bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reciprocal Regulation of DSCR1 (Down Syndrome Critical Region 1) Expression and NFAT (Nuclear Factor of Activated T Cells) Activation in Megakaryocytes.
Authors: Kyttaelae Satu , Habermann Ivonne , Bornhaeuser Martin , Ehninger Gerhard , Kiani Alexander 
Published: April 2020

Abstract
NFAT (Nuclear Factor of Activated T cells) is a family of calcium-induced, calcineurin-dependent transcription factors, well characterized as central regulators of inducible gene expression in T lymphocytes but now known to function also in several other cell types in various adaptation and differentiation processes. Activation of NFAT by the phosphatase calcineurin is counteracted by several inhibitory kinases and can be completely blocked by the immunosuppressant Cyclosporin A. The Down syndrome critical region 1 (DSCR1; also termed CSP1, MCIP1 or RCAN1) gene belongs to the calcipressin family of endogenous calcineurin inhibitors and is expressed in several isoforms, one of which (isoform C, coded by exons 4–7) has been described to be a transcriptional target for NFAT in striated muscle, endothelial, and neural cells. The DSCR1 gene is located within the Down syndrome critical region of human chromosome 21 and is, together with 200–300 other genes, overexpressed about 1.5-fold in patients with Down syndrome (DS). Previously, dysregulation of NFAT signaling by overexpression of DSCR1 has been implicated in causing various of the pathophysiological features observed in DS patients. Children with DS also suffer from an about 500-fold increased incidence of acute megakaryocytic leukemia; the respective roles of NFAT or DSCR1 in megakaryocytes of either normal individuals or those with DS, however, has not yet been established. Here we show that DSCR1 is upregulated during megakaryocytic differentiation in a lineage-specific manner, and in mature megakaryocytes is further strongly induced by calcineurin stimulation. DSCR1 expression in megakaryocytes is regulated by NFAT, since overexpression of NFATc2 enhances, while overexpression of the specific inhibitor of NFAT activation, VIVIT, suppresses expression of the gene. We further demonstrate that DSCR1 does not only represent an NFAT target in megakaryocytes, but itself acts an inhibitor of NFAT signaling in these cells. Overexpression of DSCR1 in CMK cells as well as in primary megakaryocytes by retroviral transduction profoundly suppressed ionomycin-induced dephosphorylation and nuclear translocation of NFATc2, as well as transactivation of an NFAT-dependent promoter construct. Finally, overexpression of DSCR1 in megakaryocytes markedly downregulated both the constitutive and induced expression of Fas Ligand, a pro-apoptotic gene recently established as a NFAT target in megakaryocytes. Together, these results suggest that DSCR1 acts as an NFAT-induced NFAT inhibitor in megakaryocytes and, when overexpressed, interferes with the expression of NFAT-dependent megakaryocytic genes.
A Human Lymphoid Progenitor Capable of Circulating and Seeding the Thymus.
Authors: Six Emmanuelle M. , Bonhomme Delphine , Monteiro Marta , Beldjord Kheira , Garrigue Alexandrine , Dal Cortivo Liliane , Rocha Benedita , Fischer Alain , Cavazzana-Calvo Marina , André-Schmutz Isabelle 
Published: April 2020

Abstract
Identification of a thymus-seeding progenitor originating from human bone marrow constitutes a key milestone in understanding and correcting defects in T-cell development. Here, we report the characterization of a novel human bone marrow lymphoid-restricted subpopulation which is part of the lineage-negative CD34+CD10+ progenitor population and which can be distinguished from B-cell-committed precursors by the absence of CD24 expression. We demonstrated that these Lin-CD34+CD10+CD24- progenitors lack myeloid and erythroid potential but can generate B, T and NK lymphocytes following culture on MS5 or OP9-hDelta1 stroma. The gene expression profile of this population, analyzed by a multiplex RT-PCR assay, revealed co-expression of RAG1, TdT, PAX5, CD3ε and IL-7Rα. These progenitors are not only present in the bone marrow but also in the blood throughout life, suggesting an ability to circulate. Moreover we showed that the Lin-CD34+CD10+CD24- cells also correspond to the most immature population of the thymus which gives rise to Lin-CD34+CD7+ T-cell precursors. Taken as a whole these findings unravel for the first time the existence of a postnatal lymphoid-restricted population which is capable of migrating from the bone marrow to the thymus.
