Publications by authors named "Alice Rousseau"

11 Publications

  • Page 1 of 1

Iron-loaded transferrin potentiates erythropoietin effects on erythroblast proliferation and survival: a novel role through transferrin receptors.

Exp Hematol 2021 Jul 30;99:12-20.e3. Epub 2021 May 30.

Institut Hospitalo-Universitaire (IHU) Imagine, Université Sorbonne Paris cité, Assistance Publique-Hôpitaux de Paris, Hôpital Necker, Paris, France; INSERM U1163, Université Paris Descartes, Faculté de Médecine, Hôpital Necker, Paris, France; Laboratory of Excellence GReX, Paris, France; Department of Physiology, Faculty of Science, Mahidol University, Bangkok, Thailand. Electronic address:

Red blood cell production, or erythropoiesis, is a proliferative process that requires tight regulation. Erythropoietin (Epo) is a glycoprotein cytokine that plays a major role in erythropoiesis by triggering erythroid progenitors/precursors of varying sensitivity. The concentration of Epo in bone marrow is hypothesized to be suboptimal, and the survival of erythroid cells has been suggested to depend on Epo sensitivity. However, the key factors that control Epo sensitivity remain unknown. Two types of transferrin receptors (TfRs), TfR1 and TfR2, are known to play a role in iron uptake in erythroid cells. Here, we hypothesized that TfRs may additionally modulate Epo sensitivity during erythropoiesis by modulating Epo receptor (EpoR) signaling. Using an Epo-sensitive UT-7 (UT7/Epo) erythroid cell and human erythroid progenitor cell models, we report that iron-loaded transferrin, that is, holo-transferrin (holo-Tf), synergizes with suboptimal Epo levels to improve erythroid cell survival, proliferation, and differentiation. This is accomplished via the major signaling pathways of erythropoiesis, which include signal transducer and activator of transcription 5 (STAT5), mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK), and phosphoinositide-3-kinase (PI3K)/AKT. Furthermore, we found that this cooperation is improved by, but does not require, the internalization of TfR1. Interestingly, we observed that loss of TfR2 stabilizes EpoR levels and abolishes the beneficial effects of holo-Tf. Overall, these data reveal novel signaling properties of TfRs, which involve the regulation of erythropoiesis through EpoR signaling.
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http://dx.doi.org/10.1016/j.exphem.2021.05.005DOI Listing
July 2021

2D multislice MP2RAGE sequence for fast T mapping at 7 T: Application to mouse imaging and MR thermometry.

Magn Reson Med 2020 09 21;84(3):1430-1440. Epub 2020 Feb 21.

Centre de Résonance Magnétique des Systèmes Biologiques, UMR 5536, CNRS/Université de Bordeaux, Bordeaux, France.

Purpose: To develop a 2D radial multislice MP2RAGE sequence for fast and reliable T mapping at 7 T in mice and for MR thermometry.

Methods: The 2D-MP2RAGE sequence was performed with the following parameters: TI -TI -MP2RAGE = 1000-3000-9000 ms. The multiple dead times within the sequence were used for interleaved multislice acquisition, enabling one to acquire six slices in 9 seconds. The excitation pulse shape, inversion selectivity, and interslice gap were optimized. In vitro comparison with the inversion-recovery sequence was performed. The T variations with temperature were measured on tubes with T ranging from 800 ms to 2000 ms. The sequence was used to acquire T maps continuously during 30 minutes on the brain and abdomen of healthy mice.

Results: A three-lobe cardinal sine excitation pulse, combined with an inversion slice thickness and an interslice gap of respectively 150% and 50% of the imaging slice thickness, led to a SD and bias of the T measurements below 1% and 2%, respectively. A linear dependence of T with temperature was measured between 10°C and 60°C. In vivo, less than 1% variation was measured between successive T maps in the mouse brain. In the abdomen, no obvious in-plane motion artifacts were observed but respiratory motion in the slice dimension led to 6% T underestimation.

Conclusion: The multislice MP2RAGE sequence could be used for fast whole-body T mapping and MR thermometry. Its reconstruction method would enable on-the-fly reconstruction.
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http://dx.doi.org/10.1002/mrm.28220DOI Listing
September 2020

A variant erythroferrone disrupts iron homeostasis in -mutated myelodysplastic syndrome.

Sci Transl Med 2019 07;11(500)

Université de Paris, Paris 75006, France.

