Search

Studies of the choroid plexus lag behind those of the more widely known blood-brain barrier, despite a much longer history. This review has two overall aims. The first is to outline long-standing areas of research where there are unanswered questions, such as control of cerebrospinal fluid (CSF) secretion and blood flow. The second aim is to review research over the past 10 years where the focus has shifted to the idea that there are choroid plexuses located in each of the brain’s ventricles that make specific contributions to brain development and function through molecules they generate for delivery via the CSF. These factors appear to be particularly important for aspects of normal brain growth. Most research carried out during the twentieth century dealt with the choroid plexus, a brain barrier interface making critical contributions to the composition and stability of the brain’s internal environment throughout life. More recent research in the twenty-first century has shown the importance of choroid plexus-generated CSF in neurogenesis, influence of sex and other hormones on choroid plexus function, and choroid plexus involvement in circadian rhythms and sleep. The advancement of technologies to facilitate delivery of brain-specific therapies via the CSF to treat neurological disorders is a rapidly growing area of research. Conversely, understanding the basic mechanisms and implications of how maternal drug exposure during pregnancy impacts the developing brain represents another key area of research.

Experimentally targeting mouse choroid plexus (ChP) provides a valuable approach for investigating mechanisms of ChP-cerebrospinal fluid (CSF) biology. Here, we provide a protocol to deliver adeno-associated viral vectors (AAVs) by in utero intracerebroventricular (ICV) injection to ChP epithelial cells. We begin by describing steps for induction anesthesia of the pregnant dam, laparotomy, and in utero ICV injection. We also detail post-surgical care and immunoblot validation. For complete details on the use and execution of this protocol, please refer to Jang et al. (2022).

Introduction: Tyrosine kinase (TK) fusions are common events in the development of resistance to targeted therapy for non-small cell lung cancer (NSCLC) and others. The mechanisms by which recurrent breakpoints are generated in solid tumors and by which they are selected are unclear. APOBEC3 proteins are the main factors for mutations in solid cancers and the mutagenic activity of APOBEC3 can activate the DNA damage response by contributing to double-strand break (DSB) formation. However, the possibility that APOBEC3 proteins could induce chromosomal translocations in solid tumors has not been investigated. In addition, mechanistic explanations on how recurrent chromosomal translocation occur in lung cancer and solid tumors in precise genomic breakpoints and with specific partners are lacking. In this work, we present a newly developed functionally active chromosomal translocation sequencing (FACTS) approach to provide insights on the mechanisms that determine the selection of oncogenic fusions in human cancers. Methods: We applied FACTS to lung cells to map genome-wide translocations when DNA DSB is introduced in TK genes by the CRISPR/Cas9 system. We generated genomic maps of DNA breakpoints joining to anaplastic lymphoma kinase (ALK) before and after selection by high-throughput genome-wide translocation sequencing (HTGTS). We tested the effect of APOBEC3 proteins in an overexpression system or in an all seven APOBEC3 gene knockout lung cells by FACTS. Results: Overexpression of APOBEC3 proteins significantly increased the formation of functional fusions compared to control cells. In addition, deletion of APOBEC3 genes significantly decreased the formation of functional fusions compared to APOBEC3 wild-type cells. With the FACTS data and bioinformatics analyses, we found that gene expression rather than locus accessibility dictates the selection of TK fusions and that TK fusions are likely selected from a pool of translocations occurring at the right position in transcribe genes. In addition, we found that active transcription in silent genes was sufficient to introduce the spontaneous formation of functional fusions. By using HTGTS approach, we found that breakpoints before selection did not show a preferential strand bias, but after selection the breakpoints showed a strong bias. By comparing oncogenic potential of EML4-ALK fusion variants, we found that protein stability, but not subcellular localization, is key to determining the exon usage of EML-ALK fusions. In addition, we revealed that the selection of fusion partners for each TK is more likely dictated by protein stability rather than by mRNA expression. Conclusion: FACTS allows rapid and comprehensive mapping of functional chromosomal translocations and provides insights into the mechanisms of their formation and selection. The FACTS approach could be used to predict the oncogenic activity of fusion proteins to guide clinical decisions. Citation Format: Taek-Chin Cheong, Ahram Jang, Qi Wang, Giulia C. Leonardi, Maria K. Lehtinen, Marian H. Harris, Roberto Chiarle. Mechanisms of oncogenic tyrosine kinase fusion formation and selection in human cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 313.