Disruption of the Osteoblast Niche by G-CSF Induces Hematopoietic Stem Cell Quiescence and Loss of Long-Term Repopulating Activity.
Authors: Gopalan Priya K. , Christopher Matthew J. , Link Daniel C. 
Published: April 2020

Abstract
There is evidence that hematopoietic stem cells (HSC) are physically localized to specialized areas in the bone marrow termed the vascular and osteoblast niches. It is not clear if there are differences in the capacity of these niches to support HSC function. We and others previously showed that G-CSF treatment suppresses both osteoblast number and function, effectively eliminating the osteoblast niche. In contrast, G-CSF treatment has no apparent effect on the microvasculature in the bone marrow, suggesting that the vascular niche is intact. In this study, we utilized this system to assess the capacity of each niche to support HSC function. We previously reported that the competitive repopulation capacity of bone marrow isolated from G-CSF treated mice is markedly reduced. This is not due to a simple loss of HSC in the bone marrow, as the number of HSC, phenotypically defined as lineage-CD41-CD48-CD150+ (SLAM) or lineage-Kit+Sca+CD34- cells, was comparable to control mice. Moreover, the long-term repopulating activity of sorted SLAM cells from G-CSF treated mice was reduced. This repopulating defect is not secondary to impaired homing to the bone marrow, as direct intrafemoral injection of G-CSF treated bone marrow cells failed to rescue the engraftment defect. Since G-CSF is able to stimulate HSC proliferation, we predicted that the defect in repopulating activity might be secondary to loss of HSC quiescence. Contrary to our prediction, the percentage of quiescent HSC in the bone marrow was actually increased in G-CSF treated mice. Whereas 28.0 ± 3.4% of control SLAM cells were labeled after treatment with BrdU for 48 hours, only 7.5 ± 0.8% of SLAM cells isolated from G-CSF mice were labeled (p &lt; 0.008). Moreover, the percentage of SLAM cells in G0, as determined by Hoechst and pyronin staining, was increased in G-CSF treated mice (80.3 ± 5.0% versus 65.5 ± 6.8% in untreated mice, p=0.104). To elucidate the molecular mechanisms by which disruption of the osteoblast niche leads to a loss of HSC activity, we performed RNA profiling experiments on SLAM cells sorted from G-CSF or saline-treated mice. Consistent with the quiescent phenotype, a significant increase in the expression of the cell cycle inhibitor, Cdkn1a (p21waf1), was observed in G-CSF treated SLAM cells. Collectively, these data show that the osteoblast and vascular niches are not functionally redundant and suggest that it is the osteoblast niche that is key to maintaining long-term repopulating activity of HSC.
Loss of Gfi1 Impedes Development of T-Cell Lymphoma upon Exposure to N-ethyl-N-nitrosourea but Predisposes to Severe Myleodysplastic Changes.
