7q11.23 CNV alters ribosomal biogenesis, mTOR and neuronal intrinsic excitability [RNA-seq]

Copy number variations (CNVs) at 7q11.23 cause Williams-Beuren (WBS) and 7q microduplication syndromes (7Dup). Both neurodevelopmental disorders (NDDs) feature mild to moderate intellectual disability, accompanied by symmetrically opposite neurocognitive and behavioral features. Although significant progress has been made in understanding the molecular mechanisms underlying 7q11.23-related pathophysiologies, the interplay between different layers of gene expression and the propagation of opposite symmetry arising from CNV remains elusive. Here, we uncovered 7q11.23 dosage-dependent symmetrically opposite dynamics in neuronal differentiation and intrinsic excitability. By integrating transcriptomics, translatomics and proteomics of patient-derived and isogenic induced neurons, we found that genes related to neuronal transmission follow 7q11.23 dosage and are transcriptionally controlled, while translational factors and ribosomal genes are post-transcriptionally buffered. Consistently, we found a deregulated mTOR pathway, with phospho-S6 (pS6) being downregulated in WBS and upregulated in 7Dup. Surprisingly phospho-4E-BP (p4E-BP) was going in the opposite direction, reflecting the total 4E-BP levels, thus highlighting the different roles of pS6 and p4E-BP during neurogenesis. Therefore, our work emphasizes the importance of multilayer research when investigating complex NDDs, highlighting ribosomal biogenesis and paving the way for novel treatments by uncoupling the role of pS6 and p4E-BPs in NDDs.