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 7

DEK stimulates ERK1/2, AKT, and p38 MAPK phosphorylation in LSK CD150+ and myeloid-enriched progenitor (LK) cells.

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DEK stimulates ERK1/2, AKT, and p38 MAPK phosphorylation in LSK CD150+ a...
(A–C) C57BL/6 BM LSK CD150+ cells and LK cells were examined by flow cytometry for ERK1/2 (A), AKT (B), and p38 MAPK (C) phosphorylation 15, 30, and 60 minutes, or 16 hours following vehicle, rhIL-8, or rmDEK treatment. *P < 0.05, **P < 0.01, and ***P < 0.001 when comparing groups with vehicle control at the same time point (1-way ANOVA with post hoc Tukey’s multiple-comparisons test). Data are mean ± SD of triplicate tubes. (D) Heatmap representation of the 186 differentially expressed genes (DEGs) when comparing vehicle-treated with rmDEK-treated Lin– BM. Unsupervised hierarchical clustering was performed to group samples (columns) and genes (rows) by similarities in data structure. Genes listed to the right of the heatmap represent factors with known induction by signaling cascades that exhibit crosstalk with CXCR2 response, including, but not limited to, AKT signaling, MAPK signaling, and NF-κB signaling. (E) Ontologic assessments conducted on DEK-mediated transcriptional changes with the RNA-Enrich program. A subset of concepts from the analysis ranked by significance is shown.