The choroid plexus (ChP) produces cerebrospinal fluid and forms an essential brain barrier. ChP tissues form in each brain ventricle, each one adopting a distinct shape, but remarkably little is known about the mechanisms underlying ChP development. Here, we show that epithelial WNT5A is crucial for determining fourth ventricle (4V) ChP morphogenesis and size in mouse. Systemic Wnt5a knockout, or forced Wnt5a overexpression beginning at embryonic day 10.5, profoundly reduced ChP size and development. However, Wnt5a expression was enriched in Foxj1-positive epithelial cells of 4V ChP plexus, and its conditional deletion in these cells affected the branched, villous morphology of the 4V ChP. We found that WNT5A was enriched in epithelial cells localized to the distal tips of 4V ChP villi, where WNT5A acted locally to activate non-canonical WNT signaling via ROR1 and ROR2 receptors. During 4V ChP development, MEIS1 bound to the proximal Wnt5a promoter, and gain- and loss-of-function approaches demonstrated that MEIS1 regulated Wnt5a expression. Collectively, our findings demonstrate a dual function of WNT5A in ChP development and identify MEIS transcription factors as upstream regulators of Wnt5a in the 4V ChP epithelium.

For many cancer patients, chemotherapy produces untreatable life-long neurologic effects termed chemotherapy-related cognitive impairment (CRCI). We discovered that the chemotherapy methotrexate (MTX) adversely affects oxidative metabolism of non-cancerous choroid plexus (ChP) cells and the cerebrospinal fluid (CSF). We used a ChP-targeted adeno-associated viral (AAV) vector approach in mice to augment CSF levels of the secreted antioxidant SOD3. AAV-SOD3 gene therapy increased oxidative defense capacity of the CSF and prevented MTX-induced lipid peroxidation in the hippocampus. Furthermore, this gene therapy prevented anxiety and deficits in short-term learning and memory caused by MTX. MTX-induced oxidative damage to cultured human cortical neurons and analyses of CSF samples from MTX-treated lymphoma patients demonstrated that MTX diminishes antioxidant capacity of patient CSF. Collectively, our findings motivate the advancement of ChP- and CSF-targeted anti-oxidative prophylactic measures to relieve CRCI.

The choroid plexus (ChP) produces cerebrospinal fluid and forms an essential brain barrier. ChP tissues form in each brain ventricle, each one adopting a distinct shape, but remarkably little is known about the mechanisms underlying ChP development. Here, we show that epithelial WNT5A is crucial for determining fourth ventricle (4V) ChP morphogenesis and size in mouse. Systemic Wnt5a knockout, or forced Wnt5a overexpression beginning at embryonic day 10.5, profoundly reduced ChP size and development. However, Wnt5a expression was enriched in Foxj1-positive epithelial cells of 4V ChP plexus, and its conditional deletion in these cells affected the branched, villous morphology of the 4V ChP. We found that WNT5A was enriched in epithelial cells localized to the distal tips of 4V ChP villi, where WNT5A acted locally to activate non-canonical WNT signaling via ROR1 and ROR2 receptors. During 4V ChP development, MEIS1 bound to the proximal Wnt5a promoter, and gain- and loss-of-function approaches demonstrated that MEIS1 regulated Wnt5a expression. Collectively, our findings demonstrate a dual function of WNT5A in ChP development and identify MEIS transcription factors as upstream regulators of Wnt5a in the 4V ChP epithelium.