Myelodysplastic syndromes (MDS) with ring sideroblasts are hematopoietic stem cell disorders with erythroid dysplasia and mutations in the splicing factor gene. Patients with MDS with mutations often accumulate excessive tissue iron, even in the absence of transfusions, but the mechanisms that are responsible for their parenchymal iron overload are unknown. Body iron content, tissue distribution, and the supply of iron for erythropoiesis are controlled by the hormone hepcidin, which is regulated by erythroblasts through secretion of the erythroid hormone erythroferrone (ERFE). Here, we identified an alternative transcript in patients with MDS with the mutation. Induction of this transcript in primary -mutated bone marrow erythroblasts generated a variant protein that maintained the capacity to suppress hepcidin transcription. Plasma concentrations of ERFE were higher in patients with MDS with an gene mutation than in patients with wild-type MDS. Thus, hepcidin suppression by a variant ERFE is likely responsible for the increased iron loading in patients with -mutated MDS, suggesting that ERFE could be targeted to prevent iron-mediated toxicity. The expression of the variant transcript that was restricted to -mutated erythroblasts decreased in lenalidomide-responsive anemic patients, identifying variant ERFE as a specific biomarker of clonal erythropoiesis.
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http://dx.doi.org/10.1126/scitranslmed.aav5467DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8005358PMC
July 2019

The fraction of CD117/c-KIT-expressing erythroid precursors predicts ESA response in low-risk myelodysplastic syndromes.

Cytometry B Clin Cytom 2019 05 9;96(3):215-222. Epub 2019 Apr 9.

Service d'Hématologie-Immunologie-Transfusion, Hôpitaux Universitaires Paris Ile de France Ouest, Boulogne 92100, France.

Background: Compelling evidence has emerged for the relevance of flow cytometry (FC) in the diagnostic work-up of myelodysplastic syndromes (MDS) but due to technical issues, the erythroid lineage has been under investigated, specifically in the therapeutic context.

Methods: Using the "no red cell lysis" method developed to set up the RED-score, we specifically quantified the fraction of CD117/c-KIT-expressing erythroid precursors in a cohort of 144 MDS patients and studied the correlation with response to erythropoiesis-stimulating agents (ESA) in a sub cohort of 63 low-risk MDS patients.

Results: We confirmed the previously reported increase in CD117/c-KIT-expressing erythroid precursors in a subset of MDS patients and demonstrated a strong association between a cut off of CD117/c-KIT-expressing erythroid precursors ≥3% and ESA response (P = 0.001), independent of red blood cell requirement. From our observations, we hypothesized that a decrease in CD117/c-KIT-expressing erythroid precursors could be a mechanism of ESA failure. Moreover, the fraction of CD117/c-KIT-expressing erythroid precursors was correlated with progression-free survival in low-risk MDS patients (P = 0.018). In vitro, we demonstrated in an EPO dependent cell line that CD117/c-KIT expression is necessary for cell survival under EPO stimulation.

Conclusions: The quantification of the CD117/c-KIT-expressing erythroid precursors could be proposed as a new theranostic and prognostic marker in MDS treated by ESA. Future studies will be required to determine whether modulating CD117/c-KIT expression and signaling could be used to improve anemia in MDS. © 2019 International Clinical Cytometry Society.
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http://dx.doi.org/10.1002/cyto.b.21781DOI Listing
May 2019

Dyserythropoiesis evaluated by the RED score and hepcidin:ferritin ratio predicts response to erythropoietin in lower-risk myelodysplastic syndromes.

Haematologica 2019 03 4;104(3):497-504. Epub 2018 Oct 4.

Department of Hematology, CHU Grenoble-Alpes, Grenoble.

Erythropoiesis-stimulating agents are generally the first line of treatment of anemia in patients with lower-risk myelodysplastic syndrome. We prospectively investigated the predictive value of somatic mutations, and biomarkers of ineffective erythropoiesis including the flow cytometry RED score, serum growth-differentiation factor-15, and hepcidin levels. Inclusion criteria were no prior treatment with erythropoiesis-stimulating agents, low- or intermediate-1-risk myelodysplastic syndrome according to the International Prognostic Scoring System, and a hemoglobin level <10 g/dL. Patients could be red blood cell transfusion-dependent or not and were given epoetin zeta 40 000 IU/week. Serum erythropoietin level, iron parameters, hepcidin, flow cytometry Ogata and RED scores, and growth-differentiation factor-15 levels were determined at baseline, and molecular analysis by next-generation sequencing was also conducted. Erythroid response (defined according to the International Working Group 2006 criteria) was assessed at week 12. Seventy patients, with a median age of 78 years, were included in the study. There were 22 patients with refractory cytopenia with multilineage dysplasia, 19 with refractory cytopenia with unilineage dysplasia, 14 with refractory anemia with ring sideroblasts, four with refractory anemia with excess blasts-1, six with chronic myelomonocytic leukemia, two with del5q-and three with unclassifiable myelodysplastic syndrome. According to the revised International Prognostic Scoring System, 13 had very low risk, 47 had low risk, nine intermediate risk and one had high-risk disease. Twenty patients were transfusion dependent. Forty-eight percent had an erythroid response and the median duration of the response was 26 months. At baseline, non-responders had significantly higher RED scores and lower hepcidin:ferritin ratios. In multivariate analysis, only a RED score >4 (=0.05) and a hepcidin:ferritin ratio <9 (=0.02) were statistically significantly associated with worse erythroid response. The median response duration was shorter in patients with growth-differentiation factor-15 >2000 pg/mL and a hepcidin:ferritin ratio <9 (=0.0008 and =0.01, respectively). In multivariate analysis, both variables were associated with shorter response duration. Erythroid response to epoetin zeta was similar to that obtained with other erythropoiesis-stimulating agents and was correlated with higher baseline hepcidin:ferritin ratio and lower RED score. .
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http://dx.doi.org/10.3324/haematol.2018.203158DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6395339PMC
March 2019

