Neutrophil Aging, Regulated By Microbiota-Derived Signals, Promotes Sickle Cell Vaso-Occlusion

Vaso-occlusion is one of the most common complications in sickle cell disease (SCD). Our previous studies have shown that neutrophils play an important role in promoting sickle cell vaso-occlusion by capturing sickle red blood cells (sRBC) through activated αMβ2 integrin (Mac-1). However, high Mac-1 activity was only observed in a small subset of adherent neutrophils (Nat. Med. 2009;15:384). Recent studies have shown that a CD62Llow CXCR4high subset of neutrophils represents the cells that have truly aged in vivo (Cell. 2013;153:1025). Since aged neutrophils may have experienced activation signals when they survey the whole body, we hypothesized that they are over-active cells that promote sickle cell vaso-occlusion. To test this possibility, we first analyzed the correlation between CD62L expression and Mac-1 activity of adherent neutrophils using multichannel fluorescence intravital microscopy and albumin-coated fluosphere beads that specifically bind activated Mac-1. We found a strong inverse correlation where neutrophils with lower CD62L expression showed greater bead binding capacity (P < 0.001). Mice deficient in P-selectin (Selp-/-), an adhesion molecule required for neutrophil clearance from the circulation, showed a dramatic increase in the percentages of CD62Llow CXCR4high aged neutrophils (wild-type / Selp-/-: 9.0 ± 1.0% / 74.7 ± 2.1%, P < 0.01). When purified neutrophils from Selp-/- mice were transferred into wild-type recipients, these aged neutrophils exhibited significantly higher Mac-1 activity compared to those purified from wild-type animals (wild-type / Selp-/-: 0.26 ± 0.06 / 1.52 ± 0.35 beads per adherent neutrophil, P < 0.05). Since microbial products derived from the microbiota could translocate into the system and modulate the innate immunity (Nat. Rev. Microbiol. 2011;9:233), we hypothesized that microbiota-derived signals could regulate the neutrophil aging process. To test this idea, we depleted the microbiota by treating mice with ampicillin, neomycin, metronidazole and vancomycin for 4 weeks. In these mice, the numbers of CD62Llow CXCR4high aged neutrophils were significantly decreased, and this reduction was reversible by intragastric gavage of Lipopolysaccharide (LPS; Control / Antibiotics-treated (ABX) / ABX + LPS: 87.2 ± 20.3 / 12.9 ± 2.0 / 83.9 ± 60.0 cells / μL blood, P < 0.05 between first two groups). To analyze the kinetics of neutrophil aging in vivo, we transferred blood from CD45.1+ mice into CD45.2+ control or antibiotics-treated mice, and monitored the percentages of CD62Llow CXCR4high population in CD45.1+ donor neutrophils. Strikingly, the aging process of donor neutrophils was significantly slower in antibiotics-treated recipients (Control / ABX: 78.2 ± 3.4% / 45.7 ± 7.7%, 5h after transfer, P < 0.01; 95.5 ± 0.7 / 67.1 ± 7.8%, 9h after transfer, P < 0.05). Since MyD88 mediates the signaling of most toll-like receptors (TLRs), we analyzed the neutrophil aging phenotypes in LysM-Cre/MyD88-flox mice, in which MyD88 is specifically deleted in the myeloid lineage. Similarly, we observed a dramatic decrease in the numbers of aged neutrophils in these mice (wild-type / LysM-Cre/MyD88-flox: 70.1 ± 22.2 / 23.8 ± 3.7 cells / μL blood, P = 0.08), and also a significantly slower aging process when we transferred blood from LysM-Cre/MyD88-flox mice into wild-type recipients (wild-type / LysM-Cre/MyD88-flox: 15.0 ± 3.1% / 5.0 ± 1.0%, 10min after transfer, P=0.09; 49.7 ± 5.2% / 12.0 ± 1.5%, 5h after transfer, P < 0.05; 59.6 ± 2.0% / 19.5 ± 3.2%, 9h after transfer, P < 0.01). To test whether neutrophil aging was relevant in SCD, we depleted the microbiota in a humanized SCD mouse model (“Berkeley” mice). Five weeks after depletion, we observed a dramatic decrease in the numbers of aged neutrophils (Control SCD / ABX SCD: 4392 ± 574 / 819 ± 358 cells/ μL blood, P < 0.01), and a significant improvement of splenomegaly (Control SCD / ABX SCD: 691.7 ± 46.4 / 453.5 ± 28.5 mg, P<0.05). Further, preliminary data indicate that microbiota depletion could protect against vaso-occlusive crisis induced by TNF-α and surgical trauma, leading to prolonged survival. Taken together, these data suggest that aged neutrophils, modulated by microbiota-derived signals, represent an over-active subset of neutrophils that promotes sickle cell vaso-occlusion. Gaining understanding of neutrophil aging may lead to novel ways to control the manifestations of the disease and its complications. Disclosures: No relevant conflicts of interest to declare.

