This work investigates how neural circuits transition from seizure-resistant to seizure-prone states by leveraging an Angelman syndrome (AS) mouse model that lacks the maternal Ube3a allele. The model exhibits heightened susceptibility to seizure kindling, enabling study of mechanisms underlying epileptogenesis. The authors combine cell type–targeted genetic manipulations, regional analyses, and electrophysiology to identify circuit- and homeostasis-related contributors to increased seizure susceptibility.
A principal finding is that parvalbumin interneurons function as critical gatekeepers of seizure susceptibility in this AS model. Selective deletion of the maternal Ube3a allele specifically in PV-expressing (PV+) interneurons reproduces the enhanced epileptogenesis observed in the global AS model. This cell type–specific manipulation therefore phenocopies the seizure-prone phenotype, implicating PV+ interneuron dysfunction as a necessary contributor to the enhanced kindling response.
These results emphasize the role of PV+ inhibitory circuits in constraining pathological excitation. Because the PV+ interneuron-specific manipulation phenocopied the AS model, the data support a model in which loss of UBE3A in fast-spiking inhibitory neurons undermines their gatekeeping function during activity-dependent network perturbation such as kindling.
Complementary rescue experiments showed that broad restoration of UBE3A expression across GABAergic neurons confers seizure resistance in the AS model context. Restoring UBE3A in inhibitory neurons counteracts the enhanced epileptogenesis seen with global loss, indicating that UBE3A function within inhibitory populations is sufficient to oppose the transition to a seizure-prone state.
Together with the PV+ deletion data, these findings delineate a cell type–specific landscape in which loss of UBE3A in inhibitory neurons—especially PV+ interneurons—promotes epileptogenesis, whereas re-establishing UBE3A in inhibitory cells can restore network resilience against kindling.
The authors report pathological remodeling of the extracellular matrix (ECM) in the dentate gyrus, and importantly note that this remodeling tracks with post-kindling seizure susceptibility. The dentate gyrus therefore emerges as a region of particular relevance to the heightened epileptogenesis in this AS model.
By linking ECM alterations in the dentate gyrus to susceptibility after kindling, the study highlights how region-specific homeostatic plasticity and extracellular milieu changes may contribute to maladaptive network states. The association between dentate ECM remodeling and seizure risk suggests that microenvironmental and structural changes in hippocampal subfields can parallel and perhaps facilitate circuit dysfunction.
Mechanistic electrophysiologic work in the study uncovers a two-hit phenomenon during kindling in AS model mice. First, kindling fails to recruit compensatory inhibition onto dentate granule cells; inhibitory engagement that would typically counter increased excitation is deficient. Second, instead of being held in check by appropriate inhibitory feedback, dentate granule cells develop maladaptive intrinsic hyperexcitability.
This combination—loss of recruited inhibition plus intrinsic excitability changes in principal cells—constitutes a two-hit process that promotes epileptogenesis in the AS model. The pattern aligns with the genetic and cell type–specific data implicating inhibitory neuron dysfunction: when inhibitory compensation is impaired, principal cell properties can shift toward a seizure-prone phenotype.
The integrated findings link cell type–specific inhibitory dysfunction and altered homeostatic plasticity to the emergence of epileptogenesis in an Angelman syndrome model. Identifying PV+ interneurons and dentate gyrus homeostatic dysregulation as central contributors suggests that future therapeutic approaches could target specific inhibitory circuits or regional homeostatic mechanisms rather than applying only broad antiseizure strategies.
While this work is preclinical and carried out in a genetic mouse model, it provides mechanistic rationale for exploring circuit-based interventions that restore inhibitory neuron function or normalize dentate microenvironmental remodeling. The data also highlight the importance of timing and cell type when considering strategies to prevent the transition from seizure resistance to seizure susceptibility.
The authors declare no competing interests. Funding sources listed in the source include the Simons Foundation (SFARI) and multiple National Institute of Neurological Disorders and Stroke and Eunice Kennedy Shriver National Institute of Child Health and Human Development awards as reported in the original article. Specific grant numbers and awards were provided in the source document.