Biology subjects

McCabe, B. D.

Publications and source records attributed to McCabe, B. D..

10 recordsLinked to original sources

bioRxiv2026

Spontaneous neurotransmitter release is regulated by Unc-5

The spontaneous quantal release of single vesicles of neurotransmitter in the absence of an action potential is a universal feature of all neuronal chemical synapses. These miniature events have long been thought to be stochastic and unregulated, leading to measurement of their frequency as a widely employed estimate of the number of synaptic connections within neuronal networks. Here we show using high resolution live imaging of Drosophila adult glutamatergic synapses that the spontaneous release of neurotransmitter occurs from only a subset of synaptic release sites. We discover that the proportion of release sites participating in spontaneous neurotransmitter release is regulated by a novel synaptic function of the transmembrane signalling receptor Unc-5 which is heparan sulfate proteoglycan dependent, but Netrin independent. We show that synaptic Unc-5 forms a complex with the SNARE protein Syntaxin to regulate neurotransmitter release. The depletion of Unc-5 in adult synapses diminishes miniature events, inducing terminal degeneration and behavioural decline. Our results reveal that spontaneous neurotransmitter release is a singular, essential and independently regulated property of synapses that is critical for the structural integrity and behavioural contribution of synaptic connections.

neuroscience↗

bioRxiv2026

The phosphatidylserine-binding proteins Turandots protect the peripheral nervous system from antimicrobial peptide toxicity

Inflammation increases with aging and contributes to neurodegeneration, yet the principles that determine how immune effectors target host neural tissue remain poorly understood. Antimicrobial peptides (AMPs) are central components of innate immune defenses strongly induced upon infection and upon aging. Studies have shown that AMPs can exhibit cytotoxicity toward host cells, pointing to a role in neurodegeneration. We show that cationic AMPs selectively bind and damage motoneurons that expose phosphatidylserine (PS), an anionic phospholipid normally restricted to the inner leaflet of the plasma membrane. Both infection and aging increase neuronal PS exposure alongside AMP expression. AMP binding occurs in a PS-dependent manner, leading to synaptic bouton fragmentation, accelerated neuronal aging, and locomotor decline. This toxicity is prevented in Drosophila by Turandot proteins, which reduce AMP-PS interactions on motoneurons. Together, our findings define a molecular mechanism underlying neuronal susceptibility to immunopathology and a set of proteins with neuroprotective potential. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=179 HEIGHT=200 SRC="FIGDIR/small/721952v1_ufig1.gif" ALT="Figure 1"> View larger version (46K): org.highwire.dtl.DTLVardef@ca817aorg.highwire.dtl.DTLVardef@fa8cb0org.highwire.dtl.DTLVardef@12a8bd4org.highwire.dtl.DTLVardef@423907_HPS_FORMAT_FIGEXP M_FIG This study shows that infection or dysbiosis in Drosophila can simultaneously induce antimicrobial peptide expression while promoting phosphatidylserine (PS) exposure on neurons at the neuromuscular junction. Cationic antimicrobial peptides contribute to neurodegeneration by binding to neurons that expose negatively charged phospholipids such as PS. In Drosophila, a family of secreted peptides, the Turandot proteins, can protect the peripheral nervous system by binding to PS-exposed membranes. Together, these findings reveal a role for antimicrobial peptides, a key component of innate immunity, in promoting neurodegeneration as well as a potential protective mechanism by PS masking agent. C_FIG

immunology↗

bioRxiv2026

Tools for synchronous temporal control of independent transgenes in discrete Drosophila tissues

Exogenous binary gene regulatory expression systems are a linchpin technology critical for many model organism genetic manipulations including of Drosophila melanogaster. Subsequent to the initial establishment of the Gal4/UAS binary expression system, LexA/LexOp and QF/QUAS binary gene expression systems have been adopted to supplement and expand the tissue specific control of genes expression in Drosophila. Here, we have developed a compendium of modular vectors that enable robust, reproducible, and high throughput parallel construction of transgenes that produce either Gal4, LexA or QF2 transcription factors under specific gene enhancers and compatible partner vectors that allow transgenes to be regulated by these factors under UAS, LexOp, or QUAS control. Expanding upon this foundation, we have generated a novel hybrid binary gene regulatory system derived from QF and Gal4 - QFG4, that enables simultaneous coordinate regulation of UAS and QUAS transgenes by Gal80, allowing synchronous temporal control of independent transgene expression in distinct cells or tissues. We envision these new tools will facilitate novel and increasingly sophisticated interrogation of cell and tissue interactions particularly in contexts where temporal control is paramount.

