Biology subjects

Gillespie, A.

Publications and source records attributed to Gillespie, A..

5 recordsLinked to original sources

bioRxiv2026

Reinforcing Nicotine Doses Activate Supramammillary VGluT2 Neurons in Mice

BackgroundAlthough nicotine reinforcement is often attributed to mesolimbic dopamine neurons in the ventral tegmental area, accumulating evidence indicates that additional brain circuits contribute to its reinforcing effects. AimsThe hypothalamic supramammillary region (SuM) has been implicated as one such substrate, yet the cellular targets and circuit mechanisms through which nicotine engages this region remain poorly understood. MethodsWe combined RNAscope in situ hybridization to identify nicotinic acetylcholine receptor (nAChR) subunits, intravenous nicotine self-administration in mice to determine doses that reliably support reinforcement, and fiber photometry to monitor calcium activity in SuM VGluT2 neurons in vivo. ResultsMice exhibited reliable nicotine self-administration across a range of doses under fixed-ratio and progressive-ratio schedules. RNAscope analysis revealed prominent expression of the {beta}2 nAChR subunit in VGluT2-expressing neurons projecting from the SuM to the medial septum. Fiber photometry recordings showed that reinforcing doses of nicotine produced rapid, infusion-locked increases in GCaMP signals in SuM VGluT2 neurons. ConclusionsThese findings identify nAChR-expressing SuM neurons as a candidate circuit substrate engaged by reinforcing doses of nicotine and extend current models of nicotine reinforcement beyond canonical mesolimbic dopamine pathways.

neuroscience↗

bioRxiv2026

SF3B3 / SF3B5 form a metazoan specific transcription module of the U2 snRNP that coordinates Pol II elongation in a splicing independent manner

Co-transcriptional splicing is a conserved feature of eukaryotic gene expression. However, establishing the functional nature of this process has been difficult. Here using high throughput CRISPR/Cas9 screens we surprisingly find that SF3B3, the third largest subunit of the U2 snRNP complex, is a major regulator of RNA Pol II pause release and processivity. Remarkably, the absence of SF3B3 dramatically perturbs transcription but U2 snRNP assembly and RNA splicing remains unaffected. Mechanistically, SF3B3 coordinates the chromatin occupancy of transcriptional kinases (CDK9/12/13) alongside the PAF1c and Integrator complexes to regulate Pol II. Structure / function analyses of SF3B3 revealed that a metazoan specific 18aa sequence within its disordered tail phenocopies its loss and mediates the physical association and stability of SF3B5. We show that loss of SF3B5 mirrors SF3B3 deficiency suggesting this submodule, although resident within the U2 snRNP complex, evolved to primarily coordinate RNA Pol II in a splicing-independent manner.

molecular biology↗

bioRxiv2024

Catalytic inhibition of KAT6/KAT7 enhances the efficacy and overcomes primary and acquired resistance to Menin inhibitors in MLL leukaemia

Understanding the molecular pathogenesis of MLL fusion oncoprotein (MLL-FP) leukaemia has spawned epigenetic therapies that have improved clinical outcomes in this often-incurable disease. Using genetic and pharmacological approaches, we define the individual and combined contribution of KAT6A, KAT6B and KAT7, in MLL-FP leukaemia. Whilst inhibition of KAT6A/B is efficacious in some pre-clinical models, simultaneous targeting of KAT7, with the novel inhibitor PF-9363, increases the therapeutic efficacy. KAT7 interacts with Menin and the MLL complex and is co-localised at chromatin to co-regulate the MLL-FP transcriptional program. Inhibition of KAT6/KAT7 provides an orthogonal route to targeting Menin to disable the transcriptional activity of MLL-FP. Consequently, combined inhibition rapidly evicts the MLL-FP from chromatin, potently represses oncogenic transcription and overcomes primary resistance to Menin inhibitors. Moreover, PF-9363 or genetic depletion of KAT7 can also overcome acquired genetic/non-genetic resistance to Menin inhibition. These data provide the molecular rationale for rapid clinical translation of combination therapy in MLL-FP leukaemia.

cancer biology↗

bioRxiv2021

Identification of leptospiral protein antigens recognized by WC1+ γδ T cell subsets as target for development of recombinant vaccines

Pathogenic Leptospira species cause leptospirosis, a neglected zoonotic disease recognized as a global public health problem. It is also the cause of the most common cattle infection that results in major economic losses due to reproductive problems. {gamma}{delta} T cells play a role in the protective immune response in livestock species against Leptospira while human {gamma}{delta} T cells also respond to Leptospira. Thus, activation of {gamma}{delta} T cells has emerged as a potential component for optimization of vaccine strategies. Bovine {gamma}{delta} T cells proliferate and produce IFN-{gamma} in response to vaccination with inactivated leptospires and this response is mediated by a specific subpopulation of the WC1-bearing {gamma}{delta} T cells. WC1 molecules are members of the group B scavenger receptor cysteine rich (SRCR) superfamily and are composed of multiple SRCR domains, of which particular extracellular domains act as ligands for Leptospira. Since WC1 molecules function as both pattern recognition receptors and {gamma}{delta} TCR coreceptors, the WC1 system has been proposed as a novel target to engage {gamma}{delta} T cells. Here, we demonstrate the involvement of leptospiral protein antigens in the activation of WC1+ {gamma}{delta} T cells and identified two leptospiral outer membrane proteins able to interact directly with them. Interestingly, we show that the protein-specific {gamma}{delta} T cell response is composed of WC1.1+ and WC1.2+ subsets, although a greater number of WC1.1+{gamma}{delta} T cells respond. Identification of protein antigens will enhance our understanding of the role {gamma}{delta} T cells play in the leptospiral immune response and in recombinant vaccine development.

immunology↗

bioRxiv2020

Large-scale analysis of DNA methylation identifies cellular alterations in blood from psychosis patients and molecular biomarkers of treatment-resistant schizophrenia.

ObjectivePsychosis - a complex and heterogeneous neuropsychiatric condition characterized by hallucinations and delusions - is a common feature of schizophrenia. There is evidence for altered DNA methylation (DNAm) associated with schizophrenia in both brain and peripheral tissues. We aimed to undertake a systematic analysis of variable DNAm associated with psychosis, schizophrenia, and treatment-resistant schizophrenia, also exploring measures of biological ageing, smoking, and blood cell composition derived from DNAm data to identify molecular biomarkers of disease. MethodsWe quantified DNAm across the genome in blood samples from 4,483 participants from seven case-control cohorts including patients with schizophrenia or first-episode psychosis. Measures of biological age, cellular composition and smoking status were derived from DNAm data using established algorithms. DNAm and derived measures were analyzed within each cohort and the results combined by meta-analysis. ResultsPsychosis cases were characterized by significant differences in measures of blood cell proportions and elevated smoking exposure derived from the DNAm data, with the largest differences seen in treatment-resistant schizophrenia patients. DNAm at 95 CpG sites was significantly different between psychosis cases and controls, with 1,048 differentially methylated positions (DMPs) identified between schizophrenia cases and controls. Schizophrenia-associated DMPs colocalize to regions identified in genetic association studies, with genes annotated to these sites enriched for pathways relevant to disease. Finally, a number of the schizophrenia associated differences were only present in the treatment-resistant schizophrenia subgroup. ConclusionsWe show that DNAm data can be leveraged to derive measures of blood cell counts and smoking that are strongly associated with psychosis. Our DNAm meta-analysis identified multiple DMPs associated with both psychosis and a more refined diagnosis of schizophrenia, with evidence for differential methylation associated with treatment-resistant schizophrenia that potentially reflects exposure to clozapine.

genomics↗