Biology subjects

Wall, S. C.

Publications and source records attributed to Wall, S. C..

4 recordsLinked to original sources

bioRxiv2026

Bidirectional disruption of Lrrk2 function drives T cell dysregulation and an exhaustion-like immune response

Background: Neurodegenerative diseases including Parkinson's disease (PD) are increasingly associated with dysfunction in both central and peripheral immune systems. Pathogenic mutations in leucine-rich repeat kinase 2 (LRRK2) represent a major cause of familial PD, while common polymorphisms are associated with inflammatory diseases. Methods: Here, using immunophenotyping flow cytometry and quantitative PCR (qPCR), we compared immune cell populations and function across both the central and peripheral immune systems in C57BL/6J wild type (WT), Lrrk2 p.G2019S knock-in (GKI) and Lrrk2 knock-out (LKO) models in basal and ex vivo immune-stimulated conditions. Results: With a focus on T cell biology, compared to their WT counterparts at baseline, GKI mice exhibit higher populations of Cd8+ and TH17 T cell subsets in the brain, whereas LKO mice exhibited unique central memory (TCM), follicular helper (TFH), and TH2 lineages. In the periphery, GKI mice demonstrated higher TH1, TH2, and TH17 subset expansions, whereas peripheral alterations in LKO are largely restricted to TH17 subsets. Within mutant genotypes, a striking discrepancy was observed between baseline gene expression and the translated proteins encoded, that reveals a fundamental loss of basal immune homeostasis. This phenomenon was further exposed following an acute (6-hour) ex vivo lipopolysaccharide (LPS) immune challenge. Following stimulation, GKI immune cells had reduced transcription, alongside stalled translation, for almost all effector molecules examined, while LKO immune cells had fewer transcriptional changes compared to wild type. Overall, both mutant lines had stalled or flatline effector molecule production after immune stimulation, suggesting a profound loss of functional responsiveness. This hypothesis was supported by a significant increase in surface protein of the inhibitory receptor Pd-1 on regulatory T cells (TREG) and TH1/TH2 Cd4+ T cell subsets in GKI mice. LKO immune landscapes trended toward similar exhaustion patterns, albeit less evident. Conclusions: These data suggest that bidirectional disruptions to normal Lrrk2 function break immune homeostasis. Immune cell function should be carefully considered when targeting LRRK2 kinase activity in patients with PD.

immunology↗

bioRxiv2025

Peripheral inflammation mediates midbrain Lrrk2 kinase activity via Rab32 expression

Mutations that increase leucine-rich repeat kinase 2 (LRRK2) activity confer significant risk for Parkinsons disease (PD), yet incomplete disease penetrance suggest additional factors are required to manifest disease. We recently identified RAB32 Ser71Arg as a Mendelian gene for PD. Here, we establish Rab32 as a key mediator linking peripheral inflammation to Lrrk2 activation. We show that Rab32 and Rab38 expression are modestly, but inversely, correlated with their homolog Rab29. In vivo, peripheral lipopolysaccharide (LPS)-induced inflammation selectively induced Rab32 expression in midbrain Iba1+ microglia but not dopaminergic neurons, where it localized to Lamp1+ lysosomal compartments and correlated with Lrrk2 kinase activity. LPS similarly induces Rab32 expression in human induced pluripotent stem cell-derived microglia, demonstrating a unified biological response to inflammation across species. Promoter analysis identified Tfe3, a master regulator of lysosomal biogenesis and autophagy, as a key driver of Rab32 expression induced Lrrk2 kinase activation. During inflammation, Tfe3 translocated to the nucleus of midbrain Iba1+ microglia to induce Rab32 expression and Lrrk2 kinase activity. Knockdown of Tfe3, but not Tfeb, mitigates these effects, establishing Rab32 as a physiological rheostat of Lrrk2 activity. This mechanistic pathway enables peripheral inflammation to modulate LRRK2 activity and highlights Rab32/Tfe3 as a therapeutic targeting for neuroprotection in PD.

cell biology↗

bioRxiv2023

Inhibition of LRRK2 kinase activity rescues deficits in striatal dopamine dynamics in VPS35 p.D620N knock-in mice

Dysregulation of dopamine neurotransmission profoundly affects motor, motivation and learning behaviors, and is often observed during the prodromal phase of Parkinsons disease (PD). However, the mechanism underlying these pathophysiological changes remains to be elucidated. Mutations in vacuolar protein sorting 35 (VPS35) and leucine-rich repeat kinase 2 (LRRK2) both lead to autosomal dominant PD, and VPS35 and LRRK2 may physically interact to govern the trafficking of synaptic cargos within the endo-lysosomal network in a kinase-dependent manner. To better understand the functional role of VPS35 and LRRK2 on dopamine physiology, we examined Vps35 haploinsufficient (Haplo) and Vps35 p.D620N knock-in (VKI) mice and how their behavior, dopamine kinetics and biochemistry are influenced by LRRK2 kinase inhibitors. We found Vps35 p.D620N significantly elevates LRRK2-mediated phosphorylation of Rab10, Rab12 and Rab29. In contrast, Vps35 haploinsufficiency reduces phosphorylation of Rab12. While striatal dopamine transporter (DAT) expression and function is similarly impaired in both VKI and Haplo mice, that physiology is normalized in VKI by treatment with the LRRK2 kinase inhibitor, MLi-2. As a corollary, VKI animals show a significant increase in amphetamine induced hyperlocomotion, compared to Haplo mice, that is also abolished by MLi-2. Taken together, these data show Vps35 p.D620N confers a gain-of-function with respect to LRRK2 kinase activation, and VPS35 and LRRK2 functionally interact to regulate DAT trafficking and striatal dopamine neurotransmission.

neuroscience↗

bioRxiv2021

Single-Cell Profiling of the Antigen-Specific Response to BNT162b2 SARS-CoV-2 RNA Vaccine

RNA-based vaccines against SARS-CoV-2 are critical to limiting COVID-19 severity and spread. Cellular mechanisms driving antigen-specific responses to these vaccines, however, remain uncertain. We used single-cell technologies to identify and characterized antigen-specific cells and antibody responses to the RNA vaccine BNT162b2 in longitudinal samples from a cohort of healthy donors. Mass cytometry and machine learning pinpointed a novel expanding, population of antigen-specific non-canonical memory CD4+ and CD8+ T cells. B cell sequencing suggested progression from IgM, with apparent cross-reactivity to endemic coronaviruses, to SARS-CoV-2-specific IgA and IgG memory B cells and plasmablasts. Responding lymphocyte populations correlated with eventual SARS-CoV-2 IgG and a donor lacking these cell populations failed to sustain SARS-CoV-2-specific antibodies and experienced breakthrough infection. These integrated proteomic and genomic platforms reveal an antigen-specific cellular basis of RNA vaccine-based immunity. ONE SENTENCE SUMMARYSingle-cell profiling reveals the cellular basis of the antigen-specific response to the BNT162b2 SARS-CoV-2 RNA vaccine.

immunology↗