Authors: Khandanpour Cyrus , Duehrsen Ulrich , Möröy Tarik 
Published: April 2020

Abstract
Exogenous toxic substances often cause the initiation and development of leukemia and lymphoma by acting as mutagens. N-ethyl-N-nitrosourea (ENU) is a paradigmatic example for such a substance, which introduces point mutations in the genome through DNA damage and repair pathways. ENU is widely used to experimentally induce T-cell lymphomas in mice. We have used ENU to investigate whether the hematopoietic transcription factor Gfi1 is required for lymphomagenesis. The Gfi1 gene was originally discovered as a proviral target gene and a series of experiments with transgenic mice had suggested a role of Gfi1 as a dominant oncogene with the ability to cooperate with Myc and Pim genes in the generation of T-cell lymphoma. In addition, Gfi1 deficient mice showed a defect in T-cell maturation but also aberration in myeloid differentiation and an accumulation of myelomonocytic cells. ENU was administered i.p. once a week for three weeks with a total dose of 300mg/kg to wild type (wt) and Gfi1 null mice. Wild type mice (12/12) predominantly developed T-cell tumors and rarely acute myeloid leukemia, as expected. However, only 2/8 Gfi1 −/− mice succumbed to lymphoid neoplasia; they rather showed a severe dysplasia of the bone marrow that was more pronounced than in wt controls. These changes in Gfi1 null mice were accompanied by a dramatic decrease of the LSK (Lin-, Sca1- and c-Kit+) bone marrow fraction that contains hematopoietic stem cells and by a higher percentage (18%) of bone marrow cells, not expressing any lineage markers (CD4, CD 8, Ter 119, Mac1, Gr1, B220, CD3). In particular, we found that the LSK subpopulation of Gfi1 deficient mice showed a noticeable increase in cells undergoing apoptosis suggesting a role of Gfi1 in hematopoietic stem cell survival. In addition, Gfi1−/− bone marrow cells and thymic T-cells were more sensitive to DNA damage such as radiation and exposure to ENU than their wt counterparts pointing to a role of Gfi1 in DNA damage response. Our results indicate that Gfi1 is required for development of T-cell tumors and that a loss of Gfi1 may sensitize hematopoietic cells and possibly hematopoietic stem cells for programmed cell death. Further studies have to show whether interfering with Gfi1 expression or function might represent a tool in the therapy of leukemia.
Deficiency in GATA-4 or GATA-6 Diminishes Definitive Hematopoiesis in Murine Embryonic Stem Cell Derived Embryoid Bodies.
Authors: Pierre Monique S. , Yoder Mervin 
Published: April 2020

Abstract
Formation of mesoderm derived blood islands in the mouse embryonic yolk sac requires the presence of visceral endoderm (VE) and VE derived factors. Murine embryonic stem (ES) cells can be differentiated into embryoid bodies (EBs) which serve as an in vitro model recapitulating many embryonic developmental processes, including formation of early hematopoietic cells. Previous investigators have reported that differentiation of ES cells deficient in either GATA-4 or GATA-6 results in EBs with disrupted differentiation of visceral endoderm and defective blood island formation. In the current study, we have compared GATA-4 and GATA-6 null ES cell derived EBs to wild-type EBs in their ability to commit to early hematopoietic lineages using hematopoietic progenitor colony assays, and used RT-PCR to assess the expression of endoderm genes. As expected, we observed differences in expression of endoderm genes in wild-type and GATA-4 or GATA-6 null EBs. Blast colony forming cell assays and primitive erythroid progenitor assays revealed no difference in the ability of wild-type and GATA-4 or GATA-6 null EBs to form hemangioblast or primitive erythroid progenitor colonies. In contrast, comparisons of definitive hematopoietic progenitor colonies from day 8, 9 and 10 GATA-4 and GATA-6 null EBs revealed a significant reduction in colony numbers at day 8 (p-values &lt; 0.05) compared to wild-type. Strikingly, definitive progenitor colony numbers are rescued nearly to wild-type levels after the addition of the visceral endoderm derived factor vascular endothelial growth factor (VEGF) during EB differentiation. Furthermore, this rescue response can be blocked by the addition of soluble Flk-1 (VEGF receptor) to EB cultures. These results suggest that GATA-4 and GATA-6 transcription factors and/or visceral endoderm are not necessary for hemangioblast, primitive erythroid, or definitive progenitor emergence from EBs but play a role in definitive progenitor expansion in EBs.
Pulmonary Function Tests and Their Correlation with Tricuspid Regurgitant Jet Velocity in Pediatric Sickle Cell Disease Patients.
Authors: Arteta Manuel , Campbell Andrew D. , Minniti Caterina , Ensing Greg , Sable Craig , Rana Sohail , Darbari D. , Onyinye Onyekwere , Kato Greg J. , Gladwin Mark T. , Castro Oswaldo L. , Gordeuk Victor R. 
