Biology subjects

Dando, O.

Publications and source records attributed to Dando, O..

11 recordsLinked to original sources

bioRxiv2026

Loss of FMRP leads to translationally relevant functional connectivity differences in a rat model of Fragile X Syndrome

Fragile X syndrome (FXS), a leading monogenic cause of intellectual disability and autism-related features, results from loss of fragile X messenger ribonucleoprotein (FMRP). Although early synaptic and cellular abnormalities associated with the loss of FMRP are well described, it remains unclear how these changes shape the maturation of large-scale functional networks, or whether early pharmacological intervention can normalize circuit development. Our previous work demonstrated that cognitive deficits in Fmr1-/y rats emerge during development and can be prevented by brief early-life lovastatin treatment. Here, we asked whether large-scale functional connectivity (FC) shows a similarly dynamic developmental trajectory and whether early intervention alters its emergence. Using longitudinal resting-state functional magnetic resonance imaging (rsfMRI), we found that Fmr1-/y rats displayed an age-dependent FC phenotype, with increased connectivity within the retrosplenial cortex (RSC) at 4 weeks but reduced connectivity within the RSC and distributed brain networks by adulthood compared with wild-type controls. This suggests FC abnormalities emerge over development rather than representing a stable deficit. In contrast to its effects on cognitive measures, brief early-life lovastatin treatment rescues did not prevent the emergence of connectivity abnormalities. Reduced RSC FC was also observed in a small cohort of individuals with FXS (n = 5 per group), supporting further investigation of functional connectivity measures alongside behavioural and molecular endpoints in translational studies of FXS.

neuroscience↗

bioRxiv2026

APOE4 genotype, blood-brain barrier leakage and ischaemic stroke subtype and location

BackgroundApolipoprotein E (APOE) has been implicated in blood-brain barrier (BBB) dysfunction and may influence ischaemic cerebrovascular disease and cerebral small-vessel disease (cSVD). This study examined associations between APOE genotype, BBB permeability, and infarct distribution in patients with mild ischemic stroke. MethodsWe recruited patients with mild ischemic stroke who underwent structural and dynamic contrast-enhanced MRI (DCE-MRI) and APOE genotyping. Infarct type and location, white matter hyperintensities (WMH), and perivascular spaces (PVS) were assessed. BBB-related metrics were quantified using fractional plasma volume (vP) and permeability-surface area product (PS) across five brain regions of interest: deep grey matter (DGM), hippocampus, thalamus, normal-appearing white matter (NAWM), and WMH. Associations between genotype, BBB metrics, vascular risk factors, and age were evaluated using linear mixed-effects models. Binary logistic regression was also applied to assess the association between APOE status and infarct location by vascular territory (anterior vs posterior circulation). ResultsAmong 147 patients with APOE genotype and BBB measures, APOE4 carriers (n=44) demonstrated a greater proportion of posterior circulation infarcts than E3/E3 individuals (n=80; 56.4% versus 32.9%), including higher frequencies of posterior cerebral artery cortical, posterior borderzone, and thalamic infarcts. Mean PS and vP did not differ significantly by genotype. Increasing age was associated with lower PS across multiple regions and lower vP in WMH, while higher vascular risk burden was associated with lower vP in NAWM and WMH. Inclusion of regional BBB metrics did not substantially alter APOE4 effect estimates in infarct-location models. ConclusionsAPOE4 carriers showed a posterior-predominant infarct distribution despite similar BBB permeability and vascularity measures. Age and vascular risk burden were more strongly associated with BBB-related imaging metrics than APOE genotype. These findings add to evidence suggesting that APOE genotype may influence regional cerebrovascular vulnerability and that this effect is unlikely to be fully explained by DCE-MRI-derived measures of BBB permeability and vascularity alone.

neuroscience↗

bioRxiv2026

Pericyte Loss Reprogrammes Capillary Endothelium and Drives White Matter Injury in Small Vessel Disease

