Biology subjects

Williams, M. E.

Publications and source records attributed to Williams, M. E..

9 recordsLinked to original sources

bioRxiv2026

A clinically identified Kirrel3 variant disrupts trans-synaptic circuit assembly

Trans-synaptic adhesion molecules guide selective connections between neurons to establish circuit specificity. Yet, there are gaps in the understanding of how many synaptic adhesion molecules function in vivo and if clinically identified variants perturb their function. Using cell-type-specific deletion in the mouse hippocampus, we show that Kirrel3 is required in both pre-synaptic DG neurons and post-synaptic GABA neurons to form DG-to-GABA excitatory synapses that drive a feed-forward inhibitory connection to CA3. These data provide in vivo, genetic evidence for a homophilic trans-synaptic Kirrel3 interaction driving synapse formation. Moderately increasing or decreasing wildtype Kirrel3 expression did not detectably alter synapse formation or CA3 neuron activity. In contrast, expression of a Kirrel3 missense variant identified in an individual with autism dominantly disrupts synapse formation and CA3 activity in vivo, providing a mechanism by which a single missense allele could disrupt circuit assembly and contribute to disease.

neuroscience↗

bioRxiv2026

A Microglial Regulatory Program Linked to Neuropsychiatric Disorders

Hoxb8 is a transcription factor required for the normal function of a specialized microglial population. Loss of Hoxb8 causes compulsive overgrooming and anxiety-like behaviors in mice, with greater severity in females after sexual maturity. However, the Hoxb8-dependent transcriptional program in microglia remains poorly understood. Here, we integrated Hoxb8 chromatin occupancy, transcriptional responses, and chromatin contacts to classify genes by their spatial relationship to Hoxb8 binding. Hoxb8 occupied thousands of genomic regions, but only a subset of associated genes responded transcriptionally. Locally associated, Hoxb8-activated genes were linked to immune signaling and hormone responsiveness, whereas locally associated, Hoxb8-suppressed genes were linked to cell-cycle and genome-maintenance processes. Distally associated genes contributed to neuronal and intercellular communication and were enriched for genes associated with obsessive-compulsive disorder and anxiety. These findings reveal a functionally organized Hoxb8-dependent transcriptional program and identify potential connections between Hoxb8 activity in microglia, hormone responsiveness, intercellular communication, and neuropsychiatric disease risk.

neuroscience↗

bioRxiv2026

Molecular architecture of meiotic pro-crossover factor HEI10 reveals coupling of higher-order assembly and ubiquitin chain formation

In meiosis, crossovers between homologous chromosomes generate genetic diversity and are required for accurate chromosome segregation, ensuring fertility. In mammals, HEI10 is one of three pro-crossover RING-domain factors implicated in protein modification by ubiquitin and/or SUMO and characterised by their dynamic accumulation at future crossover sites. However, the molecular architecture and enzymatic activity of mammalian HEI10 have remained unknown. Here, we show that human HEI10 has E3-ubiquitin ligase activity that depends on its higher-order assembly. We report the crystal structure of the HEI10 core, revealing how a 29-nm rod-like tetramer is formed through head-to-head association of two coiled-coil dimers that results in clustering of four RING domains around the molecular centre. HEI10 tetramers self-assemble through RING, coiled-coil, and C-terminal interfaces into fibrous and spherical higher-order structures. Structure-guided mutants show that higher-order assembly is required for HEI10 to catalyse K63-linked ubiquitin chain formation in vitro, with the most active species likely corresponding to a loose, non-fibrous network of assembled HEI10 molecules. Arabidopsis thaliana HEI10 retains the tetrameric core and higher-order assembly behaviour, suggesting a conserved principle of HEI10 function.

biochemistry↗

bioRxiv2025

Generating clonal seeds using non-reduction in female4 (nrf4), a novel meiotic mutant of maize

