Biology subjects

Gerby, B.

Publications and source records attributed to Gerby, B..

5 recordsLinked to original sources

bioRxiv2026

USP7 maintains hematopoietic stem cell dormancy and function by stabilizing HMGA2

Hematopoietic stem cell (HSC) longevity critically depends on maintaining a deep dormant state, yet the molecular mechanisms that preserve this rare and functionally essential population remain poorly understood. Here, we identify the deubiquitinase USP7 as a key regulator of long-term HSC dormancy. Using a Usp7+/- mouse model, we uncover selective depletion of hematopoietic stem and progenitor cells (HSPCs), which is associated with impaired long-term repopulation capacity. Strikingly, H2B-GFP label-retention assays reveal a profound loss of dormant HSCs in Usp7+/- mice, demonstrating a failure to maintain the most quiescent stem cell fraction in vivo. Consistently, single-cell RNA sequencing shows erosion of the transcriptional dormancy program, linking USP7 activity to the preservation of stem cell identity at both functional and molecular levels. Mechanistically, ultra-low-input proteomic profiling and biochemical approaches identify HMGA2 as a novel USP7 substrate, suggesting that ubiquitin-dependent regulation of chromatin architecture contributes to the control of HSC dormancy. Together, our findings establish USP7 as a critical regulator of HSC dormancy, revealing a previously unrecognized post-translational mechanism controlling stem cell longevity, with implications for aging, regeneration, and hematopoietic disorders.

cell biology↗

bioRxiv2025

Targeting glucocorticoid-induced CD20 activation in preclinical models of B-ALL

Pediatric B-cell acute lymphoblastic leukemia (B-ALL) is effectively controlled with contemporary multi-agent chemotherapy, resulting to 5-year survival rates above 90%. However, relapse occurs in 15-20% of patients due to minimal residual disease (MRD), characterized by the presence of persisting and resistant leukemic cells, and associated with a poor clinical outcome. Despite its prognostic relevance, the molecular features driving MRD are poorly characterized. In this study, we developed patient-derived xenograft (PDX) models from matched diagnosis and relapse B-ALL samples combined to chemotherapy to mimic MRD in vivo. Drug-tolerant leukemic cells were profiled using single-cell RNA sequencing and we identified a transcriptionally distinct MRD-like population enriched for cell-quiescence, inflammatory stress, and B-cell receptor pathway signatures. Strikingly, the B-lymphocyte surface antigen CD20, encoding by MS4A1 gene, emerged as a consistent upregulated marker in MRD cells from PDXs and patients with diverse oncogenic subtypes. We further demonstrated that CD20 expression is induced by glucocorticoid exposure, creating a therapeutic opportunity where anti-CD20 monoclonal antibodies selectively eradicated MRD cells in vivo. Our data highlight CD20 not only as a biomarker but as an actionable vulnerability in B-ALL MRD, supporting clinical evaluation of anti-CD20 immunotherapy during induction treatment to kill drug-resistant cells and reduce relapse risk.

cancer biology↗

bioRxiv2025

Signals from the bone marrow B cell niches shape pre-leukemic fate in murine B cell acute lymphoblastic leukemia

The bone marrow (BM) microenvironment plays a key role in supporting B cell development. In acute lymphoblastic leukemia (B-ALL), the acquisition of oncogenic driver mutations blocks B cell differentiation at specific stages. When these pre-leukemic cells acquire secondary mutations, B-ALL develops. However, the role of the BM microenvironment in pre-leukemic cell fate remains unknown. Here, using a murine model of spontaneous B-ALL development, we show that disrupted pre-BCR signaling in pre-leukemic cells modifies their fate. Blocking expression of the pre-BCR ligand Galectin-1 by the microenvironment impaired pre-leukemic cell proliferation and leukemia-initiating capacity. Consequently, B-ALL development was delayed, and B-ALL had a more mature phenotype, with cells expressing a BCR. Secondary mutations were also altered by changes to Galectin-1 expression, in its absence mutations almost exclusively affected IL-7R signaling rather than both pre-BCR and IL-7R signaling. These results show that signals from BM niches can directly influence pre-leukemic B cell fate.