Pericytes are critical regulators of cerebrovascular homeostasis, yet their contribution to small vessel disease (SVD) and white matter injury remains incompletely understood. Here, we use an inducible Atp13a5-driven genetic strategy to selectively label and ablate brain pericytes, enabling integrated morphological, functional, and transcriptomic analyses across the neurogliovascular unit. Single-cell RNA sequencing and tissue-level mapping identified distinct pericyte subtypes distributed along the vascular tree and revealed subtype-specific vulnerability following depletion. Moderate pericyte loss induced transient cerebrovascular dysfunction characterised by reduced cerebral blood flow and increased blood-brain barrier (BBB) permeability, accompanied by delayed white matter abnormalities, including altered diffusion MRI metrics, oligodendrocyte progenitor cell responses, and myelin loss. At the molecular level, pericyte depletion reprogrammed capillary endothelial cells toward an activated venular-like state characterised by VCAM-1 induction, reduced expression of the BBB-associated transporter MFSD2A, and activation of type I interferon signalling pathways. Cross-species analyses revealed enrichment of human white matter hyperintensity-associated SVD gene signatures across endothelial subtypes following pericyte depletion. Together, these findings identify pericyte dysfunction as a driver of endothelial inflammatory remodelling and white matter injury and establish mechanistic links between microvascular pericyte loss and human SVD.

neuroscience↗

bioRxiv2026

Abrupt Pericyte Loss Precedes Endothelial Activation in Cerebral Small Vessel Disease

Cerebral small vessel disease (cSVD) is a leading cause of stroke and vascular cognitive impairment, yet the cellular mechanisms underlying microvascular dysfunction in human disease remain incompletely understood. In particular, the relationship between pericyte alterations and endothelial activation, two key features of blood-brain barrier dysfunction, remains unresolved. Here, we performed a quantitative single-vessel analysis of the human cortical microvasculature across increasing cSVD severity and ageing. Using multiplex immunohistochemistry combined with spectral unmixing and automated image analysis, we analysed 11,409 microvascular fragments from post-mortem brain tissue derived from 20 cases. Endothelial cells, pericytes, and endothelial activation were assessed using PECAM-1, PDGFR{beta}, and VCAM-1, respectively. Microvascular density and diameter differed between cortical grey matter and the underlying white matter, with white matter vessels being less dense and wider in controls. While vessel diameter remained stable across disease stages, microvascular density increased with cSVD severity and age in the white matter. At the molecular level, PDGFR{beta} signal decreased markedly with increasing cSVD severity, consistent with progressive pericyte loss. This reduction was observed in both grey and white matter and correlated with disease severity and age. Notably, intermediate disease groups displayed marked heterogeneity, with vessels exhibiting either preserved or near-complete pericyte coverage, suggesting a potentially bimodal transition. In parallel, endothelial markers PECAM-1 and VCAM-1 increased significantly with disease severity, reflecting endothelial activation. Unsupervised Gaussian mixture clustering of marker expression identified three vascular states characterised by (i) preserved pericytes with low endothelial activation, (ii) marked pericyte loss without endothelial activation, and (iii) combined pericyte depletion and endothelial activation. These clusters broadly aligned with clinical severity but revealed intermediate states not captured by post-mortem diagnosis alone. Together, these findings suggest that pericyte loss and endothelial activation are partially dissociated processes that occur in a sequential progression in human cSVD, supporting pericyte dysfunction as an early event and highlighting it as a potential therapeutic target in microvascular disease.

pathology↗

bioRxiv2025

Astrocytes control motor neuronal mitochondrial axonal transport deficits in C9ORF72 ALS.