genetics↗

bioRxiv2026

An integrated synthetic biology and robotics approach for neutralising landmines in post-war communities

Unexploded ordnances (UX.Os) and landmines endanger lives and hinder the economic progress of communities living in post-conflict zones. Currently, the primary method for clearing UX.Os relies on metal detection and manual removal of UX.Os - an expensive, time-consuming, and hazardous process. This study, derived from the 2024 EPFL iGEM project SYNPLODE, presents a new approach that integrates synthetic biology and aerial drone robotics, proposing a novel, end-to-end, safe, and efficient solution to address UX.Os. Starting from bacteria engineered to detect and degrade 2,4,6-trinitrotoluene (TNT), a common explosive in landmines, our solution is designed for three main tasks: detecting TNT and RDX, breaking these compounds down into non-explosive byproducts, and confirming explosive neutralisation. To deploy this solution safely in UXO-contaminated areas, we designed, built, and tested an aerial drone capable of spraying explosive-degrading bacteria. Combining synthetic biology, robotics, mathematical modelling, and affected community engagement, our solution aims to improve UXO and landmine clearance by offering a scalable and cost-effective approach for deactivating UX.Os without risking human lives.

synthetic biology↗

bioRxiv2025

Highly frequent undesired insertional mutagenesis during Drosophila genome editing

CRISPR/Cas9 based genome editing employing Homology Directed Repair (HDR) from template vector sequences is a widely used technique to enable precise insertions, deletions or modifications to genes. Here, we describe an undesired and highly frequent editing event when using conventional CRISPR/Cas9 plus HDR methods for Drosophila melanogaster germline genome editing. We find that the template vector employed for HDR repair unwantedly and commonly inserts into the genome. We observe this deviation from the desired edit at multiple genomic locations, with different HDR vectors and with multiple genome editing designs. To avoid these events, we have generated a novel HDR template vector that enables animals with these undesired insertions to be identified and excluded. Our results suggest that HDR based genome edited animals must be carefully screened for unwanted vector template genomic integration in order to avoid misleading interpretations of genome editing outcomes.

molecular biology↗

bioRxiv2024

Upregulation of FasII underlies synergistic neuropathological and behavioral defects in a Drosophila model of myotonic dystrophy

Myotonic dystrophy type 1 (DM1) is a multisystemic disorder that has been extensively studied for decades, yet our understanding of its neuropathological aspect remains rudimentary. In this study, we characterized a novel model of DM1 neuropathology by expressing untranslated expanded CUG repeats at the Drosophila larval neuromuscular junction. In this model, both pre- and postsynaptic expression of CUG repeats participate to induce reduction of synaptic boutons, increase of arbor disassembly and impairment of larval locomotor activity. We found that the expression of CUG repeats caused an upregulation of the cell adhesion molecule, FasII (NCAM1 in mammals), in both the motor neurons and the body wall muscles. Knockdown of fasII was sufficient to rescue bouton numbers and locomotor impairment in this model. Further analyses identified the upregulation of the FasII-C isoform as a major contributor of these phenotypes. Remarkably, overexpressing the FasII-A-PEST+ isoform rescued the synaptic and behavioral defects, likely by outcompeting the upregulated FasII-C. Our study provided the foundation for a basic mechanism of synapse dysregulation in DM1.

neuroscience↗

bioRxiv2023

Sexually dimorphic mechanisms of VGLUT-mediated protection from dopaminergic neurodegeneration

Parkinsons disease (PD) targets some dopamine (DA) neurons more than others. Sex differences offer insights, with females more protected from DA neurodegeneration. The mammalian vesicular glutamate transporter VGLUT2 and Drosophila ortholog dVGLUT have been implicated as modulators of DA neuron resilience. However, the mechanisms by which VGLUT2/dVGLUT protects DA neurons remain unknown. We discovered DA neuron dVGLUT knockdown increased mitochondrial reactive oxygen species in a sexually dimorphic manner in response to depolarization or paraquat-induced stress, males being especially affected. DA neuron dVGLUT also reduced ATP biosynthetic burden during depolarization. RNA sequencing of VGLUT+ DA neurons in mice and flies identified candidate genes that we functionally screened to further dissect VGLUT-mediated DA neuron resilience across PD models. We discovered transcription factors modulating dVGLUT-dependent DA neuroprotection and identified dj-1{beta} as a regulator of sex-specific DA neuron dVGLUT expression. Overall, VGLUT protects DA neurons from PD-associated degeneration by maintaining mitochondrial health.

