bluuebunny/crossref_metadata_2025_split huggingface dataset:
SCL and Associated Proteins Distinguish Active from Repressive GATA Transcription Factor Complexes.
Authors: Deng Wulan , Tripic Tamara , Cheng Yong , Zhang Ying , Vakoc Christopher , Hardison Ross , Blobel Gerd 
Published: April 2020

Abstract
GATA-1 controls hematopoietic development by activating and repressing gene transcription, yet the in vivo mechanisms that specify these opposite activities are unknown. By examining the composition of GATA-1 associated protein complexes in a conditional erythroid rescue system, we detected the SCL/TAL1, LMO2, Ldb1, E2A complex in vivo at all positively acting GATA-1-bound elements examined. ChIP-on-chip tiling arrays for SCL and Ldb1 revealed that chromatin occupancy of SCL and Ldb1 are extremely tightly correlated. Importantly, they showed a strong tendency for co-occupancy with GATA-1. In deed, all regions occupied by GATA-1 that showed enhancer activity were occupied by SCL and Ldb1, independent of the proximity of E-box sequences. Similarly, the SCL complex is present at all activating GATA elements in megakaryocytes and mast cells. In striking contrast, at sites where GATA-1 functions as a repressor, the SCL complex is depleted. A DNA-binding defective form of SCL maintains association with a subset of active GATA elements indicating that GATA-1 is a key determinant for SCL recruitment. Knockdown of LMO2 selectively impairs activation but not repression by GATA-1. ETO-2, an SCL-associated protein with the potential for transcription repression is also absent from GATA-1-repressed genes but, unlike SCL, fails to accumulate at GATA-1 activated genes. Together, these studies identify the SCL complex as a critical and consistent determinant of positive GATA-1 activity in multiple GATA-1-regulated hematopoietic cell lineages.
Bidirectional Control of Transcription Factor GATA2 and Cyclin/Cdks in Hematopoietic Cells.
Authors: Minegishi Naoko , Harigae Hideo , Yamamoto Masayuki 
Published: April 2020

Abstract
GATA2 is a transcription factor indispensable for development and maintenance of hematopoietic stem cells. Hematopoietic stem cells in G0 phase express GATA2 (Suzuki N, PNAS 103: 2202 2006), but proliferating hematopoietic progenitor cells, as well as proliferating cells in several other tissues, also express this factor. Gata2 knockout experiments indicate that GATA2 regulates cell proliferation; however, precise mechanisms have not been elucidated. Previously, we found oscillatory expressions of GATA2 during the cell cycle. In G1/S and G2/M phases, Cdk4 and Cdk2, forming complexes with several cyclins, phosphorylate GATA2 and induce GATA2 degradation (Koga S, Blood109: 4200, 2007). In this study, we demonstrate the bidirectional control between GATA2 and Cyclin/Cdk systems. To identify GATA2 target genes regulating cell proliferation, we searched for conserved GATA factor-binding sequences in evolutionarily conserved regions (ECRs, http://ecrbrowser.dcode.org), and found conserved GATA sequences in ECRs in intron 3 and intron 4 of the CyclinD2 (Ccnd2) gene, and in intron 3 and 3′UTR of the CyclinE1 (Ccne1) gene. In ChIP experiments using synchronized Ba/F3 and P815 cells, GATA2 binding to these regions was high in late G1 phase, and then rapidly declined in early S phase. One hour treatment using a Cdk1/2 inhibitor, roscovitine, cancelled this regression in early S phase, implicating Cdk2 as a negative regulator of GATA2 binding to target genes. Significant GATA2 binding to Ccnd2 and Ccne1 genes was also detected in embryonic day 13.5 fetal liver cells. Exogenous GATA2 expression augmented transcriptional activity of these binding regions in luciferase assay. Induction of GATA2 siRNA repressed Ccnd2 and Ccne1 mRNA expression. Furthermore, Ccnd2 and Ccne1 mRNA expression, as well as Gata2 mRNA expression, was significantly reduced in placental and aortic regions of embryonic day 10.0 conceptihar boring insertions of green fluorescent protein cDNA at translation start sites of bothGata2 alleles (Minegishi N, Blood102: 896, 2003). These results indicate that Ccnd2 andCcne1 genes are direct targets of GATA2. GATA2 binds to Ccnd2 and Ccne1 genes and activates their transcription in the G1 phase of proliferating cells. In G1/S transition, Cdk2activity, probably enhanced by CyclinE1 expression, attenuate GATA2 binding to Ccnd2and Ccne1 genes. In this fashion, bidirectional control of GATA2 and G1 cyclins may contribute to the transient expression of CyclinD2 and CyclinE1 in G1 phase, and to the acceleration of S-phase entry. In addition, it appears plausible that lack of Cdk activities causes differences in GATA2 functions in hematopoietic stem cells in G0 phase.
The G Protein-Coupled Receptor cysLT1 Mediates Gi Protein-Dependent Chemotaxis and Adhesion of CD34+ Cells in Vitro Similar to CXCR4, but Not Progenitor Mobilization in Vivo.
Authors: Drost Adriana , Jaggy Lena , Kanz Lothar , Möhle Robert 
Published: April 2020

