Cecilia Abreu - Academia.edu (original) (raw)

Papers by Cecilia Abreu

Research paper thumbnail of Anatomy, physiology, manipulation and veterinary applications of the reticular groove. Review

Revista Mexicana de Ciencias Pecuarias, 2019

El cierre del surco reticular en los rumiantes es un mecanismo primario, casi exclusivo de los an... more El cierre del surco reticular en los rumiantes es un mecanismo primario, casi exclusivo de los animales lactantes, que hace posible el paso de los alimentos desde el orificio del cardias al abomaso, evitando las fermentaciones no deseadas en el rumen y el retículo. En esta revisión se describen algunos aspectos anatómicos y fisiológicos del surco reticular, teniendo en cuenta su desarrollo embrionario y postnatal, su localización topográfica, se estructura, su inervación, su circulación sanguínea y su histología. También se describen los métodos directos e indirectos utilizados para el estudio de su funcionamiento. Finalmente, la revisión se concentra en el manejo de las técnicas para manipular el reflejo de cierre del surco reticular y sus aplicaciones veterinarias tanto en la estimulación como en la inhibición, dado que la posibilidad de controlar este reflejo es de gran interés para la administración oral de diversos medicamentos en el tratamiento de ciertas enfermedades, así como para un mejor aprovechamiento de algunos tipos de alimentos.

Research paper thumbnail of Histological changes of the liver and metabolic correlates in ewes with pregnancy toxemia

Arquivo Brasileiro de Medicina Veterinária e Zootecnia, 2009

The histological changes of the liver in ewes with pregnancy toxemia were characterized. Ten ewes... more The histological changes of the liver in ewes with pregnancy toxemia were characterized. Ten ewes were fed on grass ad libitum, and another ten were starved from day 130 of pregnancy for up to four days. Liver puncture biopsies were performed at days 70, 100, 130, and 140 of pregnancy, and at day 45 in postpartum. Seric hydroxybutyrate (HB), non-esterified fatty acids (NEFA), aspartate aminotransferase, and alkaline phosphatase were dosed. Histological preparations revealed similar incidence and intensity of mild liver steatosis in both groups at day 130. Starved ewes become toxemic (as indicated by HB), and at day 140 exhibited more severe injury in a higher proportion (9/9 vs. 4/10; P<0.01). Almost all of them (7/9) had large amounts of small lipid droplets in almost every hepatocyte over the whole liver acinus, and higher NEFA values. At day 45 in postpartum, both groups had mild steatotic changes as initially. A positive correlation between severity of liver damage seric and ...

Research paper thumbnail of Mecanismos de daño neutrófilo-oxígeno en la lesión de isquemia y reperfusión. Manipulaciones farmacológicas

Research paper thumbnail of Effects of metabolic changes produced in ewes with subclinical pregnancy toxemia over reproductive parameters

Revista Brasileira de Zootecnia

Research paper thumbnail of Ingresos en Clínicas Veterinarias en las secciones censales 8, 19, 23 y 24 de la ciudad de Montevideo; desagregados por rubros

Redvet Revista Electronica De Veterinaria, 2013

Research paper thumbnail of Distribución por edad y sexo en veterinarios del sub – sector animales de compañía en las secciones censales 8, 19, 23 y 24 de la ciudad de Montevideo

Redvet Revista Electronica De Veterinaria, 2013

Distribución por edad y sexo en veterinarios del sub-sector animales de compañía en las secciones... more Distribución por edad y sexo en veterinarios del sub-sector animales de compañía en las secciones censales 8,

Research paper thumbnail of UreA, the major urea/H + symporter in Aspergillus nidulans

Fungal Genetics and Biology Fg B, Dec 1, 2010

We report here the characterization of UreA, a high-affinity urea/H+ symporter of Aspergillus nid... more We report here the characterization of UreA, a high-affinity urea/H+ symporter of Aspergillus nidulans. The deletion of the encoding gene abolishes urea transport at low substrate concentrations, suggesting that in these conditions UreA is the sole transport system specific for urea in A. nidulans. The ureA gene is not inducible by urea or its precursors, but responds to nitrogen metabolite repression, necessitating for its expression the AreA GATA factor. In contrast to what was observed for other transporters in A. nidulans, repression by ammonium is also operative during the isotropic growth phase. The activity of UreA is down-regulated post-translationally by ammonium-promoted endocytosis. A number of homologues of UreA have been identified in A. nidulans and other Aspergilli, which cluster in four groups, two of which contain the urea transporters characterized so far in fungi and plants. This phylogeny may have arisen by gene duplication events, giving place to putative transport proteins that could have acquired novel, still unidentified functions.Copyright © 2010 Elsevier Inc. All rights reserved.

