bluuebunny/crossref_metadata_2025_split huggingface dataset:
Intercommunication Between C-Myc and PTEN in the Regulation of Hematopoietic Stem Cell-Niche Interactions and Hematopoietic Progenitor Cell Lineage Commitment.
Authors: Guo Yinshi , Niu Chao , Breslin Peter , Zhang Shubin , Wei Wei , Tang Minghui , Zhang Jiwang 
Published: April 2020

Abstract
It was shown that c-Myc is required for the proliferation and differentiation of hematopoietic stem cells and progenitors. Mice with c-Myc deletions develop severe anemia and cytopenia. However, hematopoietic stem cells (HSCs) accumulate in significant numbers in the bone marrow (BM) of mutant mice, probably due to an increase in adhesiveness of the mutant HSCs to BM osteoblastic niche cells. Previously, we demonstrated that PTEN might play a critical role in the process of adhesion of HSCs to BM niche cells. Deletion of PTEN results in the proliferation and peripheral mobilization of HSCs, followed by a decline in these cells. PTEN mutant mice proceed to develop myeloproliferative disorders.
Here we report that c-Myc also has an essential role to play in regulating the lineage commitment of HSCs and progenitors (HSC/Ps). HSC/Ps in which c-Myc is deleted are biased toward megakaryocytic lineage differentiation at the expense of other lineages. c-Myc knockout mice develop significant thrombocytosis (3- to 5-fold increase in peripheral platelet numbers) due to an obviously increased megakaryopoiesis in BM and spleen. PTEN deletion causes down-regulation of expression of adhesive molecules, including integrins and N-cadherin, in HSCs, resulting not only in an increased mobilization of c-Myc-mutant HSCs from the BM niche but also mobilization of c-Myc-mutant megakaryocytic progenitors to the spleen. We found that HSCs and megakaryocytic progenitors are significantly reduced in BM but dramatically increased in the spleens of PTEN/c-MYC double-knockout mice, compared to c-Myc single-gene knockout mice. In addition, PTEN deletion further promotes megakaryocytic progenitor cell proliferation, as well as infiltration of these cells into the liver. PTEN/c-Myc double-gene knockout mice consistently develop megakaryocytic proliferative disorders.
We conclude that the ability of c-Myc to regulate HSC-BM niche interactions is at least partially accomplished through inhibition of PTEN function by c-Myc. In addition, c-Myc controls the lineage commitment of HSC/Ps. Deletion of c-Myc converts the myeloproliferative disorder seen in PTEN knockout mice to a megakaryocytic proliferative disorder. Whether PTEN and c-Myc mutations are likewise etiologically involved in human megakaryocytic proliferative disorders and megakaryocytic leukemia is currently a topic of active investigation in our laboratory.
Wiskott-Aldrich Syndrome Protein (WASP) Is An Effector of Kit Signaling.
