Biology subjects

Mamad, O.

Publications and source records attributed to Mamad, O..

7 recordsLinked to original sources

bioRxiv2026

CDKL5 deficiency alters cell subtype-specific molecular programmes and intercellular signalling in the mouse hippocampus

CDKL5 deficiency disorder (CDD) is a severe neurodevelopmental condition characterised by epilepsy, intellectual disability, and motor dysfunction. Loss of CDKL5 leads to altered synapse development, excitatory-inhibitory imbalances and glial changes, but the underlying molecular mechanisms remain incompletely understood, particularly at the level of individual brain cell subtypes. Here, we performed single-nucleus RNA sequencing (snRNA-seq) on the hippocampus of 12 weeks old heterozygous female Cdkl5 exon 6 deletion (Cdkl5tm1.1Joez/J) and wild-type mice to characterise cell-subtype-specific transcriptional alterations associated with CDKL5 deficiency. Analysis of 11,791 high-quality nuclei revealed cell-subtype-specific transcriptional changes across neuronal and non-neuronal populations. Differential expression was most prominent in intratelencephalic and extratelencephalic (IT-ET) glutamatergic neurons, which showed altered expression of genes involved in neuronal signalling and activity-dependent transcription, and in dentate gyrus (DG) neurons, which exhibited coordinated upregulation of multiple ribosomal protein genes. Gene set enrichment analysis revealed broader molecular alterations, with neuronal populations showing recurrent changes in pathways associated with synaptic organisation, neuronal development, axonal and dendritic processes, and neurotransmission. Altered gene expression was also evident among non-neuronal populations, although these displayed fewer changes. CellChat analysis inferred changes in predicted intercellular communication across excitatory and inhibitory neuronal populations, particularly Sema3c signalling, suggesting reorganization of hippocampal neuronal subtypes. These findings provide a single-nucleus transcriptional atlas of the hippocampus in a CDD mouse model. In our dataset, CDKL5 deficiency was associated with cell-subtype-specific alterations in gene expression, including enrichment of gene pathways related to cellular metabolism, neuronal development and synaptic organisation, alongside alteration in predicted intercellular signalling. This dataset provides a resource for investigating the cellular and molecular mechanisms underlying CDD and for prioritising candidate pathways for future therapeutic investigation.

neuroscience↗

bioRxiv2026

VECTR-Clasp: An open machine-learning and vector-based framework for objective quantification of motor dysfunction during hind-limb clasping in Cdkl5-deficient mice

Quantitative assessment of motor behaviour in rodents is central to the study of neurological disease, yet it remains constrained by manual categorical scoring systems that limit sensitivity, reproducibility, and the ability to detect subtle phenotypes. The hind-limb clasping assay, a standard test of motor dysfunction across many mouse models, is typically scored on an observer-defined categorical scale that may overlook meaningful movement features. We developed VECTR-Clasp, an open vector-based geometric framework that transforms standard pose-estimation output into continuous, body-relative kinematic measures. Combining DeepLabCut for markerless pose estimation with SimBA for automated clasping classification, our pipeline first reproduces conventional clasping detection at a level of agreement approaching that between trained human raters, and then extracts continuous geometric descriptors, including head directionality, total distance travelled, and swing count, that are inaccessible to categorical scoring. Applied to a mouse model of CDKL5 deficiency disorder, a rare neurodevelopmental condition in which motor impairment is a core clinical feature, this approach revealed previously uncharacterised motor microphenotypes: affected animals showed more constrained head direction, reduced overall movement, and fewer swings than wildtype controls. Critically, these differences were also present in affected animals that displayed no overt clasping. Together, these findings demonstrate that continuous geometric analysis of pose-estimation data uncovers motor phenotypes beyond the resolution of categorical scales, providing a more sensitive and reproducible framework for quantifying motor dysfunction. As it operates on standard pose-estimation output, the approach extends readily to other behavioural assays, disease models, and the evaluation of therapeutic interventions. Author SummaryMany neurological disorders impair movement, and researchers frequently study these deficits in mouse models. A widely used test lifts a mouse by the tail and records whether it retracts its hind limbs towards its body, a reflex associated with motor dysfunction. Traditionally, an observer watches the animal and assigns a categorical score. This approach depends on human judgement, varies between raters, and can miss subtle movement differences. We developed VECTR-Clasp, an open-source pipeline that validates machine-learning pose tracking to automate traditional clasping assessment and extends current methods using vector-based geometry. This quantifies the direction and extent of head and body movements, providing additional motor readouts. In a mouse model of CDKL5 deficiency disorder, a rare paediatric neurological disorder, VECTR-Clasp matched human scoring while revealing kinematic differences missed by standard assessment, including in animals appearing unaffected. This objective, sensitive framework could detect subtle motor changes and treatment responses across neurological diseases.