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Abstract 15445: The Sirtuin SIRT3 Blocks Doxorubicin-induced Cardiac Hypertrophic Response of Mice

Circulation ◽

10.1161/circ.130.suppl_2.15445 ◽

2014 ◽

Vol 130 (suppl_2) ◽

Author(s):

Vinodkumar Pillai ◽

Sadhana Samant ◽

Nagalingam Sundaresan ◽

Gene Kim ◽

Mahesh P Gupta

Keyword(s):

Negative Regulator ◽

Neonatal Rat ◽

Whole Body ◽

Wild Type ◽

Electron Microscopic ◽

Specific Expression ◽

Rat Cardiomyocytes ◽

Fluorescent Intensity ◽

Hypertrophic Response

Background and objective: Doxorubicin is a chemotherapeutic drug widely used to treat variety of cancers. One of the serious side effects of doxorubicin is its toxicity to the heart. Previously, we have shown that overexpression of SIRT3 blocks the hypertrophic response of the heart to agonist treatments. This study was undertaken to investigate whether SIRT3 can also attenuate the doxorubicin-induced cardiac hypertrophic response in mice. Methods and results: Neonatal rat cardiomyocytes overexpressed with SIRT3 and treated with doxorubicin (10μM) showed 28% reduced mean fluorescent intensity for CM-H 2 DCFDA dye, compared to mock infected control cells treated with doxorubicin, thus suggesting that SIRT3 was capable of blocking doxorubicin-induced ROS synthesis in cardiomyocytes. To examine the cardioprotective effects of SIRT3 in doxorubicin-induced cardiotoxicity in vivo ; we used a cumulative dose of 15mg/kg of doxorubicin for two different time points. One group of mice was treated intraperitoneally with 5mg/kg doxorubicin or an equal volume of saline every two weeks for a total of three doses. Transgenic mice having cardiac specific expression of SIRT3 (SIRT3-Tg) showed 33% reduced HW/BW ratio compared to control mice. Echocardiographic evaluation of hearts showed significantly reduced fractional shortening in control mice, compared to SIRT3-Tg mice (24.6 vs 34.7 %, P<0.05). SIRT3-Tg mice also showed significantly reduced fetal gene expression for ANF, βMHC and collagen-1 as determined by RT-PCR. Masson’s trichrome staining showed significantly reduced fibrosis in doxorubicin treated SIRT3-Tg mice compared to its control. Furthermore, electron microscopic analysis showed preserved mitochondrial and sarcomeres structures in doxorubicin treated SIRT3-Tg hearts, whereas in wild-type hearts these structures were highly disorganized. Second group of mice that received 15mg/kg dose for two weeks also showed similar results. Contrary to this, whole body SIRT3 knockout mice showed exacerbated cardiac hypertrophic response compared to wild-type mice in response to doxorubicin treatment. Conclusion: These results demonstrated that SIRT3 is an endogenous negative regulator of doxorubicin-induced cardiac hypertrophic response.

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Functional Domain Structure of Human T-Cell Leukemia Virus Type 2 Rex

Journal of Virology ◽

10.1128/jvi.77.23.12829-12840.2003 ◽

2003 ◽

Vol 77 (23) ◽

pp. 12829-12840 ◽

Cited By ~ 15

Author(s):

Murli Narayan ◽

Ihab Younis ◽

Donna M. D'Agostino ◽

Patrick L. Green

Keyword(s):

