Biology subjects

Schober, A. L.

Publications and source records attributed to Schober, A. L..

3 recordsLinked to original sources

bioRxiv2026

LRRC8A/D-containing anion channels mediate swelling-activated taurine release in the mouse brain

Volume-regulated anion channels (VRACs) are swelling-activated Cl- channels formed by heteromers of LRRC8 proteins (LRRC8A-E). VRACs mediate regulatory volume decrease by releasing Cl- and organic osmolytes, including taurine. In the brain, taurine functions as both an osmolyte and an inhibitory neuromodulator, acting as an agonist at glycine and GABAA receptors. Here, we used RNAi and genetically modified mice to (i) determine the contribution of LRRC8 subunits to swelling-activated taurine release, and (ii) test whether brain VRACs contribute to systemic osmoregulation. In astrocyte cultures lacking the essential VRAC subunit LRRC8A, swelling-activated [3H]taurine release was reduced by ~90%. Similarly, in vivo brain microdialysis revealed a [≥]90% reduction in swelling-activated taurine release in brain-wide LRRC8A knockout mice (bLRRC8A KO). RNAi experiments further confirmed LRRC8D as a key determinant of VRAC-mediated taurine release, with Lrrc8d knockdown reducing swelling activated [3H]taurine efflux by >50%. RNA-seq revealed enrichment of Lrrc8d in the hypothalamus, where astrocytic taurine release is proposed to inhibit magnocellular neurons and suppress arginine vasopressin secretion during hypoosmotic conditions. We therefore tested whether disrupting brain VRACs impairs recovery from systemic hypoosmotic stress. bLRRC8A KO mice and mice with gene trap-mediated LRRC8D depletion were challenged with an intraperitoneal injection of sterile water (7.5% body weight, under anesthesia), and serum osmolality was monitored over time. Unexpectedly, neither model showed impaired recovery from hypoosmotic challenge. Overall, this study identifies LRRC8A/D-containing VRACs as the primary conduit for swelling-activated taurine release in the brain, yet indicates that this pathway is not essential for maintaining systemic fluid-electrolyte homeostasis.

neuroscience↗

bioRxiv2022

Conditional deletion of LRRC8A in the brain protects against stroke damage independently of effect on swelling-activated glutamate release

The ubiquitous volume-regulated anion channels (VRACs), which are composed of LRRC8 proteins, facilitate cell volume homeostasis, and contribute to many other physiological processes. Prior studies demonstrated that treatment with non-specific VRAC blockers, or brain-specific deletion of the essential VRAC subunit LRRC8A, are highly protective in rodent stroke. In this work, we tested the widely accepted idea that harmful effects of VRACs in the brain are mediated by pathological release of the excitatory transmitter glutamate. We used two molecular genetic strategies to ablate LRRC8A expression in either brain astrocytes only (inducible deletion of Lrrc8aflox/flox with Aldh1l1CreERT2) or the majority of brain cells (neurons, astrocytes, and oligodendrocytes with NestinCre). To produce stroke, genetically modified mice were subjected to a 40-minute occlusion of the middle cerebral artery. The inducible deletion of astrocytic LRRC8A yielded no histological or behavioral protection. In contrast, the brain-wide LRRC8A knockout reduced ischemic infarction by ~50% in both heterozygotes (Het) and the full Lrrc8a knockout (KO) as compared to the control Lrrc8aflox/+ genotype. However, despite identical brain damage, Het and KO mice dramatically differed in their VRAC activities. Het mice had full swelling-activated glutamate release, while KO animals showed its virtual absence. These new findings refute the notion that VRAC-mediated glutamate release plays significant role in ischemic brain injury.

neuroscience↗

bioRxiv2021

Organizing Principles of Astrocytic Nanoarchitecture in the Mouse Cerebral Cortex

Astrocytes have complex roles in central nervous system (CNS) health and disease. Underlying these roles is an elaborate architecture based on frequent, extremely fine, but seemingly haphazard branches, as well as prominent features including tripartite synaptic complexes and perivascular endfeet. While broad categories of structures in astrocytes are known, the fundamental building blocks that compose them and their organizing principles have yet to be adequately defined. This is largely due to the absence of high-resolution datasets that can reveal nanoscopic features of astrocytes (i.e. 10-20nm diameter in x, y, and z) and a lack of computational approaches that can effectively interrogate astrocyte shape, organization, and nanoarchitecture. Here, we produced and analyzed multiple, high-resolution datasets of layer 2/3 mouse somatosensory cortex using focused ion beam scanning electron microscopy (8nm intervals) and computer vision approaches to provide a principled, quantitative analysis of astrocytic nanoarchitecture. A decomposition of astrocytes into fundamental parts led to the discovery of unique structural components, recurring structural motifs, and assembly of parts into an organized hierarchy. New relationships were also discerned between astrocytic processes and other CNS microanatomy including mitochondria, tripartite synapses, and cerebrovasculature. By deploying computational resources to quantitatively understand the organizing principles and nanoarchitecture of astrocytes, this study reveals the specialized anatomical adaptations of these complex cells within the CNS. One Sentence SummaryUsing high-resolution serial electron microscopy datasets and computer vision, this study provides a systematic analysis of astrocytic nanoarchitecture from multiple samples of layer 2/3 of adult mouse neocortex, and presents quantitative evidence that astrocytes organize their morphology into purposeful, classifiable assemblies with unique structural and subcellular organelle adaptations related to their physiological functions.

neuroscience↗