Since human neurons are postmitotic and long-lived, the regulation of their genomic content is crucial. Normal neuronal function is uniquely dependent on gene dosage, with diverse genome copy number alterations (CNA) associated with neurodevelopmental and neuropsychiatric conditions . In this study, we evaluated the landscape of CNA arising in normal human brains, focusing on prenatal and perinatal ages.
View Article and Find Full Text PDFLittle is known about the role of non-coding regions in the etiology of autism spectrum disorder (ASD). We examined three classes of non-coding regions: human accelerated regions (HARs), which show signatures of positive selection in humans; experimentally validated neural VISTA enhancers (VEs); and conserved regions predicted to act as neural enhancers (CNEs). Targeted and whole-genome analysis of >16,600 samples and >4,900 ASD probands revealed that likely recessive, rare, inherited variants in HARs, VEs, and CNEs substantially contribute to ASD risk in probands whose parents share ancestry, which enriches for recessive contributions, but modestly contribute, if at all, in simplex family structures.
View Article and Find Full Text PDFThe human cerebral cortex, pivotal for advanced cognitive functions, is composed of six distinct layers and dozens of functionally specialized areas. The layers and areas are distinguished both molecularly, by diverse neuronal and glial cell subtypes, and structurally, through intricate spatial organization. While single-cell transcriptomics studies have advanced molecular characterization of human cortical development, a critical gap exists due to the loss of spatial context during cell dissociation.
View Article and Find Full Text PDFLittle is known about the role of noncoding regions in the etiology of autism spectrum disorder (ASD). We examined three classes of noncoding regions: Human Accelerated Regions (HARs), which show signatures of positive selection in humans; experimentally validated neural Vista Enhancers (VEs); and conserved regions predicted to act as neural enhancers (CNEs). Targeted and whole genome analysis of >16,600 samples and >4900 ASD probands revealed that likely recessive, rare, inherited variants in HARs, VEs, and CNEs substantially contribute to ASD risk in probands whose parents share ancestry, which enriches for recessive contributions, but modestly, if at all, in simplex family structures.
View Article and Find Full Text PDFBrain organoids created from human pluripotent stem cells represent a promising approach for brain repair. They acquire many structural features of the brain and raise the possibility of patient-matched repair. Whether these entities can integrate with host brain networks in the context of the injured adult mammalian brain is not well established.
View Article and Find Full Text PDFSonic hedgehog signaling regulates processes of embryonic development across multiple tissues, yet factors regulating context-specific Shh signaling remain poorly understood. Exome sequencing of families with polymicrogyria (disordered cortical folding) revealed multiple individuals with biallelic deleterious variants in , which encodes a multi-pass transmembrane protein of unknown function. null mice demonstrated holoprosencephaly, craniofacial midline defects, eye defects, and spinal cord patterning changes consistent with impaired Shh signaling, but were without limb defects, suggesting a CNS-specific role of Tmem161b.
View Article and Find Full Text PDFKinesins are canonical molecular motors but can also function as modulators of intracellular signaling. KIF26A, an unconventional kinesin that lacks motor activity, inhibits growth-factor-receptor-bound protein 2 (GRB2)- and focal adhesion kinase (FAK)-dependent signal transduction, but its functions in the brain have not been characterized. We report a patient cohort with biallelic loss-of-function variants in KIF26A, exhibiting a spectrum of congenital brain malformations.
View Article and Find Full Text PDFPhysiological blood-tissue barriers play a critical role in separating the circulation from immune-privileged sites and denying access to blood-borne viruses. The mechanism of virus restriction by these barriers is poorly understood. We utilize induced pluripotent stem cell (iPSC)-derived human brain microvascular endothelial cells (iBMECs) to study virus-blood-brain barrier (BBB) interactions.
View Article and Find Full Text PDFHuman accelerated regions (HARs) are the fastest-evolving regions of the human genome, and many are hypothesized to function as regulatory elements that drive human-specific gene regulatory programs. We interrogate the in vitro enhancer activity and in vivo epigenetic landscape of more than 3,100 HARs during human neurodevelopment, demonstrating that many HARs appear to act as neurodevelopmental enhancers and that sequence divergence at HARs has largely augmented their neuronal enhancer activity. Furthermore, we demonstrate PPP1R17 to be a putative HAR-regulated gene that has undergone remarkable rewiring of its cell type and developmental expression patterns between non-primates and primates and between non-human primates and humans.
View Article and Find Full Text PDFHuman brain organoids provide unique platforms for modeling development and diseases by recapitulating the architecture of the embryonic brain. However, current organoid methods are limited by interior hypoxia and cell death due to insufficient surface diffusion, preventing generation of architecture resembling late developmental stages. Here, we report the sliced neocortical organoid (SNO) system, which bypasses the diffusion limit to prevent cell death over long-term cultures.