Published: April 2020

Abstract
Background: Adults and children with sickle cell disease (SCD) often have a restrictive pattern of pulmonary function and decreased DLCO. Echocardiography-determined tricuspid regurgitation jet velocity (TRV) ≥2.5 m/s occurs in about 30% of adults with SCD and is associated with increased mortality. Its prevalence and significance in children has not been established. We prospectively evaluated pulmonary function tests and their relationship to TRV in a multicenter study of children with SCD.
Methods: Patients with SCD (Hb SS, SC, Sb thalassemia or other major sickling phenotypes) aged 7 to 20 years were evaluated clinically and with spirometry, plethysmography, diffusing capacity, and echocardiography under basal circumstances. Controls were matched by ethnicity, sex and age to every sixth patient with SCD studied.
Results: Pulmonary function testing was performed in 115 of 267 children enrolled in the study as of August 2007 (93 had SCD and 22 were controls). TRV was measurable in 71 patients and 18 controls who had pulmonary function tests performed. FEV1 and FVC were significantly lower in children with SCD compared to controls and TRV was significantly higher, but FV1/FVC and TLC were not different. Among children with SCD, a higher TRV was associated with lower values for FEV1, FVC FEV1/FVC and TLC but not DLCO.
Conclusions: Similar to adults, pediatric patients with SCD had lower FEV1 and FVC than controls but almost identical FEV1/FVC suggesting restrictive lung dysfunction. In contrast to adults, DLCO was not lower among pediatric SCD patients than controls. Lower FEV1/FVC, a marker of obstructive lung dysfunction, correlated with higher TRV as did lower FVC and TLC, markers of restrictive lung dysfunction.
Table I. Summary of pulmonary function tests. Results in mean (SD) unless otherwise indicated SCD (n = 71) Control (n = 18) P *N = 52 **N = 9 ***n = 59 ****n = 13 Age (years) 13 (4) 12 (4) 0.2 Females in no. and % 30 (42%) 13 (72%) 0.023 FEV1 (% predicted) 89 (16) 99 (16) 0.025 FVC (% predicted) 93 (16) 104 (17) 0.018 FEV1/FVC (%) 84 (7) 84 (6) 0.9 TLC (% predicted) 89 (15)* 98 (18)** 0.2 Residual volume (% predicted) 105 (39)* 117 (46)** 0.5 DLCO adjusted for hemoglobin (% predicted) 99 (20)*** 88 (12)**** 0.019 TR velocity (m/sec) 2.3 (0.3) 2.1 (0.3) 0.021 Table II. Spearman Correlation of Pulmonary Function Tests with TRV in SCD Patients N R P value FEV1 (% predicted) 71 −0.299 0.011 FVC (% predicted) 71 −0.257 0.030 FEV1/FVC (%) 71 −0.257 0.030 TLC (% predicted) 52 −0.263 0.060 DLCO adj. for hemoglobin (% predicted) 59 −0.098 0.2
Epstein-Barr Virus: Main Pathogenic Agent in Hodgkin Lymphoma Associated Hemophagocytic Syndrome?.