Multiciliated cells (MCCs) in the brain reside in the ependyma and the choroid plexus (CP) epithelia. The CP secretes cerebrospinal fluid that circulates within the ventricular system, driven by ependymal cilia movement. Tumors of the CP are rare primary brain neoplasms mostly found in children. CP tumors exist in three forms: CP papilloma (CPP), atypical CPP, and CP carcinoma (CPC). Though CPP and atypical CPP are generally benign and can be resolved by surgery, CPC is a particularly aggressive and little understood cancer with a poor survival rate and a tendency for recurrence and metastasis. In contrast to MCCs in the CP epithelia, CPCs in humans are characterized by solitary cilia, frequent TP53 mutations, and disturbances to multiciliogenesis program directed by the GMNC-MCIDAS transcriptional network. GMNC and MCIDAS are early transcriptional regulators of MCC fate differentiation in diverse tissues. Consistently, components of the GMNC-MCIDAS transcriptional program are expressed during CP development and required for multiciliation in the CP, while CPC driven by deletion of Trp53 and Rb1 in mice exhibits multiciliation defects consequent to deficiencies in the GMNC-MCIDAS program. Previous studies revealed that abnormal NOTCH pathway activation leads to CPP. Here we show that combined defects in NOTCH and Sonic Hedgehog signaling in mice generates tumors that are similar to CPC in humans. NOTCH-driven CP tumors are monociliated, and disruption of the NOTCH complex restores multiciliation and decreases tumor growth. NOTCH suppresses multiciliation in tumor cells by inhibiting the expression of GMNC and MCIDAS, while Gmnc-Mcidas overexpression rescues multiciliation defects and suppresses tumor cell proliferation. Taken together, these findings indicate that reactivation of the GMNC-MCIDAS multiciliogenesis program is critical for inhibiting tumorigenesis in the CP, and it may have therapeutic implications for the treatment of CPC.

The choroid plexus (ChP), an epithelial bilayer containing a network of mesenchymal, immune, and neuronal cells, forms the blood–cerebrospinal fluid (CSF) barrier (BCSFB). While best recognized for secreting CSF, the ChP is also a hotbed of immune cell activity and can provide circulating peripheral immune cells with passage into the central nervous system (CNS). Here, we review recent studies on ChP immune cells, with a focus on the ontogeny, development, and behaviors of ChP macrophages, the principal resident immune cells of the ChP. We highlight the implications of immune cells for ChP barrier function, CSF cytokines and volume regulation, and their contribution to neurodevelopmental disorders, with possible age-specific features to be elucidated in the future.

Cerebrospinal fluid (CSF) provides vital support for the brain. Abnormal CSF accumulation, such as hydrocephalus, can negatively affect perinatal neurodevelopment. The mechanisms regulating CSF clearance during the postnatal critical period are unclear. Here, we show that CSF K+, accompanied by water, is cleared through the choroid plexus (ChP) during mouse early postnatal development. We report that, at this developmental stage, the ChP showed increased ATP production and increased expression of ATP-dependent K+ transporters, particularly the Na+, K+, Cl−, and water cotransporter NKCC1. Overexpression of NKCC1 in the ChP resulted in increased CSF K+ clearance, increased cerebral compliance, and reduced circulating CSF in the brain without changes in intracranial pressure in mice. Moreover, ChP-specific NKCC1 overexpression in an obstructive hydrocephalus mouse model resulted in reduced ventriculomegaly. Collectively, our results implicate NKCC1 in regulating CSF K+ clearance through the ChP in the critical period during postnatal neurodevelopment in mice., Abnormal CSF accumulation in the brain can lead to hydrocephalus. The mechanisms regulating CSF clearance during early development are unclear. Here, the authors show that NKCC1 regulates the clearance of both CSF K+ and fluid volume through the choroid plexus during postnatal development in mice.

Multiciliated cells (MCCs) in the brain include the ependymal cells and choroid plexus (CP) epithelial cells. The CP secretes cerebrospinal fluid that circulates within the ventricular system, driven by ependymal cilia movement. However, the mechanisms and functional significance of multiciliogenesis in the CP remain unknown. Deregulated oncogenic signals cause CP carcinoma (CPC), a rare but aggressive pediatric brain cancer. Here we show that aberrant NOTCH and Sonic Hedgehog signaling in mice drive tumors that resemble CPC in humans. NOTCH-driven CP tumors were monociliated, whereas disruption of the NOTCH complex restored multiciliation and decreased tumor growth. NOTCH suppressed multiciliation in tumor cells by inhibiting the expression of GEMC1 and MCIDAS, early regulators of multiciliogenesis. Consistently, GEMC1-MCIDAS function is essential for multiciliation in the CP, and is critical for correcting multiciliation defect in tumor cells by a NOTCH inhibitor. Disturbances to theGEMC1program are commonly observed in human CPCs characterized by solitary cilia. Consistently, CPC driven by deletion ofTrp53andRb1in mice exhibits a cilia deficit consequent to loss ofGemc1-Mcidasexpression. Taken together, these findings reveal a GEMC1-MCIDAS multiciliation program in the CP critical for inhibiting tumorigenesis, and it may have therapeutic implications for the treatment of CPC.

