Secreted nuclear protein DEK regulates hematopoiesis through CXCR2 signaling
Maegan L. Capitano, … , David M. Markovitz, Hal E. Broxmeyer
Maegan L. Capitano, … , David M. Markovitz, Hal E. Broxmeyer
Published May 20, 2019
Citation Information: J Clin Invest. 2019;129(6):2555-2570. https://doi.org/10.1172/JCI127460.
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Research Article Hematology

Secreted nuclear protein DEK regulates hematopoiesis through CXCR2 signaling

Abstract

The nuclear protein DEK is an endogenous DNA-binding chromatin factor regulating hematopoiesis. DEK is one of only 2 known secreted nuclear chromatin factors, but whether and how extracellular DEK regulates hematopoiesis is not known. We demonstrated that extracellular DEK greatly enhanced ex vivo expansion of cytokine-stimulated human and mouse hematopoietic stem cells (HSCs) and regulated HSC and hematopoietic progenitor cell (HPC) numbers in vivo and in vitro as determined both phenotypically (by flow cytometry) and functionally (through transplantation and colony formation assays). Recombinant DEK increased long-term HSC numbers and decreased HPC numbers through a mechanism mediated by the CXC chemokine receptor CXCR2 and heparan sulfate proteoglycans (HSPGs) (as determined utilizing Cxcr2–/– mice, blocking CXCR2 antibodies, and 3 different HSPG inhibitors) that was associated with enhanced phosphorylation of ERK1/2, AKT, and p38 MAPK. To determine whether extracellular DEK required nuclear function to regulate hematopoiesis, we utilized 2 mutant forms of DEK: one that lacked its nuclear translocation signal and one that lacked DNA-binding ability. Both altered HSC and HPC numbers in vivo or in vitro, suggesting the nuclear function of DEK is not required. Thus, DEK acts as a hematopoietic cytokine, with the potential for clinical applicability.

Authors

Maegan L. Capitano, Nirit Mor-Vaknin, Anjan K. Saha, Scott Cooper, Maureen Legendre, Haihong Guo, Rafael Contreras-Galindo, Ferdinand Kappes, Maureen A. Sartor, Christopher T. Lee, Xinxin Huang, David M. Markovitz, Hal E. Broxmeyer

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Figure 1

Recombinant DEK enhances ex vivo expansion of mouse Lin– BM and human CD34+ CB HSCs.

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Recombinant DEK enhances ex vivo expansion of mouse Lin– BM and human CD...
(A) Four-day HSC expansion assays using C57BL/6 Lin– BM cells. Data represent mean ± SEM fold change from input LT-HSC numbers of 6 pools of 2 mice (t test). (B and C) Donor cells (CD45.2+) from A and competitor Boy/J BM cells were infused into F1 recipients (n = 5 mice/group). 1° , primary; 2°, secondary. Percentages of donor cells in PB were examined after 2 (B) and 4 (C) months. P value compares the indicated group with day 0 input. (D) Secondary BM transplants using mice from B and C as donors. Percentages of donor cells were examined at 4 months (n = 5 mice/group). For B–D, 1-way ANOVA with post hoc Tukey’s multiple-comparisons test was performed. (E) Poisson statistical analysis from the limiting dilution analysis. Different doses of donor cells from A and competitor cells were infused into F1 recipients. Symbols represent the percentage of negative mice for each dose of cells. Solid lines indicate the best-fit linear model for each data set. Dotted lines represent 95% confidence intervals. (F) CRU in 1 × 106 transplanted cells calculated from E. (G) Four-day HSC expansion assays using human CD34+ CB cells. Data represent mean ± SEM fold change from input HSC numbers for 6 individual CBs (t test). (H and I) Donor cells from G were infused into NSG recipients (n = 5 mice/group). Percentage of donor human CD45+ cells in PB was examined after 2 (H) and 4 (I) months. P value compares indicated group with day 0 input. (J) Secondary BM transplants using mice from H and I as donors. Percent donor cells were examined at 4 months. For H–J, 1-way ANOVA with post hoc Tukey’s multiple-comparisons test was performed. (K) Poisson statistical analysis from the limiting dilution analysis utilizing mice from H–I. (L) Number of SRCs in 1 × 106 transplanted cells was calculated from K.