Nuclear Export ◽

Rna Binding ◽

Binding Capacity ◽

Leukemia Virus ◽

Functional Domain ◽

Wild Type ◽

Human T Cell ◽

T Cell Leukemia Virus ◽

Carboxy Terminal

ABSTRACT The Rex protein of human T-cell leukemia virus (HTLV) acts posttranscriptionally to induce the cytoplasmic expression of the unspliced and incompletely spliced viral RNAs encoding the viral structural and enzymatic proteins and is therefore essential for efficient viral replication. Rex function requires nuclear import, RNA binding, multimerization, and nuclear export. In addition, it has been demonstrated that the phosphorylation status of HTLV-2 Rex (Rex-2) correlates with RNA binding and inhibition of splicing in vitro. Recent mutational analyses of Rex-2 revealed that the phosphorylation of serine residues 151 and 153 within a novel carboxy-terminal domain is critical for function in vivo. To further define the functional domain structure of Rex-2, we evaluated a panel of Rex-2 mutants for subcellular localization, RNA binding capacity, multimerization and trans-dominant properties, and the ability to shuttle between the nucleus and the cytoplasm. Rex-2 mutant S151A,S153A, which is defective in phosphorylation and function, showed diffuse cytoplasmic staining, whereas mutant S151D,S153D, previously shown to be functional and in a conformation corresponding to constitutive phosphorylation, displayed increased intense speckled staining in the nucleoli. In vivo RNA binding analyses indicated that mutant S151A,S153A failed to efficiently bind target RNA, while its phosphomimetic counterpart, S151D,S153D, bound twofold more RNA than wild-type Rex-2. Taken together, these findings provide direct evidence that the phosphorylation status of Rex-2 is linked to cellular trafficking and RNA binding capacity. Mutants with substitutions in either of the two putative multimerization domains or in the putative activation domain-nuclear export signal displayed a dominant negative phenotype as well as defects in multimerization and nucleocytoplasmic shuttling. Several carboxy-terminal mutants that displayed wild-type levels of phosphorylation and localized to the nucleolus were also partially impaired in shuttling. This is consistent with the hypothesis that the carboxy terminus of Rex-2 contains a novel domain that is required for efficient shuttling. This work thus provides a more detailed functional domain map of Rex-2 and further insight into its regulation of HTLV replication.

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Investigating the Roles of the Yeats Domain in MLL-ENL Mediated Leukemogenesis

Blood ◽

10.1182/blood-2020-138622 ◽

2020 ◽

Vol 136 (Supplement 1) ◽

pp. 30-31

Author(s):

Hsiangyu Hu ◽

Nirmalya Saha ◽

Yuting Yang ◽

Sierrah Marie Grigsby ◽

Rolf Marschalek ◽

...

Keyword(s):

