like receptor 12 (NLRP12) is a member of the nucleotide-binding domain and leucine-rich repeat containing receptor inflammasome family that plays a central role in innate immunity. We previously showed that DNA damage upregulated NLRP12 in hematopoietic stem cells (HSCs) of mice deficient in the DNA repair gene Fanca. However, the role of NLRP12 in HSC maintenance is not known. Here, we show that persistent DNA damage–induced NLRP12 improves HSC function in both mouse and human models of DNA repair deficiency and aging. Specifically, treatment of Fanca–/– mice with the DNA cross-linker mitomycin C or ionizing radiation induces NLRP12 upregulation in phenotypic HSCs. NLRP12 expression is specifically induced by persistent DNA damage. Functionally, knockdown of NLRP12 exacerbates the repopulation defect of Fanca–/– HSCs. Persistent DNA damage–induced NLRP12 was also observed in the HSCs from aged mice, and depletion of NLRP12 in these aged HSCs compromised their self-renewal and hematopoietic recovery. Consistently, overexpression of NLRP12 substantially improved the long-term repopulating function of Fanca–/– and aged HSCs. Finally, persistent DNA damage–induced NLRP12 maintains the function of HSCs from patients with FA or aged donors. These results reveal a potentially novel role of NLRP12 in HSC maintenance and suggest that NLRP12 targeting has therapeutic potential in DNA repair disorders and aging.

Authors

Qiqi Lin, Limei Wu, Zhilin Ma, Fabliha Ahmed Chowdhury,1, Habibul Hasan Mazumder, Wei Du

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Figure 4

Persistent DNA damage–induced Nlrp12 maintains HSC function in aged mice.

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Persistent DNA damage–induced Nlrp12 maintains HSC function in aged mice...
(A) MMC induces persistent DNA damage in aged HSCs. Young (6- to 8-week-old) and old mice (20- to 26-month-old) WT mice were i.p. injected with a single dose of MMC (0.75 mg/kg) followed by flow cytometry analysis for γ-H2AX at different time points. Representative flow plots gated on SLAM cells (left) and kinetics (right) are shown. (B) Persistent DNA damage induces Nlrp12 upregulation in aged mice. Young (6- to 8-week-old) and old (20- to 26-month-old) WT mice were subjected to single dose (0.75 mg/kg) of MMC injection. RNA from the sorted SLAM cells was extracted for qPCR analysis for NLRP12. Samples were normalized to the level of GAPDH mRNA. The kinetics of NLRP12 expression is shown. Results are shown as means ± SD of 3 independent experiments (n = 6 per group). (C) Schematic presentation of experimental design. (D) Depletion of Nlrp12 compromises HSC function in aged mice. LSK cells from young or aged mice were transduced with lentiviral vector expressing scramble shRNA or shRNA targeting Nlrp12. Along with 2 × 105 protector cells, 2000 sorted GFP+ cells were transplanted into lethally irradiated BoyJ recipients followed by MMC injection at 2 weeks posttransplant. Donor-derived chimeras in primary recipients (left) or secondary recipients (right) were determined by flow cytometry at 16 weeks posttransplant (n = 9–12). (E) Schematic presentation of experimental design. (F) Knockdown of Nlrp12 compromises hematopoietic recovery in aged mice after 5-FU treatment. LSK cells from young or aged mice were transduced with lentiviral vector expressing scramble shRNA or shRNA targeting Nlrp12. Along with 2 × 105 protector cells, 2000 sorted GFP+ cells were transplanted into lethally irradiated BoyJ recipients followed by MMC injection at 2 weeks posttransplant. Ten weeks later, the mice were administrated with a single dose of 5-FU (150 mg/kg) by i.p. injection. WBC count was monitored over a 30-day period. Results are shown as means ± SD of 3 independent experiments (n = 9 per group). *P < 0.05; **P < 0.01; ***P < 0.001 (shNlrp12 vs. scramble in aged HSCs). Paired or unpaired 2-tailed Student’s t test was used for 2-group comparison and 1-way ANOVA for comparison of more than 2 groups.