Disrupted axonal transport and astrocyte dysfunction are implicated in amyotrophic lateral sclerosis (ALS). Here, we show these are intrinsically linked: human induced pluripotent stem cell-derived astrocytes carrying the C9ORF72 mutation disrupt axonal transport and mitochondrial function in motor neurons (MNs). Conversely, either isogenic gene-corrected astrocytes or selectively boosting C9ORF72-astrocyte mitochondrial bioenergetics rescue axonal transport deficits in C9ORF72-MNs. Thus, astrocytes have a dominant effect on axonal mitochondrial transport in the context of ALS.

neuroscience↗

bioRxiv2024

Endothelial cell Nrf2 controls neuroinflammation following a systemic insult

Systemic inflammation can lead to neuroinflammation with acute consequences such as delirium and long-lasting deleterious effects including cognitive decline and the exacerbation of neurodegenerative disease progression. Here we show that transcription factor Nrf2 controls brain endothelial cell homeostasis and barrier strength. We found that peripheral inflammation caused infiltration of macrophages, microglial activation and inflammatory reactive astrogliosis, all of which could be prevented by RTA-404, an activator of the transcription factor Nrf2 and close structural relative of the recently FDA-approved Nrf2 activator RTA-408 (Omaveloxolone). To identify the key cellular mediator(s), we generated an endothelial cell-specific Nrf2 knockout mouse. Strikingly, the effects of RTA-404 on brain endothelial activation and downstream neuroinflammatory events was abolished by endothelial cell-specific Nrf2 deletion. This places endothelial cell Nrf2 as a peripherally accessible therapeutic target to reduce the CNS-adverse consequences of systemic inflammation.

neuroscience↗

bioRxiv2024

Typical development of synaptic and neuronal properties can proceed without microglia

Brain-resident macrophages, microglia, have been proposed to play an active role in synaptic refinement and maturation, influencing plasticity and circuit-level connectivity. Here we show that a variety of neurodevelopmental processes previously attributed to microglia can proceed without them. Using a genetically modified mouse which lacks microglia (Csf1r{Delta}FIRE/{Delta}FIRE) we find that intrinsic properties, synapse number and synaptic maturation are largely normal in the hippocampal CA1 region and somatosensory cortex at stages where microglia have been implicated. Seizure susceptibility and hippocampal-prefrontal cortex coherence in awake behaving animals, processes disrupted in mice deficient in microglia-enriched genes, are also normal. Similarly, eye-specific segregation of inputs into the lateral geniculate nucleus proceeds normally in the absence of microglia. Single cell/nucleus transcriptomic analyses of neurons and astrocytes did not uncover any substantial perturbation due to microglial absence. Thus, the brain possesses remarkable adaptability to execute developmental synaptic refinement, maturation and connectivity in the absence of microglia.

neuroscience↗

bioRxiv2022

Evolutionary divergence of basal and activity-dependent exon splicing in cortical neurons

Alternative splicing of mRNA exons in mammalian neurons increases diversity of the proteome and is regulatable by signaling pathways. However, the degree of conservation of basal and signal-dependent exon usage between human neurons and those from experimental models such as mice is incompletely understood. We previously showed that cortical neuronal activity-dependent gene transcription exhibits human/mouse differences, driven by evolutionary divergence of cis-acting promoter elements (Qiu et al. 2016). Since alternative exon usage influences brain development and cognition, is controlled by neuronal activity, and is disturbed in brain disorders, we investigated human/mouse differences in exon usage in cortical neurons. Comparing orthologous exons, basal exon inclusion levels showed human-mouse conservation, but also significant differences determined by cis-acting sequences: human-mouse conservation and divergence in exon usage was recapitulated in neurons from Tc1 mice carrying human chromosome-21 (hCh21). Activity-dependent changes in exon usage also exhibited significant conservation: gene structure was more likely to be conserved in activity-regulated exons, and exons regulated in both human and mouse neurons were enriched in RBFOX and SAM68 targets, and genes were centred on cytoskeletal organisation, mRNA transcription/processing, and synaptic signaling. However, divergence was also evident, and human-specific activity-dependent exon usage was dominated by genes involved in lipid biosynthesis, signaling and trafficking. Notably, the pattern of activity-dependent usage of hCh21 exons in human neurons was not recapitulated in mouse Tc1 neurons. Thus, unlike species-specific differences in activity-dependent gene transcription, cis-acting DNA sequence divergence is insufficient to explain inter-species differences in activity-regulated exon usage. Trans-acting factors involved in activity-responsive splicing have likely also diverged.

