Pub Date : 2025-11-28DOI: 10.1016/j.exphem.2025.105330
Rajdeep Roy , Tamalika Paul , Pritam Kumar Das , Samraj Sinha , Siddhartha Sankar Ray , Maitreyee Bhattacharyya , Nabendu Biswas
Drug resistance remains a critical barrier in effective cancer therapy. Previously, we demonstrated that expression of antiapoptotic protein (X‐linked inhibitor of apoptosis protein [XIAP]), contributes to the development of TRAIL resistance in chronic myeloid leukemia (CML) cells. However, upon acquiring drug resistance (K562R and KCL22R), XIAP degradation shifted from the lysosomal to the proteasomal pathway. Consistently, XIAP expression was markedly elevated in tumor samples compared with normal controls and was significantly higher in patients with an imatinib failure (IMA-FL) than in their counterparts who were imatinib responsive (IMA-RP) within the patient cohort. Moreover, we have found that proteasomal activity increased in imatinib-resistant cells and lysosomal pathway is inhibited. Mechanistically, we found that H₂O₂-induced activation of the ERK-mTOR axis suppressed autophagy in resistant cells, facilitating this shift in degradation pathway. Interestingly, dual intervention by restoring autophagic flux via mTOR inhibition and inducing XIAP degradation using H2O2 reverted imatinib resistance in K562R cells. Thus, our findings uncover a novel ERK–mTOR–axis for upregulation of proteasomal degradation of XIAP, which could be targeted to overcome imatinib resistance by combinatorial inhibition of mTOR and XIAP in CML. This study holds the promise of a new therapeutic strategy for overcoming drug resistance in cancer.
{"title":"ERK-mTOR crosstalk suppresses autophagy and upregulates proteasomal degradation pathway to confer chronic myeloid leukemia cells resistant to imatinib","authors":"Rajdeep Roy , Tamalika Paul , Pritam Kumar Das , Samraj Sinha , Siddhartha Sankar Ray , Maitreyee Bhattacharyya , Nabendu Biswas","doi":"10.1016/j.exphem.2025.105330","DOIUrl":"10.1016/j.exphem.2025.105330","url":null,"abstract":"<div><div>Drug resistance remains a critical barrier in effective cancer therapy. Previously, we demonstrated that expression of antiapoptotic protein (X‐linked inhibitor of apoptosis protein [XIAP]), contributes to the development of TRAIL resistance in chronic myeloid leukemia (CML) cells. However, upon acquiring drug resistance (K562R and KCL22R), XIAP degradation shifted from the lysosomal to the proteasomal pathway. Consistently, XIAP expression was markedly elevated in tumor samples compared with normal controls and was significantly higher in patients with an imatinib failure (IMA-FL) than in their counterparts who were imatinib responsive (IMA-RP) within the patient cohort. Moreover, we have found that proteasomal activity increased in imatinib-resistant cells and lysosomal pathway is inhibited. Mechanistically, we found that H₂O₂-induced activation of the ERK-mTOR axis suppressed autophagy in resistant cells, facilitating this shift in degradation pathway. Interestingly, dual intervention by restoring autophagic flux via mTOR inhibition and inducing XIAP degradation using H<sub>2</sub>O<sub>2</sub> reverted imatinib resistance in K562R cells. Thus, our findings uncover a novel ERK–mTOR–axis for upregulation of proteasomal degradation of XIAP, which could be targeted to overcome imatinib resistance by combinatorial inhibition of mTOR and XIAP in CML. This study holds the promise of a new therapeutic strategy for overcoming drug resistance in cancer.</div></div>","PeriodicalId":12202,"journal":{"name":"Experimental hematology","volume":"154 ","pages":"Article 105330"},"PeriodicalIF":2.1,"publicationDate":"2025-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145647657","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-19DOI: 10.1016/j.exphem.2025.105327
Ling Ling , Jiawen Huang , Zhichen Dai , Lan Yang , Fan Yang , Fangyu Gong , Xinhui Qiu , Mengying Lv , Fangfang Wang , Jingyan Liang , Sheng He , Duonan Yu