neuroscience↗

bioRxiv2025

PolyGraph - Flexible, Biocompatible & Electrically Optimised Graphene-Polymer Composites for Next-Generation Neural Interfaces

Neural interfacing materials must deliver exceptional electrochemical performance, while integrating safely with the central nervous system. In this study we develop PolyGraph, a flexible, conductive, and biocompatible graphene-polycaprolactone (PCL) nanocomposite designed to strike this balance, which enables fabrication of conformable multichannel microelectrode arrays. Optimised liquid-phase exfoliation produces conductive, biocompatible PVP-stabilised graphene nanosheets, which are incorporated into PCL to form flexible, processable composites - PolyGraph. This material demonstrates bio- and immuno-compatibility with sensitive primary and iPSC-derived neuronal and glial cells. PolyGraph achieves low impedance ([~]1.6 {Omega} cm2 @ 1 kHz) and high charge injection capacity (11.7 mC/cm2 for a 100 ms pulse), enhanced by NaOH surface roughening and AuPd coating. Leveraging their processability, PolyGraph composites are fabricated into flexible, individually isolated microneedle electrode arrays with biomimetic soft hyaluronic acid backings. These arrays demonstrate bidirectional neural interfacing capabilities, enabling both the delivery of controlled stimulation pulses in physiological buffer and high-resolution neuronal recording in murine brain slices, with machine learning-based event classification. Together, these advances establish PolyGraph as an optimal material platform for next-generation brain-computer interfaces and soft bioelectronic devices. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=109 SRC="FIGDIR/small/673516v1_ufig1.gif" ALT="Figure 1"> View larger version (53K): org.highwire.dtl.DTLVardef@9beea5org.highwire.dtl.DTLVardef@150be08org.highwire.dtl.DTLVardef@1ec24d2org.highwire.dtl.DTLVardef@658209_HPS_FORMAT_FIGEXP M_FIG C_FIG Graphical Abstract & TOC Text PolyGraph, a flexible graphene-polycaprolactone nanocomposite, unites conductivity, biocompatibility, and processability for next-generation neural interfaces. Fabricated into microneedle arrays with ultra-flexible backings, PolyGraph enables bidirectional neuronal recording and stimulation in brain tissue, advancing brain-computer interface (BCI) and soft bioelectronic applications.

bioengineering↗

bioRxiv2025

Attenuated single neuron and network hyperexcitability following microRNA-134 inhibition in mice with drug-resistant temporal lobe epilepsy

The multi-factorial pathophysiology of acquired epilepsies lends itself to a multi-targeting therapeutic approach. MicroRNAs (miRNA) are short noncoding RNAs that individually can negatively regulate dozens of protein-coding transcripts. Previously, we reported that central injection of antisense oligonucleotides targeting microRNA-134 (Ant-134) shortly after status epilepticus potently suppressed the development of recurrent spontaneous seizures in rodent models of temporal lobe epilepsy. The mechanism(s) of these anti-seizure effects remain, however, incompletely understood. Here we show that intracerebroventricular microinjection of Ant-134 in male mice with pre-existing epilepsy caused by intraamygdala kainic acid-induced status epilepticus potently reduces the occurrence of spontaneous seizures. Recordings from ex vivo brain slices collected 2-4 days after Ant-134 injection in epileptic mice, detected a number of electrophysiological phenotypic changes consistent with reduced excitability. Specifically, Ant-134 reduced action potential bursts after current injection in CA1 neurons and reduced miniature excitatory post-synaptic current frequencies in CA1 neurons. Ant-134 also reduced general network excitability, including attenuating pro-excitatory CA1 responses to Schaffer collateral stimulation in hippocampal slices from epileptic mice. Together, the present study demonstrates inhibiting miR-134 reduces single neuron and network hyperexcitability in mice and extends support for this approach to treat drug-resistant epilepsies. Significance statementTemporal lobe epilepsy is one of the most common forms of drug-resistant epilepsy. Identifying molecular regulators of enduring states of hyperexcitability may lead to new therapeutic approaches. MicroRNAs are short noncoding RNAs that act post-transcriptionally to lower levels of sets of protein-coding genes. Here we show that inhibiting miR-134 reduces spontaneous seizures in mice with active epilepsy. Electrophysiologic recordings from brain slices collected when mice were transitioning to fewer seizures revealed changes to both single neuron and inter-regional communication properties that may explain the reduction in hippocampal network excitability. The findings support the development of this microRNA-targeting approach for epilepsy.

