Lysophosphatidic Acid Mediates Myeloid Differentiation within the Human Bone Marrow Microenvironment

Article (PDF Available)inPLoS ONE 8(5):e63718 · May 2013with49 Reads
DOI: 10.1371/journal.pone.0063718 · Source: PubMed
Lysophosphatidic acid (LPA) is a pleiotropic phospholipid present in the blood and certain tissues at high concentrations; its diverse effects are mediated through differential, tissue specific expression of LPA receptors. Our goal was to determine if LPA exerts lineage-specific effects during normal human hematopoiesis. In vitro stimulation of CD34+ human hematopoietic progenitors by LPA induced myeloid differentiation but had no effect on lymphoid differentiation. LPA receptors were expressed at significantly higher levels on Common Myeloid Progenitors (CMP) than either multipotent Hematopoietic Stem/Progenitor Cells (HSPC) or Common Lymphoid Progenitors (CLP) suggesting that LPA acts on committed myeloid progenitors. Functional studies demonstrated that LPA enhanced migration, induced cell proliferation and reduced apoptosis of isolated CMP, but had no effect on either HSPC or CLP. Analysis of adult and fetal human bone marrow sections showed that PPAP2A, (the enzyme which degrades LPA) was highly expressed in the osteoblastic niche but not in the perivascular regions, whereas Autotaxin (the enzyme that synthesizes LPA) was expressed in perivascular regions of the marrow. We propose that a gradient of LPA with the highest levels in peri-sinusoidal regions and lowest near the endosteal zone, regulates the localization, proliferation and differentiation of myeloid progenitors within the bone marrow marrow.


    • "During hematopoiesis, LPA regulates the invasion of primary hematopoietic stem cells (HSCs) into the stromal layer [19]. Additionally, LPA has been reported to mediate myeloid differentiation in human bone marrow micro-environment [20] . Of note, is our previous study that demonstrated the regulation of erythroid differentiation through activation of the LPA receptor 3 (LPA 3 ) [21] . "
    [Show abstract] [Hide abstract] ABSTRACT: Erythrocytes and megakaryocytes (MK) are derived from a common progenitor that undergoes lineage specification. Lysophosphatidic acid (LPA), a lipid growth factor was previously shown to be a regulator for erythropoietic process through activating LPA receptor 3 (LPA 3). However, whether LPA affects megakaryopoiesis remains unclear. In this study, we used K562 leukemia cell line as a model to investigate the roles of LPA in MK differentiation. We demonstrated that K562 cells express both LPA 2 and LPA 3 , and the expression levels of LPA 2 are higher than LPA 3. Treatment with phorbol 12-myristate 13-acetate, a commonly used in-ducer of megakaryopoiesis, reciprocally regulates the expressions of LPA 2 and LPA 3. By pharmacological blockers and knockdown experiments, we showed that activation of LPA 2 suppresses whereas, LPA 3 promotes megakar-yocytic differentiation in K562. The LPA 2-mediated inhibition is dependent on β-catenin translocation, whereas reactive oxygen species (ROS) generation is a downstream signal for activation of LPA 3. Furthermore, the hema-topoietic transcriptional factors GATA-1 and FLI-1, appear to be involved in these regulatory mechanisms. Taken together, our results suggested that LPA 2 and LPA 3 may function as a molecular switch and play opposing roles during megakaryopoiesis of K562 cells.
    Full-text · Article · May 2015
    • "This hindered the use of plasma as blank analytical matrix and interfered with our ability to validate the method. Since depletion strategies (for example, using charcoal [41, 42]) did not perform well in our hands, we switched to a surrogate plasma-like matrix constituted of a saline solution containing diluted, lipid-free, bovine serum albumin (BSA, 5 g/0.1 L), which has been widely used in the past to mimic plasma in bioanalysis434445. We fully validated the method using this artificial matrix. "
    [Show abstract] [Hide abstract] ABSTRACT: We report on a new, sensitive, and fast LC-MS/MS method for the simultaneous determination of 25 key sphingolipid components in human plasma, including phosphorylated sphinganine and sphingosine, in a single 9-min run. This method enables an effective and high-throughput coverage of the metabolic changes involving the sphingolipidome during physiological or pathological states. The method is based on liquid–liquid extraction followed by reversed-phase LC-MS/MS. Exogenous odd-chain lipids are used as cost-effective but reliable internal standards. The method was fully validated in surrogate matrix and naive human plasma following FDA guidelines. Sample stability and dilution integrity were also tested and verified. Electronic supplementary material The online version of this article (doi:10.1007/s00216-015-8585-6) contains supplementary material, which is available to authorized users.
    Full-text · Article · Mar 2015
    • "Nowadays, primary culture of chondrocytes derived from normal human articular cartilage is also commercially available for researches. Several studies have revealed that LPA mediates myeloid differentiation within the human bone marrow microenvironment [13] and stimulates osteogenesis [14], cell proliferation [15], and migration [16] and inhibits apoptosis [17] in chondrocytes. The bone structure formed and enlarged from the proliferation and differentiation of mesenchymal cells condensates into chon- drocytes181920. "
    [Show abstract] [Hide abstract] ABSTRACT: Lysophosphatidic acid (LPA) has been found to mediate myeloid differentiation, stimulate osteogenesis, alter cell proliferation and migration, and inhibit apoptosis in chondrocytes. The effect of LPA on the angiogenic capability of chondrocytes is not clear. This study aimed to investigate its effect on the angiogenic capability of human chondrocytes and the underlying mechanism of these effects. Human chondrocyte cell line, CHON-001, commercialized human chondrocytes (HC) derived from normal human articular cartilage, and human vascular endothelial cells (HUVECs) were used as cell models in this study. The angiogenic capability of chondrocytes was determined by capillary tube formation, monolayer permeability, cell migration, and cell proliferation. An angiogenesis protein array kit was used to evaluate the secretion of angiogenic factors in conditioned medium. Angiogenin, insulin-like growth factor-binding protein 1 (IGFBP-1), interleukin (IL)-8, monocyte chemoattractant protein-1 (MCP-1), matrix metalloproteinase (MMP)-9, and vascular endothelial growth factor (VEGF) mRNA and protein expressions were evaluated by Q-RT-PCR and EIA, respectively. LPA receptor (LPAR) expression was determined by RT-PCR. Signaling pathways were clarified using inhibitors, Western blot analysis, and reporter assays. The LPA treatment promoted the angiogenic capability of CHON-001 cells and HC, resulting in enhanced HUVEC capillary tube formation, monolayer permeability, migration, and cell growth. Angiogenin, IGFBP-1, IL-8, MCP-1, MMP-9, and VEGF mRNA and protein expressions were significantly enhanced in LPA-treated chondrocytes. LPA2, 3, 4 and 6 were expressed in CHON-001 and HC cells. Pretreatment with the Gi/o type G protein inhibitor, pertussis toxin (PTX), and the NF-kB inhibitor, PDTC, significantly inhibited LPA-induced angiogenin, IGFBP-1, IL-8, MCP-1, MMP-9, and VEGF expressions in chondrocytes. The PTX pretreatment also inhibited LPA-mediated NF-kB activation, suggesting the presence of active Gi/NF-kB signaling in CHON-001 and HC cells. The effect of LPA on the angiogenesis-inducing capacity of chondrocytes may be due to the increased angiogenesis factor expression via the Gi/NF-kB signaling pathway.
    Full-text · Article · Jul 2014
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