Biallelic ADAM22 pathogenic variants cause progressive encephalopathy and infantile-onset refractory epilepsy.

Pathogenic variants in A Disintegrin And Metalloproteinase (ADAM) 22, the postsynaptic cell membrane receptor for the glycoprotein leucine-rich repeat glioma-inactivated protein 1 (LGI1), have been recently associated with recessive developmental and epileptic encephalopathy. However, so far, only two affected individuals have been described and many features of this disorder are unknown. We refine the phenotype and report 19 additional individuals harbouring compound heterozygous or homozygous inactivating ADAM22 variants, of whom 18 had clinical data available. Additionally, we provide follow-up data from two previously reported cases. All affected individuals exhibited infantile-onset, treatment-resistant epilepsy. Additional clinical features included moderate to profound global developmental delay/intellectual disability (20/20), hypotonia (12/20) and delayed motor development (19/20). Brain MRI findings included cerebral atrophy (13/20), supported by post-mortem histological examination in patient-derived brain tissue, cerebellar vermis atrophy (5/20), and callosal hypoplasia (4/20). Functional studies in transfected cell lines confirmed the deleteriousness of all identified variants and indicated at least three distinct pathological mechanisms: (i) defective cell membrane expression; (ii) impaired LGI1-binding; and/or (iii) impaired interaction with the postsynaptic density protein PSD-95. We reveal novel clinical and molecular hallmarks of ADAM22 deficiency and provide knowledge that might inform clinical management and early diagnostics.

The tumor suppressor Sef is a scaffold for the classical NF-κB/RELA:P50 signaling module.

The classical NF-κB transcription factor (RelA:p50) and the tumor suppressor Sef axis constitute a negative regulatory loop in which Sef, a target of NF-κB/RelA:p50, fine-tunes NF-κB/RelA:p50 transcriptional-activation in response to inflammatory stimuli trough binding to p50. Similar to the inhibitor IκBα, Sef sequesters NF-κB/RelA:p50 in the cytoplasm of unstimulated cells. Despite its key roles in regulating multiple cellular processes and its potential role as mediator between inflammation and cancer, Sef structural domains required to fulfill its tasks are poorly characterized, and how Sef specificity towards RelA:p50 is achieved is unknown. In-vitro binding assays using bacterially expressed Sef and Co-IP experiments, revealed that in addition to p50, Sef directly interacts with IκBα, and the IKKß subunit of the IKK complex which mediates RelA:p50 induction by inflammatory stimuli. These interactions are ligand-independent and do not require Sef post-translational modifications. Deletion mutagenesis mapped binding site to IKKß in a 74- residue segment juxtaposing Sef transmembrane domain, whereas several Sef regions seem to interact with IκBα. Moreover, we identified two new sites which together with the previously identified conserved tyrosine constitute three discontinuous Sef regions each indispensable for Sef binding to RelA:p50 and inhibiting its cytokine induced transcriptional activation. Contrary to IκBα, endogenous Sef is not degraded upon cytokine-stimulation, and its targeting in different cell types markedly enhances cytokine-induced NF-κB nuclear translocation. These results reveal Sef as the first scaffold that brings together the components of NF-κB/RelA:p50 signaling-module. Sef scaffolding function explains the basis for Sef specificity towards inhibiting inflammatory cytokine-induction of NF-κB/RelA:p50.