Research paper thumbnail of Biological nitrogen fixation in maize (Zea mays L.) by 15N isotope-dilution and identification of associated culturable diazotrophs

Biology and Fertility of Soils, 2009

The nitrogen-fixing capacity of a range of commercial cultivars of maize (Zea mays L.) was evalua... more The nitrogen-fixing capacity of a range of commercial cultivars of maize (Zea mays L.) was evaluated by the 15 N isotope-dilution method. Biological nitrogen fixation (BNF) expressed as percent nitrogen derived from air (Ndfa) ranged from 12 to 33 regardless of nitrogen fertilization. BNF was not affected by mineral nitrogen fertilization except on cultivar Topacio and PAU-871 cultivars. Subsequently, culturable bacterial diazotrophs were isolated from endophytic tissue of maize: seed, root, stem, and leaf. All isolates were able to grow on N-free semisolid medium. Eleven bacteria isolates showed nitrogen-fixing capacity by the reduction of acetylene to ethylene and confirmed by PCR the presence of nifH gene in their genome. Identification of the 11 isolates was performed by bacteriological methods, 16S rRNA gene sequences, and phylogenetic analysis, which indicated that the bacteria isolated were closely related to Pantoea, Pseudomonas, Rhanella, Herbaspirillum, Azospirillum, Rhizobium (Agrobacterium), and Brevundimonas. This study demonstrated that maize cultivars obtain significant nitrogen from BNF, varying by maize cultivar and nitrogen fertilization level. The endophytic diazotrophic bacteria isolated from root, stem, and leaf tissues of maize cultivars may contribute to BNF in these plants.

Research paper thumbnail of HSP90 inhibitors decrease AID levels and activity in mice and in human cells

European Journal of Immunology, 2015

Activation induced deaminase (AID) initiates somatic hypermutation and class switch recombination... more Activation induced deaminase (AID) initiates somatic hypermutation and class switch recombination of the Ig genes in antigen-activated B cells, underpinning antibody affinity maturation and isotype switching. AID can also be pathogenic by contributing to autoimmune diseases and oncogenic mutations. Moreover, AID can exert noncanonical functions when aberrantly expressed in epithelial cells. The lack of specific inhibitors prevents therapeutic applications to modulate AID functions. Here, we have exploited our previous finding that the HSP90 molecular chaperoning pathway stabilizes AID in B cells, to test whether HSP90 inhibitors could target AID in vivo. We demonstrate that chronic administration of HSP90 inhibitors decreases AID protein levels and isotype switching in immunized mice. HSP90 inhibitors also reduce disease severity in a mouse model of acute B-cell lymphoblastic leukemia in which AID accelerates disease progression. We further show that human AID protein levels are sensitive to HSP90 inhibition in normal and leukemic B cells, and that HSP90 inhibition prevents AID-dependent epithelial to mesenchymal transition in a human breast cancer cell line in vitro. Thus, we provide proof-of-concept that HSP90 inhibitors indirectly target AID in vivo and that endogenous human AID is widely sensitive to them, which could have therapeutic applications.

Research paper thumbnail of 1.14 DNA Methylation Status is Associated to Lipoprotein Lipase (LPL) Expression and can be Modulated by FC Treatment in Unmutated CLL Patients

Clinical Lymphoma Myeloma and Leukemia, 2011

Research paper thumbnail of Microenvironment Interactions in Chronic Lymphocytic Leukemia: A Delicate Equilibrium Linking the Quiescent and the Proliferative Pool

Chronic Lymphocytic Leukemia, 2012

Research paper thumbnail of 1.13 Genome Fingerprinting of a Proliferative B-cell Subset in Chronic Lymphocytic Leukemia

Clinical Lymphoma Myeloma and Leukemia, 2011

Research paper thumbnail of Surface localization of high-mobility group nucleosome-binding protein 2 on leukemic B cells from patients with chronic lymphocytic leukemia is related to secondary autoimmune hemolytic anemia

Leukemia & lymphoma, Jan 21, 2015

Chronic lymphocytic leukemia (CLL) is the main cause of autoimmune hemolytic anemia (AHA). Howeve... more Chronic lymphocytic leukemia (CLL) is the main cause of autoimmune hemolytic anemia (AHA). However, the cellular basis underlying this strong association remains unclear. We previously demonstrated that leukemic B cells from patients with CLL recognize the erythrocyte protein Band 3, a prevalent autoantigen in AHA. Here we show that the major binding site of Band 3 on leukemic cells is an extrinsic protein identified as high-mobility group nucleosome binding protein 2 (HMGN2), a nucleosome-interacting factor which has not been previously reported at the cell surface. T lymphocytes do not express HMGN2 or bind Band 3. Removal of HMGN2 from the cell membrane abrogated the capacity of Band 3-pulsed CLL cells to induce CD4 + T cell proliferation. We conclude that surface HMGN2 in leukemic B cells is involved in Band 3 binding, uptake and presentation to CD4 + T lymphocytes, and as such may favor the initiation of AHA secondary to CLL.

