Matrix Gla protein maintains normal and malignant hematopoietic progenitor cells by interacting with bone morphogenetic protein-4

Kana Kuronuma,Aya Yokoi,Tomoya Fukuoka,Muneaki Miyata,Akio Maekawa,Satowa Tanaka,Leo Matsubara,Chie Goto,Miki Matsuo,Hao-Wei Han,Mai Tsuruta,Haruka Murata,Hikari Okamoto,Natsumi Hasegawa,Shigetaka Asano,Mitsuhiro Ito

doi:10.1016/j.heliyon.2020.e03743

Abstract

Matrix Gla protein (MGP), a modulator of the BMP-SMAD signals, inhibits arterial calcification in a Glu γ-carboxylation dependent manner but the role of MGP highly expressed in a subset of bone marrow (BM) mesenchymal stem/stromal cells is unknown. Here we provide evidence that MGP might be a niche factor for both normal and malignant myelopoiesis. When mouse BM hematopoietic cells were cocultured with mitomycin C-treated BM stromal cells in the presence of anti-MGP antibody, growth of hematopoietic cells was reduced by half, and maintenance of long-term culture-initiating cells (LTC-ICs) was profoundly attenuated. Antibody-mediated blockage of MGP also inhibited growth (by a fifth) and cobblestone formation (by half) of stroma-dependent MB-1 myeloblastoma cells. MGP was undetectable in normal hematopoietic cells but was expressed in various mesenchymal cells and was aberrantly high in MB-1 cells. MGP and bone morphogenetic protein (BMP)-4 were co-induced in stromal cells cocultured with both normal hematopoietic cells and MB-1 myeloblastoma cells in an oscillating several days-periodic manner. BMP-2 was also induced in stromal cells cocultured with normal hematopoietic cells but was barely expressed when cocultured with MB-1 cells. GST-pulldown and luciferase reporter assays showed that uncarboxylated MGP interacted with BMP-4 and that anti-MGP antibody abolished this interaction. LDN-193189, a selective BMP signaling inhibitor, inhibited growth and cobblestone formation of MB-1 cells. The addition of warfarin, a selective inhibitor of vitamin K-dependent Glu γ-carboxylation, did not affect MB-1 cell growth, suggesting that uncarboxylated MGP has a biological effect in niche. These results indicate that MGP may maintain normal and malignant hematopoietic progenitor cells, possibly by modulating BMP signals independently of Glu γ-carboxylation. Aberrant MGP by leukemic cells and selective induction of BMP-4 relative to BMP-2 in stromal cells might specify malignant niche.

Highlights

Hematopoiesis is a lifelong and continuous replenishment of hematopoietic stem cells (HSCs) and their differentiation into multi-lineage mature progenies
In the view that MED1 in bone marrow (BM) stromal cells is necessary for optimal hematopoietic cell growth and hematopoietic stem or progenitor cells (HSPCs) support, that transcription of vitamin D-targeted Mgp is reduced in MED1-deficient stromal cells [10], and that a subset of BM stromal cells highly expresses Matrix Gla protein (MGP) [15, 16], we hypothesized that MGP may be a novel niche factor for hematopoiesis
When BM hematopoietic cells were cocultured with MS-5 or OP-9 BM stromal cells or mouse embryonic fibroblasts (MEFs) in the presence of anti-MGP antibody for 12 days, the number of hematopoietic cells was attenuated by over 20% compared to the controls after four days of coculture (Figure 1A-C)

Summary

Introduction

Hematopoiesis is a lifelong and continuous replenishment of hematopoietic stem cells (HSCs) and their differentiation into multi-lineage mature progenies. These processes are induced by intrinsic and extrinsic factors, the latter of which are molecules produced by a hematopoietic microenvironment called a niche that resides perivascular [1, 2]. Among the TGF-β family proteins, bone morphogenetic protein (BMP)-4 increases HSCs through. An altered niche may at times precede the onset of hematopoietic neoplasms. In such situations, neoplastic cells may use distinct niche molecules that these cells favor rather than normal blood cells [5, 6]

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