The 3′ untranslated region (3′UTR) of mRNA is crucial for post-transcriptional gene regulation, primarily through miRNAs. However, the overall role of the Gata1 3′UTR in mammals remains unclear. In this study, we knocked out the Gata1 3′UTR and observed a defect in erythropoiesis in mutant mice, evidenced by macrocytic anemia at baseline. The deletion of the Gata1 3′UTR also caused deficiencies in erythropoiesis within fetal livers. Mechanistically, removing the Gata1 3′UTR destabilizes Gata1 mRNA, leading to decreased levels of Gata1 protein. This reduced stability results from the dissociation of AU-rich elements in the 3′UTR from a trans-acting factor called ELAV-like family 1 (ELAVL1). Specifically, we conducted an RNA pulldown assay followed by mass spectrometry to identify proteins that bind to the Gata1 3′UTR. Gene Ontology analysis revealed that Elavl1 is a binding partner across nearly all categories related to mRNA stabilization. Western blotting, RNA immunoprecipitation, and mutagenesis assays confirmed the direct interaction between the Gata1 3′UTR and Elavl1. Modulating Elavl1 activity or protein levels with the small molecule inhibitor dihydro-tanshinone-I, or through ectopic expression in erythroid cells, validated Elavl1 as a stabilizing factor for Gata1 mRNA. Our results highlight the important role of the Gata1 mRNA 3′UTR in erythroid development.
{"title":"Mouse Gata1 3′UTR modulates Gata1 levels to affect erythropoiesis","authors":"Ling Ling , Jiawen Huang , Zhichen Dai , Lan Yang , Fan Yang , Fangyu Gong , Xinhui Qiu , Mengying Lv , Fangfang Wang , Jingyan Liang , Sheng He , Duonan Yu","doi":"10.1016/j.exphem.2025.105327","DOIUrl":"10.1016/j.exphem.2025.105327","url":null,"abstract":"<div><div>The 3<em>′</em> untranslated region (<em>3′UTR</em>) of mRNA is crucial for post-transcriptional gene regulation, primarily through miRNAs. However, the overall role of the <em>Gata1 3′UTR</em> in mammals remains unclear. In this study, we knocked out the <em>Gata1 3′UTR</em> and observed a defect in erythropoiesis in mutant mice, evidenced by macrocytic anemia at baseline. The deletion of the <em>Gata1 3′UTR</em> also caused deficiencies in erythropoiesis within fetal livers. Mechanistically, removing the <em>Gata1 3′UTR</em> destabilizes <em>Gata1</em> mRNA, leading to decreased levels of Gata1 protein. This reduced stability results from the dissociation of AU-rich elements in the <em>3′UTR</em> from a trans-acting factor called ELAV-like family 1 (ELAVL1). Specifically, we conducted an RNA pulldown assay followed by mass spectrometry to identify proteins that bind to the <em>Gata1 3′UTR</em>. Gene Ontology analysis revealed that Elavl1 is a binding partner across nearly all categories related to mRNA stabilization. Western blotting, RNA immunoprecipitation, and mutagenesis assays confirmed the direct interaction between the <em>Gata1 3′UTR</em> and Elavl1. Modulating Elavl1 activity or protein levels with the small molecule inhibitor dihydro-tanshinone-I, or through ectopic expression in erythroid cells, validated Elavl1 as a stabilizing factor for <em>Gata1</em> mRNA. Our results highlight the important role of the <em>Gata1</em> mRNA 3<em>′</em>UTR in erythroid development.</div></div>","PeriodicalId":12202,"journal":{"name":"Experimental hematology","volume":"154 ","pages":"Article 105327"},"PeriodicalIF":2.1,"publicationDate":"2025-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145573460","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-19DOI: 10.1016/j.exphem.2025.105326
Kavita Bisht, Valérie Barbier, Svetlana Shatunova, Ingrid G. Winkler, Jean-Pierre Lévesque
Stem cell antigen-1 (SCA1) is widely used to identify mouse hematopoietic stem cells (HSCs) and multipotent progenitors (MPPs) among lineage-negative KIT+ (LK) cells. However, SCA1 is expressed only in a few inbred mouse strains and becomes strongly upregulated in LK cells following in vivo challenge with interferons, lipopolysaccharide (LPS), or pathogens, leading to incorrect analysis of HSC functional subsets and delineation of HSC, MPP, and lineage-restricted progenitor phenotypes. Endothelial protein C receptor CD201 can be used as an alternative marker for mouse and even human HSC. However, whether CD201 expression changes following infectious challenge is unknown. Unlike SCA1, CD201 expression did not change on mouse LK cells in response to LPS in vivo. Long-term competitive transplantations with CD201+, CD201−, or SCA1+ LK cells showed that most reconstituting HSCs are within the LK CD201+ population after LPS challenge. However, the long-term competitive repopulation potential of LK SCA1+ cells from LPS-treated mice was much more severely reduced than that of LK CD201+ cells from the same LPS-treated donors, suggesting that the LK SCA1+ population in challenged donors becomes contaminated with CD201− progenitors devoid of long-term repopulation potential. Based on the CD201 gating strategy, we reassessed the effect of LPS on HSC and MPP cycling and mobilization and their dependency on MY88 and TRIF adaptors. In conclusion, CD201 enables a more accurate analysis of mouse HSC and MPP subsets in all inbred strains in septic conditions or steady state.
