Felix, R. | Search bioRxiv

bioRxiv2026

BODIPY-Tagged β-Lactams as Selective Quenched Activity-Based Probes to Target Human Neutrophil Elastase

Activity-based probes are indispensable tools for interrogating protease function, and quenched fluorescent variants enable dynamic, real-time imaging of enzymatic activity. Despite these advances, very few quenched activity-based probes (qABPs) have been reported for serine proteases, which constitute the largest and most diverse mechanistic class of proteases. {beta}-Lactams have been extensively used to develop molecular tools and drugs designed to bind or be hydrolysed by serine-dependent bacterial enzymes. Here, we report the first monocyclic {beta}-lactam-containing qABPs for detecting serine proteases. Both the enzyme-triggered activation mechanism and intrinsic reactivity of the probes were highly dependent on the relative position of the BODIPY-FL fluorophore and quencher moiety at the {beta}-lactam core. qABPs displaying the most efficient turn-on mechanism were shown to selectively target human neutrophil elastase (HNE) in different human cell lysates. The most successful qABP was rapidly internalised and targeted HNE in U937 cells and human neutrophils. These results demonstrate the potential of the modular {beta}-lactam warhead to develop turn-on probes to track neutrophil serine proteases in live cells

pharmacology and toxicology↗

bioRxiv2021

Structural and functional organization of visual responses in the inferior olive of larval zebrafish

The olivo-cerebellar system plays an important role in vertebrate sensorimotor control. According to a classical theory of cerebellar cortex, the inferior olive (IO) provides Purkinje cells with error information which drives motor learning in the cerebellum. Here we investigate the sensory representations in the IO of larval zebrafish and their spatial organization. Using single-cell labeling of genetically identified IO neurons we find that they can be divided into at least two distinct groups based on their spatial location, dendritic morphology, and axonal projection patterns. In the same genetically targeted population, we recorded calcium activity in response to a set of visual stimuli using 2-photon imaging. We found that most IO neurons showed direction selective and binocular responses to visual stimuli and that functional properties were spatially organized within the IO. Light-sheet functional imaging that allowed for simultaneous activity recordings at the soma and axonal level revealed tight coupling between soma location, axonal projections and functional properties of IO neurons. Taken together, our results suggest that anatomically-defined classes of inferior olive neurons correspond to distinct functional types, and that topographic connections between IO and cerebellum contribute to organization of the cerebellum into distinct functional zones.

neuroscience↗