Biology subjects

Cameron, L.

Publications and source records attributed to Cameron, L..

5 recordsLinked to original sources

bioRxiv2026

Structural basis for alternative 3' splice site selection in the human spliceosome active center

O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=200 SRC="FIGDIR/small/741260v1_ufig1.gif" ALT="Figure 1"> View larger version (97K): org.highwire.dtl.DTLVardef@279388org.highwire.dtl.DTLVardef@46d636org.highwire.dtl.DTLVardef@997672org.highwire.dtl.DTLVardef@12f40ee_HPS_FORMAT_FIGEXP M_FIG C_FIG Key findingsO_LICryo-EM reveals SDE2 as a novel factor stabilizing the spliceosome active center C_LIO_LISDE2 {Delta}N structures visualize a stalled C* state with impaired docking-factor engagement. C_LIO_LISDE2, Prp18, and FAM32A read a cis-code to stabilize weaker proximal 3'-ss. C_LIO_LISDE2 {Delta}N destabilizes 3'-ss docking and rescues BRCA1 and CFTR mis-splicing in vivo. C_LI Accurate alternative splicing requires discrimination between adjacent 3' splice sites (3'-ss) during catalysis and is disrupted by pathogenic AG-gain mutations that create competing 3'-ss. Here, we present cryo-EM structures of human spliceosomes assembled on native-sequence pre-mRNAs, revealing how the catalytic core controls alternative 3'-ss selection. SDE2 is a previously unrecognized active-center component that promotes a docking-competent spliceosome conformation. Machine learning, in vivo transcriptomics, and in vitro biochemistry show how SDE2 cooperates with FAM32A and Prp18 to act as readers of a cis-regulatory code that governs 3'-ss selection during catalysis. These factors promote weaker, proximal site use by counteracting an intrinsic distal bias generated by active-site interactions with the distal-site -4 nucleotide. Structural or genetic perturbation of these exon-ligation factors destabilizes proximal 3'-ss docking and restores canonical splicing in disease-relevant CFTR and BRCA1 AG-gain alleles. Our work establishes the spliceosome active center as a tunable regulatory hub for alternative splicing.

molecular biology↗

bioRxiv2025

Homocitrullinated Peptides Drive Pro-Inflammatory T-Cell Responses in a Humanized Mouse Model of Rheumatoid Arthritis

ObjectiveAnti-homocitrullinated protein/peptide antibodies (AHCPA) are specific to rheumatoid arthritis (RA) and predictive of worse prognosis, suggesting a pathogenic role for autoreactivity to homocitrullinated antigens. However, T-cell responses to homocitrullinated peptides remain largely unexplored. We investigated these responses in a humanized HLA-DR4-transgenic (DR4tg) mouse model of RA, which expresses the strongest genetic risk factor for this disease. MethodsDR4tg mice were injected subcutaneously with a homocitrullinated peptide called HomoCitJED while control mice received phosphate-buffered saline. After 10 days, T-cells were analyzed for their phenotypic characteristics, cytokine production, and proliferative capacities in the draining lymph nodes (dLNs) and spleens by flow cytometry, enzyme-linked immunosorbent assays, and ProQuantum immunoassays. ResultsHomoCitJED immunization drove robust expansion of T helper (Th) 1, Th17 and hybrid Th1/Th17 CD4+ T cells in dLNs, alongside elevated CD25 activation marker within these subsets. Intracellular cytokine staining confirmed effector activity, revealing higher frequencies of IL-17A+, TNF-+IL-17A+, and IFN-{gamma}+IL-17A+ CD4+ T cells. CD4+ T cells from dLNs also up-regulated the exhaustion markers LAG-3 and Tim-3. CD8+ T cells (Tc) mirrored these findings, as HomoCitJED immunization augmented CD25 and KLRG1 expression, Tc1/Tc17-type IL-17A and IFN-{gamma}/IL-17A production, and antigen-specific proliferation. Additionally, Tim-3, LAG-3 and PD-1 expression on these subsets was augmented. ConclusionsA homocitrullinated peptide elicited Th1/Th17 and Tc1/Tc17 responses marked by concurrent activation and exhaustion signatures, pointing to a dysregulated T-cell state. These findings position homocitrulline-driven T-cell imbalance across both CD4+ and CD8+ T-cell compartments as a potential mechanistic contributor to RA pathogenesis and a target for future immunomodulatory therapies.