Cell Growth ◽

Acute Leukemia ◽

Transcriptional Activation ◽

Fusion Proteins ◽

Conflicts Of Interest ◽

Leukemic Cell ◽

Leukemic Cells ◽

Fusion Partner ◽

Wild Type

Approximately 10% of acute leukemia involves rearrangement at chromosome 11q23, giving rise to a relatively aggressive form of acute leukemia characterized by MLL1 (KMT2A) fusion proteins. Despite the identification of >100 MLL1 fusion partners, the majority are members of several similar transcriptional activation complexes including: The Super Elongation Complex (SEC), AEP and EAP (SEC used hereafter). MLL fusion-driven acute leukemia is characterized by deregulated activity of the SEC and the H3K79 methyltransferase DOT1L. This leads to altered epigenetic landscapes at and deregulated transcription of pro-leukemic MLL1-fusion target genes like HoxA9 and Meis1. Thus, targeting these transcriptional and epigenetic complexes has become an attractive therapeutic strategy for treating MLL-fusion leukemia. Eleven-Nineteen-Leukemia (ENL or MLLT1) is the third most common MLL1 fusion partner and a component of the SEC. Recently, wild type ENL was identified as an essential factor for leukemic cell growth. The ENL protein possesses a C-terminal ANC-homology domain (AHD) necessary for SEC recruitment and is essential for MLL-fusion mediated leukemogenesis. In addition, ENL contains a highly conserved N-terminal YEATS domain that functions as an epigenetic reader for acetylated H3K9, H3K18 or H3K27, which is essential for leukemic cell growth. Additionally, the ENL YEATS domain directly interacts with the Polymerase Associated Factor 1 complex (PAF1c), an epigenetic regulator protein complex essential for MLL-fusion mediated leukemogenesis. These studies highlight the importance of the YEATS domain in regulating wild type ENL function in leukemic cells. However, the importance of the YEATS domain in the context of MLL-ENL mediated leukemia remains to be elucidated. In this study, we investigate the clinical relevance and leukemic importance of the ENL YEATS domain in MLL-ENL leukemias. We first analyzed t(11;19) (MLL-ENL) patient data to determine the sites of chromosomal translocation within the ENL gene. We found that the YEATS domain (coded by exons 2 through 4) is retained in 84.1% of MLL-ENL patients (n=302). Specifically, 50.7% (n=153) of these patients possess breakpoints located 5' of the first exon of the ENL gene, while 33.4% (n=101) of the patients display breakpoints within the first intron of ENL gene. These data point towards a tendency for YEATS domain retention in MLL-ENL fusion proteins in t(11;19) patients. We next tested whether the YEATS domain was functional in MLL-ENL mouse leukemia models. Our data shows the YEATS domain is required for MLL-ENL leukemogenesis in vivo, as deletion of the YEATS domain destroys MLL-ENL leukemogenesis and increases apoptosis in cell culture. Transcriptionally, deletion of the YEATS domain decreased expression of pro-leukemic genes such as Meis1 and the anti-apoptotic gene Bclxl. To dissect the contribution of different YEATS domain functions in MLL-ENL leukemogenesis, we engineered YEATS domain mutants defective in interacting with PAF1 or acetylated H3K9/K18/K27. Disrupting the YEATS-PAF1 or YEATS-H3Kac interaction decreased MLL-ENL mediated colony formation exvivo and significantly increased leukemia latency in vivo. The MLL-ENL YEATS domain mutants will be used in future studies to determine how the YEATS domain affects 1) MLL-ENL fusion localization, 2) key protein complexes localization (i.e. SEC and PAF1c) and 3) the epigenetic landscapes (i.e. H3K79me2/3 and H3K4me3) at pro-leukemic targets. To further interrogate the YEATS-PAF1 interaction in MLL-ENL mediated leukemia, we identified the minimal region of the PAF1 protein required for the YEATS-PAF1 interaction. This PAF1 protein fragment will be used to biochemically characterize the structure of the PAF1-YEATS interaction, which might aid in therapeutically targeting specific YEATS interactions in MLL-ENL leukemia. Our results demonstrate for the first time, to our knowledge, an essential role for the YEATS domain in MLL-ENL mediated leukemogenesis. Additionally, our genetic studies elucidate the importance of the YEATS domain interaction with either the PAF1c or H3Kac in MLL-ENL leukemias. Taken together, our study establishes a rationale for exploring the effectiveness of small molecule development aimed at disrupting either the YEATS-H3Kac or the YEATS-PAF1 interaction as a therapeutic intervention for treating MLL-ENL leukemia patients. Disclosures No relevant conflicts of interest to declare.

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ABCG2 C.421C>A Is Associated with Higher Trough Imatinib Plasma Levels in Patients with Chronic Myeloid Leukemia.

Blood ◽

10.1182/blood.v114.22.110.110 ◽

2009 ◽

Vol 114 (22) ◽

pp. 110-110

Author(s):

Naoto Takahashi ◽

Masatomo Miura ◽

Stuart A Scott ◽

Kenichi Sawada

Keyword(s):

Chronic Myeloid Leukemia ◽

Plasma Levels ◽

Myeloid Leukemia ◽

Drug Transport ◽

Conflicts Of Interest ◽

Nucleotide Polymorphisms ◽

Wild Type ◽

Large Patient

Abstract Abstract 110 [Background] Despite the excellent efficacy of imatinib for the treatment of chronic myeloid leukemia (CML), trough imatinib plasma levels can vary widely among patients. This may be due, in part, to inter-individual variation in imatinib metabolism and drug transport efficacy. To investigate the role of genetic variation in the pharmacokinetics of imatinib, we analyzed common single nucleotide polymorphisms within important imatinib pathway genes including ABCG2 (BCRP), ABCB1 (MDR1), ABCC2 (MRP2), CYP3A5, and SLC22A1 (OCT1) in 67 CML patients treated with imatinib. In addition, trough imatinib plasma levels were determined using high-performance liquid chromatography-tandem mass spectrometry. [Results] Distinct imatinib pharmacokinetics were identified in association with ABCG2 c.421C>A (p.Q141K; rs2231142) genotype. Specifically, the presence of the variant c.421A allele was significantly (p=0.024) associated with higher imatinib concentrations [median Cmin/Dose 2.70 (range: 1.50-8.30) ng/ml/mg; n=25] compared to patients with the wild-type ABCG2 (c.421C/C) genotype [median Cmin/Dose 2.27 (range: 0.37-5.30) ng/ml/mg; n=42]. ABCG2 is an efflux transporter for many xenobiotics, including imatinib, and is expressed at high levels in the human liver. Previous studies indicate that c.421A causes a 40% reduction in imatinib transport in vitro when compared to the wild-type genotype. Our data suggest that CML patients with ABCG2 c.421A allele may have deficient ABCG2 activity in vivo, resulting in reduced hepatic excretion of imatinib. Of note, although less common among Africans and individuals of European decent, the ABCG2 c.421C>A allele occurs at a high frequency in the Japanese (0.311) and Han Chinese (0.289) populations. [Conclusion] The association of ABCG2 c.421C>A with imatinib pharmacokinetics may explain why some Japanese CML patients administered less than 400 mg/day of imatinib have clinically sufficient trough imatinib plasma levels. Prospective studies are warranted to confirm the association between ABCG2 genotype and imatinib pharmacokinetics in large patient populations. Disclosures: No relevant conflicts of interest to declare.

