RESUMO
The Shank3 gene encodes the major postsynaptic scaffolding protein SHANK3. Its mutation causes a syndromic form of autism spectrum disorder (ASD): Phelan-McDermid Syndrome (PMDS). It is characterized by global developmental delay, intellectual disorders (ID), ASD behavior, affective symptoms, as well as extra-cerebral symptoms. Although Shank3 deficiency causes a variety of molecular alterations, they do not suffice to explain all clinical aspects of this heterogenic syndrome. Since global gene expression alterations in Shank3 deficiency remain inadequately studied, we explored the transcriptome in vitro in primary hippocampal cells from Shank3∆11(-/-) mice, under control and lithium (Li) treatment conditions, and confirmed the findings in vivo. The Shank3∆11(-/-) genotype affected the overall transcriptome. Remarkably, extracellular matrix (ECM) and cell cycle transcriptional programs were disrupted. Accordingly, in the hippocampi of adolescent Shank3∆11(-/-) mice we found proteins of the collagen family and core cell cycle proteins downregulated. In vitro Li treatment of Shank3∆11(-/-) cells had a rescue-like effect on the ECM and cell cycle gene sets. Reversed ECM gene sets were part of a network, regulated by common transcription factors (TF) such as cAMP responsive element binding protein 1 (CREB1) and ß-Catenin (CTNNB1), which are known downstream effectors of synaptic activity and targets of Li. These TFs were less abundant and/or hypo-phosphorylated in hippocampi of Shank3∆11(-/-) mice and could be rescued with Li in vitro and in vivo. Our investigations suggest the ECM compartment and cell cycle genes as new players in the pathophysiology of Shank3 deficiency, and imply involvement of transcriptional regulators, which can be modulated by Li. This work supports Li as potential drug in the management of PMDS symptoms, where a Phase III study is ongoing.
Assuntos
Matriz Extracelular , Hipocampo , Camundongos Knockout , Proteínas do Tecido Nervoso , beta Catenina , Animais , Proteínas do Tecido Nervoso/genética , Proteínas do Tecido Nervoso/metabolismo , Hipocampo/metabolismo , Matriz Extracelular/metabolismo , Camundongos , beta Catenina/metabolismo , beta Catenina/genética , Transtornos Cromossômicos/genética , Transtornos Cromossômicos/metabolismo , Deleção Cromossômica , Ciclo Celular/efeitos dos fármacos , Ciclo Celular/genética , Transtorno Autístico/genética , Transtorno Autístico/metabolismo , Cromossomos Humanos Par 22/genética , Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico/metabolismo , Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico/genética , Masculino , Transcriptoma/genética , Transtorno do Espectro Autista/genética , Transtorno do Espectro Autista/metabolismo , Transtorno do Espectro Autista/tratamento farmacológico , Camundongos Endogâmicos C57BL , Lítio/farmacologia , Proteínas dos Microfilamentos/metabolismo , Proteínas dos Microfilamentos/genética , Células CultivadasRESUMO
Mutations or deletions of the SHANK3 gene are causative for Phelan-McDermid syndrome (PMDS), a syndromic form of autism spectrum disorders (ASDs). We analyzed Shank3Δ11(-/-) mice and organoids from PMDS individuals to study effects on myelin. SHANK3 was found to be expressed in oligodendrocytes and Schwann cells, and MRI analysis of Shank3Δ11(-/-) mice revealed a reduced volume of the corpus callosum as seen in PMDS patients. Myelin proteins including myelin basic protein showed significant temporal and regional differences with lower levels in the CNS but increased amounts in the PNS of Shank3Δ11(-/-) animals. Node, as well as paranode, lengths were increased and ultrastructural analysis revealed region-specific alterations of the myelin sheaths. In PMDS hiPSC-derived cerebral organoids we observed an altered number and delayed maturation of myelinating cells. These findings provide evidence that, in addition to a synaptic deregulation, impairment of myelin might profoundly contribute to the clinical manifestation of SHANK3 deficiency.