Research paper thumbnail of Dissecting CLL microenvironment signals in unmutated patients: MicroRNA-22 regulates PTEN/AKT/FOXO pathway in proliferative leukemic cells

Leukemia & Lymphoma, 2014

Chronic lymphocytic leukemia (CLL) is characterized by accumulation of clonal B cells arrested in... more Chronic lymphocytic leukemia (CLL) is characterized by accumulation of clonal B cells arrested in G0/G1 stages that coexist, in different proportions, with proliferative B cells. Understanding the crosstalk between the proliferative subsets and their milieu could provide clues on CLL biology. We previously identified one of these subpopulations in the peripheral blood from unmutated patients that appears to be a hallmark of a progressive disease. Aiming to characterize the molecular mechanism underlying this proliferative behavior, we performed gene expression analysis comparing the global mRNA and microRNA expression of this leukemic subpopulation, and compared it with their quiescent counterparts. Our results suggest that proliferation of this fraction depend on microRNA-22 overexpression that induces phosphatase and tensin homolog downregulation and phosphoinositide 3-kinase (PI3K)/AKT pathway activation. Transfection experiments demonstrated that miR-22 overexpression in CLL B cells switches on PI3K/AKT, leading to downregulation of p27 À Kip1 and overexpression of Survivin and Ki-67 proteins. We also demonstrated that this pathway could be triggered by microenvironment signals like CD40 ligand/interleukin-4 and, more importantly, that this regulatory loop is also present in lymph nodes from progressive unmutated patients. Altogether, these results underline the key role of PI3K/AKT pathway in the generation of the CLL proliferative pool and provide additional rationale for the usage of PI3K inhibitors.

Research paper thumbnail of Methylation status regulates lipoprotein lipase expression in chronic lymphocytic leukemia

Leukemia & Lymphoma, 2013

Among diff erent prognostic factors in chronic lymphocytic leukemia (CLL), we previously demonstr... more Among diff erent prognostic factors in chronic lymphocytic leukemia (CLL), we previously demonstrated that lipoprotein lipase (LPL) is associated with an unmutated immunoglobulin profi le and clinical poor outcome. Despite the usefulness of LPL for CLL prognosis, its functional role and the molecular mechanism regulating its expression are still open questions. Interaction of CLL B-cells with the tissue microenvironment favors disease progression by promoting malignant B-cell growth. Since tissue methylation can be altered by environmental factors, we investigated the methylation status of the LPL gene and the possibility that overexpression could be associated with microenvironment signals. Our results show that a demethylated state of the LPL gene is responsible for its anomalous expression in unmutated CLL cases and that this expression is dependent on microenvironment signals. Overall, this work proposes that an epigenetic mechanism, triggered by the microenvironment, regulates LPL expression in CLL disease. Leuk Lymphoma Downloaded from informahealthcare.com by INSERM on 10/03/13

Research paper thumbnail of Activation of the PI3K/AKT pathway by microRNA-22 results in CLL B-cell proliferation

Leukemia, 2014

Chronic lymphocytic leukemia (CLL) is characterized by accumulation of clonal B cells arrested in... more Chronic lymphocytic leukemia (CLL) is characterized by accumulation of clonal B cells arrested in G0/G1 stages that coexist, in different proportions, with proliferative B cells. Understanding the crosstalk between the proliferative subsets and their milieu could provide clues on CLL biology. We previously identified one of these subpopulations in the peripheral blood from unmutated patients that appears to be a hallmark of a progressive disease. Aiming to characterize the molecular mechanism underlying this proliferative behavior, we performed gene expression analysis comparing the global mRNA and microRNA expression of this leukemic subpopulation, and compared it with their quiescent counterparts. Our results suggest that proliferation of this fraction depend on microRNA-22 overexpression that induces phosphatase and tensin homolog downregulation and phosphoinositide 3-kinase (PI3K)/AKT pathway activation. Transfection experiments demonstrated that miR-22 overexpression in CLL B cells switches on PI3K/AKT, leading to downregulation of p27 À Kip1 and overexpression of Survivin and Ki-67 proteins. We also demonstrated that this pathway could be triggered by microenvironment signals like CD40 ligand/interleukin-4 and, more importantly, that this regulatory loop is also present in lymph nodes from progressive unmutated patients. Altogether, these results underline the key role of PI3K/AKT pathway in the generation of the CLL proliferative pool and provide additional rationale for the usage of PI3K inhibitors.