neuroscience↗

bioRxiv2024

A stolen future: aberrant hippocampal neurogenesis produces glial cells in epilepsy

Adult hippocampal neurogenesis is disturbed in epilepsy. The increased neuronal activity in the epileptic brain leads to an increased production of newborn cells, increased mossy fibre sprouting and altered integration of new neurons within the hippocampus. Here, we set out to investigate increased astrocyte numbers following status epilepticus. We used immunolabelling of brain sections from the mouse intra-amygdala kainic acid model of epilepsy and publicly available single cell RNA sequencing datasets to assess newborn cells in the dentate gyrus. Similar to published series we found on increased number of reactive astrocytes present in the epileptic hippocampus. Additionally, we identified a cell population that expressed neurogenesis (doublecortin) and astrocyte (glial fibrillary acidic protein) markers in the epileptic brain, both in mouse and in human tissue. We further evaluated the expression profile of these cells. Immunolabelling showed expression of mature astrocyte markers aquaporin 4 and glutamate transporter-1. The single cell RNA sequencing data highlighted expression of neurogenesis and astrocyte markers in the doublecortin/glial fibrillary acidic protein-expressing cells. In conclusion, epilepsy pushes early neuroblasts to fate-switch to an astrocyte lineage as seen in the kainic acid-induced mouse model and in human resected brain tissue. Further understanding how neurogenesis is altered in epilepsy and whether the neuroblast fate-switch can be reverted will help in finding novel therapy strategies for epilepsy and other neurological diseases associated with aberrant adult hippocampal neurogenesis. Key MessagesFollowing kainic acid-induced status epilepticus early neuroblasts appear to undergo a fate-switch to an astrocyte lineage. We were able to confirm the presence of cells positive for early neurogenesis and astrocyte markers in human epileptic tissue using scRNAseq data.

neuroscience↗

bioRxiv2023

Brain cell-specific origin of circulating microRNA biomarkers in experimental temporal lobe epilepsy

The diagnosis of epilepsy is complex and challenging and would benefit from the availability of molecular biomarkers, ideally measurable in a biofluid such as blood. Experimental and human epilepsy are associated with altered brain and blood levels of various microRNAs (miRNAs). Evidence is lacking, however, as to whether any of the circulating pool of miRNAs originates from the brain. To explore the link between circulating miRNAs and the pathophysiology of epilepsy, we first sequenced argonaute 2 (Ago2)-bound miRNAs in plasma samples collected from mice subject to status epilepticus induced by intraamygdala microinjection of kainic acid. This identified time-dependent changes in plasma levels of miRNAs with known neuronal and microglial-cell origins. To explore whether the circulating miRNAs had originated from the brain, we generated mice expressing FLAG-Ago2 in neurons or microglia using tamoxifen-inducible Thy1 or Cx3cr1 promoters, respectively. FLAG immunoprecipitates from the plasma of these mice after seizures contained miRNAs, including let-7i-5p and miR-19b-3p. Taken together, these studies confirm that a portion of the circulating pool of miRNAs in experimental epilepsy originates from the brain, increasing support for miRNAs as mechanistic biomarkers of epilepsy.

neuroscience↗

bioRxiv2017

Extra-field spike-timed activity shifts the place field center of mass to encode aversion experience

The hippocampal place cells encode spatial representation but it remains unclear how they store concurrent positive or negative experiences. Here, we report on place field reconfiguration in response to an innately aversive odor trimethylthiazoline (TMT). The advantage of TMT is the absence of learning curve required for associative fear conditioning. Our study investigated if CA1 place cells, recorded from behaving rats, remap randomly or if their reconfiguration depends on the location of the aversive stimulus perception. Exposure to TMT increased the amplitude of hippocampal beta oscillations in two arms of a maze (TMT arms). We found that a population of place cells with fields located outside the TMT arms increased their activity (extra-field spiking) in the TMT arms during the aversive episodes. These cells exhibited significant shift of the center of mass towards the TMT arms in the subsequent post-TMT recording. The induction of extra-field plasticity was mediated by the basolateral amygdala complex (BLA). Photostimulation of the BLA triggered aversive behavior, synchronized response of hippocampal local field oscillations, augmented theta rhythm amplitude and increased the spiking of place cells for the first 100ms after the light delivery. This occurred only for the extra-field-but not for intra-field spikes. Optogenetic BLA-triggered an increase in extra-field spiking activity correlated to the degree of place field plasticity in the post-ChR2 recording session. Our findings demonstrate that the increased extra-field activity during aversive episodes mediates the degree of subsequent field plasticity.

neuroscience↗