Abstract
CysLT1, which is expressed in several cell types during inflammation and allergy, and the homing related chemokine receptor CXCR4 both belong to the family of G protein-coupled receptors (GPCR). Similar to CXCR4, the cysteinyl-leukotriene receptor cysLT1 is strongly expressed in CD34+ cell lines and CD34+ hematopoietic progenitor cells (HPC). We therefore compared the effects mediated by cysLT1 on HPC to those observed after activation of CXCR4. The most potent cysLT1 ligand LTD4 induced chemotaxis and adhesion of CD34+ HPC to endothelial cells, immobilized VCAM-1 and fibronectin, which was comparable to effects induced by the CXCR4 ligand SDF-1. CysLT1- and CXCR4-mediated effects were inhibited by pertussis toxin (PTX), suggesting that both GPCRs employ the same Gi-protein-dependent signaling pathways in CD34+ HPC. This is supported by identical time courses of intracellular calcium fluxes and actin polymerization induced by LTD4 and SDF-1, as measured by time-dependent flow cytometry. Given the striking similarities of cysLT1- and CXCR4-mediated effects in vitro, one might expect also overlapping functions in vivo. We therefore investigated whether blocking of cysLT1 is associated with HPC mobilization. As cysLT1 antagonists are established for therapy and prophylaxis in patients with allergic and exercise-induced asthma, circulating CD34+ progenitors were enumerated after initiation of a treatment with the cysLT1 antagonist montelukast, used as asthma prophylaxis in otherwise healthy subjects. The number of CD34+ cells or white blood counts did not differ significantly from the baseline value 2, 4, 8, 12, and 24 hours after administration of 10 mg montelukast, in contrast to previous studies analyzing stem cell mobilization induced by CXCR4 antagonists. This corresponds with our in vitro findings that LTD4 is produced by bone marrow endothelium and stromal cells only when deprived of hematopoietic cells, in contrast to the constitutive production of SDF-1. We conclude that cysLT1 is not involved in bone marrow retention of HPC during steady-state hematopoiesis, but may modulate HPC homing when its ligands are produced either locally (i.e. bone marrow aplasia) or systemically (i.e. inflammation).
p16INK4a Is a Key Downstream Mediator of the Deleterious Effects of FoxO Deficiency on Maintenance of the Hematopoietic Stem Cell Compartment.
Authors: Tothova Zuzana , Sykes Stephen M , Leeman Dena S , Horner James W , Sharpless Norman , DePinho Ronald A , Gilliland D. Gary 
Published: April 2020

