Biology subjects

Krueger-Burg, D.

Publications and source records attributed to Krueger-Burg, D..

7 recordsLinked to original sources

bioRxiv2026

Consequences of sustained modulation of VIP-expressing neurons in mouse corticolimbic regions on anxiety-related avoidance behaviors, social functioning, and associative fear learning

GABAergic inhibitory neurons play a central role in shaping network dynamics, and accordingly, their dysfunction is implicated in the pathophysiology of various psychiatric, neurodevelopmental, and neurological disorders. In the past decade, studies on vasoactive intestinal polypeptide-expressing inhibitory neurons (VIP+ neurons) have positioned them as critical components of this circuitry. In particular, VIP+ neurons have been proposed to function within a canonical disinhibitory circuit motif, preferentially inhibiting other interneuron subtypes, to ultimately modulate the gain and activity of local pyramidal neurons. However, their contribution to psychiatrically relevant behavioral endophenotypes is still not fully understood, limiting our ability to target these neurons for therapeutic purposes. In the present study, we systematically assessed the functional contribution of VIP+ neurons to affective and social behaviors. To this end, we used a chemogenetic approach to manipulate the activity of VIP+ neurons in core corticolimbic regions, including the medial prefrontal cortex (mPFC), basolateral amygdala (BLA), and ventral hippocampus (vHPC). The consequences of either activating or inhibiting VIP+ neurons in these regions were observed while mice underwent a battery of behavioral tasks assessing anxiety-related avoidance behaviors, social interest and recognition, and associative fear learning. While sustained modulation of VIP+ neurons had no significant effect on anxiety-related or social behaviors in any of the brain regions assessed, it produced a robust reduction in associative fear learning specifically in the mPFC. These findings demonstrate that the consequences of sustained VIP+ neuron modulation depend on both anatomical location and behavioural context. Moreover, they identify VIP+ neurons in the mPFC as potentially clinically relevant targets for interventions aimed at modulating fear-related circuits.

neuroscience↗

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↗

bioRxiv2022

Phosphorylation Determines Whether Neuroligin-3 is at Excitatory or Inhibitory Synapses in Different Regions of the Brain

Neuroligin-3 is a postsynaptic adhesion molecule involved in development, function, and pathologies of synapses in the brain. It is a genetic cause of autism and a potent component of the tumor microenvironment in gliomas. There are four Neuroligins that operate at distinct synapse types, selectively interacting with presynaptic adhesion and postsynaptic scaffold proteins. We investigated the subcellular localization and scaffold specificities of synaptic Neuroligin-3 and demonstrate an unexpected pattern of localization to excitatory synapses in cortical areas, and inhibitory synapses in subcortical areas. Using phosphoproteomics, we identify Neuroligin-3-specific serine phosphorylation in cortex and hippocampus that obstructs a key binding site for inhibitory synapse scaffolds. Using in utero CRISPR/Cas9 knockout and replacement with phosphomimetic mutants, we demonstrate that phosphorylation at this site determines excitatory versus inhibitory synapse localization of Neuroligin-3 in vivo. Our data reveal a mechanism that differentially regulates the balance of Neuroligin-3 between excitatory and inhibitory synapses, adding to our emerging understanding of their role in the development of brain connectivity and associated pathologies.

neuroscience↗

bioRxiv2021

Neuronal cholesterol synthesis is essential for repair of chronically demyelinated lesions in mice

Astrocyte-derived cholesterol supports brain cells under physiological conditions. However, in demyelinating lesions, astrocytes downregulate cholesterol synthesis and the cholesterol that is essential for remyelination has to originate from other cellular sources. Here, we show that repair following acute versus chronic demyelination involves distinct processes. In particular, we found that in chronic myelin disease, when recycling of lipids is often defective, de novo neuronal cholesterol synthesis is critical for regeneration. By gene expression profiling, genetic loss of function experiments and comprehensive phenotyping, we provide evidence that neurons increase cholesterol synthesis in chronic myelin disease models and MS patients. In mouse models, neuronal cholesterol facilitated remyelination specifically by triggering OPC proliferation. Our data contribute to the understanding of disease progression and have implications for therapeutic strategies in MS patients.

neuroscience↗

bioRxiv2021

Ageing-associated myelin dysfunction drives amyloid deposition in mouse models of Alzheimer's disease

The prevalence of Alzheimers disease (AD), the leading cause of dementia, shows a strict age-dependency, but why ageing constitutes the main risk factor for this disease is still poorly understood. Brain ageing affects oligodendrocytes1 and the structural integrity of myelin sheaths2, the latter associated with secondary neuroinflammation3. Since oligodendrocytes support axonal and neuronal health4-7, we hypothesised that ageing-associated loss of myelin integrity could be an upstream risk factor for neuronal amyloid-{beta} (A{beta}) deposition, the primary neuropathological hallmark of AD. Here, we show that in AD mouse models different genetically induced defects of myelin integrity or demyelinating injuries are indeed potent drivers of amyloid deposition in vivo, quantified by whole brain light sheet microscopy. Conversely, the lack of myelin in the forebrain provides protection against plaque deposition. Mechanistically, we find that myelin dysfunction causes the accumulation of the A{beta} producing machinery within axonal swellings and increases cortical amyloid precursor protein (APP) cleavage. Surprisingly, AD mice with dysfunctional myelin lack plaque-corralling microglia but show a disease-associated microglia (DAM)-like signature as revealed by bulk and single cell transcriptomics. These activated microglia, however, are primarily engaged with myelin, preventing the protective reactions of microglia to A{beta} plaques. Our data suggest a working model, in which age-dependent structural defects of myelin promote plaque formation, directly and indirectly, and are thus an upstream AD risk factor. Improving oligodendrocyte health and myelin integrity could be a promising target to delay AD.g

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↗