Biology subjects

Wilson, T. J.

Publications and source records attributed to Wilson, T. J..

6 recordsLinked to original sources

bioRxiv2026

Fasciclin 2 Cooperates with Discs Large to Maintain Epithelial Architecture

Cell adhesion molecules of the immunoglobulin superfamily (IgCAMs) coordinate adhesive interactions with intracellular organization during tissue morphogenesis. In the Drosophila follicular epithelium, epithelial maintenance depends on reintegration, a process in which mitotically displaced cells reincorporate into the epithelial monolayer. Previous work identified the IgCAMs Fasciclin 2 (Fas2) and Neuroglian (Nrg) as parallel, partially redundant regulators of reintegration, but the intracellular mechanisms linking adhesion to reintegration remained unclear. Here, we show that Fas2 supports reintegration through two mechanistically distinct modes: a transmembrane mode and a GPI-linked mode. Although both contribute to reintegration, the transmembrane mechanism is more effective and depends on stabilization of a cortical Fas2 pool through intracellular coupling. Using yeast two-hybrid screening, genetics, and fluorescence recovery after photobleaching (FRAP), we identify the scaffold protein Discs large (Dlg1) as a functional intracellular partner of transmembrane Fas2. Partial disruption of Dlg1 preferentially sensitizes epithelia in which the parallel Nrg-dependent reintegration mechanism is compromised, consistent with Dlg1 functioning primarily within the Fas2-dependent reintegration arm. While Dlg1 is not required for Fas2 membrane localization, Dlg1 disruption increases the mobile fraction of transmembrane Fas2, indicating that Dlg1 promotes retention of a stabilized cortical Fas2 pool. Together, these findings support a model in which epithelial reintegration depends on coordinated adhesion-scaffold coupling and reveal mechanistic parallels between epithelial reintegration and IgCAM-dependent processes in the developing nervous system.

cell biology↗

bioRxiv2026

The structure and catalytic mechanism of new cellular and viral HDV ribozymes

We have determined the molecular structure and investigated the catalytic mechanism of two new ribozymes of the Hepatitis delta virus family, found in the nematode Caenorhabditis briggsae and virus Ackermannviridae. Crystal structures of both conform to the double-pseudoknot architecture adopted by the viral HDV ribozyme. The C. briggsae ribozyme has been determined both pre- and post-cleavage. In the former both nucleotides flanking the scissile phosphate are observed, along with a metal ion, and cytosine 75 N3 bound to the O5 leaving group. The pH dependence of cleavage rate reveals a pKa of 6.6 and together with the inactivity of a C75U mutant provides evidence for its role as general acid. In contrast to other nucleolytic ribozymes that use catalytic metal ions, reaction rate does not depend on the pKa of the divalent metal ion. Limited adjustment of structure of the active center is consistent with direct bonding of the metal ion to the O2 and non-bridging O, suggesting that the ion acts as a Lewis acid to activate nucleophilic attack. This mechanism appears to be general for the HDV ribozyme class, and distinguishes it from the majority of nucleolytic ribozymes that use general base catalysis.

biochemistry↗

bioRxiv2025

Essential Role of B Cells in Early Defense Against Acinetobacter baumannii Pulmonary Infections

Treatment of antibiotic-resistant Acinetobacter baumannii infections has become exceedingly challenging, leading to higher morbidity and mortality. Therefore, the development of new therapeutics to treat these infections is critically needed, and immunotherapy is one potential treatment option. Immune responses against this pathogen, particularly lymphocyte- mediated responses, are not well understood. In this study, we investigated the role of B cells in innate resistance to A. baumannii pulmonary infection using a B cell-deficient ({micro}MT) mouse model. B cell-deficient mice were impaired in clearing A. baumannii from the lung, liver, and spleen and failed to prevent extrapulmonary dissemination of A. baumannii after infection. Transcriptomic analyses indicated that the lack of B cells was associated with reduced expression of several genes encoding antimicrobial proteins. In addition, B cell deficiency was associated with pulmonary eosinophilia and increased pulmonary recruitment of Ly6C+ NK cells following A. baumannii infection. This study demonstrates the significant role of B cells in providing early protection against A. baumannii infection and implicates B cell-dependent mechanisms beyond antibody-mediated bacterial resistance.