Authors: Mani Maheswaran , Venkatasubrahmanyam Shivkumar , Sanyal Mrinmoy , Yang Yujun , Huang Jing , Levy Shoshana , Butte Atul , Weinberg Kenneth I. , Jahn Thomas 
Published: April 2020

Abstract
Wiskott-Aldrich Syndrome (WAS) is an X-linked recessive immunodeficiency disorder with eczema, thrombocytopenia and high susceptibility to opportunistic and pyogenic infections. The gene product of the WAS locus, WAS protein (WASP), is expressed in a hematopoietic-specific fashion and regulates cytoskeletal actin reorganization via Cdc42 and Arp2/3 interactions. Non-random inactivation of the X chromosome carrying the defective WASP gene in all peripheral blood cells from obligate female carriers of WAS suggests a selective advantage of hematopoietic stem cells or immature progenitor cells expressing the intact WASP gene. Because such progenitor cells are dependent on the Kit receptor/Kit ligand (KL) pathway, we tested whether or not WASP plays a role in signaling responses through Kit. WASP and interacting proteins WIP and Arp2/3 were strongly phosphorylated in response to KL stimulation of Mo7e cells. Time kinetics revealed onset of tyrosine phosphorylation of WASP as early as 1 min and a maximum at 5 min after KL stimulation. Although real-time KL-induced actin reorganization and KL-mediated spreading of bone marrow-derived mast cells (BMMC) on fibronectin-coated surfaces were grossly normal, KL-induced formation of filopodia was significantly decreased in number and size in the absence of WASP. In addition, KL-induced calcium-flux in BMMCs was aberrant in the absence of WASP suggesting that KL-dependent calcium signals and cytoskeletal rearrangement are linked through WASP. When BMMC cultures were established from WASP heterozygous female mice using KL as a growth factor, the cultures initially contained a mixture of WASP positive and negative populations. KL-driven differentiation into mature BMMCs eventually resulted in homogenous WASP positive cultures derived from the WASP positive progenitors. Thus, WASP expression conferred a selective advantage to the development of Kit-dependent hematopoiesis consistent with the selective advantage of WASP positive blood cells observed in WAS heterozygous female humans. Finally, KL-mediated gene expression in BMMCs derived from WASP negative mice or WT controls was compared and revealed in summary that at least 30% of all changes are WASP-dependent. The results indicate that WASP is downstream of Kit signaling and necessary for Kit-mediated filopodia formation, cell survival and gene expression.
Elevated Circulating Stromal Derived Factor-1 Levels in Sickle Cell Disease.
Authors: Landburg Precious , Nur Erfan , Maria Naomi , Biemond Bart J. , Brandjes Dees P.M. , Schnog John-John , Duits Ashley 
Published: April 2020

Abstract
Inflammation and angiogenesis are of importance in the pathophysiology of sickle cell disease (SCD). Recently, the chemokine Stromal Derived Factor-1 (SDF-1) has been shown to be a key mediator of angiogenesis and inflammation. In this study we determined serum SDF-1 levels in consecutive adult sickle cell patients during the clinically asymptomatic state as well as during painful crisis. Serum SDF-1 levels were significantly elevated in HbSS/HbSβ0-thalassemia patients ([n=39], 3805 pg/mL (2121–6790)) as opposed to HbSC/HbSβ+-thalassemia patients ([n=18], 2405 pg/mL (1365–3047)) and healthy HbAA controls (n=25, 2623 pg/mL (2435–2988)) (p=0.04). During painful crisis SDF-1 levels increased significantly in both HbSS/HbSβ0-thalassemia ([n=24]) 26040 pg/mL (20135–27960)) and HbSC/HbSβ+-thalassemia patients ([n=5], 12666 pg/mL (3936–24453)) (p&lt;0.001 and p=0.01, respectively). Paired sample analysis was possible in 8 patients (SDF-1 determined in steady state and during painful crisis) and all patients demonstrated a strong SDF-1 increment from steady state levels (p=0.01) and serial measurements, available from 11 patients, showed persistently elevated SDF-1 levels well beyond crisis abatement (data not shown). Furthermore, SDF-1 levels were significantly higher in sickle cell patients with pulmonary hypertension as compared to patients without pulmonary hypertension in both HbSS/HbSβ0-thalassemia (PHT+ [n=8]: 6549 pg/mL (3893–7159), PHT- [n=24]: 2945 pg/mL (1560–6627)) and HbSC/HbSβ+-thalassemia (PHT+ [n=4] 3316 pg/mL (2900–6417) and PHT- [n=12] 2146 pg/mL (1138–2592)) patients (p=0.02 and p=0.01, respectively). SDF-1 levels were not related to other forms of organ damage, nor were they significantly associated with hemoglobin levels, the percentage of fetal hemoglobin or leukocyte counts in the clinically asymptomatic state (data not shown). Taken together, elevated circulating SDF-1 levels occur in patients with SCD and may play a role in the pathophysiology of acute and specific chronic disease related complications.
WIP Is a Chaperone for Wiskott-Aldrich Syndrome Protein.
