Autism spectrum disorder (ASD) is a neurodevelopmental disorder with an unclear pathogenesis. Growing evidence implicates excitatory/inhibitory (E/I) imbalance in ASD pathophysiology, prompting an investigation into gamma-aminobutyric acid (GABA)-mediated inhibitory transmission. The transcription factor Paired Box 2 (Pax2), essential for GABAergic interneuron specification, participates in the regulation of neural developmental processes. Our previous work demonstrated an E/I imbalance in the neurotransmitter system and reduced GABAARα2-positive neurons in the prefrontal cortex (PFC) of Pax2 neuron-specific deletion mice, though the internal molecular regulatory mechanism remained elusive. In this study, we generated GABAergic neuron-specific Pax2 knockdown mice via injection of AAV-shPax2 virus and comprehensively evaluated ASD-related behaviors, revealing autism-like behaviors, such as impaired social novelty and repetitive behaviors. Molecular analysis revealed upregulation of Tcf7l2, a key downstream mediator of the Wnt/β-catenin signaling pathway. Functional assessment confirmed hyperactivation of the Wnt/β-catenin signaling pathway in GABAergic neuron Pax2 knockdown mice. Notably, pharmacological intervention with esculetin, an inhibitor of the Wnt/β-catenin pathway, ameliorated the observed autism-like behaviors. These findings establish a pathogenic axis wherein GABAergic neuron-specific Pax2 deficiency induces hyperactivation of the Wnt/β-catenin signaling pathway and disrupts E/I balance, ultimately driving autism-like behavioral phenotypes. Our results further identify inhibition of Wnt/β-catenin signaling as a promising therapeutic strategy for ASD.
In vivo results demonstrated that NT supplementation attenuated repetitive behaviors and improved social interactions in the BTBR cohort, revealing pronounced sex-dimorphic responsiveness.
F. D’Egidio, M., 14 A. DAngelo et al.· 0 citations
Background/Objectives: Transcription factor 4 (TCF4) is a proneural basic helix–loop–helix transcription factor that plays a critical role in brain development and is associated with a variety of psychiatric disorders, including autism spectrum disorder (ASD), major depressive disorder, and schizophrenia. Autosomal dominant mutations in TCF4 result in a profound neurodevelopmental disorder called Pitt–Hopkins Syndrome (PTHS). Germline TCF4 loss-of-function (LOF) studies using human and mouse models have identified dysregulation in neural cell proliferation, genesis, and specification, which leads to disruption in neuronal, astroglial, and oligodendroglial lineages. In this study, we focused on the role of TCF4 in the genesis of the astrocyte lineage, specifically in the context of modeling PTHS. Methods: We investigated the expression of astrocyte marker genes in primary astrocyte cultures and whole-brain lysates, as well as assessed pan- and subclass-specific astrocyte markers, using immunohistochemical (IHC) analysis in a heterozygous mouse model of PTHS. Lastly, we tracked ventrally derived astrocytes using an Nkx2.1 reporter mouse to investigate misallocation of ventrally derived astrocytes into the dorsal cortex, a phenotype previously observed when both Tcf4 alleles were conditionally deleted in the Nkx2.1 lineage. Results: We show that germline heterozygous mutations in Tcf4 had no effect on the expression of astrocyte markers via qPCR or astrocyte cell density with IHC analysis. Germline heterozygous Tcf4 LOF also did not result in misallocation of ventrally derived astrocytes into the dorsal cortex. Conclusions: These data indicate that germline heterozygous TCF4 LOF, which models PTHS, does not appear to significantly affect the astrocyte lineage at the cell population level.
Sarain Stump, Joseph F. Bohlen, BaDoi N. Phan et al.· Neuroglia· 0 citations
The findings implicate disrupted SYTL4-RAB27A-dependent vesicle trafficking in ASD pathogenesis and identify SYTL4 and RAB27A as previously unrecognized contributors to autism-associated synaptic deficits and behavior.