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Sequence-Specific Conversion of βA- to βS-Globin by Small Fragment Homologous Replacement In Hematopoietic Stem/Progenitor Cells.

Blood ◽

10.1182/blood.v116.21.3754.3754 ◽

2010 ◽

Vol 116 (21) ◽

pp. 3754-3754

Author(s):

Alireza Abdolmohammadi ◽

Rosalie Maurisse ◽

Babek Bedayat ◽

David DeSemir ◽

Damian Laber ◽

...

Keyword(s):

Progenitor Cells ◽

Sickle Cell ◽

Sickle Cell Anemia ◽

Dna Sequences ◽

Conflicts Of Interest ◽

Globin Gene ◽

Specific Gene ◽

Small Fragment ◽

Wild Type ◽

Hematopoietic Stem

Abstract Abstract 3754 Introduction: An ultimate goal of gene therapy is the development of effective strategies to correct mutant genomic sequences in pathologic cells. To that end, studies have been undertaken to evaluate the therapeutic potential of an oligo/polynucleotide-based sequence-specific gene modification strategy, small fragment homologous replacement (SFHR) in the correction of the mutation giving rise to sickle cell anemia. Small DNA fragments (SDFs) comprising the sickle cell anemia mutation (an A>T transversion in codon 6) and flanking DNA sequences in the human b-globin gene were introduced into Hematopoietic Stem/Progenitor Cells (HSPCs). The studies presented indicated modification at the level of DNA, RNA, and protein when cells were differentiated into erythrocytes. Methods: In this study, SFHR was used to convert A>T in codon 6 of the b-globin gene in CD34+/CD38-/Lin- HSPCs isolated from full term umbilical cord blood as a proof of principle. HSPCs were transfected with a defined number of a 559-bp SDF using the Amaxa electroporation (nucleofection) system. After growing the transfected cells in stem cell media containing EPO for different time intervals up to 32 days, RNA was extracted and DNase I-treated before further analysis. Erythrocytes were also analyzed using antibodies that differentiate between wild-type hemoglobin A (HBA) and sickle cell hemoglobin S (HBS). Results: RFLP analysis of a 430-bp PCR product generated from mRNA-derived cDNA with the DdeI enzyme indicated conversion of bA- to bS-globin. Sequencing of the 430-bp amplicon showed the A > T conversion. Analysis of the transfected wild-type HSPC-derived erythrocytes with HBA and HBS specific antibodies demonstrated the presence of a subpopulation of cells expressing HBS. These data are consistent with previous studies showing both conversion of bS- to bA-globin in SC1 cells and bA- to bS-globin in HSPCs after electroporation and microinjection of SDF, respectively. Conclusion: These studies represent a critical next step in developing SFHR as a therapy for sickle cell disease, in that they demonstrate long-term SFHR-mediated modification of b-globin following mass transfection by electroporation of HSPCs. Disclosures: No relevant conflicts of interest to declare.