{"title":"Endothelial protein C receptor CD201 is a better marker than stem cell antigen-1 to identify mouse long-term reconstituting hematopoietic stem cells following septic challenge","authors":"Kavita Bisht, Valérie Barbier, Svetlana Shatunova, Ingrid G. Winkler, Jean-Pierre Lévesque","doi":"10.1016/j.exphem.2025.105326","DOIUrl":"10.1016/j.exphem.2025.105326","url":null,"abstract":"<div><div>Stem cell antigen-1 (SCA1) is widely used to identify mouse hematopoietic stem cells (HSCs) and multipotent progenitors (MPPs) among lineage-negative KIT<sup>+</sup> (LK) cells. However, SCA1 is expressed only in a few inbred mouse strains and becomes strongly upregulated in LK cells following in vivo challenge with interferons, lipopolysaccharide (LPS), or pathogens, leading to incorrect analysis of HSC functional subsets and delineation of HSC, MPP, and lineage-restricted progenitor phenotypes. Endothelial protein C receptor CD201 can be used as an alternative marker for mouse and even human HSC. However, whether CD201 expression changes following infectious challenge is unknown. Unlike SCA1, CD201 expression did not change on mouse LK cells in response to LPS in vivo. Long-term competitive transplantations with CD201<sup>+</sup>, CD201<sup>−</sup>, or SCA1<sup>+</sup> LK cells showed that most reconstituting HSCs are within the LK CD201<sup>+</sup> population after LPS challenge. However, the long-term competitive repopulation potential of LK SCA1<sup>+</sup> cells from LPS-treated mice was much more severely reduced than that of LK CD201<sup>+</sup> cells from the same LPS-treated donors, suggesting that the LK SCA1<sup>+</sup> population in challenged donors becomes contaminated with CD201<sup>−</sup> progenitors devoid of long-term repopulation potential. Based on the CD201 gating strategy, we reassessed the effect of LPS on HSC and MPP cycling and mobilization and their dependency on MY88 and TRIF adaptors. In conclusion, CD201 enables a more accurate analysis of mouse HSC and MPP subsets in all inbred strains in septic conditions or steady state.</div></div>","PeriodicalId":12202,"journal":{"name":"Experimental hematology","volume":"154 ","pages":"Article 105326"},"PeriodicalIF":2.1,"publicationDate":"2025-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145573449","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-07DOI: 10.1016/j.exphem.2025.105288
Adela S. Cellucci , Danila B. Yañuk , Paola R. Lev , Ana C. Glembotsky , Nora P. Goette , María C. Lira , Geraldine De Luca , Laureano J. Kamiya , Paula G. Heller , Rosana F. Marta
Cytoreductive treatment is a main strategy to reduce thrombotic complications and ameliorate symptoms in Phi-negative myeloproliferative neoplasms (MPNs) comprising essential thrombocythemia, polycythemia vera, and primary myelofibrosis. Based on the observation of differences in platelet size during microscopic analysis of blood smears from MPN patients, in this work we studied whether these differences could be dependent on the type of cytoreductive drug used for patients’ treatment and whether changes in platelet size could be induced by the effect of these drugs on thrombopoiesis. Maximum platelet diameter (MPD) was measured in 120 patients with MPN. The effect of drugs on thrombopoiesis was evaluated in normal megakaryocytes (MKs) obtained from cord blood–derived CD34+ hematopoietic progenitors. Anagrelide (ANA), α-interferon (IFN), and ruxolitinib (Ruxo) increased, whereas hydroxyurea (HU) decreased platelet size. MK incubation with these drugs revealed that ANA and IFN induced abnormal proplatelet (PP) architecture and affected microtubular structure, but only ANA altered actin organization, whereas neither Ruxo nor HU modified MK cytoskeleton. By bioinformatic analysis, RANTES downregulation was identified as a candidate responsible for ANA-induced abnormalities. RANTES downregulation was confirmed in MK incubated with ANA but not with IFN. Addition of recombinant RANTES reverted ANA-induced cytoskeletal abnormalities. Evaluation of RANTES plasmatic levels and platelet RNA expression in patients with MPN showed RANTES decrease in both samples during ANA treatment, suggesting that in vitro findings could reflect ANA action in vivo. In conclusion, this study demonstrates the influence of cytoreductive drugs on platelet size and reveals their differential mechanisms of action during platelet production.
