Biology subjects

Wenger, S.

Publications and source records attributed to Wenger, S..

3 recordsLinked to original sources

bioRxiv2025

Ca2+-phospholipid-dependent regulation of Munc13-1 is essential for post-tetanic potentiation at mossy fiber synapses and supports working memory

Hippocampal mossy fiber (hMF) to CA3 pyramidal cell synapses are thought to support the formation of working memory through presynaptic short-term facilitation (STF) and post-tetanic potentiation (PTP). However, the molecular mechanisms underlying these transient forms of synaptic enhancement remain poorly understood. We show here that Munc13-1-mediated priming of synaptic vesicles (SVs) at active zones controls hMF STF and PTP in response to Ca2+-phospholipid and Ca2+-calmodulin (CaM) signaling. Knock-in mice expressing Munc13-1 variants that are insensitive to Ca2+-phospholipid and Ca2+-CaM signaling exhibit severely impaired STF and PTP at hMF synapses. Moreover, the PTP-induction threshold is strongly increased upon the loss of Ca2+-phospholipid-Munc13-1 signaling. Since these synaptic defects are accompanied by working memory deficits, especially in mice expressing the Ca2+-phospholipid-insensitive Munc13-1 variant, we conclude that Ca2+-dependent regulation of Munc13-1-mediated SV priming co-determines hMF short-term plasticity and working memory formation.

neuroscience↗

bioRxiv2022

Functional Neuroligin-2-MDGA1 interactions differentially regulate synaptic GABAARs and cytosolic gephyrin aggregation

AO_SCPLOWBSTRACTC_SCPLOWThe function of GABAergic synapses is critically shaped by cell adhesion proteins that recruit GABAARs to synapses and mediate transsynaptic signalling, but the synapse-type-specific function of such synaptic adhesion proteins and their mutual interaction remain incompletely understood. A ubiquitous cell adhesion protein at GABAergic synapses is Neuroligin-2 (Nlgn2), which recruits synaptic GABAARs by promoting the assembly of the postsynaptic gephyrin scaffold. While Nlgn2 is present at virtually all GABAergic synapses throughout the forebrain, its loss affects different GABAergic synapse subtypes with different severity, indicating that synapse-specific interactors and synapse-organizer-redundancies define the function of Nlgn2 for a given synapse type. Here we investigated how Nlgn2 function at GABAergic synapses in mouse hippocampal area CA1 is modulated by two recently identified interaction partners, MDGA1 and MDGA2. We show that Nlgn2 and MDGA1 colocalize most prominently in the stratum radiatum (S.R.) of area CA1, and that combined Nlgn2 and MDGA1 deletion causes a layer-specific exacerbation of the loss of gephyrin puncta in layer S.R. seen following Nlgn2 deletion. Intriguingly, combined Nlgn2 and MDGA1 deletion concurrently ameliorates the abnormal cytosolic gephyrin aggregation, the reduction in inhibitory synaptic transmission and the exacerbated anxiety-related behavior seen in Nlgn2 knockout (KO) mice. In contrast, heterozygous deletion of MDGA2 in Nlgn2 KO mice has only minor effects on gephyrin and GABAAR puncta and does not normalize cytosolic gephyrin aggregates, inhibitory synaptic transmission or anxiety-related behavior. Our data indicate that MDGA1, but not MDGA2, modulates Nlgn2 function, primarily by regulating the formation of cytosolic gephyrin aggregates. Given that both Nlgn2 and the MDGA family of proteins have been linked to psychiatric disorders, such as autism and schizophrenia, our data lead to the notion that abnormal gephyrin aggregation may contribute to the pathophysiology of these disorders, and that intervention with gephyrin aggregation could present a novel therapeutic strategy.

neuroscience↗

bioRxiv2019

Altered theta / beta frequency synchrony links abnormal anxiety-related behavior to synaptic inhibition in Neuroligin-2 knockout mice.

Inhibitory synaptic transmission plays a key role in the circuits underlying anxiety behaviors, but the network mechanisms by which disruptions in synaptic inhibition contribute to pathological anxiety processing remain largely unknown. Here we addressed this question in mice lacking the inhibitory synapse-specific adhesion protein Neuroligin-2 (Nlgn2), which display widespread reduction in inhibitory synaptic transmission as well as a pronounced anxiety phenotype. To investigate how the lack of synaptic inhibition alters the communication between key brain regions in anxiety processing, we recorded local field potentials (LFPs) simultaneously from a network of brain regions involved in anxiety processing, including the basolateral amygdala (BLA), centromedial amygdala, bed nucleus of the stria terminalis, prefrontal cortex and ventral hippocampus (vHPC). We found that LFP power in the vHPC was profoundly increased while vHPC-directed theta frequency synchrony was disrupted in Nlgn2 KO mice under anxiogenic conditions. Instead, deletion of Nlgn2 increased beta frequency synchrony across the anxiety network, and the theta / beta synchrony ratio strongly predicted anxiety behaviors in an open field paradigm. Local deletion of Nlgn2 in the vHPC and BLA revealed that they encode distinct aspects of the anxiety phenotype of the Nlgn2 KO mice, with vHPC linked to anxiety induced freezing and BLA linked to reduction in exploratory activity. Together, our data demonstrate that alterations in long-range functional connectivity link synaptic inhibition to abnormal anxiety behaviors, and that Nlgn2 KO mice represent an interesting model to study the role of inhibitory synaptic transmission in the circuits underlying anxiety disorders.

neuroscience↗