Authors: Sasahara Yoji , de la Fuente Miguel A , Ramesh Narayanaswamy , Tsuchiya Shigeru , Geha Raif S 
Published: April 2020

Abstract
WASP, the product of the gene mutated in Wiskott-Aldrich syndrome (WAS), plays a critical role in T cell activation and actin reorganization. WIP is a WASP-interacting protein that binds to Ena-VASP homology 1 (EVH1) domain of WASP. We previously reported functional roles of WIP in the recruitment and activation of WASP in T cells. To investigate a role of WIP in WASP degradation and understand the reason why most missense mutations in WAS patients are in EVH1 domain of WASP, we examined WASP levels in WIP knockout (WIP−/−) T cells and mechanisms of WASP degradation following T cell receptor (TCR) ligation. WASP protein levels, but not mRNA levels, were severely diminished in T cells from WIP−/− mice and were restored by introduction of full-length or WASP binding domain of WIP. A fraction of WASP was cleaved by Ca-dependent protease calpain, ubiquitinated and degraded by the proteasome following TCR ligation. Inducible expression of WASP binding domain of WIP increased WASP levels in vivo and recombinant WIP protein protected WASP from degradation by calpain in vitro. Treatment with the proteasome inhibitors MG132 and bortezomib increased WASP protein levels in T cells from WIP−/− mice and in T and B lymphocytes from two WAS patients with missense mutations (R86H and T45M) that disrupted WIP binding. The calpain inhibitor calpeptin also increased WASP protein levels in activated T cells and B cells from the WAS patients. Despite its ability to increase WASP levels, proteasome inhibitors failed to correct the impaired IL-2 gene expression and low F-actin content in T cells from the R86H WAS patient (published in PNAS, 104, p926–931, 2007). These results demonstrate that WIP stabilizes WASP in normal T cells and that WIP deficiency or impaired WASP-WIP interaction in WAS patients with missense mutation in WIP binding site results in WASP degradation.
Notch Pathway Activation by a Combination of Activating NOTCH1-Receptor and Inactivating FBXW7 Mutations Robustly Predicts Excellent Early Treatment Response in Pediatric T-ALL.
Authors: Kox Corinne , Leible Svenja , Breit Stephen , Stanulla Martin , Schrappe Martin , Muckenthaler Martina Ulrike , Kulozik Andreas 
Published: April 2020

Abstract
In contrast to pre B-ALL, robust DNA-based biomarkers with prognostic and predictive value are not available in T-ALL. We have previously shown that common activating mutations of the NOTCH1 receptor predict good early treatment response and excellent long term outcome in T-ALL (Breit et al., Blood 2006). We now aimed at analyzing if recently described inactivating mutations of FBXW7, the E3 ubiquitin ligase of NOTCH, contribute to the predictive power of the Notch1 pathway activation in pediatric T-ALL.
Figure Figure
We genotyped FBXW7 in 137 T-ALL and found inactivating mutations in 22 patients. We next analyzed the influence of this mutation on treatment response and found that most patients with FBXW7 mutations showed a prednisone good response (PGR; 19/22), whereas PGR was observed in only 58/115 with no FBWX7 mutation (p=0.0006). This beneficial effect of FBXW7 inactivating mutations is enhanced when the NOTCH1 mutational status was considered. Among 17 patients with NOTCH1 and FBXW7 mutations, only 1 showed a prednisone poor response (PPR; p=0.0003). These results suggest a synergistic effect of NOTCH1 and FBXW7 mutations in early treatment response in pediatric T-ALL.
Notably, FBXW7 mutations occur in the group of leukemias with NOTCH1 heterodimerisation (HD) domain mutations only and do not occur in those with truncations of the PEST domain, where FBXW7 physiologically targets NOTCH for degradation. One might thus predict that patients with NOTCH1-HD/PEST double mutations would be biologically similar to those with NOTCH1-HD/FBXW7 double mutations. A comparison of early treatment response between these groups indeed showed PGR in 10/13 patients with NOTCH1-HD/PEST and 16/17 with NOTCH1-HD/FBXW7 status. Furthermore, these groups taken together exhibit a significantly better prednisone response than both, the patients with single mutations in either NOTCH1 or in FBXW7 or those with detectable mutations in neither NOTCH1 nor FBWX7 (see bar diagram).
