Biology subjects

Humby, T.

Publications and source records attributed to Humby, T..

12 recordsLinked to original sources

bioRxiv2026

Physiological and behavioural characterisation of a novel steroid sulfatase-deficient mouse

BackgroundSteroid sulfatase (STS) cleaves sulfate groups from steroid hormones. In humans, STS deficiency is associated with X-linked ichthyosis (a dermatological disorder), neurodevelopmental/mood conditions, and cardiac arrhythmias. Until recently, no single-gene knockout mammalian model existed to investigate these associations; previous work in such a model has been limited to skin phenotypes. MethodsWe generated a novel C57BL/6J mouse model with a deletion in critical exon 2 of Sts. We then examined gene expression and enzyme activity in liver and brain samples of homozygous mice, and assessed the breeding performance and health of male and female deletion-carriers. Subsequently, we compared performance across a range of behavioural paradigms in wildtype and homozygous male and female mice: elevated plus maze, open field, rotarod, spontaneous alternation, and acoustic startle/prepulse inhibition. We also investigated serum steroid hormone levels by liquid chromatography-mass spectrometry and measured heart weights and two morphological indices (bodyweight/tibia length) post mortem. ResultsHomozygous mice almost completely lacked STS expression/activity. Genetically-altered mice exhibited grossly-normal breeding performance, health, and endocrinology. Homozygous mice were more active, and had higher normalised heart weights, than wildtype mice. We also found significant genotype x sex interactions on bodyweight, and on two behavioural measures (potentially reflecting lower anxiety in homozygous males and heightened anxiety in homozygous females). ConclusionsThe Sts-deletion mouse represents an experimentally-tractable model in which to identify and characterise phenotypes associated with STS deficiency. The mechanistic basis of the genotype-phenotype associations described here requires further investigation, and whether such associations translate to humans remains to be tested.

animal behavior and cognition↗

bioRxiv2024

Sex-dependent effects of Setd1a haploinsufficiency on development and adult behaviour

Withdrawal StatementThe authors have withdrawn this manuscript due to a duplicate posting of manuscript number BIORXIV/2021/471949. Therefore, the authors do not wish this work to be cited as reference for the project. If you have any questions, please contact the corresponding author. The correct preprint can be found at doi: 10.1101/2021.12.10.471949.

animal behavior and cognition↗

bioRxiv2021

Behavioural consequences of Setd1a haploinsufficiency in mice: evidence for heightened emotional reactivity and impaired sensorimotor gating

A number of studies implicate the loss of function (LoF) mutations affecting the histone methyl transferase SETD1A in the aetiology of a range of neurodevelopmental disorders including schizophrenia. Here, we examined the behavioural consequences of haploinsufficiency of Setd1a in a mouse model. We find evidence for changes in a number of phenotypes of relevance to schizophrenia, including increased anxiety-related behaviour, enhanced acoustic startle response, and decreased pre-pulse inhibition of acoustic startle. The sensorimotor gating deficits in Setd1a+/- mice could not be rescued by haloperidol or risperidone, suggesting that these antipsychotics are ineffective for ameliorating schizophrenia-relevant phenotypes in Setd1a+/- mice and point to deficits in neural systems other than the monoamine system. These phenotypes are emerging as key features of a number of other mouse models of rare neurodevelopmental disorders caused by LoF mutations in genes encoding epigenome modifiers suggesting they may act in a network to modulate brain development. Taken together these data strengthen the support for the use of Setd1a haploinsufficient mice as a model for the biological basis of schizophrenia, and point towards possible underpinning neural mechanisms.

neuroscience↗

bioRxiv2021

Behavioural and molecular characterisation of the Dlg2 haploinsufficiency rat model of genetic risk for psychiatric disorder