{"title":"Cytoreductive treatment differentially affects platelet size and cytoskeletal megakaryocyte organization during thrombopoiesis in myeloproliferative neoplasms","authors":"Adela S. Cellucci , Danila B. Yañuk , Paola R. Lev , Ana C. Glembotsky , Nora P. Goette , María C. Lira , Geraldine De Luca , Laureano J. Kamiya , Paula G. Heller , Rosana F. Marta","doi":"10.1016/j.exphem.2025.105288","DOIUrl":"10.1016/j.exphem.2025.105288","url":null,"abstract":"<div><div>Cytoreductive treatment is a main strategy to reduce thrombotic complications and ameliorate symptoms in Phi-negative myeloproliferative neoplasms (MPNs) comprising essential thrombocythemia, polycythemia vera, and primary myelofibrosis. Based on the observation of differences in platelet size during microscopic analysis of blood smears from MPN patients, in this work we studied whether these differences could be dependent on the type of cytoreductive drug used for patients’ treatment and whether changes in platelet size could be induced by the effect of these drugs on thrombopoiesis. Maximum platelet diameter (MPD) was measured in 120 patients with MPN. The effect of drugs on thrombopoiesis was evaluated in normal megakaryocytes (MKs) obtained from cord blood–derived CD34+ hematopoietic progenitors. Anagrelide (ANA), α-interferon (IFN), and ruxolitinib (Ruxo) increased, whereas hydroxyurea (HU) decreased platelet size. MK incubation with these drugs revealed that ANA and IFN induced abnormal proplatelet (PP) architecture and affected microtubular structure, but only ANA altered actin organization, whereas neither Ruxo nor HU modified MK cytoskeleton. By bioinformatic analysis, RANTES downregulation was identified as a candidate responsible for ANA-induced abnormalities. RANTES downregulation was confirmed in MK incubated with ANA but not with IFN. Addition of recombinant RANTES reverted ANA-induced cytoskeletal abnormalities. Evaluation of RANTES plasmatic levels and platelet RNA expression in patients with MPN showed RANTES decrease in both samples during ANA treatment, suggesting that <em>in vitro</em> findings could reflect ANA action <em>in vivo</em>. In conclusion, this study demonstrates the influence of cytoreductive drugs on platelet size and reveals their differential mechanisms of action during platelet production.</div></div>","PeriodicalId":12202,"journal":{"name":"Experimental hematology","volume":"153 ","pages":"Article 105288"},"PeriodicalIF":2.1,"publicationDate":"2025-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145476589","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-01DOI: 10.1016/j.exphem.2025.104924
Norika Liu , Atsushi Nakano
The cells that comprise the circulatory system not only share developmental origins but also mutually support each other’s differentiation during early embryogenesis. Although classical models attribute embryonic hematopoiesis in mammals to the yolk sac and aorta-gonad-mesonephros (AGM) region, we and others have identified the embryonic heart as a transient hematopoietic niche. A subset of endocardial cells in the outflow tract and atrioventricular canal undergo endothelial-to-hematopoietic transition (EHT) in an Nkx2-5-dependent manner, mirroring the tinman-regulated cardio-hematopoietic program in Drosophila. These hemogenic endocardial cells, enriched in the cushion region—the primordia of cardiac valves and septa—not only contribute to local hematopoiesis but also give rise to tissue macrophages that facilitate valve morphogenesis.