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Profilin 1 Is Essential for Retention and Metabolism of Hematopoietic Stem Cells in Bone Marrow

Blood ◽

10.1182/blood.v120.21.1224.1224 ◽

2012 ◽

Vol 120 (21) ◽

pp. 1224-1224

Author(s):

Junke Zheng ◽

Chengcheng Zhang

Keyword(s):

Stem Cells ◽

Bone Marrow ◽

Conflicts Of Interest ◽

Bone Marrow Failure ◽

Actin Binding ◽

Wild Type ◽

Cell Fates ◽

Hematopoietic Stem ◽

Multiple Cell

Abstract Abstract 1224 How stem cells interact with the microenvironment to regulate their cell fates and metabolism is largely unknown. Here we show that, in a hematopoietic stem cell (HSC) -specific inducible knockout model, the cytoskeleton-modulating protein profilin 1 (pfn1) is essential for the maintenance of multiple cell fates and metabolism of HSCs. The deletion of pfn1 in HSCs led to bone marrow failure, loss of quiescence, increased apoptosis, and mobilization of HSCs in vivo. In reconstitution analyses, pfn1-deficient cells were selectively lost from mixed bone marrow chimeras. By contrast, pfn1 deletion did not significantly affect differentiation or homing of HSCs. When compared to wild-type cells, levels of expression of Hif-1a, EGR1, and MLL were lower and an earlier switch from glycolysis to mitochondrial respiration with increased ROS level was observed in pfn1-deficient HSCs. This switch preceded the detectable alteration of other cell fates. Importantly, treatment of pfn1-deficient mice with the antioxidant N-acetyl-l-cysteine reversed the ROS level and loss of quiescence of HSCs, suggesting that pfn1 maintained metabolism is required for the quiescence of HSCs. Furthermore, we demonstrated that expression of wild-type pfn1 but not the actin-binding deficient or poly-proline binding-deficient mutants of pfn1 rescued the defective phenotype of pfn1-deficient HSCs. This result indicates that actin-binding and proline-binding activities of pfn1 are required for its function in HSCs. Thus, pfn1 plays an essential role in regulating the retention and metabolism of HSCs in the bone marrow microenvironment. Disclosures: No relevant conflicts of interest to declare.

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Prostaglandin E Synthase Is Upregulated By Gas6 during Cancer-Induced Venous Thromboembolism

Blood ◽

10.1182/blood.v124.21.111.111 ◽

2014 ◽

Vol 124 (21) ◽

pp. 111-111

Author(s):

Meghedi N Aghourian ◽

Catherine A Lemarie ◽

Francois-Rene Bertin ◽

Mark D Blostein

Keyword(s):

Endothelial Cells ◽

Venous Thromboembolism ◽

Microarray Analysis ◽

Conflicts Of Interest ◽

Prostaglandin E ◽

Wild Type ◽

Prostaglandin E Synthase ◽

Murine Lung

Abstract Venous thromboembolism (VTE) is the most common morbid complication related to cancer and its treatments. Although malignancies are characterized by a hypercoagulable state leading to VTE, the pathophysiology of this state has not been well studied. Growth arrest specific 6 (Gas6) is a protein that has pro-coagulant properties. Gas6 deficient mice develop smaller venous thrombi as compared to wild type mice, and express less tissue factor in the endothelium when challenged with thrombotic stimuli. We hypothesize that Gas6 may be involved in cancer-induced venous thrombosis. In order to test this hypothesis, venous thrombi were induced in wild type (WT) and Gas6 null (-/-) mice injected with M27 murine lung cancer cell lines. Thrombus size was measured using ultrasonography, thrombus weight and histology. We observed that WT mice with cancer developed larger thrombi than their healthy counterparts (p<0.05). However, these larger thrombi induced by cancer were not seen in Gas6-/- mice, suggesting that Gas6 has a pathophysiologic role in promoting malignancy associated VTE. Whole genome microarray analysis was then used to identify differential gene expression in WT and Gas6-/- endothelial cells co-cultured with M27 murine lung carcinoma cells. Microarray analysis revealed that prostaglandin E synthase (PTGES) was increased in WT endothelial cells but not in Gas6-/- cells co-cultured with M27. These results were confirmed using real-time PCR and immunofluorescence staining (p<0.05). In WT endothelial cells, PTGES expression was regulated through ERK1/2 phosphorylation. We also show that co-culture of WT endothelial cells with M27 augments the secretion of PGE2, the enzymatic product of PTGES. PGE2 activates platelets in vitro after binding to its receptor, EP3. In vivo, EP3 receptor antagonism reversed the effect of cancer-induced thrombosis in WT mice. These results show that Gas6, through upregulation of PGE2, contributes to cancer-induced VTE. Disclosures No relevant conflicts of interest to declare.

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hnRNP K: A Tumor Suppressor or Oncogene?