Research paper thumbnail of Lipoprotein lipase expression in unmutated CLL patients is the consequence of a demethylation process induced by the microenvironment

Research paper thumbnail of UreA, the major urea/H+ symporter in Aspergillus nidulans

Fungal Genetics and Biology, 2010

We report here the characterization of UreA, a high-affinity urea/H + symporter of Aspergillus ni... more We report here the characterization of UreA, a high-affinity urea/H + symporter of Aspergillus nidulans. The deletion of the encoding gene abolishes urea transport at low substrate concentrations, suggesting that in these conditions UreA is the sole transport system specific for urea in A. nidulans. The ureA gene is not inducible by urea or its precursors, but responds to nitrogen metabolite repression, necessitating for its expression the AreA GATA factor. In contrast to what was observed for other transporters in A. nidulans, repression by ammonium is also operative during the isotropic growth phase. The activity of UreA is down-regulated post-translationally by ammonium-promoted endocytosis. A number of homologues of UreA have been identified in A. nidulans and other Aspergilli, which cluster in four groups, two of which contain the urea transporters characterized so far in fungi and plants. This phylogeny may have arisen by gene duplication events, giving place to putative transport proteins that could have acquired novel, still unidentified functions.

Research paper thumbnail of CCR4 expression in a case of cutaneous Richter’s transformation of chronic lymphocytic leukemia (CLL) to diffuse large B-cell lymphoma (DLBCL) and in CLL patients with no skin manifestations

European Journal of Haematology, 2011

Richter&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;... more Richter&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s transformation of B-cell chronic lymphocytic leukemia (CLL) to cutaneous diffuse large B-cell lymphoma (DLBCL) is very rare. We took the advantage of one of these cases to test the hypothesis that the chemokine receptor CCR4 is involved in the homing of CLL cells to skin. We evaluated CCR4 expression by flow cytometry in both circulating and skin CD19(+) leukemic cells from a patient with cutaneous DLBCL. As controls, we used peripheral blood samples from CLL patients without skin manifestations and from elderly healthy donors. We found that both DLBCL cells derived from the original CLL clone and circulating CLL cells from this patient expressed CCR4. Although it was previously reported that CCR4 is not expressed in CLL cells, we found that a low but significant proportion of leukemic cells from CLL patients with no skin manifestations do express CCR4. There was a positive correlation between the expression of CCR4 and the percentage of ZAP-70 of each sample. Moreover, we consistently observed a higher expression of CCR4 within CD19(+)CD38(+) and CD19(+)Ki67(+) subsets compared to CD19(+)CD38(-) and CD19(+)Ki67(-) lymphocytes from the same sample, respectively. We conclude that the chemokine receptor CCR4 is not a special feature of CLL cells with skin manifestation, but rather it is expressed in a low but significant proportion of peripheral blood CLL cells.

Research paper thumbnail of High expression of AID and active class switch recombination might account for a more aggressive disease in unmutated CLL patients: link with an activated microenvironment in CLL disease

Blood, 2010

Interaction of chronic lymphocytic leukemia (CLL) B cells with tissue microenvironment has been s... more Interaction of chronic lymphocytic leukemia (CLL) B cells with tissue microenvironment has been suggested to favor disease progression by promoting malignant B-cell growth. Previous work has shown expression in peripheral blood (PB) of CLL B cells of activation-induced cytidine deaminase (AID) among CLL patients with an unmutated (UM) profile of immunoglobulin genes and with ongoing class switch recombination (CSR) process. Because AID expression results from interaction with activated tissue microenvironment, we speculated whether the small subset with ongoing CSR is responsible for high levels of AID expression and could be derived from this particular microenvironment. In this work, we quantified AID expression and ongoing CSR in PB of 50 CLL patients and characterized the expression of different molecules related to microenvironment interaction. Our results show that among UM patients (1) high AID expression is restricted to the subpopulation of tumoral cells ongoing CSR; (2) this small subset expresses high levels of proliferation, antiapoptotic and progression markers (Ki-67, c-myc, Bcl-2, CD49d, and CCL3/4 chemokines). Overall, this work outlines the importance of a cellular subset in PB of UM CLL patients with a poor clinical outcome, high AID levels, and ongoing CSR, whose presence might be a hallmark of a recent contact with the microenvironment.

