Biology subjects

Garbett, K.

Publications and source records attributed to Garbett, K..

5 recordsLinked to original sources

bioRxiv2025

Cytoplasmic tail composition modulates the G protein and arrestin-3 signaling bias of the adhesion GPCR LPHN2

The class B2 Adhesion GPCRs (aGPCRs) combine cell adhesion with GPCR signaling to control diverse developmental and physiological processes. How aGPCRs interact with and integrate distinct groups of effectors including G proteins, arrestins, and G protein receptor kinases (GRKs) remains unclear. Here, we find that diversity in the aGPCR C-terminal intracellular tail modulates G protein activation, arrestin-3 recruitment, and utilization of selective GRKs in LPHN2, a postsynaptic aGPCR essential for synapse formation. The C-terminal tail of LPHN2 is required for G protein activation and arrestin-3 recruitment. LPHN2 with an intact tail recruits arrestin-3 in the absence of G protein activation, suggesting constitutive arrestin-3-biased signaling. Alternative splicing of the LPHN2 tail modulates G protein activation and arrestin-3 binding independently, supporting that it controls G protein vs arrestin-3 bias. GRKs are important but not essential for arrestin-3 recruitment to LPHN2. Moreover, GRK2 increases arrestin-3 recruitment only in a subset of LPHN2 variants. Collectively, these results show that the mechanisms of the interactions of class B2 aGPCRs and arrestin are distinct from those of class A GPCRs and that splicing of the LPHN2 C-terminal tail determines G protein vs arrestin bias.

molecular biology↗

bioRxiv2025

Coordinated dynamics of excitatory and inhibitory synapse assembly

Diverse synaptic connections self-organize into neural circuits during brain development. A balance between excitatory and inhibitory synaptic function is required for information processing by these neural circuits. Despite the importance of this balance, the interplay between excitatory and inhibitory synaptic assembly during circuit establishment remains unclear due to a lack of means to monitor both processes simultaneously. Here, we develop imaging and analysis methods to visualize and track excitatory and inhibitory synapses. By applying these approaches, we find that despite continual dynamics, excitatory and inhibitory synaptic density remain at steady-state levels during synapse maturation. These results indicate balanced excitatory and inhibitory synapse assembly despite continual synaptic turnover.

neuroscience↗

bioRxiv2025

The Adhesion GPCR ADGRL2 engages Gα13 to Enable Epidermal Differentiation

Homeostasis relies on signaling networks controlled by cell membrane receptors. Although G-protein-coupled receptors (GPCRs) are the largest family of transmembrane receptors, their specific roles in the epidermis are not fully understood. Dual CRISPR-Flow and single cell Perturb-seq knockout screens of all epidermal GPCRs were thus performed, uncovering an essential requirement for adhesion GPCR ADGRL2 (latrophilin 2) in epidermal differentiation. Among potential downstream guanine nucleotide-binding G proteins, ADGRL2 selectively activated G13. Perturb-seq of epidermal G proteins and follow-up tissue knockouts verified that G13 is also required for epidermal differentiation. A cryo-electron microscopy (cryo-EM) structure in lipid nanodiscs showed that ADGRL2 engages with G13 at multiple interfaces, including via a novel interaction between ADGRL2 intracellular loop 3 (ICL3) and a G13-specific QQQ glutamine triplet sequence in its GTPase domain. In situ gene mutation of this interface sequence impaired epidermal differentiation, highlighting an essential new role for an ADGRL2-G13 axis in epidermal differentiation.

cell biology↗

bioRxiv2024

Structure of the extracellular region of the adhesion GPCR CELSR1 reveals a compact module which regulates G protein-coupling

The Cadherin EGF Laminin G seven-pass G-type receptor subfamily (CELSR/ADGRC) is one of the most conserved among adhesion G protein-coupled receptors and is essential for animal development. The extracellular regions (ECRs) of CELSRs are large with 23 adhesion domains. However, molecular insight into CELSR function is sparsely available. Here, we report the 3.8 [A] cryo-EM reconstruction of the mouse CELSR1 ECR and reveal that 14 domains form a compact module mediated by conserved interactions majorly between the CADH9 and C-terminal GAIN domains. In the presence of Ca2+, the CELSR1 ECR forms a dimer species mediated by the cadherin repeats putatively in an antiparallel fashion. Cell-based assays reveal the N-terminal CADH1-8 repeat is required for cell-cell adhesion and the C-terminal CAHD9-GAIN compact module can regulate cellular adhesion. Our work provides molecular insight into how one of the largest GPCRs uses defined structural modules to regulate receptor function.

biochemistry↗

bioRxiv2023

Extensive characterization of a Williams Syndrome murine model shows Gtf2ird1-mediated rescue of select sensorimotor tasks, but no effect on enhanced social behavior

Williams Syndrome is a rare neurodevelopmental disorder exhibiting cognitive and behavioral abnormalities, including increased social motivation, risk of anxiety and specific phobias along with perturbed motor function. Williams Syndrome is caused by a microdeletion of 26-28 genes on chromosome 7, including GTF2IRD1, which encodes a transcription factor suggested to play a role in the behavioral profile of Williams Syndrome. Duplications of the full region also lead to frequent autism diagnosis, social phobias, and language delay. Thus, genes in the region appear to regulate social motivation in a dose-sensitive manner. A Complete Deletion mouse, heterozygously eliminating the syntenic Williams Syndrome region, has been deeply characterized for cardiac phenotypes, but direct measures of social motivation have not been assessed. Furthermore, the role of Gtf2ird1 in these behaviors has not been addressed in a relevant genetic context. Here, we have generated a mouse overexpressing Gtf2ird1, which can be used both to model duplication of this gene alone and to rescue Gtf2ird1 expression in the Complete Deletion mice. Using a comprehensive behavioral pipeline and direct measures of social motivation, we provide evidence that the Williams Syndrome Critical Region regulates social motivation along with motor and anxiety phenotypes, but that Gtf2ird1 complementation is not sufficient to rescue most of these traits, and duplication does not decrease social motivation. However, Gtf2ird1 complementation does rescue light-aversive behavior and performance on select sensorimotor tasks, perhaps indicating a role for this gene in sensory processing or integration.

animal behavior and cognition↗