Cerebrospinal fluid (CSF) is a vital liquid, providing nutrients, signalling molecules, and clearing out toxic byproducts from the brain. The CSF is produced by the choroid plexus (ChP), a protective epithelial barrier that also prevents free entry from the blood. Here, we establish human ChP organoids with a selective barrier and CSF-like fluid secretion in self-contained compartments. We show that this in vitro barrier exhibits the same selectivity to small molecules as in vivo, and that ChP-CSF organoids can predict CNS permeability of novel compounds. The transcriptomic and proteomic signature of ChP-CSF organoids reveal a high degree of similarity to in vivo. Finally, the intersection of single cell transcriptomics and proteomic analysis uncovers key human CSF components produced by previously unidentified specialized epithelial subtypes.

Cerebrospinal fluid (CSF) provides vital support for the brain. Abnormal CSF accumulation is deleterious for perinatal neurodevelopment, but how CSF leaves the brain during this critical period is unknown. We found in mice a postnatal neurodevelopmental transition phase featuring precipitous CSF K+ clearance, accompanied by water, through the choroid plexus (ChP). The period corresponds to a human fetal stage when canonical CSF clearance pathways have yet to form and congenital hydrocephalus begins to manifest. Unbiased ChP metabolic and ribosomal profiling highlighted this transition phase with increased ATP yield and activated energy-dependent K+ transporters, in particular the Na+-K+-Cl− and water cotransporter NKCC1. ChP-targeted NKCC1 overexpression enhanced K+-driven CSF clearance and enabled more permissive cerebral hydrodynamics. Moreover, ventriculomegaly in an obstructive hydrocephalus model was improved by ChP-targeted NKCC1 overexpression. Collectively, we identified K+-driven CSF clearance through ChP during a transient but critical neurodevelopmental phase, with translational value for pathologic conditions.

The choroid plexus (ChP) produces cerebrospinal fluid and forms a critical barrier between the brain and the circulation. While the ChP forms in each brain ventricle, it adopts a different shape in each one and remarkably little is known about the mechanisms underlying its development. Here, we show that epithelial WNT5A is critical for determining fourth ventricle (4V) ChP morphogenesis and size. SystemicWnt5aknockout, or forced WNT5A overexpression beginning at E10.5, profoundly reduced the size and development of ChP in all ventricles. However, conditional deletion ofWnt5aexpression inFoxj1-expressing epithelial cells affected only the branched, villous morphology of the 4V ChP. We found that WNT5A was enriched in epithelial cells localized to the distal tips of 4V ChP villi, where WNT5A acted locally to activate non-canonical Wnt signaling via Ror1/Ror2 receptors. During 4V ChP development, MEIS1 bound to the proximalWnt5apromoter, and gain- and loss-of-function approaches demonstrated that MEIS1 regulatedWnt5aexpression. Collectively, our findings demonstrate a dual function of WNT5A in ChP development and identify MEIS1 and MEIS2 as upstream regulators ofWnt5ain the 4V ChP epithelium.

The choroid plexus (ChP) epithelium is a source of secreted signaling factors in cerebrospinal fluid (CSF) and a key barrier between blood and brain. Here, we develop imaging tools to interrogate these functions in adult lateral ventricle ChP in wholemount explants and in awake mice. By imaging epithelial cells in intact ChP explants, we observed calcium activity and secretory events that increased in frequency following delivery of serotonergic agonists. Using chronic two-photon imaging in awake mice, we observed spontaneous subcellular calcium events as well as strong agonist-evoked calcium activation and cytoplasmic secretion into CSF. Three-dimensional imaging of motility and mobility of multiple types of ChP immune cells at baseline and following immune challenge or focal injury revealed a range of surveillance and defensive behaviors. Together, these tools should help illuminate the diverse functions of this understudied body-brain interface.

We summarize recent work illuminating how cerebrospinal fluid (CSF) regulates brain function. More than a protective fluid cushion and sink for waste, the CSF is an integral CNS component with dynamic and diverse roles emerging in parallel with the developing CNS. This review examines the current understanding about early CSF and its maturation and roles during CNS development and discusses open questions in the field. We focus on developmental changes in the ventricular system and CSF sources (including neural progenitors and choroid plexus). We also discuss concepts related to the development of fluid dynamics including flow, perivascular transport, drainage, and barriers.

