•EMCN is a novel marker of human HSCs.•EMCN is a more specific marker of HSCs than CD34 as it can discriminate HSCs from lineage-committed HPCs.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Summary
The haematopoietic hormone erythropoietin (EPO) has neuroprotective properties and is currently being explored for treatment of stroke and other neurological disorders. Short-term, high-dose ...treatment with EPO seems to improve neurological function of stroke patients but may be associated with increased thrombotic risk, whereas alternative non-erythropoietic neuroprotective derivatives of EPO, such as carbamylated EPO (CEPO), may be devoid of such side-effects. We investigated the effects of short-term, high-dose treatment with EPO and CEPO on platelet function and haemostasis in healthy mice and rats. Animals received three daily doses of EPO or CEPO (50 μg/kg), and blood was compared with respect to alterations in haematology and platelet reactivity. In rats, treatment with EPO increased the haematocrit to >50% and the mean platelet volume by 37%,while CEPO had no effect on these parameters. Platelets from EPO-treated rats showed an increased sensitivity to thrombin receptor agonist peptides and elevated plasma levels of soluble P-selectin (sP-selectin) were found in treated mice. Further indicators of platelet hyperreactivity in EPO, but not CEPO-treated animals, were significantly increased aggregatory responses to collagen in whole blood and platelet-rich plasma (PRP).The increased platelet reactivity was paralleled by a decreased bleeding time after tail transection in rats. Samples from EPO-treated rats showed an attenuated response to ADP in whole blood aggregometry and thrombelastography (TEG) platelet mapping but not in apyrase-treated PRP, suggesting involvement of ADP receptor desensitization. These findings suggest that while EPO affects various aspects of platelet function, CEPO is devoid of such effects.
Nonsense-mediated mRNA decay (NMD) is a post-transcriptional surveillance process that eliminates mRNAs containing premature termination codons (PTCs). NMD has been hypothesized to impact on several ...aspects of cellular function; however, its importance in the context of a mammalian organism has not been addressed in detail. Here we use mouse genetics to demonstrate that hematopoietic-specific deletion of Upf2, a core NMD factor, led to the rapid, complete, and lasting cell-autonomous extinction of all hematopoietic stem and progenitor populations. In contrast, more differentiated cells were only mildly affected in Upf2-null mice, suggesting that NMD is mainly essential for proliferating cells. Furthermore, we show that UPF2 loss resulted in the accumulation of nonproductive rearrangement by-products from the Tcrb locus and that this, as opposed to the general loss of NMD, was particularly detrimental to developing T-cells. At the molecular level, gene expression analysis showed that Upf2 deletion led to a profound skewing toward up-regulated mRNAs, highly enriched in transcripts derived from processed pseudogenes, and that NMD impacts on regulated alternative splicing events. Collectively, our data demonstrate a unique requirement of NMD for organismal survival.
Resistance of cancer patients to DNA damaging radiation therapy and chemotherapy remains a major problem in the clinic. The current review discusses the molecular mechanisms of therapy resistance in ...acute myeloid leukemia (AML) conferred by cooperative chemotherapy-induced DNA damage response (DDR) and mutational activation of PI3K/AKT signaling. In addition, strategies to overcome resistance are discussed, with particular focus on studies underpinning the vast potential of therapies combining standard chemotherapy AML regimens with small molecule inhibitors targeting key regulatory hubs at the interface of DDR and oncogenic signaling pathways.
The secretory leukocyte protease inhibitor (SLPI) re‐establishes homeostasis at sites of infection by virtue of its ability to exert antimicrobial activity, to suppress LPS‐induced cellular immune ...responses, and to reduce tissue damage through inhibition of serine proteases released by polymorphonuclear neutrophil granulocytes (PMNs). Microarray analysis of bone marrow (BM) populations highly enriched in promyelocytes, myelocytes/metamyelocytes (MYs), and BM neutrophils demonstrates a transient, high mRNA expression of SLPI and genuine secondary granule proteins (GPs) in MYs. Consistent with this finding, immunostaining of BM cells showed SLPI and the secondary GP lactoferrin (LF) to be present in cells from the myelocyte stage and throughout neutrophil differentiation. Subcellular fractionation studies demonstrated the colocalization of SLPI and LF in subcellular fractions highly enriched in secondary granules. Finally, exocytosis studies demonstrated a corelease of SLPI and LF within minutes of activation. Collectively, these findings strongly indicate that SLPI is localized in secondary granules of PMNs. However, the amount of SLPI detected in PMNs is low compared with primary keratinocytes stimulated by growth factors involved in wound healing. This implicates that neutrophil‐derived SLPI might not contribute essentially to re‐establishment of homeostasis at sites of infection but rather, exert physiologically relevant intracellular activities. These might include the protection of secondary GPs against proteolytic activation and/or degradation by proteases, which might be dislocated to secondary granules at minute amounts as a consequence of spillover.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Flt3 has emerged as a potential regulator of hematopoietic stem cells (HSC). Sixty percent of cells in the mouse marrow Lin
−Sca1
+c-kit
+ HSC pool expressed flt3. Although single cell cloning showed ...comparable high proliferative, myeloid, B, and T cell potentials of Lin
−Sca1
+c-kit
+flt3
+ and Lin
−Sca1
+c-kit
+flt3
− cells, only Lin
−Sca1
+c-kit
+flt3
− cells supported sustained multilineage reconstitution. In striking contrast, Lin
−Sca1
+c-kit
+flt3
+ cells rapidly and efficiently reconstituted B and T lymphopoiesis, whereas myeloid reconstitution was exclusively short term. Unlike c-kit, activation of flt3 failed to support survival of HSC, whereas only flt3 mediated survival of Lin
−Sca1
+c-kit
+flt3
+ reconstituting cells. Phenotypic and functional analysis support that Lin
−Sca1
+c-kit
+flt3
+ cells are progenitors for the common lymphoid progenitor. Thus, upregulation of flt3 expression on Lin
−Sca1
+c-kit
+ HSC cells is accompanied by loss of self-renewal capacity but sustained lymphoid-restricted reconstitution potential.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The diagnosis of a life-threatening disease can lead to depression and anxiety resulting in pharmacological treatment. However, use of psychotropic drugs (antidepressants, anxiolytics, and ...antipsychotics) in acute myeloid leukaemia (AML) and myelodysplastic syndrome (MDS) is undetermined.
