Biology subjects

Talbot, L.

Publications and source records attributed to Talbot, L..

4 recordsLinked to original sources

bioRxiv2025

Senolytics Restore Hematopoietic Stem Cells Function in Sickle Cell Disease

Sickle Cell Disease (SCD) is a blood disorder affecting millions worldwide. Emerging evidence reveals that SCD pathophysiology increases risk of myeloid malignancies and hematopoietic stem cell (HSC) dysfunction, possibly due to pathological stress on bone marrow. To investigate this further, we interrogated mice and individuals with SCD and observed extended cell cycle times, oxidative stress, DNA damage, senescence, and dysregulation of molecular programs associated with these processes in bone marrow hematopoietic stem and progenitor cells (HSPCs). Human SCD HSPCs displayed poor hematopoietic potential ex vivo. SCD mice displayed a dramatic loss of transplantable bone marrow HSPCs, which was reversed upon treatment of SCD mice with the senolytic agent, ABT-263 (navitoclax). Thus, senolytics restore bone marrow function during SCD in mice and represent a novel strategy to improve bone marrow health in individuals with SCD and improve the safety of potentially curative gene therapies that utilize autologous HSPCs from individuals with SCD.

cell biology↗

bioRxiv2025

Tunneling CARs: Increasing CAR T tumor infiltration through the overexpression of MMP7 and SPP1

Chimeric antigen receptor T cell (CART) therapy has demonstrated remarkable efficacy in hematologic malignancies but has struggled to achieve comparable success in solid tumors. A key obstacle is the extracellular matrix (ECM) in solid tumors, which significantly impedes CART cell infiltration. In clinical trials, neuroblastoma (NB) has shown responsiveness to GD2-directed CART therapy, however, the failure of GD2.CARTs to effectively clear bulky disease - characterized by dense ECM - highlights the critical challenge of infiltration. In this study, we demonstrate that GD2.CARTs exhibit a unique infiltration-restriction compared to other CARTs and endogenous T cells. A separate analysis of clinical datasets identified MMP7 and SPP1 (OPN) as candidate genes to improve the infiltration of GD2.CARTs as these were upregulated in tumor-infiltrating leukocytes. MMP-7 and OPN overexpression enhanced CART extravasation (p < .001) and interstitial movement (p < .05) in ECM-dense environments in vitro. Overexpression of either OPN (p < .0001) or MMP-7 (p < .001) improved tumor infiltration in a xenograft model of NB. This resulted in improved tumor control (94% reduction in tumor burden, p < .05) and a survival extension in OPN-GD2.CART treated mice compared to unmodified GD2.CARTs (median of 148 days, p < .05). OPN overexpression did not increase off-target infiltration into healthy tissues or promote tumor metastasis, highlighting its potential for safe therapeutic application. Our study provides a framework for further exploration of gene modifications to improve CART infiltration and efficacy in solid tumors and identifies SPP1 as a candidate gene to improve GD2.CART treatment of bulky tumors.

immunology↗

bioRxiv2022

Augmenting CAR NK cell Anti-tumor Activity by Synapse Tuning

Introductory ParagraphChimeric antigen receptor (CAR) technologies have been clinically implemented for the treatment of hematological malignancies; however, solid tumors remain resilient to CAR therapeutics1-3. Natural Killer (NK) cells may provide an optimal class of immune cells for CAR-based approaches due to their inherent anti-tumor functionality. We sought to tune CAR synapses in NK cells by adding an intracellular scaffolding protein binding site to the CAR. We employed a PDZ binding motif (PDZbm) that specifically binds Scribble4 resulting in additional scaffolding crosslinking to enhance synapse formation and cell polarization5,6. Combined effects of this novel CAR design resulted in increased effector cell functionality in vitro and in vivo. Synapse-tuned CAR-NK cells exhibited amplified synaptic strength, number and abundance of secreted cytokines, enhanced killing of tumor cells, and prolonged survival with tumor clearance in two solid tumor models. Thus, synapse tuning has the potential to improve the efficacy of CAR-based cell therapeutics.

immunology↗

bioRxiv2022

Structure-function-dynamics relationships in the peculiar Planktothrix PCC7805 OCP1: impact of his-tagging and carotenoid type.

The orange carotenoid protein (OCP) is a photoactive protein involved in cyanobacterial photoprotection. Here, we report on the functional, spectral and structural characteristics of the peculiar Planktothrix PCC7805 OCP (Plankto-OCP). We show that this OCP variant is characterized by higher photoactivation and recovery rates, and a stronger energy-quenching activity, compared to other OCP studied thus far. We characterize the effect of the functionalizing carotenoid and of his-tagging on these reactions, and identify the time scales on which these modifications affect photoactivation. The presence of a his-tag at the C-terminus has a large influence on photoactivation, thermal recovery and PBS-fluorescence quenching, and likewise for the nature of the carotenoid that additionally affects the yield and characteristics of excited states and the ns-s dynamics of photoactivated OCP. By solving the structures of Plankto-OCP in the ECN- and CAN-functionalized states, each in two closely-related crystal forms, we further unveil the molecular breathing motions that animate Plankto-OCP at the monomer and dimer levels. We finally discuss the structural changes that could explain the peculiar properties of Plankto-OCP. HighlightsO_LIComplete functional characterization of Synechocystis and Planktothrix OCP C_LIO_LIHitherto unknown structures of ECN- and CAN-functionalized Planktothrix OCP C_LIO_LIInsights into fs-s timescale photodynamics of ECN- and CAN-functionalized Synechocystis and Planktothrix OCP C_LI

biophysics↗