Ajith, A. | bioRxiv Science

bioRxiv2026

Altered volume-regulated anion channel activity contributes to depression and anxiety-related molecular and behavioural phenotypes in zebrafish

Major depressive disorder (MDD) is a leading cause of global morbidity and mortality. Unfortunately, a substantial proportion of patients do not respond adequately to currently available therapies, highlighting the need for new therapeutic targets. Here, we investigated the role of volume-regulated anion channel (VRAC) in depression-related phenotypes using zebrafish. Disruption of VRAC function, either by pharmacological inhibition or morpholino-mediated knockdown of lrrc8aa, the zebrafish ortholog of mammalian LRRC8A, the obligatory subunit required for VRAC function, induced anxiety- and depression-like behaviours in zebrafish larvae and altered the expression of genes associated with affective disorders. Transcriptomic analysis of lrrc8aa-deficient larvae revealed dysregulation of pathways involved in neuronal signalling and cellular stress responses. Conversely, pharmacological activation of VRAC with zinc pyrithione (ZPT) improved behavioural abnormalities and partially restored altered gene expression. In adult zebrafish subjected to chronic unpredictable stress, ZPT produced antidepressant- and anxiolytic-like effects comparable to those of imipramine and normalized elevated monoamine oxidase (mao) expression. Together, these findings indicate that reduced VRAC function contributes to depression- and anxiety-related behavioural and molecular phenotypes and identify VRAC as a potential target for the development of novel antidepressant therapies. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=149 SRC="FIGDIR/small/740018v1_ufig1.gif" ALT="Figure 1"> View larger version (42K): org.highwire.dtl.DTLVardef@d81884org.highwire.dtl.DTLVardef@131b8e9org.highwire.dtl.DTLVardef@162d1d0org.highwire.dtl.DTLVardef@bcdb82_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2026

A neuropsychiatric disease-associated mutation in LRRC8B disrupts cellular calcium signaling, mitochondrial function, and bioenergetics

Leucine-rich repeat-containing 8 (LRRC8) proteins form the volume-regulated anion channel (VRAC) and participate in diverse physiological processes, including cell volume regulation, gliotransmitter release, and insulin secretion. In mammals, five paralogs (LRRC8A-E) exist; LRRC8A is the obligatory subunit that assembles into functional hexameric channels with LRRC8C, D, or E. LRRC8B is distinct: we previously demonstrated its role in regulating endoplasmic reticulum (ER) Ca{superscript 2} homeostasis and ER Ca{superscript 2} leak. A LRRC8B variant (Y380S) identified in an Indian family with severe mental illness has been associated with disease pathology, but its molecular and cellular consequences remain unknown. Here, we show that this disease-associated mutant perturbs Ca{superscript 2} signalling, mitochondrial bioenergetics, and redox homeostasis. Both wild-type and mutant LRRC8B localize to the ER and mitochondria. LRRC8B knockdown significantly reduced mitochondrial Ca{superscript 2} uptake and maximal respiratory the Y380S mutant phenocopied LRRC8B knockdown, altering ER Ca{superscript 2} release, elevating basal cytosolic Ca{superscript 2}, and impairing mitochondrial Ca{superscript 2} uptake, consistent with a dominant-negative mechanism. The mutant further induced mitochondrial dysfunction, including loss of membrane potential, oxidative stress, and defective antioxidant responses, ultimately compromising cellular bioenergetics and viability. Mechanistically, the Y380S mutation disrupted LRRC8B interaction with the mitochondrial outer membrane channel VDAC. These findings identify LRRC8B-VDAC coupling as a key determinant of mitochondrial Ca{superscript 2} handling and provide a mechanistic link between LRRC8B dysfunction and neuropsychiatric disease. HighlightsO_LIA psychiatric disease-associated LRRC8B variant (Y380S) acts as a dominant-negative regulator of ER Ca{superscript 2} homeostasis. It enlarges the releasable ER Ca{superscript 2} pool and reduces cell viability. C_LIO_LILRRC8B promotes mitochondrial Ca{superscript 2} uptake through interaction with VDAC. The Y380S mutation disrupts this interaction, reducing mitochondrial Ca{superscript 2} uptake. C_LIO_LIThe Y380S mutant increases mitochondrial superoxide production without activating compensatory antioxidant responses. C_LIO_LIThe mutant also causes mitochondrial membrane depolarization and bioenergetic failure, as evidenced by reduced oxygen consumption rate and ATP production. C_LI Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=140 SRC="FIGDIR/small/718892v1_ufig1.gif" ALT="Figure 1"> View larger version (47K): org.highwire.dtl.DTLVardef@1f314d3org.highwire.dtl.DTLVardef@1dc3908org.highwire.dtl.DTLVardef@124445aorg.highwire.dtl.DTLVardef@39326_HPS_FORMAT_FIGEXP M_FIG C_FIG

cell biology↗