Blood ◽

10.1182/blood.v124.21.259.259 ◽

2014 ◽

Vol 124 (21) ◽

pp. 259-259

Author(s):

Miguel Gallardo ◽

Hun Ju Lee ◽

Carlos E. Bueso-Ramos ◽

Xiaorui Zhang ◽

Laura R. Pageon ◽

...

Keyword(s):

Bone Marrow ◽

Tumor Suppressor ◽

Conflicts Of Interest ◽

Chromosome 9 ◽

Wild Type ◽

Differentiation Potential ◽

Hematopoietic Stem ◽

Hnrnp K ◽

Differentiation And Proliferation

Abstract Heterogeneous nuclear ribonucleoprotein K (hnRNP K) is an RNA and DNA binding protein that regulates critical pathways controlling differentiation and proliferation programs. While alterations in hnRNP K expression are associated with neoplastic malignancies, we currently do not understand how changes in hnRNP K expression contribute to tumor phenotypes in vivo. Previous biochemical and cell line studies demonstrate that hnRNP K transcriptionally regulates p53-dependent activities, suggesting it functions as a potential tumor suppressor. However, hnRNP K has also been shown to positively regulate c-Myc expression, indicating it may behave as an oncogene. The HNRNP K gene maps to a region of chromosome 9 (9q21.32), which is lost in a subset of patients with acute myeloid leukemia (AML). RNA expression analyses of patient samples with AML that harbor 9q21.32 deletions revealed a significant reduction in HNRNP K expression compared to wild type control samples, supporting the notion that hnRNP K acts as a tumor suppressor (Figure 1A). However, patients with AML who do not harbor a 9q21.32 deletion displayed a significant increase in hnRNP K expression (Figure 1A). Thus, to examine the association between altered hnRNP K expression and disease status in patients with AML, we performed reverse phase protein array (RPPA) analysis on CD34+ bone marrow cells from 415 de novo AML patient as well as healthy donor controls. Interestingly, we observed a significant correlation between elevated hnRNP K levels and poor outcomes, which supports the idea that hnRNP K has oncogenic potential (Figure 1A). Together, these observations indicate that any change in hnRNP K expression may contribute to the etiology of AML and supports the idea that hnRNP K may potentially act as either a haploinsufficient tumor suppressor or oncogene in AML. To directly interrogate these possibilities in vivo, we generated mouse models that either harbor a deletion of one hnRNP K allele (hnRNP K+/-) or overexpressed hnRNP K (hnRNP KTg) in the hematological compartment. Western blot analyses demonstrated that hnRNP K haploinsufficiency results in a significant reduction in hnRNP K expression while tissue-specific activation of hnRNP K resulted in overexpression of hnRNP K. Similar to our observation in AML patients, either hnRNP K haploinsufficiency or overexpression resulted in similar phenotypes in vitro and in vivo. Lin-CD117+ hematopoietic stem cells (HSCs) from hnRNP K+/- and hnRNP KTg mice had significant increases in differentiation and proliferation potential as determined by colony formation assays. In these experiments, we observed a significant increase in the number of total colonies and number of cells per colony in both hnRNP K+/- and hnRNP KTg HSCs as compared to wild type HSCs (Figure 1B). In vivo analyses of the hnRNP K+/- and hnRNP KTg mice revealed a significant increase in myeloid hyperplasia in the peripheral blood and bone marrow, increased tumor formation, genomic instability, and decreased survival compared to wild type mice (Figure 1C). Interestingly, both increased and decreased hnRNP K expression resulted in alterations in similar pathways that regulate differentiation and proliferations potential (e.g.; p53 and c-Myc pathways and alterations in C/EBP expression). Together, these clinical and animal model studies illustrate that either over-expression or under-expression of hnRNP K lead to strikingly similar phenotypes that directly impact the etiology of AML. Furthermore, these data not only implicate that hnRNP K behaves as both a tumor suppressor and oncogene, but also suggest that it functions as a master toggle that dictates the proliferation and differentiation potential of HSCs. We are currently using Whole Transcriptome Shotgun Sequencing (RNA-Seq) and ChIP-Seq to evaluate the mechanisms by which increased and decreased hnRNP K expression impact hematologic malignancies. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

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Unusual Presentation for Unusual Infection: Disseminated Mycobacterium Avium-Intracellulare complex (MAC) in Patient with Sickle Cell Anemia Mimicking Blood Transfusion Reaction