immunology↗

bioRxiv2024

Human genetic variation reveals FCRL3 is a lymphocyte receptor for Yersinia pestis

Yersinia pestis is the gram-negative bacterium responsible for plague, one of the deadliest and most feared diseases in human history. This bacterium is known to infect phagocytic cells, such as dendritic cells and macrophages, but interactions with non-phagocytic cells of the adaptive immune system are frequently overlooked despite the importance they likely hold for human infection. To discover human genetic determinants of Y. pestis infection, we utilized nearly a thousand genetically diverse lymphoblastoid cell lines in a cellular genome-wide association study method called Hi-HOST (High-throughput Human in-vitrO Susceptibility Testing). We identified a nonsynonymous SNP, rs2282284, in Fc receptor like 3 (FCRL3) associated with bacterial invasion of host cells (p=9x10-8). FCRL3 belongs to the immunoglobulin superfamily and is primarily expressed in lymphocytes. rs2282284 is within a tyrosine-based signaling motif, causing an asparagine-to-serine mutation (N721S) in the most common FCRL3 isoform. Overexpression of FCRL3 facilitated attachment and invasion of non-opsonized Y. pestis. Additionally, FCRL3 colocalized with Y. pestis at sites of cellular attachment, suggesting FCRL3 is a receptor for Y. pestis. These properties were variably conserved across the FCRL family, revealing molecular requirements of attachment and invasion, including an Ig-like C2 domain and a SYK interaction motif. Direct binding was confirmed with purified FCRL5 extracellular domain. Following attachment, invasion of Y. pestis was dependent on SYK and decreased with the N721S mutation. Unexpectedly, this same variant is associated with risk of chronic hepatitis C virus infection in BioBank Japan. Thus, Y. pestis hijacks FCRL proteins, possibly taking advantage of an immune receptor to create a lymphocyte niche during infection.

genetics↗

bioRxiv2023

Linking folding dynamics and function of SAM/SAH riboswitches at the single molecule level

Riboswitches are found in the 5-UTR of many bacterial mRNAs. They function as cisacting regulatory elements that control downstream gene expression through ligand-induced conformational changes. Here, we used single-molecule FRET to map the conformational landscape of the SAM/SAH riboswitch and probe how co-transcriptional ligand-induced conformational changes of this translational switch alter ribosome accessibility. The folding of the riboswitch is highly heterogenous, indicating a complex and rugged conformational landscape that enables sampling of the ligand-bound conformation even in the absence of the ligand. Upon ligand binding, the landscape shifts towards the ligand-bound conformation. Mutations at key stabilizing structures alter the ligand-free folding behavior and decrease ligand responsiveness. We also explored translational regulation through folding kinetics by utilizing short oligonucleotides to probe the accessibility of the Shine-Dalgarno sequence within the riboswitch. Additionally, we employed a helicase-based vectorial folding assay to simulate co-transcriptional folding. We find that a competition between ligand binding and ribosome binding is fined tuned via the kinetics of folding. During transcription, the riboswitch takes minutes before reaching equilibrated conformations, and such slow equilibration decreases the effective ligand affinity. Overall, our data demonstrate the significance of conformational polymorphism in RNA function, emphasizing the utilization of complex folding landscapes for regulating ribosome accessibility through ligand induction. Furthermore, we provide direct evidence on how folding kinetics modulate this regulation process.

biophysics↗

bioRxiv2020

An Axon-Pathfinding Mechanism Preserves Epithelial Tissue Integrity

Dividing cells often move apically within epithelial tissue layers, likely to escape the spatial confinement of their neighbors. Because of this movement, daughter cells may be born displaced from the tissue layer. Reintegration of these displaced cells helps support tissue growth and maintain tissue architecture. In the Drosophila follicular epithelium, reintegration relies on the immunoglobulin-superfamily cell-adhesion molecules (IgCAMs) Neuroglian and Fasciclin 2, which line cell-cell borders1. These molecules have been described in epithelia, but are well-studied for their roles in neural development2-8. We show here that reintegration works in the same way as IgCAM-mediated axon growth and pathfinding; it relies not only on extracellular adhesion but also mechanical coupling between IgCAMs and the lateral Spectrin-Based Membrane Skeleton. Our work indicates that reintegration is mediated by a distinct epithelial cell-cell junction that is compositionally and functionally equivalent to junctions made between axons.

cell biology↗