Dentate Gyrus Morphogenesis is Regulated by an Autism Risk Gene Trio Function in Granule Cells
Research Background and Objectives
Autism Spectrum Disorders (ASDs) are a group of highly heritable neurodevelopmental disorders, primarily characterized by abnormal social interactions, communication deficits, and restricted repetitive behaviors or interests. Previous studies have reported structural changes in brain regions including the hippocampus in autism patients and their mouse models. Particularly, in patients with ASD, focal structural deformities in the granule cell (GC) layer of the hippocampal dentate gyrus (DG) and ectopic distribution of GCs are especially prominent. However, previous research on the mechanisms of ASD risk genes in DG developmental abnormalities has been insufficient.
In this study, we investigated the role of a highly susceptible ASD gene, Trio, in the morphogenesis of mouse DG. We found that the deletion of the Trio gene leads to postnatal DG developmental deficits and displays autism-related behaviors. These findings not only reveal the specific role of Trio in DG development but also provide new clues for understanding the pathophysiological mechanisms of ASD.
Paper Source and Author Information
This research paper was collaboratively completed by scholars including Mengwen Sun, Weizhen Xue, Hu Meng, Xiaoxuan Sun, Tianlan Lu, Weihua Yue, Lifang Wang, Dai Zhang, and Jun Li from the Institute of Mental Health, Peking University. The paper was published in “Neuroscience Bulletin” in February 2024.
Research Methods
Experimental Design
The experimental design included multiple biological experiments on Trio gene conditional knockout mice, such as morphological detection, behavioral tests, immunofluorescence staining, and Western blotting. The specific steps are as follows:
Mouse Breeding
All mice were bred and handled according to the guidelines of the Animal Ethics Committee of Peking University. Trio conditional knockout (cKO) mice were obtained by mating Triofl/fl mice with mice expressing the Cre recombinase gene. Various mouse strains used in the experiments were of C57BL/6 background.
Morphological Detection
30-micron thick coronal sections were used to examine the hippocampal morphology of mice at different developmental stages, comparing the DG size and structural changes between control and Trio-deficient mice.
Immunofluorescence
Immunofluorescence staining of brain sections was performed to detect the number and distribution of different cell types in the DG, including cells marked by PAX6, TBR2, PROX1, and NEUN.
Behavioral Tests
To assess autism-related behaviors, the research team conducted a series of behavioral tests on mice, including the three-chamber social interaction test, hole-board test, marble burying test, light-dark box test, elevated plus maze test, and open field test.
Spatial Transcriptomics
To analyze the gene expression patterns of different neurons during DG development and the specific role of Trio, the research team used spatial transcriptomics technology for cell type classification and functional analysis of the DG.
Experimental Results
Trio Gene Deficiency Leads to DG Developmental Deficits
Morphological examination results showed that the brains of Triofl/fl;Emx1-Cre mice were smaller than those of control mice, with significantly abnormal DG size and morphology. Particularly in the upper blade area of the DG, granule cells showed a serrated arrangement, indicating that the impact of Trio deficiency on DG development is mainly concentrated in the postnatal stage.
Trio Deficiency Affects Cell Distribution and Migration
Immunofluorescence results showed that in Trio-deficient mice, the number of PAX6+ progenitor cells and TBR2+ intermediate progenitor cells in the DG was significantly reduced, as was the number of PROX1+ and NEUN+ neurons. The distribution pattern of these cells in the DG also changed significantly, with progenitor cell migration pathways obstructed in early postnatal mice, leading to disorganization of the granule cell layer.
Different Effects of Trio on Excitatory Neuron Migration
Through spatial transcriptomics, the research team found that Trio expression levels differed in different types of neurons, indicating that Trio has cell type-specific roles in regulating neuron migration and cytoskeleton organization. In Trio-deficient mice, changes in related signaling pathways and gene expression were mainly concentrated in late-developing excitatory neurons.
Trio Involvement in Regulating Autism-Related Behaviors
Behavioral test results confirmed that Trio-deficient mice exhibited autism-related behavioral abnormalities, including impaired social novelty recognition and increased stereotypical behaviors. These findings suggest that DG developmental deficits caused by Trio deficiency are associated with core behavioral symptoms of autism.
Research Conclusions and Significance
This study comprehensively reveals the specific role of the Trio gene in DG development and its relationship with autism-related behaviors. The results not only further enrich the understanding of ASD pathophysiological mechanisms but also provide new targets and directions, offering important references for future treatment of autism and other neurodevelopmental disorders.
As an emerging research direction, the relationship between Trio and DG development provides a new perspective for exploring the pathogenesis of autism. Future research can further investigate the role of Trio in other brain regions and at different developmental stages, thereby more comprehensively revealing the pathogenic mechanisms of ASD and providing basic data support for clinical interventions.
Research Highlights and Innovations
- Discovery of Trio’s Key Role in DG Development: Through a series of biological experiments and behavioral tests, the role of the Trio gene in DG development and its relationship with autism-related behaviors were clearly defined.
- Spatial Transcriptomics: For the first time, spatial transcriptomics technology was applied to reveal the specific expression and mechanism of action of Trio in different types of neurons.
- Autism Behavior Correlation Verification: Behavioral tests verified the association between DG developmental deficits caused by Trio deficiency and core behavioral symptoms of autism.
Conclusion
This study not only reveals the important role of the Trio gene in DG development and ASD-related behaviors but also provides new ideas for future exploration of pathological mechanisms and potential therapeutic targets for neurodevelopmental disorders. The research team’s efforts provide valuable scientific basis for the combination of brain science and clinical medicine, demonstrating the potential and hope of precision medicine in solving complex neurological diseases.