immunology↗

bioRxiv2021

MethodsJ2: A Software Tool to Improve Microscopy Methods Reporting

Proper reporting of metadata is essential to reproduce microscopy experiments, interpret results and share images. Experimental scientists can report details about sample preparation and imaging conditions while imaging scientists have the expertise required to collect and report the image acquisition, hardware and software metadata information. MethodsJ2 is an ImageJ/Fiji based software tool that gathers metadata and automatically generates text for the methods section of publications.

bioinformatics↗

bioRxiv2020

Ocean acidification induces subtle shifts in gene expression and DNA methylation in mantle tissue of the Eastern oyster (Crassostrea virginica)

Early evidence suggests that DNA methylation can mediate phenotypic responses of marine calcifying species to ocean acidification (OA). Few studies, however, have explicitly studied DNA methylation in calcifying tissues through time. Here, we examined the phenotypic and molecular responses in the extrapallial fluid and mantle (fluid and tissue at the calcification site) in the Eastern oyster (Crassostrea virginica) exposed to experimental OA over 80 days. Oysters were reared under three experimental pCO2 treatments ( control, 580 atm; moderate OA, 1000 uatm; high OA, 2800 atm) and sampled at 6 time points (24 hours - 80 days). We found that high OA initially induced changes in the pH of the extrapallial fluid (pHEPF) relative to the external seawater, but the magnitude of this difference was highest at 9 days and diminished over time. Calcification rates were significantly lower in the high OA treatment compared to the other treatments. To explore how oysters regulate their extrapallial fluid, gene expression and DNA methylation were examined in the mantle-edge tissue of oysters from day 9 and 80 in the control and high OA treatments. Mantle tissue mounted a significant global molecular response (both in the transcriptome and methylome) to OA that shifted through time. Although we did not find individual genes that were significantly differentially expressed to OA, the pHEPF was correlated with the eigengene expression of several co-expressed gene clusters. A small number of OA-induced differentially methylated loci were discovered, which corresponded with a weak association between OA-induced changes in genome-wide gene body DNA methylation and gene expression. Gene body methylation, however, was not significantly correlated with the eigengene expression of pHEPF correlated gene clusters. These results suggest that in C. virginica, OA induces a subtle response in a large number of genes, but also indicates that plasticity at the molecular level may be limited. Our study highlights the need to re-assess the plasticity of tissue-specific molecular responses in marine calcifiers, as well as the role of DNA methylation and gene expression in mediating physiological and biomineralization responses to OA.

molecular biology↗

bioRxiv2018

IL-2 Modulates Th2 cell Responses to Glucocorticoid: A Cause of Persistent Type 2 Inflammation?

BackgroundInhaled glucocorticosteroids (GCs) are the main treatment for asthma as they reduce type 2 cytokine (IL-4, IL-5 and IL-13) expression and induce apoptosis. Asthma severity is associated with GC insensitivity, increased type 2 inflammation and circulating Th2 cells. Since IL-2 is a T cell survival factor, we assessed whether IL-2 levels associate with the proportion of Th2 cells and/or correlate with clinical features of asthma severity.\n\nMethodsPeripheral blood from asthma patients (n=18) was obtained and Th2 cell numbers determined by flow cytometry. Peripheral blood cells were activated with mitogen (24hrs) and supernatant levels of IL-2 and IL-13 measured by ELISA. In vitro differentiated Th2 cells were treated with dexamethasone and IL-2 and assessed for apoptosis by flow cytometry staining of Annexin V. Level of mRNA for anti-apoptotic (BCL-2) and pro-apoptotic (BIM) genes as well as IL-13 were determined by qRT-PCR.\n\nResultsIL-2 produced by activated peripheral blood cells correlated negatively with lung function (FEV1) and positively with daily dose of inhaled GC. When patients were stratified based on IL-2 level, high IL-2 producers made more IL-13 and had more circulating Th2 cells. In vitro, increasing the level of IL-2 in the culture media was associated with resistance to DEX-induced apoptosis, more BCL-2 and less BIM mRNA. Th2 cells cultured with higher IL-2 also had more IL-13 mRNA and required higher concentrations of DEX for cytokine suppression.\n\nConclusions and Clinical RelevanceIL-2 modulates Th2 cell responses to GC, supporting both their survival and pro-inflammatory capacity, suggesting that a patients potential to produce IL-2 may be a determinant in asthma severity.

immunology↗