Biology subjects

Usher, S. G.

Publications and source records attributed to Usher, S. G..

4 recordsLinked to original sources

bioRxiv2026

A deep learning-generated hASIC1a miniprotein inhibitor confers neuroprotection in stroke

Ion channels remain notoriously recalcitrant drug targets despite their extensive pathophysiological significance. Acid-sensing ion channels (ASICs) are proton-gated cation channels that cause neuronal death when excessively activated, such as during ischaemic stroke. This acidosis-driven injury pathway remains unchallenged by existing therapeutics. Here we generate two de novo designed hASIC1a-specific miniproteins by developing a platform that integrates computational miniprotein design, high-throughput automated patch clamp screening, biophysical and structural characterisation, and in vivo validation. We identify a subtype-selective hASIC1a inhibitor, Denasin1, which achieves near-complete inhibition with nanomolar potency. Denasin1 is disordered in solution but adopts the computationally predicted helix-turn-helix fold when bound to the extracellular acidic pocket of hASIC1a. Crucially, Denasin1 reduces infarct volume by > 50% in a murine model of ischaemic stroke. We thereby establish our de novo design platform as a route to develop potent and selective ion channel modulators.

biophysics↗

bioRxiv2025

Coupling between acid-sensing ion channel 1a and the monocarboxylate transporter family shapes cellular pH response

Proton-mediated activation of acid-sensing ion channel 1a (ASIC1a) leads to influx of sodium and, to a lesser extent, calcium, followed by rapid and complete desensitization. However, various ASIC1a-expressing cell types display atypical proton-induced currents characterized by altered proton sensitivity and slow and incomplete desensitization. The origin of this functional diversity and its physiological relevance remain unclear. Here, we show that the monocarboxylate transporter 1 (MCT1) interacts with ASIC1a, leading to subtype-specific modulation of proton sensitivity and desensitization. We delineate the molecular mechanism of the ASIC1a-MCT1 coupling and find that the presence of MCT1 is required for the distinct ASIC1a-mediated currents observed in glioblastoma cells, the most lethal brain cancer in adults. Strikingly, presence of ASIC1a together with MCT1 significantly prolongs the lifespan of mice intracranially injected with glioblastoma cells. We thus uncover the basis for altered ASIC1a function in glioblastoma and highlight the importance of deciphering the cell-type specific ASIC1a interactome.

biophysics↗

bioRxiv2024

The sodium leak channel NALCN is regulated by neuronal SNARE complex proteins

The sodium leak channel NALCN is vital for the regulation of electrical activity in neurons and other excitable cells, and mutations in the channel or its auxiliary proteins lead to severe neurodevelopmental disorders. Here we show that the neuronal SNARE complex proteins syntaxin and SNAP25, which enable synaptic transmission in the nervous system, inhibit the activity of the NALCN channel complex in both heterologous systems and primary neurons. The existence of this interaction suggests that the neurotransmitter release machinery can regulate electrical signalling directly, and therefore modulate the threshold for its own activity. We further find that reduction of NALCN currents is sufficient to promote cell survival in syntaxin-depleted cells. This suggests that disinhibited NALCN may cause the puzzling phenomenon of rapid neuronal cell death in the absence of syntaxin. This interaction may offer opportunities for future drug development against genetic diseases linked to both NALCN- and SNARE protein-containing complexes.

neuroscience↗

bioRxiv2021

The dynamic interplay of PIP2 and ATP in the regulation of the KATP channel

ATP-sensitive potassium (KATP) channels couple the intracellular ATP concentration to insulin secretion. KATP channel activity is inhibited by ATP binding to the Kir6.2 tetramer and activated by phosphatidylinositol-4,5-bisphosphate (PIP2). Here, we use molecular dynamics (MD) simulation, electrophysiology and fluorescence spectroscopy to show that ATP and PIP2 occupy different binding pockets that share a single amino acid residue, K39. When both ligands are present, K39 shows a greater preference to co-ordinate with PIP2 than ATP. A neonatal diabetes mutation at K39 (K39R) increases the number of hydrogen bonds formed between K39 and PIP2, reducing ATP inhibition. We also find direct effects on nucleotide binding from mutating E179, a residue proposed to interact with PIP2. Our work suggests PIP2 and ATP interact allosterically to regulate KATP channel activity.

biochemistry↗