These findings challenge the traditional view of hematopoietic compartmentalization and establish a novel paradigm in which the heart itself contributes to hematopoietic development. Using lineage tracing and knockout mouse models, we further show that endocardial-derived macrophages persist into adulthood as tissue-resident macrophages, particularly within cardiac valves and vasculature. Functionally, these cells appear to modulate tissue homeostasis and suppress pathological fibrosis.
In summary, our study reveals that the embryonic heart acts as a local hematopoietic organ, supplying a distinct macrophage population that contributes to both cardiac morphogenesis and long-term homeostasis. These insights broaden our understanding of the interplay between hematopoiesis and cardiogenesis and suggest new avenues for investigating tissue-resident immune cell ontogeny.
{"title":"2011 – THE EMBRYONIC HEART AS A TRANSIENT HEMATOPOIETIC SITE FOR MACROPHAGE-MEDIATED CARDIAC REMODELING","authors":"Norika Liu , Atsushi Nakano","doi":"10.1016/j.exphem.2025.104924","DOIUrl":"10.1016/j.exphem.2025.104924","url":null,"abstract":"<div><div>The cells that comprise the circulatory system not only share developmental origins but also mutually support each other’s differentiation during early embryogenesis. Although classical models attribute embryonic hematopoiesis in mammals to the yolk sac and aorta-gonad-mesonephros (AGM) region, we and others have identified the embryonic heart as a transient hematopoietic niche. A subset of endocardial cells in the outflow tract and atrioventricular canal undergo endothelial-to-hematopoietic transition (EHT) in an Nkx2-5-dependent manner, mirroring the tinman-regulated cardio-hematopoietic program in Drosophila. These hemogenic endocardial cells, enriched in the cushion region—the primordia of cardiac valves and septa—not only contribute to local hematopoiesis but also give rise to tissue macrophages that facilitate valve morphogenesis.</div><div>These findings challenge the traditional view of hematopoietic compartmentalization and establish a novel paradigm in which the heart itself contributes to hematopoietic development. Using lineage tracing and knockout mouse models, we further show that endocardial-derived macrophages persist into adulthood as tissue-resident macrophages, particularly within cardiac valves and vasculature. Functionally, these cells appear to modulate tissue homeostasis and suppress pathological fibrosis.</div><div>In summary, our study reveals that the embryonic heart acts as a local hematopoietic organ, supplying a distinct macrophage population that contributes to both cardiac morphogenesis and long-term homeostasis. These insights broaden our understanding of the interplay between hematopoiesis and cardiogenesis and suggest new avenues for investigating tissue-resident immune cell ontogeny.</div></div>","PeriodicalId":12202,"journal":{"name":"Experimental hematology","volume":"151 ","pages":"Article 104924"},"PeriodicalIF":2.1,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145620047","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-01DOI: 10.1016/j.exphem.2025.104930
Alexandra Preston , Joe Frost , Megan Teh , Mohsin Badat , Andrew Armitage , Ruggiero Norfo , Sarah Wideman , Muhammad Hanifi , Natasha White , Noemi Roy , Christian Babbs , Bart Ghesquiere , James Davies , Andrew Howden , Linda Sinclair , Jim Hughes , Mira Kassouf , Robert Beagrie , Douglas Higgs , Hal Drakesmith
α-globin’s genomic next-door neighbor, Nprl3, contains 4 of the 5 α-globin enhancers. Nprl3 negatively regulates mTORC1, a master controller of cell metabolism. Nprl3, α-globin, and the α-globin enhancers have been colocated for >500 million years. However, the function of this genomic linkage is unknown.