View Article and Find Full Text PDFGlioblastomas exhibit vast inter- and intra-tumoral heterogeneity, complicating the development of effective therapeutic strategies. Current in vitro models are limited in preserving the cellular and mutational diversity of parental tumors and require a prolonged generation time. Here, we report methods for generating and biobanking patient-derived glioblastoma organoids (GBOs) that recapitulate the histological features, cellular diversity, gene expression, and mutational profiles of their corresponding parental tumors.
View Article and Find Full Text PDFBrain organoids are self-assembled three-dimensional aggregates generated from pluripotent stem cells with cell types and cytoarchitectures that resemble the embryonic human brain. As such, they have emerged as novel model systems that can be used to investigate human brain development and disorders. Although brain organoids mimic many key features of early human brain development at molecular, cellular, structural and functional levels, some aspects of brain development, such as the formation of distinct cortical neuronal layers, gyrification, and the establishment of complex neuronal circuitry, are not fully recapitulated.
View Article and Find Full Text PDFHuman brain organoids, 3D self-assembled neural tissues derived from pluripotent stem cells, are important tools for studying human brain development and related disorders. Suspension cultures maintained by spinning bioreactors allow for the growth of large organoids despite the lack of vasculature, but commercially available spinning bioreactors are bulky in size and have low throughput. Here, we describe the procedures for building the miniaturized multiwell spinning bioreactor SpinΩ from 3D-printed parts and commercially available hardware.
View Article and Find Full Text PDFMutations of DISC1 (disrupted-in-schizophrenia 1) have been associated with major psychiatric disorders. Despite the hundreds of DISC1-binding proteins reported, almost nothing is known about how DISC1 interacts with other proteins structurally to impact human brain development. Here we solved the high-resolution structure of DISC1 C-terminal tail in complex with its binding domain of Ndel1.
View Article and Find Full Text PDFTechnologies to differentiate human pluripotent stem cells into three-dimensional organized structures that resemble organs are pushing the frontiers of human disease modeling and drug development. In response to the global health emergency posed by the Zika virus (ZIKV) outbreak, brain organoids engineered to mimic the developing human fetal brain have been employed to model ZIKV-induced microcephaly. Here, we discuss the advantages of brain organoids over other model systems to study development and highlight recent advances in understanding ZIKV pathophysiology and its underlying pathogenesis mechanisms.
View Article and Find Full Text PDFZika virus (ZIKV) infection causes microcephaly and has been linked to other brain abnormalities. How ZIKV impairs brain development and function is unclear. Here we systematically profiled transcriptomes of human neural progenitor cells exposed to Asian ZIKV, African ZIKV, and dengue virus (DENV).
View Article and Find Full Text PDFIn response to the current global health emergency posed by the Zika virus (ZIKV) outbreak and its link to microcephaly and other neurological conditions, we performed a drug repurposing screen of ∼6,000 compounds that included approved drugs, clinical trial drug candidates and pharmacologically active compounds; we identified compounds that either inhibit ZIKV infection or suppress infection-induced caspase-3 activity in different neural cells. A pan-caspase inhibitor, emricasan, inhibited ZIKV-induced increases in caspase-3 activity and protected human cortical neural progenitors in both monolayer and three-dimensional organoid cultures. Ten structurally unrelated inhibitors of cyclin-dependent kinases inhibited ZIKV replication.
View Article and Find Full Text PDFThe current outbreak of Zika virus-associated diseases in South America and its threat to spread to other parts of the world has emerged as a global health emergency. Insights from cell and animal models to understand how Zika virus causes severe birth defects may lead to treatments and prevention of these diseases.
View Article and Find Full Text PDFTo change shape, divide, form junctions, and migrate, cells reorganize their cytoskeletons in response to changing mechanical environments [1-4]. Actin cytoskeletal elements, including myosin II motors and actin crosslinkers, structurally remodel and activate signaling pathways in response to imposed stresses [5-9]. Recent studies demonstrate the importance of force-dependent structural rearrangement of α-catenin in adherens junctions [10] and vinculin's molecular clutch mechanism in focal adhesions [11].
View Article and Find Full Text PDFCerebral organoids, three-dimensional cultures that model organogenesis, provide a new platform to investigate human brain development. High cost, variability, and tissue heterogeneity limit their broad applications. Here, we developed a miniaturized spinning bioreactor (SpinΩ) to generate forebrain-specific organoids from human iPSCs.
View Article and Find Full Text PDFThe suspected link between infection by Zika virus (ZIKV), a re-emerging flavivirus, and microcephaly is an urgent global health concern. The direct target cells of ZIKV in the developing human fetus are not clear. Here we show that a strain of the ZIKV, MR766, serially passaged in monkey and mosquito cells efficiently infects human neural progenitor cells (hNPCs) derived from induced pluripotent stem cells.
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