These data indicate that activation of the Notch1 pathway by a combination of receptor gain of function mutations and inactivating mutations of its E3 ubiquitin ligase has a strong favorable effect on in-vivo prednisone sensitivity. Notch pathway activation may thus define a novel group of biomarkers that predict early treatment response and thus help to stratify risk of children and adolescents with T-ALL.
Negative Effect of KIR Alloreactivity in Recipients of Umbilical Cord Blood Transplantation Depends on Transplantation Conditioning Intensity
Authors: Brunstein Claudio , Wagner John E. , Weisdorf Daniel , Cooley Sarah , Noreen Harriet , Barker Juliet , DeFor Todd , Verneris Michael , McGlave Philip B. , Blazar Bruce R. , Miller Jeffrey S. 
Published: April 2020

Abstract
Transplant strategies involving natural killer (NK) cell alloreactivity (KIR-ligand mismatch [KIR-L mismatch]) have demonstrated superior outcomes for patients receiving T cell depleted HLA haploidentical hematopoietic stem cell allografts. It is unknown whether KIR-L mismatch has a similar effect in recipients of partially HLA-matched umbilical cord blood (UCB) grafts which contain comparatively few T-cells. We examined the clinical impact of KIR-L mismatch in 257 UCB recipients treated with either a myeloablative (n=155) or reduced intensity (n=102) regimen. After myeloablative conditioning, KIR-L mismatch had no demonstrable effect on grades III–IV acute GVHD (17% [CI, 6–28%] vs. 17% [CI, 10–24], p=.97), transplant-related mortality (TRM) (27% [CI, 14–40%] vs. 18% [CI, 11–25%], p=.19), relapse at 2 yrs (18% [95%CI, 6–30%] vs. 28% [95%CI, 19–27%], p=.37) and survival at 3 yrs (50% [CI, 32–68%] vs. 57% [CI, 47–67%], p=.46). In contrast, following reduced intensity conditioning when the engrafting unit was KIR-L mismatched there was a significantly higher incidence of grades III–IV acute GVHD (42% [CI, 27–59) vs. 13% [CI, 5–21], p &lt; .01). Multivariate analysis confirmed NK cell alloreactivity as the only predictive factor associated with severe acute GVHD was (RR 1.8, CI [1.1–2.9]; p=.02). TRM was higher (27% [CI, 12–42%] vs. 12% [CI, 5–19%], p=.03) and three year survival was poorer (32% [CI, 15–59%] vs. 52% [CI, 47–67%], p=.03) when the engrafting unit was KIR-L mismatched, but relapse was unaffected (39% [95%CI, 21–57%] vs. 47% [95%CI, 34–60%], p=.72). KIR-L mismatch in recipients of a RIC UCB transplant was associated with a significant increased risk of death (RR 1.8, 95%CI, 1.0–3.1, p=.05). This data identify divergent effects of NK cell alloreactivity which are unmasked when comparing myeloablative versus RIC transplant platforms. We conclude that KIR-L mismatch should be avoided in recipients of a reduced intensity UCB transplant.
Clinical Implications of Killer Cell Immunoglobulin-Like Receptor (KIR) Genotypes on Autologous Peripheral Blood Stem Cell Transplantation for Acute Myelogenous Leukemia Patients.