Using a mouse in which the Nprl3 promoter is deleted (with no effect on the α-globin enhancers), we showed that Nprl3 is required for optimal erythropoiesis in fetal liver and bone marrow. On embryonic day 13.5 (E13.5) in the fetal liver, Nprl3−/− erythroid cells failed to develop beyond the proerythroblast stage. Metabolite profiling, RNA-Seq and proteomics showed that Nprl3−/− erythroblasts have overactivated mTORC1 signaling, overcharged glycolysis, and suppressed autophagy. Competitive bone marrow-fetal liver chimeras indicated a hematopoietic-intrinsic Nprl3 requirement for erythropoiesis. To study human erythropoiesis, we induced NPRL3-knockout by RNP-editing primary CD34+ cells. Edited progenitors produced fewer enucleated erythroid cells and exhibited defective mTORC1 signaling responses to fluctuating iron, amino acid, and erythropoietin (EPO) availability. Nprl3 tunes the metabolism of developing erythroid cells to their nutritional environment.
Nprl3 expression is highly elevated in erythroid cells. We showed that this is due to the interaction between the Nprl3 promoter and α-globin enhancers. We eliminated interactions (in cis) between Nprl3 and the enhancers, while maintaining enhancer control of α-globin. Remarkably, our approach resulted in erythropoietic impairment reminiscent of the Nprl3−/− genotype (with E13.5 erythroid development inhibited at the same stage of differentiation). Therefore, the ancient transcriptional hub of Nprl3, α-globin, and their enhancers supports the erythroid-specific upregulation of Nprl3 and coordinates metabolic control with red blood cell development.
{"title":"2017 – ANCIENT GENOMIC LINKAGE OF NPRL3 AND Α-GLOBIN COUPLES METABOLISM WITH ERYTHROID DEVELOPMENT","authors":"Alexandra Preston , Joe Frost , Megan Teh , Mohsin Badat , Andrew Armitage , Ruggiero Norfo , Sarah Wideman , Muhammad Hanifi , Natasha White , Noemi Roy , Christian Babbs , Bart Ghesquiere , James Davies , Andrew Howden , Linda Sinclair , Jim Hughes , Mira Kassouf , Robert Beagrie , Douglas Higgs , Hal Drakesmith","doi":"10.1016/j.exphem.2025.104930","DOIUrl":"10.1016/j.exphem.2025.104930","url":null,"abstract":"<div><div>α-globin’s genomic next-door neighbor, Nprl3, contains 4 of the 5 α-globin enhancers. Nprl3 negatively regulates mTORC1, a master controller of cell metabolism. Nprl3, α-globin, and the α-globin enhancers have been colocated for >500 million years. However, the function of this genomic linkage is unknown.</div><div>Using a mouse in which the Nprl3 promoter is deleted (with no effect on the α-globin enhancers), we showed that Nprl3 is required for optimal erythropoiesis in fetal liver and bone marrow. On embryonic day 13.5 (E13.5) in the fetal liver, Nprl3−/− erythroid cells failed to develop beyond the proerythroblast stage. Metabolite profiling, RNA-Seq and proteomics showed that Nprl3−/− erythroblasts have overactivated mTORC1 signaling, overcharged glycolysis, and suppressed autophagy. Competitive bone marrow-fetal liver chimeras indicated a hematopoietic-intrinsic Nprl3 requirement for erythropoiesis. To study human erythropoiesis, we induced NPRL3-knockout by RNP-editing primary CD34+ cells. Edited progenitors produced fewer enucleated erythroid cells and exhibited defective mTORC1 signaling responses to fluctuating iron, amino acid, and erythropoietin (EPO) availability. Nprl3 tunes the metabolism of developing erythroid cells to their nutritional environment.</div><div>Nprl3 expression is highly elevated in erythroid cells. We showed that this is due to the interaction between the Nprl3 promoter and α-globin enhancers. We eliminated interactions (in cis) between Nprl3 and the enhancers, while maintaining enhancer control of α-globin. Remarkably, our approach resulted in erythropoietic impairment reminiscent of the Nprl3−/− genotype (with E13.5 erythroid development inhibited at the same stage of differentiation). Therefore, the ancient transcriptional hub of Nprl3, α-globin, and their enhancers supports the erythroid-specific upregulation of Nprl3 and coordinates metabolic control with red blood cell development.</div></div>","PeriodicalId":12202,"journal":{"name":"Experimental hematology","volume":"151 ","pages":"Article 104930"},"PeriodicalIF":2.1,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145620065","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-01DOI: 10.1016/j.exphem.2025.104928
Lev Kats , Emily Gruber , Sree Kumar , Rheana Franich , Omer Gilan , Tiffany Khong , Andrew Spencer
Multiple myeloma (MM) is a common plasma cell malignancy that remains mostly incurable. We analyzed the Cancer Gene Dependency Map and identified menin as a therapeutically actionable MM vulnerability. Gene knockout and menin inhibitor (iMenin) therapy experiments across an extensive panel of MM cell lines confirmed that ∼20% are highly sensitive to menin disruption, with an additional ∼40% demonstrating a partial response. Similar findings were also made in a separate custom panel of early passage MM lines that more closely recapitulate genetic alterations found in patients with MM.
