An antisense oligonucleotide-based strategy to ameliorate cognitive dysfunction in the 22q11.2 Deletion Syndrome

Abstract

Up-regulation of Mirta22/Emc10 is a major transcriptional effect of the 22q11.2-associated microRNA dysregulation and underlies key cellular as well as behavioral deficits. EMC10 is a component of the ER membrane complex, which promotes membrane insertion of a subset of polytopic and tail-anchored membrane proteins. Here we show that EMC10 expression is elevated in hiPSC-derived neurons from 22q11.2 deletion carriers and that reduction of EMC10 levels restores defects in neurite outgrowth and calcium signaling. Moreover, using injection of Antisense Oligonucleotides, we demonstrate that normalization of Emc10 levels in adult mouse brain rescues social memory deficits. The observations that elevated EMC10 expression is deleterious in 22q11.2 deletion carriers and that sustained elevation of EMC10 throughout the adult life can interfere with neural processes point to manipulations of EMC10 levels and downstream targets as a specific venue to ameliorate or even prevent disease progression in 22q11.2 deletion syndrome.

Aberrant pace of cortical neuron development in brain organoids from patients with 22q11.2 deletion syndrome and schizophrenia

“…We also tested whether there are alterations in neuronal activity in patient compared to control organoids using as a proxy system-wide glutamate-induced Ca 2+ transients. Comparisons of three pairs at day 259 identified a significant decrease in Ca 2+ peak amplitude in case compared to control cells ( P = 5.78×10 -12 , average number of cells per organoid: n=89 patient, n=124 control, Fig 1c,d,e ) consistent with previous findings in monolayer cultures of both mouse and patient neurons 12,13,14 . Thus, despite the lack of overt effects in growth, patient organoids display different functional properties, validating their usefulness as a preclinical model for studying the disease mechanisms underlying 22q11.2 deletions.…”

“…We first examined the dysregulation of microRNAs (miRNAs) as a potential mechanism for the asynchronous expression of maturation-associated genes. We have previously shown that 22q11.2 deletion results in brain-enriched miRNA downregulation and an upregulation in target gene expression due to (i) hemizygosity of DGCR8 27,28 , a component of the “microprocessor” complex that is essential for miRNA production and (ii) hemizygosity of miRNA genes residing within the deletion 12,28, 29 . To assess the contribution of miRNA dysregulation to our observed cellular and RNA-seq phenotypes we performed bulk miRNA sequencing on suspension from 3 pairs of 8-10 DIV70 organoids.…”

“…We identified 3 main patterns of trajectory divergence between patients and controls (Fig 6d ). First, genes that are upregulated in patient progenitors and remain upregulated over time as exemplified by EMC10 (a regulator of membrane protein trafficking whose upregulation impedes the acquisition of full neuronal functionality in patient neurons and animal models 12,29,31 ) and PEG3 (a cell cycle regulator that is typically highly expressed in progenitor cells but not in differentiated neurons 32 ). Second, genes that show upregulation in progenitors but the changes dissipate over time as exemplified by TCF3 (a WNT signaling antagonist that increases neural progenitor cell self-renewal and represses neuronal differentiation 33,34 ).…”

“…Another noteworthy target is the EMC10 gene, which shows altered temporal expression trajectory along the entire EN lineage at DIV70 and significant upregulation in patient RG ( P = 1.56×10 - 6 ), IPC-nEN ( P = 5.3×10 - 5 ) and EN ( P = 7.3×10 - 6 ) but not in astrocytes, choroid or interneuron lineage cells ( Supplemental Table S2 ). Indeed effective knockdown to near WT levels of EMC10 in patient iPSC-derived neurons leads to restoration of key morphological and functional EN alterations emerging due to 22q11.2 deletions 12 . Furthermore, normalization of Emc10 levels in either developing or adult mouse brain rescues several 22q11.2 deletion associated behavioral deficits 12, 31 , establishing a clear link between miRNA regulatory mechanisms and aspects of the behavioral manifestations observed in 22q11.2 deletion carriers.…”

“…Indeed effective knockdown to near WT levels of EMC10 in patient iPSC-derived neurons leads to restoration of key morphological and functional EN alterations emerging due to 22q11.2 deletions 12 . Furthermore, normalization of Emc10 levels in either developing or adult mouse brain rescues several 22q11.2 deletion associated behavioral deficits 12, 31 , establishing a clear link between miRNA regulatory mechanisms and aspects of the behavioral manifestations observed in 22q11.2 deletion carriers.…”