Somatosensory over-reactivity is common among patients with autism spectrum disorders (ASDs) and is hypothesized to contribute to core ASD behaviors. However, effective treatments for sensory over-reactivity and ASDs are lacking. We found distinct somatosensory neuron pathophysiological mechanisms underlie tactile abnormalities in different ASD mouse models and contribute to some ASD-related behaviors. Developmental loss of ASD-associated genes Shank3 or Mecp2 in peripheral mechanosensory neurons leads to region-specific brain abnormalities, revealing links between developmental somatosensory over-reactivity and the genesis of aberrant behaviors. Moreover, acute treatment with a peripherally restricted GABAA receptor agonist that acts directly on mechanosensory neurons reduced tactile over-reactivity in six distinct ASD models. Chronic treatment of Mecp2 and Shank3 mutant mice improved body condition, some brain abnormalities, anxiety-like behaviors, and some social impairments but not memory impairments, motor deficits, or overgrooming. Our findings reveal a potential therapeutic strategy targeting peripheral mechanosensory neurons to treat tactile over-reactivity and select ASD-related behaviors. Treatment with a peripherally restricted GABAA receptor agonist in multiple distinct autism spectrum disorder mouse models reveals a potential therapeutic strategy for select ASD-related behaviors., National Institutes of Health (U.S.) (Grants F31 MH098641A, R01 MH097104), National Institute of Mental Health (U.S.) (Conte Center Grant P50 MH094271)

Cells of the developing central nervous system are particularly susceptible to formation of double-stranded DNA breaks (DSBs) arising from physiological and/or environmental insults. Therefore, efficient repair of DSBs is especially vital for maintaining cellular health and proper functioning in the developing brain. Here, increased expression of DSB initiating and nonhomologous end joining repair machinery in newborn neurons in the developing brains of both mouse and human are demonstrated. In parallel, the first characterization is provided of the brain phenotype in the Lig4(R278H/R278H) (Lig4(R/R)) mouse model of DNA Ligase 4 (LIG4) syndrome, in which a hypomorphic Lig4 mutation, originally identified in patients, impedes nonhomologous end joining. It is shown that Lig4(R/R) mice develop nonprogressive microcephaly, resulting primarily from apoptotic death of newborn neurons that is both spatially and temporally specific during peak cortical neurogenesis. This apoptosis leads to a reduction in neurons throughout the postnatal cerebral cortex, but with a more prominent impact on those of the lower cortical layers. Together, these findings begin to uncover the pathogenesis of microcephaly in LIG4 syndrome and open avenues to more focused investigations on the critical roles of DSB formation and repair in vulnerable neuronal populations of the brain.

Massive, coordinated cellular changes accompany the transition of central nervous system (CNS) progenitors from forebrain neurectodermal cells to specified neuroepithelial cells. We previously found that c-MYC regulates the changing ribosomal and proteostatic landscapes in mouse forebrain precursors at embryonic days E8.5 vs. E10.5 (before vs. after neural tube closure; NTC) (Chau et al., 2018). Here we demonstrate parallel coordinated transcriptional changes in metabolic machinery during this same stage of forebrain specification. Progenitors showed striking mitochondrial structural changes transitioning from glycolytic cristae at E8.5, to more traditional mitochondria at E10.5. Accordingly, glucose usage shifted in progenitors such that E8.5 progenitors relied on glycolysis, and after NTC increasingly used oxidative phosphorylation. This metabolic shift was matched by changes in surrounding amniotic and cerebrospinal fluid proteomes. Importantly, these mitochondrial morphological shifts depend on c-MYC downregulation. Together, our findings demonstrate metabolic shifting accompanies dynamic organelle and proteostatic remodeling of progenitor cells during the earliest stages of forebrain development.

The choroid plexus (ChP), located in each brain ventricle, produces cerebrospinal fluid (CSF) and forms the blood-CSF barrier, but is under-characterized. Here, we combine single cell RNA-Seq and spatial mapping of RNA and proteins to construct an atlas of each ChP in the developing and adult mouse brain. Each ChP comprises of epithelial, endothelial, mesenchymal, immune, neuronal, and glial cells, with distinct subtypes, differentiation states and anatomical locations. Epithelial, fibroblast, and macrophage populations had ventricle-specific, regionalized gene expression programs across the developing brain. Key cell types are retained in adult, with loss of developmental signatures and maturation of ventricle-specific regionalization in the epithelial cells. Expression of cognate ligand-receptor pairs across cell subtypes suggests substantial cell-cell interactions within the ChP. Our atlas sheds new light on the development and function of the ChP brain barrier system, and will facilitate future studies on its role in brain development, homeostasis and disease.

