Purinergic P2Y14 receptor modulates stress-induced hematopoietic stem/progenitor cell senescence
Joonseok Cho, Rushdia Yusuf, Sungho Kook, Eyal Attar, Dongjun Lee, Baehang Park, Tao Cheng, David T. Scadden, Byeong Chel Lee
Joonseok Cho, Rushdia Yusuf, Sungho Kook, Eyal Attar, Dongjun Lee, Baehang Park, Tao Cheng, David T. Scadden, Byeong Chel Lee
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Research Article

Purinergic P2Y14 receptor modulates stress-induced hematopoietic stem/progenitor cell senescence

Abstract

Purinergic receptors of the P2Y family are G protein–coupled surface receptors that respond to extracellular nucleotides and can mediate responses to local cell damage. P2Y-dependent signaling contributes to thrombotic and/or inflammatory consequences of tissue injury by altering platelet and endothelial activation and immune cell phagocytosis. Here, we have demonstrated that P2Y14 modifies cell senescence and cell death in response to tissue stress, thereby enabling preservation of hematopoietic stem/progenitor cell function. In mice, P2Y14 deficiency had no demonstrable effect under homeostatic conditions; however, radiation stress, aging, sequential exposure to chemotherapy, and serial bone marrow transplantation increased senescence in animals lacking P2Y14. Enhanced senescence coincided with increased ROS, elevated p16INK4a expression, and hypophosphorylated Rb and was inhibited by treatment with a ROS scavenger or inhibition of p38/MAPK and JNK. Treatment of WT cells with pertussis toxin recapitulated the P2Y14 phenotype, suggesting that P2Y14 mediates antisenescence effects through Gi/o protein–dependent pathways. Primitive hematopoietic cells lacking P2Y14 were compromised in their ability to restore hematopoiesis in irradiated mice. Together, these data indicate that P2Y14 on stem/progenitor cells of the hematopoietic system inhibits cell senescence by monitoring and responding to the extracellular manifestations of tissue stress and suggest that P2Y14-mediated responses prevent the premature decline of regenerative capacity after injury.

Authors

Joonseok Cho, Rushdia Yusuf, Sungho Kook, Eyal Attar, Dongjun Lee, Baehang Park, Tao Cheng, David T. Scadden, Byeong Chel Lee

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Figure 6

P2Y14 is involved in the modulation of cellular redox homeostasis.

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P2Y14 is involved in the modulation of cellular redox homeostasis. (A an...
(A and B) MitoSOX staining in gated LSK cells. Mitochondrial superoxide was measured within LSK cells in vivo (6 Gy TBI) (A) and in vitro (1.6 Gy, in vitro IR) (B). NAC was treated as described in the legend to Figure 2. Representative histograms of MitoSOX staining in gated LSK cell (A, left). The accompanying graphs show percentage of LSK cells positive for MitoSOX fluorescence in vivo (A) and in vitro (B). The data are representative of at least 3 independent experiments. The 1-tailed Student’s t test was used. (C) JC-1 staining in gated LSK cells. WT and P2ry14–/– BM cells were irradiated as described in B. A decrease in the ratio of red (FL2: 585 nm) to green (FL1: 530 nm) indicates mitochondrial depolarization. The data are representative of 3 independent experiments, each with BM cells pooled from at least 2 mice per group. The 1-tailed Student’s t test was used. (D) Mice of the indicated genotypes were exposed to TBI (3 × 5 Gy, 15 days apart). NAC (100 mg/kg) was injected s.c. 4 hours before and 2 hours after TBI and once daily thereafter for 6 days. This procedure was repeated after each TBI. The number of total BM (left) and LSK (middle) cells was counted. Mice (n = 4) were individually analyzed for each group. Right: mice (n = 6/genotype) were exposed to TBI (6 Gy). NAC was administered as described in Figure 2C, and percentage of SA–β-gal+ LSK cells was assessed. *P < 0.05; **P < 0.01.