Anthony Wynshaw-Boris

Mutations in the PTEN gene have been implicated in autism spectrum disorders (ASD), particularly among individuals with comorbid macrocephaly. In our previous study, we demonstrated that the PTEN p.Ile135Leu variant, in an ASD-related genetic background dependent fashion, disrupts both cortical neurogenesis and gliogenesis. While abnormal cerebellar development is a recognized feature of ASD, the specific cellular targets and timing of disruptions during cerebellar differentiation and development remain poorly understood. To investigate these aspects, we applied our previously established cerebellar organoid protocol and used isogenic human iPSC lines harboring this PTEN-variant. We examined the expression of Purkinje cells, granule cells, interneurons, and glial cells prior to 22 weeks of differentiation, assessed genes expression at 8 weeks, and evaluated spontaneous spikes activity in Purkinje cells after 11 weeks. We observed that cell-type-specific expression patterns differed between the PTEN p.Ile135Leu variant in control versus ASD-genetic backgrounds. However, these background differences were diminished in PTEN knockout lines across both backgrounds. Our single-cell RNA sequencing (scRNA-seq) dataset revealed that the PTEN p.Ile135Leu variant increased the number of interneuron progenitor cells, whereas PTEN knockout led to an expansion of meningeal-like cells in both genetic contexts. Moreover, both the PTEN p.Ile135Leu variant and PTEN knockout abolished spontaneous simple spikes activity in Purkinje cells across both backgrounds, including PTEN-corrected patient-derived lines. Together, these findings provide direct evidence linking PTEN dysfunction and genetic background to altered cerebellar differentiation and neuronal network activity in human cerebellar organoids.

The alteration of neural progenitor cell (NPC) proliferation underlies autism spectrum disorders (ASD). It remains unclear whether targeting convergent downstream targets among mutations from different genes and individuals can rescue this alteration. We identified PBX1 as a convergent target of three autism risk genes: CTNNB1 , PTEN , and DVL3 , using isogenic iPSC-derived 2D NPCs. Overexpression of the PBX1a isoform effectively rescued increased NPC proliferation in all three isogenic ASD-related variants. Dysregulation of PBX1 in NPCs was further confirmed in publicly available datasets from other models of ASD. These findings spotlight PBX1 , known to play important roles during olfactory bulb/adult neurogenesis and in multiple cancers, as an unexpected and key downstream target, influencing NPC proliferation in ASD and neurodevelopmental syndromes.

Dr Charis Eng, MD, PhD, the Sondra J. and Stephen R. Hardis Endowed Chair in Cancer Genomic Medicine and the founding director of the Genomic Medicine Institute at the Cleveland Clinic, passed away on August 13, 2024, after a courageous battle with metastatic breast cancer. Charis's influence was profound in so many ways, including numerous contributions to cancer genetics/genomics by performing at the highest levels of research, building specialty clinics for patients in clinical genetics and cancer, and finally in training the next generation of researchers and clinicians. Her imprint on Human Molecular Genetics was essential.

Neurons within the cerebellum form temporal–spatial connections through the cerebellum, and the entire brain. Organoid models provide an opportunity to model the early differentiation of the developing human cerebellum, which is difficult to study in vivo, and affords the opportunity to study neurodegenerative and neurodevelopmental diseases of the cerebellum. Previous cerebellar organoid models focused on early neuron generation and single cell activity. Here, we modify previous protocols to generate more mature cerebellar organoids that allow for the establishment of several classes of mature neurons during cerebellar differentiation and development, including the establishment of neural networks during whole-organoid maturation. This will provide a means to study the generation of several more mature cerebellar cell types, including Purkinje cells, granule cells and interneurons expression as well as neuronal communication for biomedical, clinical and pharmaceutical applications.

The contribution of progenitor subtypes to generate the billions of neurons during human cortical neurogenesis is not well understood. We developed the Cortical ORganoid Lineage Tracing (COR-LT) system for human cortical organoids. Differential fluorescent reporter activation in distinct progenitor cells leads to permanent reporter expression, enabling the progenitor cell lineage of neurons to be determined. Surprisingly, nearly all neurons produced in cortical organoids were generated indirectly from intermediate progenitor cells. Additionally, neurons of different progenitor lineages were transcriptionally distinct. Isogenic lines made from an autistic individual with and without a likely pathogenic variant in the CTNNB1 gene demonstrated that the variant substantially altered the proportion of neurons derived from specific progenitor cell lineages, as well as the lineage-specific transcriptional profiles of these neurons, suggesting a pathogenic mechanism for this mutation. These results suggest individual progenitor subtypes play unique roles in generating the diverse neurons of the human cerebral cortex.

Autism spectrum disorders (ASD) display both phenotypic and genetic heterogeneity, impeding the understanding of ASD and development of effective means of diagnosis and potential treatments. Genes affected by genomic variations for ASD converge in dozens of gene ontologies (GOs), but the relationship between the variations at the GO level have not been well elucidated. In the current study, multiple types of genomic variations were mapped to GOs and correlations among GOs were measured in ASD and control samples. Several ASD-unique GO correlations were found, suggesting the importance of co-occurrence of genomic variations in genes from different functional categories in ASD etiology. Combined with experimental data, several variations related to WNT signaling, neuron development, synapse morphology/function and organ morphogenesis were found to be important for ASD with macrocephaly, and novel co-occurrence patterns of them in ASD patients were found. Furthermore, we applied this gene ontology correlation analysis method to find genomic variations that contribute to ASD etiology in combination with changes in gene expression and transcription factor binding, providing novel insights into ASD with macrocephaly and a new methodology for the analysis of genomic variation.

SUMMARY: Alterations in cortical neurogenesis are implicated in neurodevelopmental disorders including autism spectrum disorders (ASDs). The contribution of genetic backgrounds, in additional to ASD risk genes, on cortical neurogenesis remain understudied. Here, using isogenic induced pluripotent stem cell (iPSC)-derived neural progenitor cells (NPCs) and cortical organoid models, we report that a heterozygous PTEN p.I135L mutation found in an ASD patient with macrocephaly activates PI3K/AKT and dysregulates cortical neurogenesis in an ASD genetic background-dependent fashion. Transcriptome analysis at both bulk and single cell level revealed PTEN p.I135L mutation and ASD genetic background affected genes involved in neurogenesis, neural development and synapse signaling. We also found that this PTEN p.I135L mutation led to overproduction of NPC subtypes as well as neuronal subtypes including both deep and upper layer neurons in its ASD background, but not when introduced into a control genetic background. These findings provide experimental evidence that both a PTEN p.I135L mutation and ASD genetic background contribute to cellular features consistent with ASD associated with macrocephaly.

Autism spectrum disorders (ASD) display both phenotypic and genetic heterogeneity, impeding the understanding of ASD and development of effective means of diagnosis and potential treatments. Genes affected by genomic variations for ASD converge in dozens of gene ontologies (GOs), but the relationship between the variations at the GO level have not been well elucidated. In the current study, multiple types of genomic variations were mapped to GOs and correlations among GOs were measured in ASD and control samples. Several ASD-unique GO correlations were found, suggesting the importance of co-occurrence of genomic variations in genes from different functional categories in ASD etiology. Combined with experimental data, several variations related to WNT signaling, neuron development, synapse morphology/function and organ morphogenesis were found to be important for ASD with macrocephaly, and novel co-occurrence patterns of them in ASD patients were found. Further, we applied this gene ontology correlation analysis method to find genomic variations that contribute to ASD etiology in combination with changes in gene expression and transcription factor binding, providing novel insights into ASD with macrocephaly and a new methodology for the analysis of genomic variation.