Authors: Menard Fanny , Besson Caroline , Rince Patricia , Lambotte Olivier , Lazure Thierry , Canioni Danielle , Hermine Olivier , Brousset Pierre , Legendre Claire , Martin Antoine , Gaulard Philippe , Raphael Martine , Larroche Claire 
Published: April 2020

Abstract
Hemophagocytic syndrome (HPS) is characterized by an uncontrolled proliferation of macrophages displaying extensive phagocytosis of hematopoietic cells that can be associated with non Hodgkin lymphomas. However, Hodgkin lymphoma associated with hemophagocytic syndrome (HL-HPS) has rarely been published. We report here a large series of 34 patients presenting HL-HPS. Histological analysis and Epstein-Barr Virus (EBV) studies were performed. The 34 patients were enrolled from 1992 to 2006. HPS diagnosis was based on usual clinico-biological criteria. Bone marrow aspiration or biopsy were performed in all cases and confirmed HPS, showing hemophagocytic features in scattered macrophages. HL was documented on histological material in all 34 patients. The biopsies were performed on different localizations: lymph nodes (n=18), bone marrow (n=27), liver (n=2) and tonsil (n=1). All histological slides were reviewed and classified according to the World Health Organization (WHO) Lymphoma classification. The presence of EBV in the tumour cells was detected using EBER RNA in situ hybridization and the expression of viral proteins LMP-1, EBNA-2 by immunoperoxidase. Patients were 26 men and 8 women (sex ratio M/F = 3.3). The median age was 45 years (range 19–84). HIV status was negative in 26 patients and positive in 8 patients. All patients were in clinical stage IVB. HL subtypes (18 lymph nodes) were Mixed Cellularity (n=12, 67%), Nodular Sclerosis (n=2, 11%) and Lymphocyte Depleted (n=4, 22%). Extra nodal tissues were highly infiltrated by tumour cells in all cases. The presence of EBV in tumour cells was detected in 32 out of the 34 patients (94%). In all EBV positive cases, high levels of LMP-1 without EBNA2 expression were detected, defining a latency II. This study reports the largest series to date of HL-HPS. The features of HL-HPS are particular by the high proportion of mixed cellularity subtypes (67%) in contrast to the frequency of nodular sclerosis subtypes observed in the general population of non overt immunosuppressed patients, and by the striking high proportion of EBV associated HL (32 out of the 34 patients, 94%). Our findings suggest not only a pathogenic role of EBV, but also a defective immune system in the control of EBV infection in HL-HPS patients.The high predominance of male in our population of HPS-HL (sex ratio M/F = 4.3 after exclusion of HIV positive patients) and the strong association with EBV could suggest X-linked immune defect in these patients.
Oxygen Levels and HIV-1 Transcription.
Authors: Nekhai Sergei , Charles Sharroya , Ammosova Tatyana , Cardenas Jessica , Jerebtsova Marina , Ayodeji Abisola A. , Niu Xiaomei , Ray Patricio E. , Kashanchi Fatah , Gordeuk Victor R. 
Published: April 2020

Abstract
HIV-1 progression may be faster and survival shorter in HIV-positive patients with higher iron stores. Some studies indicate that iron stimulates HIV-1 viral replication and iron chelation decreases viral replication in cultured cells. Iron depletion may remove iron from prolyl hydroxylases and increases HIF-1a protein level thus mimicking hypoxia. Recent studies indicate that moderate hypoxia (3–6% O2) may be the physiological O2 concentration that macrophages and T cells encounter in certain organs in vivo. Cellular metabolism of macrophages and T cells cultured at atmospheric 21% O2 is significantly different from cells cultured at 3–6% O2 [1] . Interestingly, HIV-1 progression might be slower in sickle cell disease patients who have anemia-related hypoxia [2]. HIV-1 replicates efficiently in activated T cells or macrophages, in part due to the increased levels of NF-kB that enhance HIV-1 transcription in cooperation with HIV-1 Tat. HIV-1 Tat induces transcription of HIV-1 genes by recruiting host cell Cdk9/cyclin T1 to TAR RNA. Our recent studies point to a host cell kinase, CDK2, that phosphorylates HIV-1 Tat and induces HIV-1 transcription [3]. We also showed that iron chelators reduce cellular activity of CDK2 and inhibit HIV-1 transcription [4]. Here we analyzed the effect of 3% versus 21% O2 concentration on HIV-1 transcription and replication and cellular activities of CDK2 and CDK9. Using reporter assays, we found that 3% O2 inhibited HIV-1 Tat-induced transcription and viral replication. CDK9 activity but not CDK2 activity was inhibited in the cells cultured under 3% O2. Thus inhibition of CDK2 by iron chelators that we previously observed might not be directly related to upregulation of HIF1a. Rather, our results indicate that HIV-1 transcription is suppressed at physiological oxygen levels likely due to deregulation of CDK9 thus providing a new insight into the HIV-1 latency. These findings suggest that consideration should be given to studying the effect of small molecular inhibitors of HIF-1 on HIV-1 transcription and replication.