Summary The choroid plexus (ChP) regulates brain development by secreting instructive cues and providing a protective brain barrier. Here, we show that polyI:C-mediated maternal immune activation leads to an inflammatory response in the developing embryonic mouse brain that manifests as pro-inflammatory cerebrospinal fluid (CSF) and accumulation of ChP macrophages. Elevation of CSF-CCL2 was sufficient to drive ChP immune cell recruitment, activation, and proliferation. In addition, ChP macrophages abandoned their regular tiling pattern and relocated to the ChP-free margin where they breached the weakened epithelial barrier. We further found that these immune cells entered from the ChP into the brain via anatomically specialized “hotspots” at the distal tips of ChP villi. In vivo two-photon imaging demonstrated that surveillance behaviors in ChP macrophages had already emerged at this early stage of embryogenesis. Thus, the embryonic ChP forms a functional brain barrier that can mount an inflammatory response to external insults.

Aberrant Notch signalling has been linked to many cancers including choroid plexus (CP) tumours, a group of rare and predominantly paediatric brain neoplasms. We developed animal models of CP tumours, by inducing sustained expression of Notch1, that recapitulate properties of human CP tumours with aberrant NOTCH signalling. Whole-transcriptome and functional analyses showed that tumour cell proliferation is associated with Sonic Hedgehog (Shh) in the tumour microenvironment. Unlike CP epithelial cells, which have multiple primary cilia, tumour cells possess a solitary primary cilium as a result of Notch-mediated suppression of multiciliate differentiation. A Shh-driven signalling cascade in the primary cilium occurs in tumour cells but not in epithelial cells. Lineage studies show that CP tumours arise from monociliated progenitors in the roof plate characterized by elevated Notch signalling. Abnormal SHH signalling and distinct ciliogenesis are detected in human CP tumours, suggesting the SHH pathway and cilia differentiation as potential therapeutic avenues.

The choroid plexus (ChP) epithelium is a source of secreted signaling factors in cerebrospinal fluid (CSF) and a key barrier between blood and brain. Here, we develop imaging tools to interrogate these functions in adult lateral ventricle ChP in whole-mount explants and in awake mice. By imaging epithelial cells in intact ChP explants, we observed calcium activity and secretory events that increased in frequency following delivery of serotonergic agonists. Using chronic two-photon imaging in awake mice, we observed spontaneous subcellular calcium events as well as strong agonist-evoked calcium activation and cytoplasmic secretion into CSF. Three-dimensional imaging of motility and mobility of multiple types of ChP immune cells at baseline and following immune challenge or focal injury revealed a range of surveillance and defensive behaviors. Together, these tools should help illuminate the diverse functions of this understudied body-brain interface.

Forebrain precursor cells are dynamic during early brain development, yet the underlying molecular changes remain elusive. We observed major differences in transcriptional signatures of precursor cells from mouse forebrain at embryonic days E8.5 vs. E10.5 (before vs. after neural tube closure). Genes encoding protein biosynthetic machinery were strongly downregulated at E10.5. This was matched by decreases in ribosome biogenesis and protein synthesis, together with age-related changes in proteomic content of the adjacent fluids. Notably, c-MYC expression and mTOR pathway signaling were also decreased at E10.5, providing potential drivers for the effects on ribosome biogenesis and protein synthesis. Interference with c-MYC at E8.5 prematurely decreased ribosome biogenesis, while persistent c-MYC expression in cortical progenitors increased transcription of protein biosynthetic machinery and enhanced ribosome biogenesis, as well as enhanced progenitor proliferation leading to subsequent macrocephaly. These findings indicate large, coordinated changes in molecular machinery of forebrain precursors during early brain development.

Obesity during adolescence shapes lifelong sleep circuitry via serotonin.