Genetic studies implicate disruption to the DLG2 gene in copy number variants as increasing risk for schizophrenia, autism spectrum disorders and intellectual disability. To investigate psychiatric endophenotypes associated with DLG2 haploinsufficiency (and concomitant PSD-93 protein reduction) a novel clinically relevant Dlg2+/- rat was assessed for abnormalities in anxiety, sensorimotor gating, hedonic reactions, social behaviour, and locomotor response to the N-Methyl-D-aspartic acid receptor antagonist phencyclidine. Dlg gene and protein expression were also investigated to assess model validity. Reductions in PSD-93 messenger RNA and protein were observed in the absence of compensation by other related genes or proteins. Behaviourally Dlg2+/- rats show potentiated locomotor response to phencyclidine, as is typical of psychotic disorder models, in the absence of deficits in the other behavioural phenotypes assessed here. This shows that the behavioural effects of Dlg2 haploinsufficiency may specifically relate to psychosis vulnerability but are subtle, providing a contrast to the gross deficits in Dlg2 homozygous models (Winkler, et al., 2018; Yoo et al., 2020a) which do not so specifically model the single chromosome DLG2 deletion in carriers of risk-associated copy number variants.

genetics↗

bioRxiv2021

Selective behavioural impairments in mice heterozygous for the cross disorder psychiatric risk gene DLG2

Mutations affecting DLG2 are emerging as a genetic risk factor associated with neurodevelopmental psychiatric disorders including schizophrenia, autism spectrum disorder and bipolar disorder. Discs large homolog 2 (DLG2) is a member of the membrane-associated guanylate kinase protein superfamily of scaffold proteins, a component of the post-synaptic density in excitatory neurons and regulator of synaptic function and plasticity. It remains an important question whether and how haploinsuffiency of DLG2 contributes to impairments in basic behavioural and cognitive functions that may underlie symptomatic domains in patients that cross diagnostic boundaries. Using a heterozygous Dlg2 mouse model we examined the impact of reduced Dlg2 expression on functions commonly impaired in neurodevelopmental psychiatric disorders including motor co-ordination and learning, pre-pulse inhibition and habituation to novel stimuli. The heterozygous Dlg2 mice exhibited behavioural impairments in long-term motor learning and long-term habituation to a novel context, but not motor co-ordination, initial responses to a novel context, PPI of acoustic startle or anxiety. We additionally showed evidence for the reduced regulation of the synaptic plasticity-associated protein cFos in the motor cortex during motor learning. The sensitivity of selective behavioural and cognitive functions, particularly those dependent on synaptic plasticity, to reduced expression of DLG2 give further credence for DLG2 playing a critical role in specific brain functions but also a mechanistic understanding of symptom expression shared across psychiatric disorders.

neuroscience↗

bioRxiv2021

Comparison of mouse models reveals the molecular bases for psychotic illness in Prader-Willi syndrome

Prader-Willi Syndrome (PWS) is a neurodevelopmental disorder caused by mutations affecting paternal chromosome 15q11-q13, and characterized by hypotonia, hyperphagia, impaired cognition and behavioural problems. Psychotic illness is a challenging problem for individuals with PWS and has different rates of prevalence in distinct PWS genotypes. Previously, we demonstrated behavioural and cognitive endophenotypes of relevance to psychiatric illness in a mouse model for one of the associated PWS genotypes, namely PWS-IC, in which deletion of the imprinting centre leads to loss of paternal imprinted gene expression and over-expression of Ube3a. Here we examine the broader gene expression changes that are specific to the psychiatric endophenotypes seen in this model. To do this we compared the brain transcriptomic profile of the PWS-IC mouse to the PWS-cr model that carries a deletion of the PWS minimal critical interval spanning the snoRNA Snord116 and Ipw. Firstly, we examined the same behavioural and cognitive endophenotypes of relevance to psychiatric illness in the PWS-cr mice. Unlike the PWS-IC mice, PWS-cr exhibit no differences in locomotor activity, sensory-motor gating, and attention. RNA-seq analysis of neonatal whole brain tissue revealed a greater number of transcriptional changes between PWS-IC and wild-type littermates, than between PWS-cr and wild-type littermates. Moreover, the differentially expressed genes in the PWS-IC brain were enriched for GWAS variants of episodes of psychotic illness but, interestingly, not schizophrenia. These data illustrate the molecular pathways that may underpin psychotic illness in PWS and have implication for potential therapeutic interventions.