Blood ◽

10.1182/blood.v124.21.4980.4980 ◽

2014 ◽

Vol 124 (21) ◽

pp. 4980-4980

Author(s):

Nayf Edrees ◽

Thomas H. Howard

Keyword(s):

Blood Culture ◽

Sickle Cell ◽

Mycobacterium Avium ◽

Mycobacterium Avium Complex ◽

Conflicts Of Interest ◽

Venous Catheter ◽

Whole Body ◽

Transfusion Reaction ◽

Mycobacterium Avium Intracellulare ◽

Slow Grower

Abstract Nontuberculous mycobacteria (NTM) are ubiquitous free living soil and water– borne organisms that cause numerous clinical syndromes including lymphadenitis, skin, soft tissue and pulmonary infections, however disseminated infection is almost exclusively in patient with severe immunocompromise (i.e:HIV, Hematological malignancy, and bone marrow transplant). Mycobacterium avium complex (MAC) is hard to diagnose as it is considered slow grower NTM. We describe a case of disseminated Mycobacterium avium-intracellulare complex infection in teenager with sickle hemoglobinopathy with unique presentation mimicking pRBCs transfusion reaction. Patient presented on three different occasions with tachycardia, hypotension and fever within 2-24 hours following pRBCs pheresis, all three episodes were investigated and were negative for transfusion reactions. Patient had central venous catheter (CVC), frequent admissions for vaso-occlusive painful episode, on hydrocortisone for adrenal insufficiency and off Hydroxyurea for two months. Diagnosis of mycobacterium avium complex bacteremia was confirmed by two positive blood cultures, whole body CT scan showed liver nodules, spleen nodules and lung nodules. Pulmonary dissemination was confirmed by Biopsy and culture, Lymphocyte markers showed severe lymphopenia with absolute CD4 count of 64. Patient underwent treatment with three month of four antibiotics followed by 9 months of three antibiotics with removal of the central line, follow up scan showed decrease size and numbers of nodules, patient started tolerating pheresis within one month of the antibiotics initiation. NTM infection should be added to the list of pathogens in sickle cell patients with CVCs and fever and should be considered in frequent pRBC transfusion like reaction with negative workup. Routine blood culture can identify rapid growing NTM but specific mycobacterial blood culture is required in case of other NTM species (slow grower). As dissemination almost always occurs in those with impaired cellular immunity, HIV testing and lymphocyte markers should be performed Removal of involved CVCs is essential for the treatment as well as appropriate antimicrobial medications. Disclosures No relevant conflicts of interest to declare.

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Overexpression of Foxf2 in adipose tissue is associated with lower levels of IRS1 and decreased glucose uptake in vivo

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00395.2009 ◽

2010 ◽

Vol 298 (3) ◽

pp. E548-E554 ◽

Cited By ~ 4

Author(s):

Rickard Westergren ◽

Daniel Nilsson ◽

Mikael Heglind ◽

Zahra Arani ◽

Mats Grände ◽

...

Keyword(s):

Adipose Tissue ◽

Glucose Tolerance ◽

Glucose Uptake ◽

Target Genes ◽

Whole Body ◽

Wild Type ◽

Intravenous Glucose ◽

Downstream Target ◽

Protein Levels

Many members of the forkhead genes family of transcription factors have been implicated as important regulators of metabolism, in particular, glucose homeostasis, e.g., Foxo1, Foxa3, and Foxc2. The purpose of this study was to exploit the possibility that yet unknown members of this gene family play a role in regulating glucose tolerance in adipocytes. We identified Foxf2 in a screen for adipose-expressed forkhead genes. In vivo overexpression of Foxf2 in an adipose tissue-restricted fashion demonstrated that such mice display a significantly induced insulin secretion in response to an intravenous glucose load compared with wild-type littermates. In response to increased Foxf2 expression, insulin receptor substrate 1 (IRS1) mRNA and protein levels are significantly downregulated in adipocytes; however, the ratio of serine vs. tyrosine phosphorylation of IRS1 seems to remain unaffected. Furthermore, adipocytes overexpressing Foxf2 have a significantly lower insulin-mediated glucose uptake compared with wild-type adipocytes. These findings argue that Foxf2 is a previously unrecognized regulator of cellular and systemic whole body glucose tolerance, at least in part, due to lower levels of IRS1. Foxf2 and its downstream target genes can provide new insights with regard to identification of novel therapeutic targets.

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