Biology subjects

Wiseglass, G.

Publications and source records attributed to Wiseglass, G..

3 recordsLinked to original sources

bioRxiv2024

On the same side: The immune regulatory protein Vista and its ligands interact in cis

VISTA, an essential immune checkpoint regulatory protein, regulates peripheral T-cell quiescence and tolerance. Despite its potential as a target for anti-tumor and autoimmune disease therapies, uncertainty regarding VISTAs binding mode and membrane orientation has hindered these developments. Contrary to the prevailing paradigm, we found using cell aggregation assays that VISTA cannot interact with its ligands in trans (between cells). Using MST and flow cytometry, we showed that soluble VISTA binds to its ligands, suggesting that VISTAs membrane orientation restricts trans interactions. In contrast, split luciferase complementation assays showed that VISTA interacts with its ligands in cis. We propose that a disulfide bond bends VISTAs Ig domain towards the membrane in an orientation that prevents trans while enabling cis interactions. Co-expression data analysis from the cancer genome atlas showed a strong correlation between VISTA and its ligand, PSGL-1, consistent with our in-vitro cis interaction data. Our findings reveal VISTAs binding mechanism and suggest an intrinsic inhibition signaling pathway independent of additional cells. Importantly, our experimental framework provides a platform for identifying novel VISTA-targeted therapeutics.

immunology↗

bioRxiv2024

Following The Evolutionary Paths Of Highly Specific Homophilic Adhesion Proteins

Many adhesion proteins, evolutionarily related through gene duplication, exhibit distinct and precise interaction preferences and affinities crucial for cell patterning. Yet, the evolutionary path by which these proteins, which are highly similar in structure and sequence, acquire new specificity and prevent cross-interactions within their family members remains unknown. To bridge this gap, this study focuses on Drosophila Down syndrome cell adhesion molecule-1 (Dscam1) proteins, which are cell adhesion proteins that have undergone extensive gene duplication. Dscam1 evolved under strong selective pressure to achieve strict homophilic recognition, essential for neuronal self-avoidance and patterning. Through a combination of phylogenetic analysis, ancestral sequence reconstruction, and cell aggregation assays, we studied the evolutionary trajectory of Dscam1 exon 4 across various insect lineages. We demonstrated that recent Dscam1 duplications in the mosquito lineage bind with strict homophilic specificities without any cross-interactions. We found that ancestral and intermediate Dscam1 isoforms were able to maintain their homophilic bindings capabilities, with some intermediate isoforms also engaging in promiscuous interactions with other paralogs. Our results highlight the robust selective pressure for homophilic specificity integral to Dscam1 function within the process of neuronal self-avoidance. Importantly, our study suggests that the path to achieving such selective specificity does not introduce disruptive mutations that prevent self-binding but includes an evolutionary intermediate that demonstrates promiscuous heterophilic interactions. Overall, these results offer insights into evolutionary strategies that underlie adhesion protein interaction specificity.

evolutionary biology↗

bioRxiv2023

Clustered Protocadherin Cis-interactions are Required for Homophilic Combinatorial Cell-Cell Recognition Underlying Neuronal Self-Avoidance

In the developing human brain, only 53 stochastically expressed clustered protocadherin (cPcdh) isoforms enable neurites from an individual neuron to recognize and self-avoid, while maintaining contact with neurites from other neurons. Cell assays have demonstrated that self-recognition occurs only when all cPcdh isoforms perfectly match across the cell boundary, with a single mismatch in the cPcdh expression profile interfering with recognition. It remains unclear however, how a single mismatched isoform between neighboring cells, is sufficient to block erroneous recognitions. In using systematic cell aggregation experiments we show that abolishing cPcdh interactions on the same membrane (cis) results in a complete loss of specific combinatorial binding between cells (trans). Our computer simulations demonstrate that the organization of cPcdh in linear array oligomers, composed of cis and trans interactions, enhances self-recognition by increasing the concentration and stability of cPcdh trans complexes between the homotypic membranes. Importantly, we show that the presence of mismatched isoforms between cells drastically diminishes the concentrations and stability of the trans complexes. Overall, we provide an explanation for the role of the cPcdh assembly arrangements in neuronal self/non-self-discrimination underlying neuronal self-avoidance.

biochemistry↗