neuroscience↗

bioRxiv2020

Mice carrying paternal knockout of imprinted Grb10 do not show compulsive behaviours

Mice lacking paternal expression of imprinted Grb10 show a number of social behaviour deficits, including an enhanced allogrooming phenotype. However, this could also index compulsive behaviour, and the increased whisker barbering seen in Grb10+/p mice has been suggested to be indicative of a trichotillomania-type behaviour. Here we test whether compulsive behaviour is a more general phenotype in Grb10+/p mice by examining marble burying. We also examined the mice for potentially confounding anxiety phenotypes using the elevated plus maze (EPM). Grb10+/p mice showed no difference from wild-type littermate controls on any measure in the marble burying test at any age. However, Grb10+/p mice were more willing to enter, spend time on, and head-dip on the open arm of the EPM than wild-type mice. These data suggest that Grb10+/p mice are not generally more compulsive, and that the enhanced allogrooming is probably indicative of altered social behaviour. Furthermore, the altered behaviours seen on the EPM adds to other published findings suggesting that Grb10 has a role in mediating risk-taking.

animal behavior and cognition↗

bioRxiv2020

Mice lacking paternal expression of imprinted Grb10 are risk-takers

The imprinted genes Grb10 and Nesp influence impulsive behavior on a delay discounting task in an opposite manner. A recently developed theory suggests that this pattern of behavior may be representative of predicted effects of imprinted genes on tolerance to risk. Here we examine whether mice lacking paternal expression of Grb10 show abnormal behavior across a number of measures indicative of risk-taking. Although Grb10+/p mice show no difference from wild type littermates in their willingness to explore a novel environment, their behavior on an explicit test of risk-taking, namely the Predator Odour Risk-Taking task, is indicative of an increased willingness to take risks. Follow-up tests suggest that this risk-taking is not simply due to a general decrease in fear, or a general increase in motivation for a food reward, but reflects a change in the trade-off between cost and reward. These data, coupled with previous work on the impulsive behaviour of Grb10+/p mice in the delayed reinforcement task, and taken together with our work on mice lacking maternal Nesp, suggest that maternally and paternally expressed imprinted genes oppositely influence risk-taking behaviour as predicted.

genetics↗

bioRxiv2019

Complement C3 and C3aR differentially impact on learned fear and innate anxiety

Complement is a key component of the immune system with roles in inflammation and host-defence. Here we reveal novel functions of complement pathways impacting on emotional reactivity of potential relevance to the emerging links between complement and risk for psychiatric disorder. We used mouse models to assess the effects of manipulating components of the complement system on emotionality. Mice lacking the complement C3a Receptor (C3aR-/-) demonstrated a selective increase in unconditioned (innate) anxiety whilst mice deficient in the central complement component C3 (C3-/-) showed a selective increase in conditioned (learned) fear. The dissociable behavioural phenotypes were linked to different signalling mechanisms. Effects on innate anxiety were independent of C3a, the canonical ligand for C3aR, consistent with the existence of an alternative ligand mediating innate anxiety, whereas effects on learned fear were due to loss of iC3b/CR3 signalling. Our findings show that specific elements of the complement system and associated signalling pathways contribute differentially to heightened states of anxiety and fear commonly seen in psychopathology.

