Biology subjects

Wettschurack, K. W.

Publications and source records attributed to Wettschurack, K. W..

3 recordsLinked to original sources

bioRxiv2025

Human microglia in brain assembloids display region-specific diversity and respond to hyperexcitable neurons carrying SCN2A mutation

Microglia critically shape neuronal circuit development and function, yet their region-specific properties and roles in distinct circuits of the human brain remain poorly understood. In this study, we generated region-specific brain organoids (cortical, striatal, and midbrain), each integrated with human microglia, to fill this critical gap. Single-cell RNA sequencing uncovered six distinct microglial subtypes exhibiting unique regional signatures, including a subtype highly enriched for the GABAB receptor gene within striatal organoids. To investigate the contributions of microglia to neural circuitry, we created microglia-incorporated midbrain-striatal assembloids, modeling a core circuit node for many neuropsychiatric disorders including autism. Using chemogenetics to activate this midbrain-striatal circuit, we observed increased calcium signaling in microglia involving GABAB receptors. Leveraging this model, we examined microglial responses within neural circuits harboring an SCN2A nonsense (C959X) mutation associated with profound autism. Remarkably, microglia displayed heightened calcium responses to SCN2A mutation-mediated neuronal hyperactivity, and engaged in excessive synaptic pruning. These pathological effects were reversed by pharmacological inhibition of microglial GABAB receptors. Collectively, our findings establish an advanced platform to dissect human neuroimmune interactions in sub-cortical regions, highlighting the important role of microglia in shaping critical circuitry related to neuropsychiatric disorders. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=188 SRC="FIGDIR/small/657874v1_ufig1.gif" ALT="Figure 1"> View larger version (72K): org.highwire.dtl.DTLVardef@125b36eorg.highwire.dtl.DTLVardef@270079org.highwire.dtl.DTLVardef@903525org.highwire.dtl.DTLVardef@19145c4_HPS_FORMAT_FIGEXP M_FIG C_FIG TeaserModeling regional microglial diversity in sub-cortical regions is challenging. We generated human organoid and assembloid models containing microglia that acquire region-specific heterogeneity. Our work shows dynamic responses of microglia when exposed to hyperexcitable midbrain-striatal circuits, providing an exciting platform to study neuroimmune interactions in human brain development and neuropsychiatric disorders, including SCN2A mutation-mediated monogenic autism. HighlightsO_LI* Single-cell RNA sequencing analyses reveal six distinct microglial subtypes that spontaneously attain unique specialization in human cortical, striatal, and midbrain organoids. C_LIO_LI* Microglia facilitate axonal projections across regional organoids, promoting assembloid formation. C_LIO_LI* Microglia respond to hyperexcitable neurons via calcium signaling and exhibit excessive pruning of neuronal synapses. C_LIO_LI* Blocking microglial GABAB receptors normalizes calcium activity and reduces synaptic pruning, suggesting a potential targeting strategy for synaptic deficits. C_LI

neuroscience↗

bioRxiv2025

Autism-associated SCN2A deficiency disrupts cortico-striatal circuitry in human brain assembloids