Research paper thumbnail of Anatomy, physiology, manipulation and veterinary applications of the reticular groove. Review

Revista Mexicana de Ciencias Pecuarias, 2019

El cierre del surco reticular en los rumiantes es un mecanismo primario, casi exclusivo de los an... more El cierre del surco reticular en los rumiantes es un mecanismo primario, casi exclusivo de los animales lactantes, que hace posible el paso de los alimentos desde el orificio del cardias al abomaso, evitando las fermentaciones no deseadas en el rumen y el retículo. En esta revisión se describen algunos aspectos anatómicos y fisiológicos del surco reticular, teniendo en cuenta su desarrollo embrionario y postnatal, su localización topográfica, se estructura, su inervación, su circulación sanguínea y su histología. También se describen los métodos directos e indirectos utilizados para el estudio de su funcionamiento. Finalmente, la revisión se concentra en el manejo de las técnicas para manipular el reflejo de cierre del surco reticular y sus aplicaciones veterinarias tanto en la estimulación como en la inhibición, dado que la posibilidad de controlar este reflejo es de gran interés para la administración oral de diversos medicamentos en el tratamiento de ciertas enfermedades, así como para un mejor aprovechamiento de algunos tipos de alimentos.

Research paper thumbnail of Histological changes of the liver and metabolic correlates in ewes with pregnancy toxemia

Arquivo Brasileiro de Medicina Veterinária e Zootecnia, 2009

The histological changes of the liver in ewes with pregnancy toxemia were characterized. Ten ewes... more The histological changes of the liver in ewes with pregnancy toxemia were characterized. Ten ewes were fed on grass ad libitum, and another ten were starved from day 130 of pregnancy for up to four days. Liver puncture biopsies were performed at days 70, 100, 130, and 140 of pregnancy, and at day 45 in postpartum. Seric hydroxybutyrate (HB), non-esterified fatty acids (NEFA), aspartate aminotransferase, and alkaline phosphatase were dosed. Histological preparations revealed similar incidence and intensity of mild liver steatosis in both groups at day 130. Starved ewes become toxemic (as indicated by HB), and at day 140 exhibited more severe injury in a higher proportion (9/9 vs. 4/10; P<0.01). Almost all of them (7/9) had large amounts of small lipid droplets in almost every hepatocyte over the whole liver acinus, and higher NEFA values. At day 45 in postpartum, both groups had mild steatotic changes as initially. A positive correlation between severity of liver damage seric and ...

Research paper thumbnail of Mecanismos de daño neutrófilo-oxígeno en la lesión de isquemia y reperfusión. Manipulaciones farmacológicas

Research paper thumbnail of Effects of metabolic changes produced in ewes with subclinical pregnancy toxemia over reproductive parameters

Revista Brasileira de Zootecnia

Research paper thumbnail of Ingresos en Clínicas Veterinarias en las secciones censales 8, 19, 23 y 24 de la ciudad de Montevideo; desagregados por rubros

Redvet Revista Electronica De Veterinaria, 2013

Research paper thumbnail of Distribución por edad y sexo en veterinarios del sub – sector animales de compañía en las secciones censales 8, 19, 23 y 24 de la ciudad de Montevideo

Redvet Revista Electronica De Veterinaria, 2013

Distribución por edad y sexo en veterinarios del sub-sector animales de compañía en las secciones... more Distribución por edad y sexo en veterinarios del sub-sector animales de compañía en las secciones censales 8,

Research paper thumbnail of UreA, the major urea/H + symporter in Aspergillus nidulans

Fungal Genetics and Biology Fg B, Dec 1, 2010

We report here the characterization of UreA, a high-affinity urea/H+ symporter of Aspergillus nid... more We report here the characterization of UreA, a high-affinity urea/H+ symporter of Aspergillus nidulans. The deletion of the encoding gene abolishes urea transport at low substrate concentrations, suggesting that in these conditions UreA is the sole transport system specific for urea in A. nidulans. The ureA gene is not inducible by urea or its precursors, but responds to nitrogen metabolite repression, necessitating for its expression the AreA GATA factor. In contrast to what was observed for other transporters in A. nidulans, repression by ammonium is also operative during the isotropic growth phase. The activity of UreA is down-regulated post-translationally by ammonium-promoted endocytosis. A number of homologues of UreA have been identified in A. nidulans and other Aspergilli, which cluster in four groups, two of which contain the urea transporters characterized so far in fungi and plants. This phylogeny may have arisen by gene duplication events, giving place to putative transport proteins that could have acquired novel, still unidentified functions.Copyright © 2010 Elsevier Inc. All rights reserved.