Gene expression and chromatin profiling studies in iMenin-sensitive, intermediate, and refractory MM lines identified the master myeloma cell identity factor IRF4 as the major downstream target of menin inhibition. iMenin-sensitive lines are characterized by abundant deposition of the menin/MLL1 complex at the super-enhancer of IRF4, with iMenin treatment resulting in eviction of menin/MLL1 from chromatin and concomitant suppression of IRF4 and its target genes. Interestingly, iMenin sensitivity in MM also correlates with transcriptional signatures of immature B cells that are, in turn, inversely correlated with response to many current treatments, especially those that target the B-cell maturation antigen (BCMA).
In parallel, we also applied genome-wide CRISPR screening, which implicated the CREBBP/EP300/NCOR1 axis as a key modulator of iMenin sensitivity. Notably, clinical-grade menin and EP300 inhibitors demonstrated synergistic activity against primary patients with MM samples cultured ex vivo and against the syngeneic Vk*MYC MM model in vivo. Molecular analysis revealed deep and synergistic suppression of IRF4 potentiated by the combination. Altogether, our comprehensive study identified menin as a promising target in MM and charts potential paths for rapid clinical translation.
{"title":"2015 – MENIN ORCHESTRATES EXPRESSION OF THE MASTER PLASMA CELL TRANSCRIPTION FACTOR IRF4 AND IS AN ACTIONABLE TARGET IN MULTIPLE MYELOMA.","authors":"Lev Kats , Emily Gruber , Sree Kumar , Rheana Franich , Omer Gilan , Tiffany Khong , Andrew Spencer","doi":"10.1016/j.exphem.2025.104928","DOIUrl":"10.1016/j.exphem.2025.104928","url":null,"abstract":"<div><div>Multiple myeloma (MM) is a common plasma cell malignancy that remains mostly incurable. We analyzed the Cancer Gene Dependency Map and identified menin as a therapeutically actionable MM vulnerability. Gene knockout and menin inhibitor (iMenin) therapy experiments across an extensive panel of MM cell lines confirmed that ∼20% are highly sensitive to menin disruption, with an additional ∼40% demonstrating a partial response. Similar findings were also made in a separate custom panel of early passage MM lines that more closely recapitulate genetic alterations found in patients with MM.</div><div>Gene expression and chromatin profiling studies in iMenin-sensitive, intermediate, and refractory MM lines identified the master myeloma cell identity factor IRF4 as the major downstream target of menin inhibition. iMenin-sensitive lines are characterized by abundant deposition of the menin/MLL1 complex at the super-enhancer of IRF4, with iMenin treatment resulting in eviction of menin/MLL1 from chromatin and concomitant suppression of IRF4 and its target genes. Interestingly, iMenin sensitivity in MM also correlates with transcriptional signatures of immature B cells that are, in turn, inversely correlated with response to many current treatments, especially those that target the B-cell maturation antigen (BCMA).</div><div>In parallel, we also applied genome-wide CRISPR screening, which implicated the CREBBP/EP300/NCOR1 axis as a key modulator of iMenin sensitivity. Notably, clinical-grade menin and EP300 inhibitors demonstrated synergistic activity against primary patients with MM samples cultured ex vivo and against the syngeneic Vk*MYC MM model in vivo. Molecular analysis revealed deep and synergistic suppression of IRF4 potentiated by the combination. Altogether, our comprehensive study identified menin as a promising target in MM and charts potential paths for rapid clinical translation.</div></div>","PeriodicalId":12202,"journal":{"name":"Experimental hematology","volume":"151 ","pages":"Article 104928"},"PeriodicalIF":2.1,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145620058","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-01DOI: 10.1016/j.exphem.2025.104922
Zining Yang, Hui Cheng, Tao Cheng, Can Li, Jingxuan Li, Ruixia Sun
The developmental transition from early embryonic hematopoiesis to adult bone marrow hematopoiesis is a complex process that remains poorly understood. In particular, the cellular composition and regulatory mechanisms of the microenvironment during the initial engraftment and establishment of hematopoietic stem cells (HSCs) in the bone marrow are unclear. Understanding these niche components is essential to reveal how hematopoiesis develops and adapts.
