Caldwell, A. B. | Search bioRxiv

bioRxiv2022

Methadone alters transcriptional programs associated with synapse formation in human cortical organoids

Opioid use disorder (OUD) among pregnant women has become an epidemic in the United States. Pharmacological interventions for OUD involve methadone, a synthetic opioid analgesic that attenuates withdrawal symptoms and behaviors linked with maternal drug abuse. However, methadones ability to readily accumulate in neural tissue, and cause long-term neurocognitive sequelae, has led to concerns regarding its effect on prenatal brain development. We took advantage of human cortical organoid (hCO) technology to probe how this drug impacts the earliest mechanisms giving rise to the cerebral cortex. To this end, we conducted bulk mRNA sequencing of 2-month-old hCOs derived from two cell lines that were chronically treated with a clinically relevant dose of 1M methadone for 50 days. Differential expression and gene ontology analyses revealed a robust transcriptional response to methadone associated with functional components of the synapse, the underlying extracellular matrix (ECM), and cilia. Further unsupervised co-expression network and predictive protein-protein interaction analyses demonstrated that these changes occurred in concert, centered around a regulatory axis consisting of growth factors, developmental signaling pathways, and matricellular proteins. Our results demonstrate that exposure to methadone during early cortico-genesis fundamentally alters transcriptional programs associated with synapse formation, and that these changes arise by modulating extra-synaptic molecular mechanisms in the ECM and cilia. These findings provide novel insight into methadones putative effect on cognitive and behavioral development and a basis for improving interventions for maternal opioid addiction.

neuroscience↗

bioRxiv2019

Dedifferentiation orchestrated through remodeling of the chromatin landscape defines PSEN1 mutation-induced Alzheimer's Disease

Early-Onset Familial Alzheimers Disease (EOFAD) is a dominantly inherited neurodegenerative disorder elicited by mutations in the PSEN1, PSEN2, and APP genes1. Hallmark pathological changes and symptoms observed, namely the accumulation of misfolded Amyloid-{beta} (A{beta}) in plaques and Tau aggregates in neurofibrillary tangles associated with memory loss and cognitive decline, are understood to be temporally accelerated manifestations of the more common sporadic Late-Onset Alzheimers Disease. The complete penetrance of EOFAD-causing mutations has allowed for experimental models which have proven integral to the overall understanding of AD2. However, the failure of pathology-targeting therapeutic development suggests that the formation of plaques and tangles may be symptomatic and not describe the etiology of the disease3,4. Here, we use an integrative, multi-omics approach and systems-level analysis in hiPSC-derived neurons to generate a mechanistic disease model for EOFAD. Using patient-specific cells from donors harboring mutations in PSEN1 differentiated into neurons, we characterize the disease-related gene expression and chromatin accessibility changes by RNA- Seq, ATAC-Seq, and histone methylation ChIP-Seq. We show that the defining disease-causing mechanism of EOFAD is dedifferentiation, primarily through the REST-mediated repression of neuronal lineage specification gene programs and the activation of non-specific germ layer precursor gene programs concomitant with modifications in chromatin accessibility. These gene signature profiles and changes in chromatin topology illustrate that EOFAD neurons traverse the chromatin landscape from an ectodermal origin to a mixed germ lineage state. Further, a reanalysis of existing transcriptomic data from PSEN1 patient brain samples demonstrates that the mechanisms identified in our experimental system recapitulate EOFAD in the human brain. Our results comprise a disease model which describes the mechanisms culminating in dedifferentiation that precede amyloid and tau pathology formation and engender neurodegeneration.

neuroscience↗