Abstract
Regulation of oxidative stress in the hematopoietic stem cell (HSC) compartment is critical for the maintenance of HSC self-renewal. A number of reports have previously implicated p16 in aging of HSCs, pancreatic β-islet cells and subventricular zone progenitors in the brain [1–3]. In the context of the hematopoietic system, p16INK4a expression in HSCs increases with age, and correlates with decreased HSC repopulating ability, decreased self-renewal, and increased apoptosis with stress [1]. We and others have recently reported that FoxO play essential roles in the response to physiologic oxidative stress and thereby mediate quiescence and enhanced survival in the HSC compartment [4, 5]. Young mice deficient in FoxO1, FoxO3, and FoxO4 in the adult hematopoietic system, with striking similarity to aging wild-type mice, show a defect in bone marrow repopulating ability, decrease in self-renewal, myeloid skewing in differentiation and increased levels of apoptosis. Furthermore, young FoxO-deficient HSC show increased levels of p16 when compared to their wildtype counterparts. These collective findings suggested the possibility that FoxO loss could result in accelerated aging of HSC due to increased expression of p16 as a consequence of increased ROS. To test the hypothesis that p16 is one of the key mediators of FoxO loss responsible for accelerated aging of HSC, we deleted FoxO1, FoxO3, and FoxO4 in the adult hematopoietic system of mice deficient in p16INK4a. Young mice deficient in FoxO and p16 shared the same characteristics of their HSC(Lin−Sca1+c-kit+) compartment as mice deficient in FoxO only, including decreased number of HSC, increased percentage of HSC entering S/G2/M and apoptosis, and increased levels of ROS as compared to their wildtype counterparts. However, in a setting of long-term repopulation studies, bone marrow isolated from mice deficient in p16 and FoxO demonstrated a rescue of long-term repopulation for up to 20 weeks, as compared to FoxO deficient bone marrow that showed a severe defect in long-term repopulation. p16 deficiency in the setting of FoxO deficiency did not result in reduction of ROS levels in the HSC compartment. Taken together, these findings indicate that p16 is a critical downstream mediator of FoxO in the maintenance of the HSC compartment, and that it can dissociate the detrimental effects of ROS on HSC self-renewal in a setting of FoxO deficiency.
Mortality in Sickle Cell Patient Transitioning from Pediatric to Adult Program: 10 Years Grady Comprehensive Sickle Cell Center Experience.
Authors: Aduloju Si mbo O , Palmer Sheila , Eckman James R. 
Published: April 2020

Abstract
Over the last three decades there has been improvement in survival in children with sickle cell disease. Overall survival from birth to age 18 of 86% and 95% has been reported in children with sickle cell anemia (HbSS) and sickle hemoglobin C (Hb SC) disease respectively. These encouraging results are secondary to initiation of preventive measures like newborn screening, penicillin prophylaxis, immunization and stroke prevention and other supportive therapies. Ballas (Blood2004;104 supl:Abstr 3743) reported high death rate for young adults with the disease. To determine the death rates and cause of death in our population, we did a retrospective review of our patients who had recently transitioned into adult care. Mortality rate and circumstances of death in a 10 year period of transition from pediatric to adult program in Georgia Comprehensive Sickle Cell Center at Grady Memorial Hospital between 1996 and 2006 were determined. Total number of deaths was obtained from the clinical database. Death, autopsy and medical records were reviewed to determine the cause and circumstances of death. Between 1996 and 2006, 387 young adults with sickle cell disease (HbSS, HbSC, HbS beta thalassemia) transitioned to the adult program at age 18. Twenty two (5.8%) patients died during their first 10 years of transition. Mean age at death was 23.4 (range 21.6–26) and male to female ratio was 1.2 to 1. Ten patients (45%) died due to chronic organ failure all due to chronic iron overload (end stage liver disease in 8 and congestive heart failure in 2). Eight patients (36%) died due to complications of acute vaso-occlusive crisis (sudden death in 4, acute chest/multi-organ failure in 4) while 4 patients (18%) died of non-sickle related causes. Three of four who died of sudden death has documented pulmonary hypertension. Our mortality rate is lower than those reported by Ballas with the most common cause of death being complications of iron overload in chronically transfused patients. Specific interventions targeted at improving management of iron overload need to be developed for the increasing numbers of patients on chronic transfusion transitioning into adult care.
Multi-Modal Intervention for Inpatient Management of Sickle Cell Pain Significantly decreases the rate of Acute Chest Syndrome.
Authors: Reagan Megan , DeBaun Michael R. , Frei-Jones Melissa 
Published: April 2020