Authors: Kim Heeje , Choi Young , Lee Tai-Hyang , Hahn Dong-Hoon , Gang Hoei-Sung , Min Woo-Sung 
Published: April 2020

Abstract
Natural killer (NK) cell alloreactivity after allogeneic hematopoietic stem cell transplantation (HSCT) in various settings is introduced by the regulatory role of killer cell immunoglobulin-like receptors (KIR). However, no influence of NK cells on relapse or survival after autologous HSCT for patients with acute myelogenous leukemia (AML) has been demonstrated. Since it is still debated whether autologous NK cells are involved in the eradication of leukemia cells, we evaluated the role of NK cells as a susceptibility factor for long-term survival. All 67 enrolled patients who received autologous HSCT were typed for the presence or absence of 19 different KIR genes and pseudogenes using a polymerase chain reaction-based sequence-specific primer method with the Pel-Freez kit, according to the manufacturer’s protocol (Invitrogen, Carlsbad, CA). The median follow-up was 21 months (range 2–55). All patients were in first complete remission (CR), as assessed immediately before the elective transplantation. The median age of the enrolled patients was 42 years (range 16–68). There were 33 females and 34 males. All patients received our modified TAM conditioning, which consisted of fractionated total body irradiation (12 Gy, five fractions in 3 days) from day −8 to −6, followed by intermediate-dose cytarabine (Ara-C; 1.5 g/m2 over 3 h every 12 h for six doses) from day −5 to −3, and melphalan (100 mg/m2 over 30 min) on day −2 only. The peripheral blood stem cells were collected after administering granulocyte colony-stimulating factor, following consolidation chemotherapy. The patients had 7–13 KIR genes, which is similar to the range in the normal population. The median infused cell dose was 4.2 × 106/kg (range 1.7–6.3) CD34+ cells. Fifty patients were alive (75%). Of the 67 patients, 43 were in continuous CR (64%) and 14 died in relapse (21%), while 3 (4%) died due to non-relapse causes. The Kaplan-Meier estimated 4-year disease-free survival (DFS) rate was 55% (95% CI 47–62%). We evaluated whether the presence or absence of any single or combination of inhibitory or activating KIR genes in the patients affected DFS and eventfree survival (EFS). The presence of an activating KIR 2DS1 gene was critical for the DFS and EFS, as shown in a previous study of allogeneic HSCT (Kim et al., Transplantation 2007). Additionally, the presence of two activating genes in the combinations 2DS3-2DS4*003 or 2DS4*003-2DS5 tended to be associated with DFS (P=0.0866). Since our findings are based on a single disease entity, i.e., adult AML, they suggest that the presence of activating KIR genes may, at least in some ways, be critical for autologous NK immunomodulation to influence the anti-leukemic effects, especially considering the impact of activating KIR genotypes on long-term survival.
Dissection of the Human Pre-B Cell Receptor (pre-BCR) Signalling Cascade.
Authors: Lassoued Kaiss , Ibata Stella , Piec Isabelle , Alleaume Celine , Brassard Bertrand , Nyga Remy , Fuentes Vincent , Bouhlal Hicham 
Published: April 2020

Abstract
Pre-BCR acts as a critical checkpoint guards in pre-B cell selection and expansion. There is also an increasing body of evidence suggesting a role for this receptor in leukemogenesis. However, the molecular events that follow its stimulation remain largely unknown. Most of the functions that have been so far attributed to this receptor are speculative or deduced from genetic studies conducted in mice, using either knock out or transgenic mice, which makes difficult to figure out whether these functions are directly or indirectly triggered via pre-BCR stimulation. Moreover, one should also be cautious in extrapolating data from mice to humans, as many discrepancies in B cell development have been reported between both species. We extensively analyzed herein the pre-BCR signalling machinery using the human 697 and Nalm6 pre-B cell lines and F(ab′)2 anti-human heavy chain μ to stimulate pre-BCR. We showed that stimulation of this receptor results in a rapid phosphorylation of Lyn, Blk, Syk, BLNK, LAB as well as adaptors that were so far considered as T-cell specific, together with Vav, Btk, PLCγ2 and Akt, which in turns activates FKHRL and GSK3. It also induces activation of Ras and the 3 major downstream arms of the Ras/MAPKinase pathway as well as number of transcription factors that will be further discussed. Its stimulation is followed by cell cycle progression and proliferation that are associated with p27kip1 degradation and Rb phosphorylation and with c-Myc upregulation. Moreover, pre-BCR aggregation induces phosphorylation of Bcl2 on residue serine 70 suggesting that this receptor mediates anti-apoptotic signal. In addition, CD19 coligation was found to potentiate pre-BCR signalling capabilities. c-Cbl and SHIP1 are rapidly phosphorylated upon pre-BCR aggregation, probably acting as negative regulators of this receptor signalling. We bring also evidence that Syk plays a pivotal role in pre-BCR signalling cascade and functions. Altogether these findings demonstrate that pre-BCR is directly implied in the control of proliferation and survival signals in pre-B cells and describes the multiple molecular events involved in these processes. We also show that pre-BCR stimulation induces downmodulation of rag1/2 and zap70 gene transcription but not of λ5, vpre-b, CD79a, E2A and EBF. Besides its major interest in understanding the regulation of the first steps of B cell development, analysis of pre-BCR associated-signalling pathways in leukemic B cell progenitors would certainly be helpful to better characterize the ongogenic events and identify new therapeutic targets in acute lymphoblastic leukemia.