Inhibition of HIV-1 Tat-Induced Interleukin-10 Expression by Mononuclear Cells at 3% O2.
Authors: Edossa Amanuel , Gordeuk Victor R. , Nekhai Sergei 
Published: April 2020

AbstractThe production of IL-10, which counteracts the effect of pro-inflammatory cytokines such as TNF-alpha, is induced by HIV-1 Tat in monocytes/macrophages by a process regulated by CREB-1 transcription factors [1]. IL-10 has been reported to suppress HIV-1 replication in macrophages by inhibiting HIV-1 transcription [2] at a, but it has also been reported to contribute to cell-mediated immunity in the setting of HIV infection [3]. We compared Tat-induced expression of IL-10 by THP-1 monocytes at 3% O2 (20 mmHg), the tension that monocytes see in certain tissues, and atmospheric 21% O2 (150 mmHg), the conventional in vitro culture condition. THP-1 cells were treated with recombinant HIV-Tat protein in combination with or without lipopolysaccharide (LPS) and IL-10 expression was analyzed by RT-PCR and ELISA. Treatment of THP-1 cells with HIV-Tat and LPS resulted in a dose- and time-dependent increase in IL-10 expression in the cells cultured at 21% O2. In contrast under 3% O2 the expression of IL-10 was reduced by 3-fold. Treatment with tautomycin, a protein phosphatase-1 (PP1) inhibitor, prevented IL-10 expression in LPS-stimulated THP-1 cells cultured at 21% O2. Thus, PP1 is likely to participate in Tat-mediated IL-10 production. PP1 has shown to affect CREB activity [4]; therefore we propose that PP1 might be involved in the CREB-mediated IL-10 gene expression. The inability of Tat to induce IL-10 production under 3% O2 might reflect the inadequate response of HIV-1 infected macrophages in vivo that might permit viral replication in infected macrophages. Further investigation of the role of PP1 in IL-10 expression could lead to new therapeutic opportunities for HIV-1 infection.
A Rho-GTPase Effector, Rhotekin-2 (RTKN2) Is Associated with BMP8b and IL-16 Cytokine Expression and Increased Sensitivity to Apoptosis in Lymphocytes.
Authors: Collier Fiona M. , Baker Adele J. , Walder Ken , Stupka Nicole , Martin Sheree D. , Kirkland Mark A. 
Published: April 2020

Abstract
Rho GTPases are molecular switches controlling a broad range of cellular processes in lymphocytes including activation, immune response and gene transcription. They rapidly cycle between a guanosine diphosphate (GDP)-bound and guanosine triphosphate (GTP)-bound state, and the GTP-bound state is the active conformation that initiates downstream signaling pathways via effector proteins. We identified a novel Rho effector, RTKN2, that is highly expressed in lymphocytes, particulary freshly isolated CD4 T-cells; and is switched off in activated T-cells. When the protein was over-expressed in an unrelated cell line, it conferred resistance to apoptosis, and this resistance was maintained using the media alone from the over-expressing cells. In the current study we investigated genes relating to high or low expression of RTKN2 in lymphocytes. In human samples, RTKN2 expression was down regulated in PHA activated T-cells and it correlated with the expression of Zap-70, a Rho-guanine nucleotide exchange factor (GEF). We then utilized a real time cytokine array (Superarray Bioscience Corporation) to compare high versus low RTKN2 expression levels in the same population of lymphocytes. The real time array linked high levels of RTKN2 with cytokines BMP8b, (a TGF-beta family protein) and IL-16 (a modulator of T cell activation, and an inhibitor of HIV replication relationship), and this observation was confirmed in a series of T-cell samples. Further, we studied the effect of down regulation of RTKN2 in primary lymphocytes, using short hairpin (sh)RNA plasmid that also expressed GFP. Transfected GFP-positive cells had lower survival than cells transfected with scrambled (sh)RNA, and also demonstrated increased sensitivity to the the induction of apoptosis by oxysterols. These findings indicate that RTKN2 plays a role in survival of T-lymphocytes and this may be mediated through the secretion of cytokines.