Architectural and functional heterogeneity of hematopoietic stem/progenitor cells in non-del(5q) myelodysplastic syndromes.

Blood 2017 01 16;129(4):484-496. Epub 2016 Nov 16.

Institut Cochin, Paris, France.

Myelodysplastic syndromes (MDSs) are hematopoietic stem cell disorders in which recurrent mutations define clonal hematopoiesis. The origin of the phenotypic diversity of non-del(5q) MDS remains unclear. Here, we investigated the clonal architecture of the CD34CD38 hematopoietic stem/progenitor cell (HSPC) compartment and interrogated dominant clones for MDS-initiating cells. We found that clones mainly accumulate mutations in a linear succession with retention of a dominant subclone. The clone detected in the long-term culture-initiating cell compartment that reconstitutes short-term human hematopoiesis in xenotransplantation models is usually the dominant clone, which gives rise to the myeloid and to a lesser extent to the lymphoid lineage. The pattern of mutations may differ between common myeloid progenitors (CMPs), granulomonocytic progenitors (GMPs), and megakaryocytic-erythroid progenitors (MEPs). Rare STAG2 mutations can amplify at the level of GMPs, from which it may drive the transformation to acute myeloid leukemia. We report that major truncating BCOR gene mutation affecting HSPC and CMP was beneath the threshold of detection in GMP or MEP. Consistently, BCOR knock-down (KD) in normal CD34 progenitors modifies their granulocytic and erythroid differentiation. Clonal architecture of the HSPC compartment and mutations selected during differentiation contribute to the phenotypic heterogeneity of MDS. Defining the hierarchy of driver mutations provides insights into the process of transformation and may guide the search for novel therapeutic strategies.
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http://dx.doi.org/10.1182/blood-2016-03-707745DOI Listing
January 2017

Disruption of the Phosphate Transporter Pit1 in Hepatocytes Improves Glucose Metabolism and Insulin Signaling by Modulating the USP7/IRS1 Interaction.

Cell Rep 2016 09 25;16(10):2736-2748. Epub 2016 Aug 25.

INSERM U1151-CNRS UMR8253, Institut Necker-Enfants Malades (INEM), Paris Descartes University, 75993 Paris, France.

The liver plays a central role in whole-body lipid and glucose homeostasis. Increasing dietary fat intake results in increased hepatic fat deposition, which is associated with a risk for development of insulin resistance and type 2 diabetes. In this study, we demonstrate a role for the phosphate inorganic transporter 1 (PiT1/SLC20A1) in regulating metabolism. Specific knockout of Pit1 in hepatocytes significantly improved glucose tolerance and insulin sensitivity, enhanced insulin signaling, and decreased hepatic lipogenesis. We identified USP7 as a PiT1 binding partner and demonstrated that Pit1 deletion inhibited USP7/IRS1 dissociation upon insulin stimulation. This prevented IRS1 ubiquitination and its subsequent proteasomal degradation. As a consequence, delayed insulin negative feedback loop and sustained insulin signaling were observed. Moreover, PiT1-deficient mice were protected against high-fat-diet-induced obesity and diabetes. Our findings indicate that PiT1 has potential as a therapeutic target in the context of metabolic syndrome, obesity, and diabetes.
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http://dx.doi.org/10.1016/j.celrep.2016.08.012DOI Listing
September 2016

EKLF-driven PIT1 expression is critical for mouse erythroid maturation in vivo and in vitro.

Blood 2013 Jan 28;121(4):666-78. Epub 2012 Nov 28.

Inserm U845, Paris, France.