Yang Liao, Shuju Zhang, Xiaolei Zhang et al.· Proceedings of the National...· 0 citations
Hoxa5 encodes a transcription factor essential for embryonic patterning and organogenesis, with sustained expression in hindbrain precerebellar nuclei during postnatal development. Given prior evidence implicating HOXA5 in synaptogenesis and early postnatal circuit maturation, we investigated whether its inactivation during this critical developmental window contributes to neurodevelopmental disorder (NDD)-related phenotypes. Using previously generated transcriptomic data, we identified multiple deregulated genes classified as autism spectrum disorder (ASD) risk genes in the SFARI database, several of which are associated with a cerebellar phenotype in mice. We then performed a comprehensive behavioral assessment across motor, social, stereotypical, anxiety-related, and attentional domains in a postnatal inactivation mouse model (Hoxa5-cKO). Motor coordination, learning, gait, and sensorimotor functions were preserved. Social behavior assays yielded no consistent genotype-dependent effects, although results were sensitive to analytical methods and cohort variability. In contrast, Hoxa5-cKO mice exhibited increased stereotypical behaviors, including elevated scratching and marble burying, in the absence of anxiety- or locomotion-related confounds. Importantly, interpretation of social and cognitive phenotypes was impacted by well-known constraints of behavioral neuroscience. We discuss these downfalls and propose additional guidelines. Altogether, our findings indicate that postnatal Hoxa5 deficiency selectively enhances stereotyped behaviors without broadly affecting motor or social functions. The data support a model in which HOXA5 acts as a modulator of postnatal precerebellar circuit connectivity and/or function, with subtle behavioral consequences that require further research in specific genetic or environmental contexts.
Hadrien Glibert, L. Bridoux, C. Moens et al.· Behavioral and Brain Functio...· 0 citations
De novo variants in the ubiquitin-proteasome pathway are linked to autism spectrum disorder (ASD), yet their functional impact on neurodevelopment remains poorly understood. We investigated USP15, a deubiquitinating enzyme with rare damaging variants identified in individuals with ASD, using isogenic human iPSC-derived brain organoids and single-cell transcriptomics. USP15-mutant organoids showed genotype-dependent, progenitor-centered alterations during corticogenesis. Heterozygous organoids modeling haploinsufficiency displayed a shift toward later pseudotime states together with altered maturation and synaptic organization of deep-layer neurons. In contrast, homozygous organoids showed broader phenotypes, including mitotic suppression, aberrant HOX gene expression, and stress-response activation. Regulon analysis showed reduced activity of progenitor-associated regulons, including SOX2, NR2F1, and NR2F2, in heterozygous organoids, whereas homozygous organoids exhibited broader changes in transcriptional regulatory networks. Furthermore, USP15 mutant-associated gene expression patterns were significantly enriched for established ASD risk genes. Comparison with the mouse brain perturbation atlas showed that the transcriptional signature of the USP15 mutant showed notable overlap with those of Fezf2 and Foxp1 mutants, key regulators of deep-layer projection neuron identity. These findings characterize genotype-dependent neurodevelopmental phenotypes associated with reduced USP15 dosage and provide a human neural framework for investigating ASD-relevant developmental mechanisms in the context of a rare ubiquitin-pathway variant.
Tae-Hwan Park, I. Koh, Seoyoung Sung et al.· Molecules and Cells· 0 citations
The molecular mechanisms by which mutant huntingtin (mHTT) drives pathogenesis in Huntington's disease (HD) remain incompletely defined. Here we show that neurogenesis is disrupted at multiple stages of lineage progression in both rodent and human neural stem cell (NSC) models of HD. We identify a previously unrecognized phenotype characterized by aberrant expansion of early multipotent progenitors coupled to a profound defect in astrogliogenesis, whereby HD astrocytes fail to express glial fibrillary acidic protein (GFAP). Mechanistically, this defect arises from dysregulation of an epigenetic regulatory axis involving EZH2 and LIN28 upregulation together with reduced expression of the mature let-7g microRNA. Epigenetic pharmacological interventions, targeting this pathway at distinct nodes-through EZH2 modulation, let-7g restoration, or LIN28 inhibition-rescued astroglial differentiation in human HD cells and improved motor function in a Drosophila HD model. Our findings suggest that mHTT might trigger a dual-phase astroglial failure: an early developmental impairment followed by a collapse of regenerative gliogenesis. This bimodal mechanism proposes astrocytic dysfunction as a central driver of HD pathogenesis. Finally, we identify a panel of clinically relevant epigenetic compounds that, by converging on distinct targets within this axis, hold promise for stage-spanning therapeutic strategies capable of modifying disease trajectory.
Jessica Rosati, A. Casamassa, G. Ruotolo et al.· Cell Death and Differentiati...· 0 citations