neuroscience↗

bioRxiv2021

Intact Drosophila Whole Brain Cellular Quantitation reveals Sexual Dimorphism

Establishing with precision the quantity and identity of the cell types of the brain is a prerequisite for a detailed compendium of gene and protein expression in the central nervous system. Currently however, strict quantitation of cell numbers has been achieved only for the nervous system of C.elegans. Here we describe the development of a synergistic pipeline of molecular genetic, imaging, and computational technologies designed to allow high-throughput, precise quantitation with cellular resolution of reporters of gene expression in intact whole tissues with complex cellular constitutions such as the brain. We have deployed the approach to determine with exactitude the number of functional neurons and glia in the entire intact larval Drosophila central nervous system (CNS), revealing fewer neurons and more glial cells than previously predicted. We also discover an unexpected divergence between the sexes at this juvenile developmental stage, with the female CNS having significantly more neurons than that of males. Topological analysis of our data establishes that this sexual dimorphism extends to deeper features of CNS organisation. We additionally extended our analysis to quantitate the expression of voltage-gated potassium channel family genes throughout the CNS and uncover substantial differences in abundance. Our methodology enables robust and accurate quantification of the number and positioning of cells within intact organs, facilitating sophisticated analysis of cellular identity, diversity, and gene expression characteristics.

neuroscience↗

bioRxiv2020

VGLUT modulates sex differences in dopamine neuron vulnerability to age-related neurodegeneration

Age is the greatest risk factor for Parkinsons disease (PD) which causes progressive loss of dopamine (DA) neurons, with males at greater risk than females. We found that vesicular glutamate transporter (VGLUT) expression mediates vulnerability to age-related DA neurodegeneration in a sex-dependent manner, providing a new mechanism for sex differences in selective DA neuron vulnerability. These findings lay the groundwork for novel therapeutic strategies to boost neuronal resilience throughout aging.

neuroscience↗

bioRxiv2019

MiR-219 deficiency in Alzheimer’s disease contributes to neurodegeneration and memory dysfunction through post-transcriptional regulation of tau-kinase network

Intracellular accumulation of hyperphosphorylated misfolded tau proteins is one of the main neuropathological hallmarks in Alzheimers disease (AD) and related tauopathies. Hence, knowledge and understanding of disease mechanisms altering tau proteostasis and inducing cytotoxicity is critical. MicroRNAs (miRNAs) are capable of binding to and silencing many target transcripts, providing an additional level of regulation that complements canonical transcriptional pathways. Therefore, observed abnormalities in their expression patterns in neurodegeneration suggest alterations of microRNA-target networks as drivers of cellular dysfunction in the disease. Strikingly, here we have found in autopsy brain tissue that miRNA miR-219 expression levels are decreased in a brain region early affected in AD patients, the entorhinal cortex. Our bioinformatics analysis indicates miR-219 is predicted to target Calcium/calmodulin-dependent protein kinase 2 gamma subunit (CAMK2{gamma}), Tau tubulin kinase 1 (TTBK1) and Glycogen synthase kinase 3 beta (GSK3{beta}), which are all implicated in the generation of abnormal hyperphosphorylated tau. We reveal human proteomic data supporting dysregulation in the levels of predicted miR-219 targets in the entorhinal cortex. In mammalian cellular models, we found that downregulation of miR-219 de-repress synthesis of three tau kinases, CAMK2{gamma}, TTBK1 and GSK3{beta} on the post-transcriptional level resulting in tau phosphorylation and cell toxicity. Finally, we show that deficiency of miR-219 in vivo promotes age dependent neurodegeneration in the adult brain, with enhanced alterations in tau proteostasis, presynaptic terminals and memory impairment. Taken together, our data implicate miRNA dysregulation central to AD etiopathogenesis and suggest potential targets for the treatment of AD and related tauopathies.

neuroscience↗