In this study, we identify a previously unrecognized population of mature mast cells transiently present across multiple hematopoietic organs—including liver, spleen, and bone marrow—during early bone marrow hematopoiesis in both humans and mice.
These mast cells display distinct molecular markers and mature granule morphology, indicating their functional activity. Using in vitro coculture experiments, we show that mast cells directly support HSC function through the secretion of serotonin (5-HT). Depletion of mast cells during the perinatal period leads to significantly reduced 5-HT levels in the spleen and a marked decrease in hematopoietic stem and progenitor cell (HSPC) numbers. This reveals a critical role for mast cell-derived serotonin in regulating early hematopoiesis. We also provide transcriptomic profiles of mast cells from neonatal mouse hematopoietic tissues, expanding the cross-tissue transcriptomic atlas of mouse mast cells and revealing specialized gene expression signatures linked to their developmental function.
Together, these findings have revealed the new role of mast cells in supporting hematopoiesis during specific developmental windows, highlighting their significance as microenvironment regulators in the early hematopoietic development of both humans and mice.
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Pub Date : 2025-11-01DOI: 10.1016/j.exphem.2025.104906
Florian Perner
The mixed lineage leukemia (KMT2A/MLL1) gene is critical for hematopoiesis, but its translocation drives aggressive, treatment-resistant leukemias in infants and adults. Although previous targeted strategies showed limited efficacy, the recent development of menin inhibitors, disrupting the KMT2A-menin interaction, demonstrated significant promise. However, therapeutic resistance to these menin inhibitors emerges rapidly under monotherapy, highlighting a critical challenge and the need for deeper molecular understanding to guide intervention. A critical distinction between this class of compounds and conventional chemotherapeutic agents or apoptosis-inducing drugs like venetoclax lies in their mechanism of action. Unlike these agents, which typically trigger rapid cell death, menin inhibitors do not induce immediate cytotoxicity. Instead, they alleviate the differentiation blockade by reprogramming aberrant oncogenic chromatin states. As a result, the time to achieve the best clinical response is prolonged, with leukemia cells persisting for weeks to months in both preclinical models and early-phase clinical trials. During this extended period of persistence, leukemia cells undergo a complex adaptive process, transitioning into a drug-tolerant persister state that enables them to withstand therapeutic pressure. Interestingly, the molecular signatures of these persister cells closely resemble those observed in drug-tolerant cancer cells across other tumor types, suggesting a conserved mechanism of cellular plasticity that transcends cancer subtypes and treatment modalities. In leukemia, this adaptive state is characterized by cellular dormancy and the emergence of transcriptional and immunophenotypic features indicative of myeloid differentiation. These findings underscore a significant clinical challenge: in this context, defining the tipping point between a cell retaining leukemogenic potential and a terminally differentiated cell in diagnostic assays becomes difficult, if not impossible. This ambiguity highlights the need for more precise biomarkers to monitor therapeutic responses and predict clinical outcomes in patients treated with menin inhibitors.
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