neuroscience↗

bioRxiv2019

LAB-AID (Laboratory Automated Interrogation of Data): an interactive web application for visualization of multi-level data from biological experiments

A key step in understanding the results of biological experiments is visualization of the data. Many laboratory experiments contain a range of measurements that exist within a hierarchy of interdependence. An automated way to visualise and interrogate experimental data would: 1) lead to improved understanding of the results, 2) help to determine which statistical tests should be performed, and 3) easily identify outliers and sources of batch effects. Unfortunately, existing graphing solutions often demand expertise in programming, require considerable effort to import and examine such multi-level data, or are unnecessarily complex for the task at hand. Here we present LAB-AID (Laboratory Automated Interrogation of Data), an interactive tool specifically designed to automatically visualize and query hierarchical data resulting from biological experiments.

bioinformatics↗

bioRxiv2019

Familial t(1;11) translocation is associated with disruption of white matter structural integrity and oligodendrocyte-myelin dysfunction

Although the underlying neurobiology of major mental illness (MMI) remains unknown, emerging evidence implicates a role for oligodendrocyte-myelin abnormalities. Here, we took advantage of a large family carrying a balanced t(1;11) translocation, which substantially increases risk of MMI, to undertake both diffusion tensor imaging (DTI) and cellular studies to evaluate the consequences of the t(1;11) translocation on white matter structural integrity and oligodendrocyte-myelin biology. This translocation disrupts among others the DISC1 gene which plays a crucial role in brain development. We show that translocation-carrying patients display significant disruption in white matter integrity compared to familial controls. At a cellular level, we observe dysregulation of key pathways controlling oligodendrocyte development and morphogenesis in induced pluripotent stem cell (iPSC) case derived oligodendrocytes. This is associated with reduced proliferation and a stunted morphology in vitro. Further, myelin internodes in a humanized mouse model that recapitulates the human translocation as well as after transplantation of t(1;11) oligodendrocyte progenitors were significantly reduced compared to controls. Thus we provide evidence that the t(1;11) translocation has biological effects at both the systems and cellular level that together suggest oligodendrocyte-myelin dysfunction.

neuroscience↗

bioRxiv2018

Reducing tau ameliorates behavioural and transcriptional deficits in a novel model of Alzheimer’s disease

SummaryOne of the key knowledge gaps blocking development of effective therapeutics for Alzheimers disease (AD) is the lack of understanding of how amyloid beta (A{beta}) and tau cooperate in causing disease phenotypes. Within a mouse tau deficient background, we probed the molecular, cellular and behavioural disruption triggered by wild-type human taus influence on human A{beta}-induced pathology. We find that A{beta} and tau work cooperatively to cause a hyperactivity phenotype and to cause downregulation of gene transcription including many involved in synaptic function. In both our mouse model and in human post-mortem tissue, we observe accumulation of pathological tau in synapses, supporting the potential importance of synaptic tau. Importantly, tau depletion in the mice, initiated after behavioural deficits emerge, was found to correct behavioural deficits, reduce synaptic tau levels, and substantially reverse transcriptional perturbations, suggesting that lowering tau levels, particularly at the synapse, may be beneficial in AD.\n\nHighlights- Expression of human familial Alzheimers associated mutant amyloid precursor protein and presenillin 1 with wild-type human tau in the absence of endogenous tau in a novel MAPT-AD mouse model results in behavioural deficits and downregulation of genes involved in synaptic function.\n- Tau is present in pre and postsynaptic terminals in MAPT-AD mice and human AD brain. In mice, lowering synaptic tau levels was associated with improved cognition and recovered gene expression.\n- These data suggest that A{beta} and tau act cooperatively in impairing synaptic function and that lowering tau at synapses could be a beneficial therapeutic approach in AD.

neuroscience↗