Functional IDO Is Expressed on CD34+- and Monocyte-Derived Dendritic Cells According to Differentiation Status.
Authors: Curti Antonio , Trabanelli Sara , Onofri Chiara , Rutella Sergio , De Cristofaro Raimondo , Baccarani Michele , Lemoli Roberto M 
Published: April 2020

Abstract
Indoleamine 2,3-dioxigenase (IDO) is the rate-limiting enzyme in tryptophan catabolism along the kynurenine pathway. IDO expression by different cell subsets inhibits T-cell activation, proliferation and survival and induces regulatory T cells (Tregs). Although human monocyte-derived dendritic cells (Mo-DCs) have been shown to express IDO, little is known about the expression of IDO in other subsets of human DCs, including those generated from CD34+ hematopoietic progenitors (CD34+-derived DCs) In the present study, we performed a full characterization of IDO expression and function by human dendritic cells including Mo-DCs and CD34+-derived DCs. Mo-DCs were generated from purified CD14+ monocytes after culture with GM-CSF and IL-4 and then matured with CD40L, LPS alone, LPS plus IFN-gamma and a cytokine cocktail (IL-1beta, TNF-alpha, IL-6, PGE2). CD34+-derived DCs were generated from purified CD34+ cells after 7 days of culture with GM-CSF and TNF-alpha, followed by 7 day-treatment with GM-CSF and IL-4 and then matured with the same stimuli used for MoDCs. After culture, DCs were analyzed for IDO expression by real-time PCR and western immunoblot, kynurenine production, inhibition of allogenic proliferation and Tregs induction. Monocytes lack IDO expression. Immature Mo-DCs have little if any expression of IDO. During maturation, the cytokine cocktail is the most effective in up-regulating IDO, both at mRNA and protein level, which is paralleled with higher kynurenine production and inhibition of allogeneic T cell proliferation. PGE2 has a crucial role in inducing IDO expression, while IL6 has an opposite effect. Mature Mo-DCs are shown to generate a population of CD4+CD25+FOXP3+ Tregs which are capable of suppressing allogeneic T-cell proliferation. This inhibitory effect is abrogated by the addition of the IDO inhibitor 1-methyl tryptophan (1-MT). CD34+ cells lack IDO mRNA expression. During DC differentiation, IDO expression is observed at day 7, but not at day 14. Flow cytometry analysis of day 7 cells reveal a population of CD34−, CD14+, CD1a+/− cells. Similarly to Mo-DCs, maturation stimuli induce a marked up-regulation of IDO mRNA. Similar results are observed when IDO protein is measured. Production of kynurenine, inhibition of allogeneic T cell proliferation and generation of Tregs from normal CD3+ T-cells are also paralleled with IDO expression. In conclusion, in human DCs the maturation status is associated with a differential expression of IDO both in Mo-DCs and CD34+-derived DCs. Differentiation of CD34+ cells into DCs results in a transient and early expression of IDO at precursor level. Given its functional capacity to inhibit T-cell-mediated immune response, the expression of IDO along DC differentiation may indicate a protective role of the pool of precursor cells which are committed to DC lineage.