Biology subjects

Becker, L. J.

Publications and source records attributed to Becker, L. J..

4 recordsLinked to original sources

bioRxiv2025

Spared nerve injury induces long-term and brain region-specific changes in oligodendrocyte density in mice

BackgroundEmerging evidence suggests a role for non-neuronal cells in the pathophysiology of chronic pain. Chronic pain causes profound alterations of the transcriptomic program of oligodendroglia, but the effect of pain on the oligodendroglial cells themselves remains unknown. MethodsMale and female C57BL6/J mice underwent spared nerve injury (SNI). Mechanical hypersensitivity was assessed five weeks later using the von Frey test. Six weeks post-surgery, mice were perfused, brains dissected, and immunostained for oligodendrocyte precursors cells (OPC) and mature oligodendrocytes (OL) in four brain regions involved in pain chronification: anterior cingulate cortex (ACC), central amygdala (CeA), basolateral amygdala (BLA), and periaqueductal gray (PAG). ResultsWe found OL were reduced in the ACC and CeA of both sexes six weeks after SNI. Conversely, BLA OL were increased in both sexes following SNI. There was a sex-dependent effect of SNI on PAG-OL, where OL were only reduced in females. SNI did not affect OPC in any of the studied brain regions, but female PAG and BLA appeared to have fewer OPC than males independent of SNI. ConclusionLong-term nerve injury differentially affects OL in a brain region- and sex-dependent manner. This effect is observable six weeks after injury, suggesting a long-lasting impact of chronic pain on oligodendroglial cells. OPC, on the other hand, are remarkably stable. This finding aligns with previous literature showing OPC maintain homeostasis, even in pathological conditions. SignificanceOligodendrocytes ensheathe axons to increase conduction speed, stabilize neuronal connections, and fine-tune neuron-to-neuron communication. Furthermore, pharmacological stimulation of myelination improves pain-induced cognitive deficits in mice, suggesting therapeutic potential in targeting oligodendrocytes in pain. A better understanding of how pain impacts oligodendroglia is thus crucial to better understand the pathophysiology of pain and identify new therapeutic targets.

neuroscience↗

bioRxiv2025

Repurposing base editors for targeted knock-in and simultaneous knockouts to generate multiplex-edited allogeneic CAR T cells with minimal translocations

The CRISPR-Cas system enables precise genome engineering of cell therapies. For allogeneic applications, multiplex editing is frequently required to improve efficacy, persistence, and safety. However, strategies involving multiple DNA double-strand breaks (DSBs) induce genotoxicity by provoking chromosomal aberrations. Base editors, which enable sequence changes without generating DSBs, are widely used for gene disruption, but their capacity for gene insertion remains unexplored. Here, we developed Base editor-mediated knock-in (BEKI), a non-viral platform that allows targeted transgene insertion in parallel with multiplex gene disruption using a single base editor. Repurposing the Cas9 nickase domain of base editors generates paired nicks, inducing homology-directed repair (HDR). In human T cells, optimized guide RNA orientation and nick distance, together with HDR-enhancing modulators, enabled efficient transgene knock-in at the TRAC, CD3{zeta}, B2M, and CD3{varepsilon} loci. Simultaneous base editing of multiple additional genes produced chimeric antigen receptor (CAR) T cells with increased cytokine secretion, drug resistance, and resistance to allo-rejection. Compared to multiplex editing with Cas9, BEKI markedly reduced chromosomal translocations. BEKI therefore provides a streamlined, scalable strategy for multiplex CAR T-cell engineering with a single enzyme, offering a safer route to clinical-grade manufacturing of off-the-shelf therapies for cancer and autoimmune diseases. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=193 SRC="FIGDIR/small/676172v1_ufig1.gif" ALT="Figure 1"> View larger version (36K): org.highwire.dtl.DTLVardef@f5f6e5org.highwire.dtl.DTLVardef@246411org.highwire.dtl.DTLVardef@125a478org.highwire.dtl.DTLVardef@510278_HPS_FORMAT_FIGEXP M_FIG C_FIG

synthetic biology↗

bioRxiv2025

Maternal separation disrupts noradrenergic control of adult coping behaviors

Early life stress (ELS) in humans and preclinical rodent models profoundly impacts the brain and correlates with negative affective behaviors in adulthood. The locus coeruleus (LC), a stress-responsive brainstem nucleus that supplies most of the brain with norepinephrine (NE), is known to modulate negative affect. Here we used repeated maternal separation stress (MSS) to investigate the impact of ELS on the LC and stress-related behaviors in adulthood. Using ex vivo cell-attached electrophysiology, we recorded spontaneous LC firing across the lifespan from early development, pre-adolescence, adolescence, through adulthood. MSS significantly increased LC firing during early development and adulthood compared to No MSS mice. We next examined potential changes in the expression of genes linked to LC function. MSS decreased mRNA levels for both the alpha-2A adrenergic receptor and dopamine beta-hydroxylase, the enzyme necessary for NE synthesis. At the behavioral level, MSS increased locomotion in approach-avoidance exploratory assays and increased immobility in the forced swim test. Forced swim increased LC cFos expression, a marker for neuronal excitation, in both No MSS and MSS mice. However, MSS mice had significantly less cFos than No MSS controls. We then sought to reverse this MSS-induced increase in immobility by inhibiting the LC during the forced swim test. In No MSS mice, LC inhibition increased immobility time, however, LC inhibition did not affect MSS immobility. Together, this study demonstrates that MSS dysregulates LC-NE activity across the lifespan and disrupts the role of the LC in regulating coping strategies during stressful events.

neuroscience↗

bioRxiv2022

Neuropathic injury drives a generalized negative affective state in mice

Neuropathic pain causes both sensory and emotional maladaptation. Preclinical animal studies of neuropathic pain-induced negative affect could result in novel insights into the mechanisms of chronic pain. Modeling pain-induced negative affect, however, is variable across research groups and conditions. The same injury may or may not produce robust negative affective behavioral responses across different species, strains, and laboratories. Here we sought to identify negative affective consequences of the spared nerve injury model on C57BL/6J male and female mice. We found no significant effect of spared nerve injury across a variety of approach-avoidance, hedonic choice, and coping strategy assays. We hypothesized these inconsistencies may stem in part from the short test duration of these assays. To test this hypothesis, we used the homecage-based Feeding Experimentation Device version 3 to conduct 12-hour, overnight progressive ratio testing to determine whether mice with chronic spared nerve injury had decreased motivation to earn palatable food rewards. Our data demonstrate that despite equivalent task learning, spared nerve injury mice are less motivated to work for a sugar pellet than sham controls. Further, when we normalized behavioral responses across all the behavioral assays we tested, we found that a combined normalized behavioral score is predictive of injury-state and significantly correlates with mechanical thresholds. Together these results suggest that homecage-based operant behaviors provide a useful platform for modeling nerve injury-induced negative affect and that valuable pain-related information can arise from agglomerative data analyses across behavioral assays - even when individual inferential statistics do not demonstrate significant mean differences.

neuroscience↗