Abstract
Painful vaso-occlusive episodes (VOE) account for the majority of hospitalizations and nearly all morbidity in children with sickle cell disease (SCD). Frequently, VOE progresses into acute chest syndrome (ACS), a leading cause of mortality in SCD. Few strategies exist to prevent this potentially fatal complication. We present the results of a multi-modal intervention to improve the inpatient management of SCD. We performed a before-and-after prospective multi-modal intervention. All children with SCD admitted for uncomplicated VOE during the two-year study period were eligible. The multi-modal intervention included standardized VOE admission orders, monthly house staff education, and one-on-one patient and caregiver education. ACS was defined as a new radiologic density on chest radiograph. A total of 332 admissions for uncomplicated VOE occurred during the study period; 159 before the intervention and 173 during the intervention. The ACS rate declined by 50% during the intervention period (25%, 39/159 to 12%, 21/173; p=0.003). No significant difference was found in patient demographics, amount of intravenous fluid administered, frequency of normal saline bolus administration, or cumulative opioid amount delivered in first 24-hours. Patient controlled analgesia (PCA) use was more common after the intervention (52%, 82/159 vs 73%, 126/173; p=0.0001) and fewer patients required changes in analgesic dosing within the first 24-hours after admission (26%, 42/159 vs 16%, 28/173; p=0.015). PCA-use protected against progression to ACS (OR 0.5; 95% CI 0.3–0.0.94) while patients needing escalation of pain medications in the first 24-hours were more likely to develop ACS (OR 2.5; 95% CI 1.3–4.6). A multi-modal intervention to change physician behavior successfully improved patient outcomes by reducing the ACS rate.
Genomic Approaches to Identifying Risk for Pulmonary Artery Hypertension among Individuals with Sickle Cell Disease.
Authors: Silbermins Damian , De Castro Laura M. , Jonassaint Jude C , Hsu Shiaowen David , Telen Marilyn J. , Chi Jen-Tsan 
Published: April 2020

Abstract
Pulmonary artery hypertension (PAH) occurs in 30–50% of adult patients with sickle cell disease (SCD), with mortality ranging from 16 to 50% and a median survival of 25 months. Our objective was to use gene expression profiling to develop a gene signature predictor for PAH through the analysis of gene expression of blood cells from SCD patients with or without PAH. We hypothesized that these gene signatures could allow us to identify patients at risk for PAH, as well as to generate hypotheses as to the pathophysiology of PAH in SCD. We used Affymetrix U133A2 GeneChip to determine the RNA expression of both whole blood and leukocytes using PAXgene and Leukolock methods, respectively. The study population included patients homozygous for HbS or with HbSβ0 thalassemia. Subjects with PAH were ≥18 years old, in steady state, and had PAH either by 2D echo (TR jet ≥ 2.7 m/sec) or right-sided catheterization (mean PA pressure ≥ 30 mmHg). Patients were excluded if they were pregnant, had co-existing rheumatologic conditions or other inflammatory diseases, were on chronic transfusion therapy or had had a vaso-occlusive episode in the previous 4 weeks. The control subjects were patients with SCD but without PAH (TR jet ≤ 1.8 m/sec or mean PA pressure &lt;25 mmHg). Hierarchical clustering based on the gene expression pattern from 7 patients with PAH and 6 controls showed a trend for the clustering of SCD patients with PAH away from SCD patients without PAH. This trend was present for the gene expression in both whole blood and leukocytes. A Bayesian regression analysis was then performed to identify a set of predictor gene signatures for the PAH phenotype (Figure 1) in SCD. Finally, using gene set enrichment analysis, we found that the leukocytes from patients with PAH were highly enriched in the gene sets deriving from hematopoietic stem cells, corroborating the hypothesis of hyperhemolysis and higher blood cell turnover in this population. Other pathways showing upregulation in PAH were PTEN, TGFβ, cyclin D1, WNT and PPAR. Although these data are preliminary, they suggest that PAH in SCD does indeed have a distinct gene signature profile that may become useful in identifying risk for PAH prospectively, as well as in directing further investigation into the pathogenesis of PAH in SCD.
Figure Figure
Inhibition of HIV-1 by Ferroprotin Expression.
Authors: Nekhai Sergei , Foster Altreisha , Xu Min , Niu Xiaomei , Rotimi Jamie , Gordeuk Victor R. 
Published: April 2020