The discovery of increased vigor and yield in hybrid corn compared to inbred lines dates to the early 20th century. If hybrid vigor could be maintained across generations, it would revolutionize agriculture. A potential method to achieve this goal is asexual reproduction through seed (apomixis). We searched for mutants mimicking components of apomixis and here, we describe a novel meiotic mutant, non-reduction in female4 (nrf4) of Zea mays (maize), that produces unreduced female gametes - an essential component of apomixis. By combining the nrf4 mutant with the previously described matrilineal/not like dad (mtl/nld) mutant, which leads to embryo development without paternal contribution, we successfully produced clonal seeds. This is an important step towards the engineering of clonally propagated hybrids in maize, the most widely grown crop world-wide. Our findings provide new avenues for the engineering of synthetic apomixis in crops. One-Sentence SummaryThis manuscript provides a proof-of-principle that synthetic apomixis can be engineered in maize.

genetics↗

bioRxiv2024

Eosinophils protect against SARS-CoV-2 following a vaccine breakthrough infection

Waning immunity and the emergence of immune evasive SARS-CoV-2 variants jeopardize vaccine efficacy leading to breakthrough infections. We have previously shown that innate immune cells play a critical role in controlling SARS-CoV-2. To investigate the innate immune response during breakthrough infections, we modeled breakthrough infections by challenging low-dose vaccinated mice with a vaccine-mismatched SARS-CoV-2 Beta variant. We found that low-dose vaccinated infected mice had a 2-log reduction in lung viral burden, but increased immune cell infiltration in the lung parenchyma, characterized by monocytes, monocyte-derived macrophages, and eosinophils. Single cell RNA-seq revealed viral RNA was highly associated with eosinophils that corresponded to a unique IFN-{gamma} biased signature. Antibody-mediated depletion of eosinophils in vaccinated mice resulted in increased virus replication and dissemination in the lungs, demonstrating that eosinophils in the lungs are protective during SARS-CoV-2 breakthrough infections. These results highlight the critical role for the innate immune response in vaccine mediated protection against SARS-CoV-2.

immunology↗

bioRxiv2024

Inhibitory neurons defined by a synaptogenic molecule impair memory discrimination

The homophilic adhesion molecule Kirrel3 drives synapse formation between dentate granule (DG) neurons and GABA neurons, and Kirrel3 gene variants are associated with neurodevelopmental disorders in humans. However, the circuit function and behavioral relevance of Kirrel3-expressing neurons are unknown. Using intersectional genetics, we identified a population of Kirrel3-expressing GABA neurons that regulate memory discrimination in male and female mice. Using chemogenetics with in vivo electrophysiology and behavioral assays, we discovered that activating Kirrel3-expressing GABA neurons, but not parvalbumin neurons, potently inhibits CA3 neuron activity and impairs contextual memory discrimination during recall, revealing a critical role for these neurons in the retrieval of precise memories. Light and electron microscopy of Kirrel3-expressing GABA neurons suggests that they receive direct excitation from DG neurons and project onto CA3 dendrites. Together, this multi-scale approach demonstrates how cell type-specific expression of adhesion molecules mark subsets of neurons that control key features guiding memory and behavior. SIGNIFICANCE STATEMENTHere, we identified a never-before studied group of inhibitory neurons defined by expression of the gene Kirrel3, which is a synaptic cell adhesion molecule and risk gene for neurodevelopmental disorders. We show that Kirrel3 inhibitory neuron activity exerts exceptionally strong control over CA3 neuron activity and impairs the ability of mice to distinguish between different contexts during memory retrieval. Thus, Kirrel3 inhibitory neurons regulate memory precision in mice, and our study employs a powerful framework linking molecular identity and synaptic specificity to behavioral function in the adult brain.

neuroscience↗

bioRxiv2023

Modular Splicing is Linked to Evolution in the Synapse-Specificity Molecule Kirrel3