neuroscience↗

bioRxiv2019

Brain gene expression in a novel mouse model of postpartum mood disorder

IntroductionSteroid sulfatase (STS) is an enzyme which cleaves sulfate groups from a variety of steroid hormones, thereby altering their activity and solubility. The expression and activity of STS is increased in female mammalian tissues (including brain) during late pregnancy and into the postpartum period. STS-deficient human and mouse mothers (as a consequence of genetic mutation or acute pharmacological manipulation) show evidence for elevated psychopathology and abnormal behaviour respectively in the postpartum period. In mice, these behavioural effects can be partially normalised through administration of the antipsychotic ziprasidone. MethodsTo explore the neurobiology underlying these postpartum behavioural effects, we compared whole brain gene expression by microarray in behaviourally-defined new mouse mothers acutely administered the STS inhibitor 667-Coumate (10mg/kg p.o.) or vehicle solution (n=12 per group); significant changes were followed-up with pathway analysis and quantitative polymerase chain reaction (qPCR). Finally, the effects of combined 667-Coumate and antipsychotic (ziprasidone) administration (0, 0.3 and 1.0mg/kg i.p.) on the brain expression of the most robustly differentially-expressed candidate genes was examined (n[≥]7 per group). ResultsSurprisingly, no significant gene expression changes were detected between vehicle and 667-Coumate-treated brains at a False Discovery Rate (FDR) corrected p<0.1. 1,081 unique expression changes were detected at a less-stringent cut-off of p<0.05, just two top hits were verified by qPCR, and pathway analysis indicated a significant enrichment of genes involved in olfactory transduction (corrected p-value=1.8x10-3). The expression of the two most robust differentially-expressed genes (Stoml3 and Cyp2g1) was not affected by ziprasidone administration. ConclusionsBehavioural abnormalities in new mothers in the postpartum period elicited as a result of STS deficiency are likely to be the culmination of many small gene expression changes. Our data are consistent with the idea that olfactory function is key to postpartum maternal behaviour in mice, and suggest that aberrant expression of olfactory system genes may partially underlie abnormal maternal behaviour in STS-deficient women.

neuroscience↗

bioRxiv2018

Cyfip1 haploinsufficiency is associated with white matter changes, myelin thinning, reduction of mature oligodendrocytes and behavioural inflexibility

The biological basis of the increased risk for psychiatric disorders due to the pathogenic 15q11.2 copy number deletion is unknown. Previous work has shown disturbances in white matter tracts in human carriers of the deletion at this locus. Using a novel rat model, we have recapitulated low dosage of the candidate risk gene CYFIP1 present within the 15q11.2 interval to reveal alterations in white matter microstructure. Using diffusion tensor imaging, we first showed extensive white matter changes in Cyfip1 mutants that were most pronounced in the corpus callosum and external capsule. Transmission electron microscopy showed that these changes were associated with thinning of the myelin sheath in the corpus callosum. Myelin thinning was independent of changes in axon number or diameter but was associated with a reduction in the number of mature oligodendrocytes. Finally, we demonstrated functional effects on cognitive phenotypes sensitive to both disruptions in myelin and callosal circuitry.

neuroscience↗

bioRxiv2018

Impulsive choice in mice lacking paternal expression of Grb10 provides evidence for intra-genomic conflict in behavior

Imprinted genes are expressed from one parental allele only as a consequence of epigenetic events that take place in the mammalian germ line and are thought to have evolved through intra-genomic conflict between parental alleles. We demonstrate, for the first time, oppositional effects of imprinted genes on brain and behavior. Specifically, here we show that mice lacking paternal Grb10 make fewer impulsive choices, with no dissociable effects on a separate measure of impulsive action. Taken together with previous work showing that mice lacking maternal Nesp55 make more impulsive choices this suggests that impulsive choice behavior is a substrate for the action of genomic imprinting. Moreover, the contrasting effect of these two genes suggests impulsive choices are subject to intra-genomic conflict and that maternal and paternal interests pull this behavior in opposite directions. Finally, these data may also indicate that an imbalance in expression of imprinted genes contributes to pathological conditions such as gambling and drug addiction, where impulsive behavior becomes maladaptive.

genetics↗