cancer biology↗

bioRxiv2025

Trogocytosis-mediated transfer of FOLR2 from Nurse-like cells to CLL cells is linked to their activation and proliferation

Communication with the lymphoid microenvironment is crucial for survival and proliferation of neoplastic B cells in chronic lymphocytic leukemia (CLL). In this study, we examined nurse-like cells (NLCs), CLL-specific macrophages, strongly implicated in CLL pathogenesis, and their interaction with leukemic cells. Using primary patient cells, we demonstrated that NLCs express high levels of folate receptor beta (FOLR2), which correlates with increased survival of cancer cells in vitro. Furthermore, we discovered that CLL cells acquire functional FOLR2 from NLCs via trogocytosis, enhancing their folate uptake. By mimicking the CLL microenvironment with soluble factors, CD40L and IL-15, we observed a strong NLC-dependent CLL cell activation and proliferation. Moreover, we linked this phenomenon with trogocytosis, by demonstrating that FOLR2+ CLL cells are the predominant population of actively cycling cancer cells. By multiplex immunofluorescence analysis of CLL patient lymph nodes, we confirmed the presence of FOLR2 NLCs, and observed their enrichment in more aggressive and proliferative CLL cases. Finally, we detected FOLR2 cancer cells, providing evidence of trogocytosis in situ. Taken together, we propose FOLR2 as a novel marker of protective NLCs, and highlight the importance of trogocytosis in improved CLL cell adaptation, including NLC-mediated activation and proliferation. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=58 SRC="FIGDIR/small/630890v3_ufig1.gif" ALT="Figure 1"> View larger version (22K): org.highwire.dtl.DTLVardef@1cde6d6org.highwire.dtl.DTLVardef@ee0f67org.highwire.dtl.DTLVardef@1355cb3org.highwire.dtl.DTLVardef@590b29_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOScheme 1.C_FLOATNO Schematic representation of trogocytosis-mediated acquisition of NLC-derived FOLR2 by CLL cells, and its impact on promoting cancer cell adaptability to folate deprivation. 1) CLL cells enter the lymph node (LN) and engage in contact with FOLR2+ NLCs. 2) The presence of T cell- and stromal cell-derived cytokines, CD40L and IL-15 promotes the activation and trogocytosis-mediated acquisition of FOLR2 by CLL cells. 3) FOLR2 trogocytic CLL cells have an advantage in folate acquisition and show increased proliferation compared to the remaining population of cancer cells C_FIG SUMMARYO_LICLL cells acquire functional FOLR2 from NLCs via trogocytosis, a process that is closely linked with enhanced CLL cell activation and proliferation in vitro C_LIO_LIIncreased Frequency of FOLR2 expressing macrophages in more aggressive and proliferative cases of CLL. C_LIO_LIFOLR2 is a marker of M2-like protective NLCs in vitro C_LI

cancer biology↗

bioRxiv2023

Loss of HSC stemness identity is associated with exhaustion and hyporesponsiveness in GATA2 deficiency syndrome

Germline GATA2 mutations lead to a syndrome involving both immunodeficiency and myeloid malignancies. Since GATA2 is a key player in hematopoietic initiation and development, we specify the impact of these germline mutations on hematopoietic homeostasis by generated a knock-in mouse model expressing the recurrent Gata2 R396Q missense mutation. These mice exhibit a hematopoietic stem and progenitor cell (HSPC) compartment profoundly impacted with increased HSC number, decreased self-renewal potential and inability to respond to acute inflammatory stimuli. Moreover, mutated HSPCs are predisposed to be hyporesponsive, as evidenced by lower interferon signaling and enrichment of inflammatory stress signatures. Furthermore, a Gata2 allelic specific expression results in a molecular and functional heterogeneity of the mutated Long Term-HSC population. Altogether, we highlight that Gata2 plays a crucial role in the ability of HSCs to perceive and respond to their environment, and that germline mutation contributes to the decline in HSC functionality.

cell biology↗