Profound autism spectrum disorder (ASD) is frequently attributable to single-gene mutations, with SCN2A (voltage-gated sodium channel NaV1.2) protein-truncating variants (PTVs) being one of the most penetrant. Although cortico-striatal circuitry is implicated as a key node in ASD, the impact of SCN2A deficiency on human neural circuits is unknown. Using the human cortico-striatal assembloid model, we show that the autism-causing PTV SCN2A-C959X impairs long-range cortical axonal projections, reduces striatal spine density, and attenuates excitatory cortical-striatal synaptic transmission. Surprisingly, these assembloids carrying the heterozygous SCN2A nonsense mutation exhibited pronounced network hyperexcitability, a human cell-specific phenotype not observed in Scn2a+/- mice, highlighting a human-specific circuit vulnerability. Collectively, our study unveils human circuit-specific dysfunctions of SCN2A deficiency and SCN2A-mediated ASD. HighlightsO_LIAxonal projections facilitate synapse formation and functional connectivity in human brain assembloids. C_LIO_LINaV1.2 is expressed along neuronal axons, extending to soma and dendrites in human brain assembloids. C_LIO_LISCN2A-C959X disrupts axonal projection patterns, impairs excitatory synaptic transmission, reduces spine density, and results in elevated neuronal excitability. C_LI Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=90 SRC="FIGDIR/small/657036v1_ufig1.gif" ALT="Figure 1"> View larger version (27K): org.highwire.dtl.DTLVardef@6d5b1forg.highwire.dtl.DTLVardef@1795ecdorg.highwire.dtl.DTLVardef@13f0d7eorg.highwire.dtl.DTLVardef@8ee059_HPS_FORMAT_FIGEXP M_FIG C_FIG In briefO_ST_ABSSCN2A haploinsufficiency impairs cortico-striatal circuitry.C_ST_ABSSCN2A haploinsufficiency disrupts axon initial segment (AIS) integrity, leading to hyperexcitability (red arrow), reduced axon projections, and impaired synaptic transmission (decreased sEPSCs and altered network firing). These deficits result in dysfunction within the cortico-striatal circuitry.

neuroscience↗

bioRxiv2025

Restoration of excitation/inhibition balance enhances neuronal signal-to-noise ratio and rescues social deficits in autism-associated Scn2a-deficiency

Social behavior is critical for survival and adaptation, which is profoundly disrupted in autism spectrum disorders (ASD). Social withdrawal due to information overload was often described in ASD, and it was suspected that increased basal noise, i.e., excessive background neuronal activities in the brain could be a disease mechanism. However, experimental test of this hypothesis is limited. Loss-of-function mutations (deficiency) in SCN2A, which encodes the voltage-gated sodium channel NaV1.2, have been revealed as a leading monogenic cause of profound ASD. Here, we revealed that Scn2a deficiency results in robust and multifaceted social impairments in mice. Scn2a-deficient neurons displayed an increased excitation-inhibition (E/I) ratio, contributing to elevated basal neuronal noise and diminished signal-to-noise ratio (SNR) during social interactions. Notably, the restoration of Scn2a expression in adulthood is able to rescue both SNR and social deficits. By balancing the E/I ratio and reducing basal neuronal firing, an FDA-approved GABAA receptor-positive allosteric modulator improves sociability in Scn2a-deficient mice and normalizes neuronal activities in translationally relevant human brain organoids carrying autism-associated SCN2A nonsense mutation. Collectively, our findings revealed a critical role of the NaV1.2 channel in the regulation of social behaviors, and identified molecular, cellular, and circuitry mechanisms underlying SCN2A-associated disorders. HIGHLIGHTSO_LINaV1.2 deficiency leads to pronounced social deficits in mice. C_LIO_LINaV1.2 deficiency results in an overall enhanced E/I ratio, elevated basal neuronal activity, and impaired signal-to-noise ratio. C_LIO_LIBoth the enhanced E/I ratio and impaired sociability are reversible through the restoration of NaV1.2 expression in adulthood. C_LIO_LITargeted restoration of NaV1.2 in striatum-projecting neurons rescues social impairments. C_LIO_LIGABA transmission is reduced in both mouse and human organoid models of SCN2A deficiency, and acute systemic administration of GABAA receptor-positive allosteric modulators restores sociability. C_LI Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=193 HEIGHT=200 SRC="FIGDIR/small/641498v1_ufig1.gif" ALT="Figure 1"> View larger version (42K): org.highwire.dtl.DTLVardef@154a323org.highwire.dtl.DTLVardef@1a27fbaorg.highwire.dtl.DTLVardef@16fa3beorg.highwire.dtl.DTLVardef@6712c2_HPS_FORMAT_FIGEXP M_FIG C_FIG Graphical abstract: Severe Scn2a deficiency leads to a predominate decrease in GABA transmission with an overall enhanced E/I ratio, elevated basal neuronal activity, impaired SNR, and social deficits in adult NaV1.2-deficient mice.

neuroscience↗