Abstract
HIV-1 transcription is induced by viral Tat protein, which recruits transcriptional co-activators to the HIV-1 promoter. We recently showed that Tat is phosphorylated in the Ser16 and Ser 46 residues by protein kinase CDK2 and that mutations in these residues prevent HIV-1 transcription and viral replication [1]. We also found that iron depletion by iron chelators inhibits cellular activity of CDK2, prevents Tat phosphorylation and inhibits HIV-1 transcription [2]. Thus our previous studies suggest that a decrease in cellular iron might have a protective effect against HIV-1 through inhibition of CDK2 and Tat phosphorylation. Here, we analyzed the effect of the iron exporter, ferroportin, on HIV-1 transcription and viral replication. Increased expression of ferroportin by transfection in iron-treated 293T cells significantly reduced ferritin protein levels compared to increased expression of CD4 or EGFP in iron-treated cells as controls. Treatment with hepcidin increased ferritin levels in 293T cells that expressed wild type ferroportin but not the C326Y mutant of ferroprotin which is not sensitive to hepcidin. Expression of both wild type ferroportin and the C326Y mutant in 293T cells significantly inhibited HIV-1 transcription. Treatment with hepcidin partially restored HIV-1 transcription in the cells expressing wild type ferroportin and not in those expressing the C326Y mutant of ferroportin. Treatment of promonocytic THP-1 cells with iron increased cellular ferritin level. Subsequent treatment with phorbol myristate acetate (PMA) led to increased expression of ferroportin and reduced ferritin level, and this reduction in ferritin was partially alleviated by exposing the cells to hepcidin. Thus, PMA appeared to reduce intracellular iron through increased iron export by ferroportin. HIV-1 replication in iron-supplemented THP-1 cells or primary human monocytes was significantly reduced by treatment with PMA. Subsequent exposure of the PMA-treated monocytes to hepcidin partially restored HIV-1 replication, suggesting that HIV-1 was inhibited in part by the expression of ferroportin and its associated iron-exporting activity. Taken together, our results indicate that expression of ferroportin leads to reduction of cellular iron and also reduced HIV-1 transcription and replication, and that exposure to hepcidin may lead to increased cellular iron content and enhancement of HIV-1 replication. Thus our results suggest that iron depletion of cells that harbor HIV might serve as a strategy to combat this infection, and they point to the need to develop iron chelators specifically designed for HIV-1 therapy.
Novel Heterozygous Mutation 572insA in TACI Identified in a Patient with Selective IgA Deficiency.
Authors: Okada Satoshi , Kajiume Teruyuki , Tsumura Miyuki , Shirao Kenichiro , Ohno Yoshinori , Yasunaga Shin’ichiro , Ohtsubo Motoaki , Sira Mostafa Mofamed , Kanegane Hirokazu , Miyawaki Toshio , Takihara Yoshihiro , Kobayashi Masao 
Published: April 2020

Abstract
Selective IgA deficiency (SIgAD) is relatively common disease in patients with primary immunodeficiency. Recently, mutations in TNFRSF13B, encoding transmembrane activator and calcium-modulator and cyclophilin ligand interactor (TACI), have been identified in 7~15% of patients with common variable immunodeficiency (CVID) and 10% of those with SIgAD. However, the role of TACI mutations in the molecular pathogenesis underlying SIgAD is still controversial and remains unsolved. We identified a novel heterozygous single adenine insertion, 572insA, in exon 4 of TNFRSF13B in a patient with SIgAD. Although the same mutation was detected in her mother and younger brother, their serum immunoglobulin levels were within normal range. This frameshift mutation produces a truncated form of TACI protein lacking majority of the intracellular domain. Peripheral blood B cells from the patient and her siblings with the TACI mutation were able to produce immunoglobulin without inferiority in the presence of dendritic cells, CD40L and IL-10. However, IgD+ or IgM+ B cells from the patient were impaired to produce Cα mature transcripts in response to APRIL, one of the ligands for TACI, reflecting impairment of class-switch recombination required for differentiation into IgA-producing cells. Thus, the T-cell independent B cell activation is impaired in the patient. We overexpressed cDNAs for wild-type (WT), C104R and 572insA mutant TACI in HEK 293 cells, and analyzed the effect on signal transduction through TACI. Immuno-precipitation analysis revealed that either 572insA or C104R mutant associated with WT TACI and formed an oligomeric complex. C104R TACI has been previously shown to exert a dominant-negative effect on ligand-induced TACI signaling, since it forms an oligomeric complex with WT TACI and disrupts ligand-induced receptor signaling. Similarly, since 572insA TACI lacks an intracellular domain that is important for signal transduction, it may exert a dominant-negative effect on ligand-induced TACI signaling. Although the heterozygous 572insA TACI mutation disrupts ligand-induced TACI signaling, not all individuals carrying the mutation display humoral immune deficiency. Thus, an additional genetic modifier and/or an environmental factor may be required for the development of immunological abnormalities due to TACI mutations.