The PIT1/SLC20A1 protein, a well-described sodium/phosphate cotransporter and retrovirus receptor, has been identified recently as a modular of proliferation and apoptosis in vitro. The targeted deletion of the PIT1 gene in mice revealed a lethal phenotype due to severe anemia attributed to defects in liver development. However, the presence of immature erythroid cells associated with impaired maturation of the globin switch led us to investigate the role of PIT1 in hematopoietic development. In the present study, specific deletion of PIT1 in the hematopoietic system and fetal liver transplantation experiments demonstrated that anemia was associated with an erythroid cell- autonomous defect. Moreover, anemia was not due to RBC destruction but rather to maturation defects. Because Erythroid Krüppel-like Factor (EKLF)-knockout mice showed similar maturation defects, we investigated the functional link between PIT1 and EKLF. We demonstrated that EKLF increases PIT1 expression during RBC maturation by binding to its promoter in vivo and that shRNA-driven depletion of either PIT1 or EKLF impairs erythroid maturation of G1E cells in vitro, whereas reexpression of PIT1 in EKLF-depleted G1E cells partially restores erythroid maturation. This is the first demonstration of a physiologic involvement of PIT1 in erythroid maturation in vivo.
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http://dx.doi.org/10.1182/blood-2012-05-427302DOI Listing
January 2013

Identification of a novel transport-independent function of PiT1/SLC20A1 in the regulation of TNF-induced apoptosis.

J Biol Chem 2010 Nov 3;285(45):34408-18. Epub 2010 Sep 3.

Growth and Signaling Research Center, INSERM U845, F-75015 Paris, France.

PiT1/SLC20A1 is a sodium-dependent P(i) transporter expressed by most mammalian cells. Interestingly, PiT1 transcription has been shown to be up-regulated by the tumor necrosis factor α (TNF), and we have now investigated the possible involvement of PiT1 in TNF-induced apoptosis. We show that PiT1-depleted cells are more sensitive to the proapoptotic activity of TNF (i.e. when the antiapoptotic NFκB pathway is inactivated). These observations were made in the human HeLa cancer cell line either transiently or stably depleted in PiT1 by RNA interference and in immortalized mouse embryonic fibroblasts isolated from PiT1 knock-out embryos. Depletion of the closely related family member PiT2 had no effect on TNF-induced apoptosis, showing that this effect was specific to PiT1. The increased sensitivity of PiT1-depleted cells was evident regardless of the presence or absence of extracellular P(i), suggesting that a defect in P(i) uptake was not involved in the observed phenotype. Importantly, we show that the re-expression of a P(i) uptake mutant of PiT1 in PiT1(-/-) mouse embryonic fibroblasts delays apoptosis as efficiently as the WT protein, showing that this function of PiT1 is unrelated to its transport activity. Caspase-8 is more activated in PiT1-depleted cells, and our data reveal that the sustained activation of the MAPK JNK is up-regulated in response to TNF. JNK activity is actually involved in PiT1-depleted cell death because specific JNK inhibitors delay apoptosis.
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http://dx.doi.org/10.1074/jbc.M110.130989DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2966055PMC
November 2010

Efficient virus-induced gene silencing in Arabidopsis using a 'one-step' TYMV-derived vector.

Plant J 2008 Nov 4;56(4):678-90. Epub 2008 Aug 4.

Laboratoire de Virologie Moléculaire, Institut Jacques Monod, UMR 7592 CNRS-Universités Paris 6-Paris 7, 2 place Jussieu, 75251 Paris Cedex 05, France.

Virus-induced gene silencing (VIGS) is an important tool for the analysis of gene function in plants. This technique exploits recombinant viral vectors harbouring fragments of plant genes in their genome to generate double-stranded RNAs that initiate homology-dependent silencing of the target gene. Several viral VIGS vectors have already been successfully used in reverse-genetics studies of a variety of processes occurring in plants. Here, we show that a viral vector derived from Turnip yellow mosaic virus (TYMV) has the ability to induce VIGS in Arabidopsis thaliana, accession Col-0, provided that it carries an inverted-repeat fragment of the target gene. Robust and reliable gene silencing was observed when plants were inoculated simply by abrasion with intact plasmid DNA harbouring a cDNA copy of the viral genome, thus precluding the need for in vitro transcription, biolistic or agroinoculation procedures. Our results indicate that a 76 bp fragment is sufficient to cause gene silencing in leaves, stems and flowers, and that the TYMV-derived vector also has the ability to target genes expressed in meristematic tissues. The VIGS vector described here may thus represent an ideal tool for improving high-throughput functional genomics in Arabidopsis.
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http://dx.doi.org/10.1111/j.1365-313X.2008.03620.xDOI Listing
November 2008