Prescription of psychotropic drugs in Danish AML and MDS patients was compared to a cohort matched on age, sex, and country of origin from the Danish background population using national population-based registries.
In total, 2404 AML patients (median age 69 years) and 1307 MDS patients (median age 75 years) were included and each matched to five comparators from the background population. Two-year cumulative incidences showed that AML (20.6%) and MDS (21.2%) patients had a high risk of redemption of a psychotropic drug prescription compared to the background population (7.0% and 7.9%). High age, low educational level, and Charlson Comorbidity Index score ≥1 was associated with a higher risk in AML and MDS patients. Furthermore, non-curative treatment intent and performance status in AML patients, and high risk MDS were associated with elevated risk of psychotropic drug prescription.
In conclusion, diagnoses of AML and MDS were associated with a higher rate of psychotropic drugs prescription compared to the background population.
A novel protocol for studying human neutrophil differentiation in vivo as an alternative to models based on in vitro differentiation of cell lines.
The current study reports a flow cytometry‐based ...protocol for the prospective purification of human BM populations representing six successive stages of terminal neutrophil differentiation, including early promyelocytes and late promyelocytes, myelocytes, metamyelocytes, band cells, and PMN neutrophilic granulocytes. Validation experiments revealed a high purity of each bone marrow population and biological meaningful expression profiles for marker genes of neutrophil differentiation at a hitherto unprecedented resolution. Hence, the present protocol should be useful for studying neutrophil differentiation in vivo in the human setting and constitutes an important alternative to models that are based on in vitro differentiation of myeloid cell lines and HPCs.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The key myeloid transcription factor (TF), CEBPA, is frequently mutated in acute myeloid leukemia (AML), but the direct molecular effects of this leukemic driver mutation remain elusive. To ...investigate
mutant AML, we performed microscale, in vivo chromatin immunoprecipitation sequencing and identified a set of aberrantly activated enhancers, exclusively occupied by the leukemia-associated CEBPA-p30 isoform. Comparing gene expression changes in human
mutant AML and the corresponding
mouse model, we identified
, encoding CD73, as a cross-species AML gene with an upstream leukemic enhancer physically and functionally linked to the gene. Increased expression of CD73, mediated by the CEBPA-p30 isoform, sustained leukemic growth via the CD73/A2AR axis. Notably, targeting of this pathway enhanced survival of AML-transplanted mice. Our data thus indicate a first-in-class link between a cancer driver mutation in a TF and a druggable, direct transcriptional target.
CCAAT/enhancer binding protein (C/EBP)alpha is a myeloid-specific transcription factor that couples lineage commitment to terminal differentiation and cell cycle arrest, and is found mutated in 9% of ...patients who have acute myeloid leukemia (AML). We previously showed that mutations which dissociate the ability of C/EBP alpha to block cell cycle progression through E2F inhibition from its function as a transcriptional activator impair the in vivo development of the neutrophil granulocyte and adipose lineages. We now show that such mutations increase the capacity of bone marrow (BM) myeloid progenitors to proliferate, and predispose mice to a granulocytic myeloproliferative disorder and transformation of the myeloid compartment of the BM. Both of these phenotypes were transplantable into lethally irradiated recipients. BM transformation was characterized by a block in granulocyte differentiation, accumulation of myeloblasts and promyelocytes, and expansion of myeloid progenitor populations--all characteristics of AML. Circulating myeloblasts and hepatic leukocyte infiltration were observed, but thrombocytopenia, anemia, and elevated leukocyte count--normally associated with AML-were absent. These results show that disrupting the cell cycle regulatory function of C/EBP alpha is sufficient to initiate AML-like transformation of the granulocytic lineage, but only partially the peripheral pathology of AML.
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