Biology subjects

Allemand, E.

Publications and source records attributed to Allemand, E..

5 recordsLinked to original sources

bioRxiv2025

Base editing of β0 thalassemia mutations as a therapeutic strategy for β-hemoglobinopathies: efficacy and genotoxicity studies

Gene therapy has emerged as a promising curative treatment for {beta}-hemoglobinopathies, the most common genetic disorders worldwide. However, current approved approaches still have some limitations in terms of safety and efficacy. Here, we used highly processive adenine base editors (ABE) variants to precisely correct some of the most prevalent and severe {beta}-thalassemia-causing mutations in the {beta}-globin gene. Efficient editing of hematopoietic stem/progenitor cells (HSPCs) led to potent {beta}-globin expression in their erythroid progeny and persistent correction of both {beta}-thalassemia and sickle cell-{beta}-thalassemia phenotypes. Safety of this strategy was confirmed in HSPCs in vitro and in vivo by the absence of gene dysregulation or any meaningful impact on the DNA mutational burden, the RNA deamination level, the {beta}-globin gene locus integrity and the clonality of the HSPC graft. Overall, base editing-mediated gene correction is a safe and effective strategy for treating {beta}-hemoglobinopathies. One sentence summaryPreclinical safety and efficacy studies of a new gene therapy approach for patients with severe {beta}-hemoglobinopathies.

genetics↗

bioRxiv2025

Identification of CaVβ1 isoforms required for neuromuscular junction formation and maintenance

Voltage-gated Ca{superscript 2} channels (VGCCs) are regulated by four CaV{beta} subunits (CaV{beta}1-CaV{beta}4), each showing specific expression patterns in excitable cells. While primarily known for regulating VGCC function, CaV{beta} proteins also have channel-independent roles, including gene expression modulation. Among these, CaV{beta}1 is expressed in skeletal muscle as multiple isoforms. The adult isoform, CaV{beta}1D, localizes at the triad and modulates CaV1 activity during Excitation-Contraction Coupling (ECC). In this study, we investigated the lesser-known embryonic/perinatal CaV{beta}1 isoforms and their roles in neuromuscular junction (NMJ) formation, maturation, and maintenance. We found that CaV{beta}1 isoform expression is developmentally regulated through differential promoter activation. Specifically, CaV{beta}1A is expressed in embryonic muscle and reactivated in denervated adult muscle, alongside the known CaV{beta}1E isoform. Nerve injury in adult muscle triggers a shift in promoter usage, resulting in re-expression of embryonic/perinatal Cacnb1A and Cacnb1E transcripts. Functional analyses using aneural agrin-induced AChR clustering on primary myotubes demonstrated that these isoforms contribute to NMJ formation. Additionally, their expression during early postnatal development is essential for NMJ maturation and long-term maintenance. These findings reveal previously unrecognized roles of CaV{beta}1 isoforms beyond VGCC regulation, highlighting their significance in neuromuscular system development and homeostasis.

physiology↗

bioRxiv2024

VEXAS anemia is a mosaic erythroblastopenia

VEXAS (vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic) is a recently discovered autoinflammatory disorder linked to somatic mutations in the UBA1 gene, resulting in a profound cytoplasm-restricted defect in ubiquitylation. The disease is characterized by a macrocytic anemia that remains poorly understood. To investigate the erythroid lineage in VEXAS, we conducted a comprehensive study combining in vivo assessments of patients mature red cells and marrow erythroblasts, alongside in vitro base-editing models of erythropoiesis. Here we show that mature red cells do not exhibit ubiquitylation defects, and patient-derived bone marrow erythroblasts lack UBA1 mutations beyond the basophilic stage of erythroid differentiation. In vitro base editing of UBA1 variants in CD34+ primary cells resulted in high mortality during early erythroid differentiation, but not during monocytic differentiation. Edited erythroid precursors displayed TP53 overexpression linked to defective ubiquitylation and anomalies in ribosome biogenesis, reminiscent of Diamond-Blackfan anemia. We propose that VEXAS-associated anemia should be considered as a mosaic erythroblastopenia, where the severity of anemia is influenced by the quality and quantity of the UBA1-WT compartment. These insights may aid clinicians in tailoring treatment strategies.

cell biology↗

bioRxiv2022

Transcriptional units form the elementary constraining building blocks of the bacterial chromosome

Transcription generates local topological and mechanical constraints along the DNA fiber, driving for instance the generation of supercoiled chromosomal domains in bacteria. However, the global impact of transcription-based regulation of chromosome organization remains elusive. Notably, the scale of genes and operons in bacteria remains well below the resolution of chromosomal contact maps generated using Hi-C (~ 5 - 10 kb), preventing to resolve the impact of transcription on genomic organization at the fine-scale. Here, we combined sub-kb Hi-C contact maps and chromosome engineering to visualize individual transcriptional units (TUs) while turning off transcription across the rest of the genome. We show that each TU forms a discrete, transcription-induced 3D domain (TIDs). These local structures impose mechanical and topological constraints on their neighboring sequences at larger scales, bringing them closer together and restricting their dynamics. These results show that the primary building blocks of bacteria chromosome folding consists of transcriptional domains that together shape the global genome structure.

microbiology↗

bioRxiv2019

An RNA-binding protein secreted by Listeria monocytogenes activates RIG-I signaling

Recent studies have reported on the presence of bacterial RNA within or outside extracellular membrane vesicles, possibly as ribonucleoprotein complexes. Proteins that bind and stabilize bacterial RNAs in the extracellular environment have not been reported. Here, we show that the bacterial pathogen Listeria monocytogenes secretes a small RNA binding protein that we named Zea. We show that Zea binds and stabilizes a subset of L. monocytogenes RNAs causing their accumulation in the extracellular medium. Furthermore, Zea binds RIG-I, the vertebrate non-self-RNA innate immunity sensor and potentiates RIG-I-signaling leading to interferon {beta} production. By performing in vivo infection, we finally show that Zea modulates L. monocytogenes virulence. Together, this study reveals that bacterial extracellular RNAs and RNA binding proteins can affect the host-pathogen crosstalk.

cell biology↗