Research paper thumbnail of Biological nitrogen fixation in maize (Zea mays L.) by 15N isotope-dilution and identification of associated culturable diazotrophs

Biology and Fertility of Soils, 2009

The nitrogen-fixing capacity of a range of commercial cultivars of maize (Zea mays L.) was evalua... more The nitrogen-fixing capacity of a range of commercial cultivars of maize (Zea mays L.) was evaluated by the 15 N isotope-dilution method. Biological nitrogen fixation (BNF) expressed as percent nitrogen derived from air (Ndfa) ranged from 12 to 33 regardless of nitrogen fertilization. BNF was not affected by mineral nitrogen fertilization except on cultivar Topacio and PAU-871 cultivars. Subsequently, culturable bacterial diazotrophs were isolated from endophytic tissue of maize: seed, root, stem, and leaf. All isolates were able to grow on N-free semisolid medium. Eleven bacteria isolates showed nitrogen-fixing capacity by the reduction of acetylene to ethylene and confirmed by PCR the presence of nifH gene in their genome. Identification of the 11 isolates was performed by bacteriological methods, 16S rRNA gene sequences, and phylogenetic analysis, which indicated that the bacteria isolated were closely related to Pantoea, Pseudomonas, Rhanella, Herbaspirillum, Azospirillum, Rhizobium (Agrobacterium), and Brevundimonas. This study demonstrated that maize cultivars obtain significant nitrogen from BNF, varying by maize cultivar and nitrogen fertilization level. The endophytic diazotrophic bacteria isolated from root, stem, and leaf tissues of maize cultivars may contribute to BNF in these plants.

Research paper thumbnail of HSP90 inhibitors decrease AID levels and activity in mice and in human cells

European Journal of Immunology, 2015

Activation induced deaminase (AID) initiates somatic hypermutation and class switch recombination... more Activation induced deaminase (AID) initiates somatic hypermutation and class switch recombination of the Ig genes in antigen-activated B cells, underpinning antibody affinity maturation and isotype switching. AID can also be pathogenic by contributing to autoimmune diseases and oncogenic mutations. Moreover, AID can exert noncanonical functions when aberrantly expressed in epithelial cells. The lack of specific inhibitors prevents therapeutic applications to modulate AID functions. Here, we have exploited our previous finding that the HSP90 molecular chaperoning pathway stabilizes AID in B cells, to test whether HSP90 inhibitors could target AID in vivo. We demonstrate that chronic administration of HSP90 inhibitors decreases AID protein levels and isotype switching in immunized mice. HSP90 inhibitors also reduce disease severity in a mouse model of acute B-cell lymphoblastic leukemia in which AID accelerates disease progression. We further show that human AID protein levels are sensitive to HSP90 inhibition in normal and leukemic B cells, and that HSP90 inhibition prevents AID-dependent epithelial to mesenchymal transition in a human breast cancer cell line in vitro. Thus, we provide proof-of-concept that HSP90 inhibitors indirectly target AID in vivo and that endogenous human AID is widely sensitive to them, which could have therapeutic applications.

Research paper thumbnail of 1.14 DNA Methylation Status is Associated to Lipoprotein Lipase (LPL) Expression and can be Modulated by FC Treatment in Unmutated CLL Patients

Clinical Lymphoma Myeloma and Leukemia, 2011

Research paper thumbnail of Microenvironment Interactions in Chronic Lymphocytic Leukemia: A Delicate Equilibrium Linking the Quiescent and the Proliferative Pool

Chronic Lymphocytic Leukemia, 2012

Research paper thumbnail of 1.13 Genome Fingerprinting of a Proliferative B-cell Subset in Chronic Lymphocytic Leukemia

Clinical Lymphoma Myeloma and Leukemia, 2011

Research paper thumbnail of Surface localization of high-mobility group nucleosome-binding protein 2 on leukemic B cells from patients with chronic lymphocytic leukemia is related to secondary autoimmune hemolytic anemia

Leukemia & lymphoma, Jan 21, 2015

Chronic lymphocytic leukemia (CLL) is the main cause of autoimmune hemolytic anemia (AHA). Howeve... more Chronic lymphocytic leukemia (CLL) is the main cause of autoimmune hemolytic anemia (AHA). However, the cellular basis underlying this strong association remains unclear. We previously demonstrated that leukemic B cells from patients with CLL recognize the erythrocyte protein Band 3, a prevalent autoantigen in AHA. Here we show that the major binding site of Band 3 on leukemic cells is an extrinsic protein identified as high-mobility group nucleosome binding protein 2 (HMGN2), a nucleosome-interacting factor which has not been previously reported at the cell surface. T lymphocytes do not express HMGN2 or bind Band 3. Removal of HMGN2 from the cell membrane abrogated the capacity of Band 3-pulsed CLL cells to induce CD4 + T cell proliferation. We conclude that surface HMGN2 in leukemic B cells is involved in Band 3 binding, uptake and presentation to CD4 + T lymphocytes, and as such may favor the initiation of AHA secondary to CLL.

