CNTN5-/+or EHMT2-/+human iPSC-derived neurons from individuals with autism develop hyperactive neuronal networks

Abstract

Induced pluripotent stem cell (iPSC)-derived neurons are increasingly used to model Autism Spectrum Disorder (ASD), which is clinically and genetically heterogeneous. To study the complex relationship of penetrant and weaker polygenic risk variants to ASD, ‘isogenic’ iPSC-derived neurons are critical. We developed a set of procedures to control for heterogeneity in reprogramming and differentiation, and generated 53 different iPSC-derived glutamatergic neuronal lines from 25 participants from 12 unrelated families with ASD. Heterozygous de novo and rare-inherited presumed-damaging variants were characterized in ASD risk genes/loci. Combinations of putative etiologic variants (GLI3/KIF21A or EHMT2/UBE2I) in separate families were modeled. We used a multi-electrode array, with patch-clamp recordings, to determine a reproducible synaptic phenotype in 25% of the individuals with ASD (other relevant data on the remaining lines was collected). Our most compelling new results revealed a consistent spontaneous network hyperactivity in neurons deficient for CNTN5 or EHMT2. The biobank of iPSC-derived neurons and accompanying genomic data are available to accelerate ASD research.Editorial note: This article has been through an editorial process in which authors decide how to respond to the issues raised during peer review. The Reviewing Editor's assessment is that all the issues have been addressed (see decision letter).

Wide spectrum of neuronal and network phenotypes in human stem cell-derived excitatory neurons with Rett syndrome-associatedMECP2mutations

“…Five minute recordings of extracellular spontaneous action potential activity were taken to acquire high frequency spikes twice per week from week 3 to 7. Bursting and network bursting properties emerged with maturation of the cultures over time at a comparable rate as induced neurons previously recorded by MEA(Deneault et al, 2019). Raster plots of the firing patterns show individual spikes (white tick marks), bursts and network bursts across multiple electrodes (pink tick marks) for the CLT, WIBR3 and PGPC14 isogenic pairs(Fig.…”

“…This implied that decreased excitatory neuronal activity and alteration of activity-dependent gene expression regulated by MECP2 (Cohen et al, 2011) may alter circuit maturation dynamics and contribute to the observed RTT phenotypes. Recent approaches using induced excitatory neurons co-cultured with astrocytes on micro-electrode arrays (MEAs) now allow evaluation of the development of synchronous network activity and how that circuitry is affected by changes in genetic profiles that characterize neurodevelopmental disorders (Deneault et al, 2019;Frega et al, 2019;Nageshappa et al, 2016).…”

Systematic phenomics analysis of autism-associated genes reveals parallel networks underlying reversible impairments in habituation

“…1C) that may hint at a common pathological mechanism that impairs plasticity of a neural circuit's decision to respond without altering response vigor. Indeed, these Drosophila and C. elegans results may reflect a behavioral outcome of circuit-level hyperexcitability recently discovered in several human iPSC-derived neuronal culture models of a number of monogenic ASD risk factors (71,72). The results also provide a potentially plausible explanation for inconsistent reports of impaired habituation in humans, which variably employ diverse response metrics most often without genetic stratification of patient populations (15,39).…”

Human in vitro models for understanding mechanisms of autism spectrum disorder

“…The majority of these studies used cells from patients, with some also including isogenic controls [121,127,131,134,145,146], while some studies exclusively used induced mutations comparing them with isogenic Table 1). Many of the studies, from both idiopathic and genetically defined forms of ASD, found effects in one (or more) of four general categories of cellular biological processes: (1) cell cycle and proliferation, (2) cell death (specifically apoptosis), (3) cell differentiation and maturation, and (4) neuronal signaling and synaptic stimuli ( Table 1).…”

“…This limitation makes it difficult to study the effects of common variation in ASD and limits the utility of these models for non-personalized drug and genetic screening. There are many efforts in the field to overcome this limitation by generating repositories of iPSC lines that will be available to researchers [145,[181][182][183]. These large repositories will allow researchers to use larger sample sizes to study the effects of genetic background on ASD and will allow them to stratify their studies based on both symptoms and genetic background.…”