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 3

In vivo rmDEK treatment reversibly decreases CXCR4 expression and homing capability of BM cells.

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In vivo rmDEK treatment reversibly decreases CXCR4 expression and homing...
C57BL/6 mice (CD45.1–CD45.2+) were injected with 10 μg dialyzed WT rmDEK or vehicle control s.c. once a day for 2 days. BM was then collected 24 or 48 hours after final injection. (A–C) CXCR4 expression levels were examined 24 and 48 hours following the final DEK injection by flow cytometry in the CD45.1–CD45.2+ LSK CD150+ (A), LSK (B), and LK (C) cell populations. (D–F) Twelve million cells from the mice examined in A–C were injected i.v. into lethally irradiated (950 cGy, 24 hours prior) B6×Boy/J F1 mice (CD45.1+CD45.2+) hosts. Eighteen hours following injection, BM from host mice was collected and analyzed by flow cytometry for the presence of CD45.1–CD45.2+ LSK CD150+ (D), LSK (E), and LK (F) cells. In A–F, data are mean ± SEM of 5 mice per group; P value is compared with vehicle control–treated mice using 1-way ANOVA with post hoc Tukey’s multiple-comparisons test.