Research paper thumbnail of Dissecting CLL microenvironment signals in unmutated patients: MicroRNA-22 regulates PTEN/AKT/FOXO pathway in proliferative leukemic cells

Leukemia & Lymphoma, 2014

Chronic lymphocytic leukemia (CLL) is characterized by accumulation of clonal B cells arrested in... more Chronic lymphocytic leukemia (CLL) is characterized by accumulation of clonal B cells arrested in G0/G1 stages that coexist, in different proportions, with proliferative B cells. Understanding the crosstalk between the proliferative subsets and their milieu could provide clues on CLL biology. We previously identified one of these subpopulations in the peripheral blood from unmutated patients that appears to be a hallmark of a progressive disease. Aiming to characterize the molecular mechanism underlying this proliferative behavior, we performed gene expression analysis comparing the global mRNA and microRNA expression of this leukemic subpopulation, and compared it with their quiescent counterparts. Our results suggest that proliferation of this fraction depend on microRNA-22 overexpression that induces phosphatase and tensin homolog downregulation and phosphoinositide 3-kinase (PI3K)/AKT pathway activation. Transfection experiments demonstrated that miR-22 overexpression in CLL B cells switches on PI3K/AKT, leading to downregulation of p27 À Kip1 and overexpression of Survivin and Ki-67 proteins. We also demonstrated that this pathway could be triggered by microenvironment signals like CD40 ligand/interleukin-4 and, more importantly, that this regulatory loop is also present in lymph nodes from progressive unmutated patients. Altogether, these results underline the key role of PI3K/AKT pathway in the generation of the CLL proliferative pool and provide additional rationale for the usage of PI3K inhibitors.

Research paper thumbnail of Methylation status regulates lipoprotein lipase expression in chronic lymphocytic leukemia

Leukemia & Lymphoma, 2013

Among diff erent prognostic factors in chronic lymphocytic leukemia (CLL), we previously demonstr... more Among diff erent prognostic factors in chronic lymphocytic leukemia (CLL), we previously demonstrated that lipoprotein lipase (LPL) is associated with an unmutated immunoglobulin profi le and clinical poor outcome. Despite the usefulness of LPL for CLL prognosis, its functional role and the molecular mechanism regulating its expression are still open questions. Interaction of CLL B-cells with the tissue microenvironment favors disease progression by promoting malignant B-cell growth. Since tissue methylation can be altered by environmental factors, we investigated the methylation status of the LPL gene and the possibility that overexpression could be associated with microenvironment signals. Our results show that a demethylated state of the LPL gene is responsible for its anomalous expression in unmutated CLL cases and that this expression is dependent on microenvironment signals. Overall, this work proposes that an epigenetic mechanism, triggered by the microenvironment, regulates LPL expression in CLL disease. Leuk Lymphoma Downloaded from informahealthcare.com by INSERM on 10/03/13

Research paper thumbnail of Activation of the PI3K/AKT pathway by microRNA-22 results in CLL B-cell proliferation

Leukemia, 2014

Chronic lymphocytic leukemia (CLL) is characterized by accumulation of clonal B cells arrested in... more Chronic lymphocytic leukemia (CLL) is characterized by accumulation of clonal B cells arrested in G0/G1 stages that coexist, in different proportions, with proliferative B cells. Understanding the crosstalk between the proliferative subsets and their milieu could provide clues on CLL biology. We previously identified one of these subpopulations in the peripheral blood from unmutated patients that appears to be a hallmark of a progressive disease. Aiming to characterize the molecular mechanism underlying this proliferative behavior, we performed gene expression analysis comparing the global mRNA and microRNA expression of this leukemic subpopulation, and compared it with their quiescent counterparts. Our results suggest that proliferation of this fraction depend on microRNA-22 overexpression that induces phosphatase and tensin homolog downregulation and phosphoinositide 3-kinase (PI3K)/AKT pathway activation. Transfection experiments demonstrated that miR-22 overexpression in CLL B cells switches on PI3K/AKT, leading to downregulation of p27 À Kip1 and overexpression of Survivin and Ki-67 proteins. We also demonstrated that this pathway could be triggered by microenvironment signals like CD40 ligand/interleukin-4 and, more importantly, that this regulatory loop is also present in lymph nodes from progressive unmutated patients. Altogether, these results underline the key role of PI3K/AKT pathway in the generation of the CLL proliferative pool and provide additional rationale for the usage of PI3K inhibitors.

