Biology subjects

Nawrocka, W. I.

Publications and source records attributed to Nawrocka, W. I..

3 recordsLinked to original sources

bioRxiv2026

Evolution of NELL binding by dual-ligand-responsive axon guidance receptor Robo

Robo receptors are conserved across bilaterians and best known for their ability to mediate axonal repulsion in response to Slit family ligands. In mammals, this applies to Robo1 and Robo2, but mammalian Robo3 binds NELL proteins instead of Slits. The evolutionary origin of NELL-Robo interactions and the possible existence of dual-ligand responsiveness across species remain unknown. Here, we systematically analyzed Robo and NELL homologs across bilaterians and found that NELL-Robo binding is conserved among chordate Robos, but not in protostomes. We show that cephalochordate Robo and NELL can mediate axon repulsion in vitro, suggesting conserved functionality. We observed that conformational masking of the NELL-binding site is prevalent among chordate Robos, modulating NELL-Robo affinity. We also demonstrate that NELL-Robo complexes undergo liquid-liquid phase separation in vitro, a property preserved from cephalochordates to mammals. Our findings support a model in which an ancestral chordate Robo receptor was dual-responsive to Slit and NELL, still the case for some extant Robos, and vertebrate paralogs subfunctionalized, with full ligand specialization emerging in mammals.

biochemistry↗

bioRxiv2024

Nematode Extracellular Protein Interactome Expands Connections between Signaling Pathways

Multicellularity was accompanied by the emergence of new classes of cell surface and secreted proteins. The nematode C. elegans is a favorable model to study cell surface interactomes, given its well-defined and stereotyped cell types and intercellular contacts. Here we report our C. elegans extracellular interactome dataset, the largest yet for an invertebrate. Most of these interactions were unknown, despite recent datasets for flies and humans, as our collection contains a larger selection of protein families. We uncover new interactions for all four major axon guidance pathways, including ectodomain interactions between three of the pathways. We demonstrate that a protein family known to maintain axon locations are secreted receptors for insulins. We reveal novel interactions of cystine-knot proteins with putative signaling receptors, which may extend the study of neurotrophins and growth-factor-mediated functions to nematodes. Finally, our dataset provides insights into human disease mechanisms and how extracellular interactions may help establish connectomes.

biochemistry↗

bioRxiv2023

Neuronal wiring receptors Dprs and DIPs are GPI anchored and this modification contributes to their cell surface organization

The Drosophila Dpr and DIP proteins belong to the immunoglobulin superfamily of cell surface proteins (CSPs). Their hetero- and homophilic interactions have been implicated in a variety of neuronal functions, including synaptic connectivity, cell survival, and axon fasciculation. However, the signaling pathways underlying these diverse functions are unknown. To gain insight into Dpr-DIP signaling, we sought to examine how these CSPs are associated with the membrane. Specifically, we asked whether Dprs and DIPs are integral membrane proteins or membrane anchored through the addition of glycosylphosphatidylinositol (GPI) linkage. We demonstrate that Dprs and DIPs are GPI anchored to the membrane of insect cells and validate these findings for some family members in vivo using Drosophila larvae, where GPI anchor cleavage results in loss of surface labeling. Additionally, we show that GPI cleavage abrogates aggregation of insect cells expressing cognate Dpr-DIP partners. To test if the GPI anchor affects Dpr-DIP localization, we replaced it with a transmembrane domain and observed perturbation of sub-cellular localization on motor neurons and muscles. These data suggest that membrane anchoring of Dprs and DIPs through GPI linkage is required for localization and that Dpr-DIP intracellular signaling likely requires transmembrane co-receptors.

neuroscience↗