MAZ-p53-mtor axis dysregulation drives hyperproliferation in autism 16pdel11.2 neural progenitor cells

Autism spectrum disorder (ASD) encompasses biologically heterogeneous conditions, with a subset characterized by early brain overgrowth, contributing to macrocephaly, and dysregulated neural progenitor cell (NPC) dynamics. The recurrent 16p11.2 deletion (16pDel), a common ASD-associated copy number variant, provides a genetically tractable model to interrogate these mechanisms. Here, using patient-derived NPCs, we identify a robust and reproducible hyperproliferative phenotype associated with 16pDel, driven by coordinated disruption of a MAZ–p53–AKT–mTOR signaling axis. Mechanistically, reduced dosage of the transcription factor MAZ suppresses p53 expression and downstream transcriptional programs, leading to hyperproliferation and concomitant hyperactivation of mTOR signaling. Reciprocal perturbation experiments demonstrate bidirectional regulatory coupling, whereby p53 depletion further reduces MAZ expression and amplifies mTOR pathway activation, establishing a feed-forward network that sustains pathological proliferation. Activation of the mTOR pathway in control NPCs by S6K2 p-mimetics recapitulates 16pDel-associated transcriptional and proliferative phenotypes, while pharmacological interventions, p53 stabilization (Nutlin-3a), and AKT inhibition (MK-2206), restore regulatory balance and normalize NPC proliferation. Beyond core signaling mechanisms, integrative genomic analysis identifies filaggrin (FLG) as a convergent deleterious variant across independent 16pDel families. Although canonically associated with epidermal barrier function, FLG is significantly downregulated in 16pDel NPCs, suggesting a potential context-dependent role in modulating neurodevelopmental phenotypes or, alternatively, representing a background genetic variant contributing to phenotypic heterogeneity. Collectively, this study defines a mechanistically resolved, bidirectionally regulated MAZ–p53–AKT–mTOR axis as a central driver of NPC hyperproliferation in 16p11.2 deletion, linking gene dosage imbalance to aberrant growth signaling. These findings position this regulatory network as a convergent, therapeutically actionable node in ASD-associated cortical overgrowth, while also highlighting the contribution of secondary genetic modifiers, such as FLG, to disease variability.