Kirrel3 is a cell-adhesion molecule that instructs the formation of specific synapses during brain development in mouse and Kirrel3 variants may be risk factors for autism and intellectual disabilities in humans. Kirrel3 is predicted to undergo alternative splicing but brain isoforms have not been studied. Here, we present the first in-depth characterization of Kirrel3 isoform diversity in brain using targeted, long-read mRNA sequencing of mouse hippocampus. We identified 19 isoforms with predicted transmembrane and secreted forms and show that even rare isoforms generate detectable protein in the brain. We also analyzed publicly-available long-read mRNA databases from human brain tissue and found 11 Kirrel3 isoforms that, similar to mouse, encode transmembrane and secreted forms. In mice and humans, Kirrel3 diversity arises from alternative, independent use of protein-domain coding exons and alternative early translation-stop signals. Intriguingly, the alternatively spliced exons appear at branch points in the chordate phylogenetic tree, including one exon only found in humans and their closest living relatives, the great apes. Together, these results validate a simple pipeline for analyzing isoform diversity in genes with low expression and suggest that Kirrel3 function is fine-tuned by alternative splicing and may play a role in brain evolution. Significance StatementKirrel3 is an important molecule for synapse and circuit formation with gene variants that are associated with neurodevelopmental disorders, yet Kirrel3 function remains largely unknown. Here, we report new isoforms of mouse and human Kirrel3, including secreted and transmembrane forms, that suggest a diverse repertoire of Kirrel3 actions. Importantly, we identified a new Kirrel3 exon only present in humans and the other great apes with potential to play an important role in circuit formation unique to these species.

neuroscience↗

bioRxiv2022

Memory CD4 T cell subset organization in the female reproductive tract is regulated via the menstrual cycle through CCR5 signaling

Despite their importance for immunity against sexually transmitted infections (STIs), the composition of the female reproductive tract (FRT) memory CD4 T cell population in response to changes in the local tissue environment during the menstrual cycle remains poorly defined. Here we show that across humans, non-human primates (NHP), and mice, FRT CD4 T cells comprise distinct subsets corresponding to migratory memory (TMM) and resident memory (TRM) cells. TMM display tissue-itinerant trafficking characteristics, restricted FRT tissue distribution, with distinct transcriptional properties and effector responses to infection. CD4 T cell subset fluctuations synchronized with cycle-driven proinflammatory changes within the local tissue environment and oral administration of a CCR5 antagonist inhibited cycle phase-specific migratory T cell surveillance. This study provides novel insights into the dynamic nature of FRT memory CD4 T cells and identifies the menstrual cycle as a key regulator of memory T cell defense at the site of STI exposure. SummaryThe menstrual cycle regulates memory T cell surveillance.

immunology↗

bioRxiv2019

Kirrel3-mediated synapse formation is attenuated by disease-associated missense variants

Missense variants in Kirrel3 are repeatedly identified as risk factors for autism spectrum disorder and intellectual disability but it has not been reported if or how these variants disrupt Kirrel3 function. Previously, we studied Kirrel3 loss-of-function using knockout mice and showed that Kirrel3 is a synaptic adhesion molecule necessary to form one specific type of hippocampal synapse in vivo. Here, we developed a new gain-of-function assay for Kirrel3 and find that wild-type Kirrel3 induces synapse formation selectively between Kirrel3-expressing cells via homophilic, trans-cellular binding. We tested six disease-associated Kirrel3 missense variants and find that five attenuate this synaptogenic function. All variants tested traffic to the cell surface and localize to synapses similar to wild-type Kirrel3. Two tested variants lack homophilic trans-cellular binding, which likely accounts for their reduced synaptogenic function. Interestingly, we also identified variants that bind in trans but cannot induce synapses, indicating Kirrel3 trans-cellular binding is necessary but not sufficient for its synaptogenic function. Collectively, these results suggest Kirrel3 functions as a synaptogenic, cell-recognition molecule, and this function is attenuated by missense variants associated with autism spectrum disorder and intellectual disability. Thus, we provide critical insight to Kirrel3 function in typical brain development and the consequences of missense variants associated with autism spectrum disorder and intellectual disability. SIGNIFICANCE STATEMENTHere, we advance our understanding of mechanisms mediating target-specific synapse formation by providing evidence that Kirrel3 trans-cellular interactions mediate contact recognition and signaling to promote synapse development. Moreover, this is the first study to test the effects of disease-associated Kirrel3 missense variants on synapse formation, and thereby, provides a framework to understand the etiology of complex neurodevelopmental disorders arising from rare missense variants in synaptic genes.

neuroscience↗