Research paper thumbnail of Lipoprotein lipase expression in unmutated CLL patients is the consequence of a demethylation process induced by the microenvironment

Research paper thumbnail of UreA, the major urea/H+ symporter in Aspergillus nidulans

Fungal Genetics and Biology, 2010

We report here the characterization of UreA, a high-affinity urea/H + symporter of Aspergillus ni... more We report here the characterization of UreA, a high-affinity urea/H + symporter of Aspergillus nidulans. The deletion of the encoding gene abolishes urea transport at low substrate concentrations, suggesting that in these conditions UreA is the sole transport system specific for urea in A. nidulans. The ureA gene is not inducible by urea or its precursors, but responds to nitrogen metabolite repression, necessitating for its expression the AreA GATA factor. In contrast to what was observed for other transporters in A. nidulans, repression by ammonium is also operative during the isotropic growth phase. The activity of UreA is down-regulated post-translationally by ammonium-promoted endocytosis. A number of homologues of UreA have been identified in A. nidulans and other Aspergilli, which cluster in four groups, two of which contain the urea transporters characterized so far in fungi and plants. This phylogeny may have arisen by gene duplication events, giving place to putative transport proteins that could have acquired novel, still unidentified functions.

Research paper thumbnail of CCR4 expression in a case of cutaneous Richter’s transformation of chronic lymphocytic leukemia (CLL) to diffuse large B-cell lymphoma (DLBCL) and in CLL patients with no skin manifestations

European Journal of Haematology, 2011

Richter&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;... more Richter&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s transformation of B-cell chronic lymphocytic leukemia (CLL) to cutaneous diffuse large B-cell lymphoma (DLBCL) is very rare. We took the advantage of one of these cases to test the hypothesis that the chemokine receptor CCR4 is involved in the homing of CLL cells to skin. We evaluated CCR4 expression by flow cytometry in both circulating and skin CD19(+) leukemic cells from a patient with cutaneous DLBCL. As controls, we used peripheral blood samples from CLL patients without skin manifestations and from elderly healthy donors. We found that both DLBCL cells derived from the original CLL clone and circulating CLL cells from this patient expressed CCR4. Although it was previously reported that CCR4 is not expressed in CLL cells, we found that a low but significant proportion of leukemic cells from CLL patients with no skin manifestations do express CCR4. There was a positive correlation between the expression of CCR4 and the percentage of ZAP-70 of each sample. Moreover, we consistently observed a higher expression of CCR4 within CD19(+)CD38(+) and CD19(+)Ki67(+) subsets compared to CD19(+)CD38(-) and CD19(+)Ki67(-) lymphocytes from the same sample, respectively. We conclude that the chemokine receptor CCR4 is not a special feature of CLL cells with skin manifestation, but rather it is expressed in a low but significant proportion of peripheral blood CLL cells.

Research paper thumbnail of High expression of AID and active class switch recombination might account for a more aggressive disease in unmutated CLL patients: link with an activated microenvironment in CLL disease

Blood, 2010

Interaction of chronic lymphocytic leukemia (CLL) B cells with tissue microenvironment has been s... more Interaction of chronic lymphocytic leukemia (CLL) B cells with tissue microenvironment has been suggested to favor disease progression by promoting malignant B-cell growth. Previous work has shown expression in peripheral blood (PB) of CLL B cells of activation-induced cytidine deaminase (AID) among CLL patients with an unmutated (UM) profile of immunoglobulin genes and with ongoing class switch recombination (CSR) process. Because AID expression results from interaction with activated tissue microenvironment, we speculated whether the small subset with ongoing CSR is responsible for high levels of AID expression and could be derived from this particular microenvironment. In this work, we quantified AID expression and ongoing CSR in PB of 50 CLL patients and characterized the expression of different molecules related to microenvironment interaction. Our results show that among UM patients (1) high AID expression is restricted to the subpopulation of tumoral cells ongoing CSR; (2) this small subset expresses high levels of proliferation, antiapoptotic and progression markers (Ki-67, c-myc, Bcl-2, CD49d, and CCL3/4 chemokines). Overall, this work outlines the importance of a cellular subset in PB of UM CLL patients with a poor clinical outcome, high AID levels, and ongoing CSR, whose presence might be a hallmark of a recent contact with the microenvironment.