Channelopathies are disorders caused by abnormal ion channel function in differentiated excitable tissues. We discovered a unique neurodevelopmental channelopathy resulting from pathogenic variants in SCN3A, a gene encoding the voltage-gated sodium channel Na(V)1.3. Pathogenic Na(V)1.3 channels showed altered biophysical properties including increased persistent current. Remarkably, affected individuals showed disrupted folding (polymicrogyria) of the perisylvian cortex of the brain but did not typically exhibit epilepsy; they presented with prominent speech and oral motor dysfunction, implicating SCN3A in prenatal development of human cortical language areas. The development of this disorder parallels SCN3A expression, which we observed to be highest early in fetal cortical development in progenitor cells of the outer subventricular zone and cortical plate neurons and decreased postnatally, when SCN1A (Na(V)1.1) expression increased. Disrupted cerebral cortical folding and neuronal migration were recapitulated in ferrets expressing the mutant channel, underscoring the unexpected role of SCN3A in progenitor cells and migrating neurons.

SUMMARY Endosomal sorting complex required for transport (ESCRT) complex proteins regulate biogenesis and release of extracellular vesicles (EVs), which enable cell-to-cell communication in the nervous system essential for development and adult function. We recently showed human loss-of-function (LOF) mutations in ESCRT-III member CHMP1A cause autosomal recessive microcephaly with pontocerebellar hypoplasia, but its mechanism was unclear. Here, we show Chmp1a is required for progenitor proliferation in mouse cortex and cerebellum and progenitor maintenance in human cerebral organoids. In Chmp1a null mice, this defect is associated with impaired sonic hedgehog (Shh) secretion and intraluminal vesicle (ILV) formation in multivesicular bodies (MVBs). Furthermore, we show CHMP1A is important for release of an EV subtype that contains AXL, RAB18, and TMED10 (ART) and SHH. Our findings show CHMP1A loss impairs secretion of SHH on ART-EVs, providing molecular mechanistic insights into the role of ESCRT proteins and EVs in the brain., Graphical Abstract, In Brief Extracellular vesicles (EVs) are essential for cell-to-cell communication in developing brain. Coulter et al. show that the human microcephaly gene CHMP1A is required for neuroprogenitor proliferation through regulation of vesicular secretion of the growth factor sonic hedgehog (SHH). CHMP1A specifically impairs SHH secretion on a distinctive EV subtype, ART-EV.

The adult subventricular zone (SVZ) stem cell niche is comprised of multi-ciliated ependymal cells that line the brain ventricular system and adult stem cells. Papers in Neuron (Ortiz-Alvarez et al., 2019) and Cell Reports (Redmond et al., 2019) report that these cell types share a common precursor. Ortiz-Alvarez et al. further show that Geminin family members modulate the fate of daughter cells.

Cerebrospinal fluid (CSF) includes conserved factors whose function is largely unexplored. To assess the role of CSF during embryonic development, CSF was repeatedly drained from embryonic zebrafish brain ventricles soon after their inflation. Removal of CSF increased cell death in the diencephalon, indicating a survival function. Factors within the CSF are required for neuroepithelial cell survival as injected mouse CSF but not artificial CSF could prevent cell death after CSF depletion. Mass spectrometry analysis of the CSF identified retinol binding protein 4 (Rbp4), which transports retinol, the precursor to retinoic acid (RA). Consistent with a role for Rbp4 in cell survival, inhibition of Rbp4 or RA synthesis increased neuroepithelial cell death. Conversely, ventricle injection of exogenous human RBP4 plus retinol, or RA alone prevented cell death after CSF depletion. Zebrafish rbp4 is highly expressed in the yolk syncytial layer, suggesting Rbp4 protein and retinol/RA precursors can be transported into the CSF from the yolk. In accord with this suggestion, injection of human RBP4 protein into the yolk prevents neuroepithelial cell death in rbp4 loss‐of‐function embryos. Together, these data support the model that Rbp4 and RA precursors are present within the CSF and used for synthesis of RA, which promotes embryonic neuroepithelial survival. © 2015 Wiley Periodicals, Inc. Develop Neurobiol 76: 75–92, 2016

Circadian CLOCK gene expression is reduced in human epileptic brain tissue, and its deletion is epileptogenic in mice.

Choroid plexus tumors and ciliary body medulloepithelioma are predominantly pediatric neoplasms. Progress in understanding the pathogenesis of these tumors has been hindered by their rarity and lack of models that faithfully recapitulate the disease. Here, we find that endogenous Myc proto-oncogene protein is down-regulated in the forebrain neuroepithelium, whose neural plate border domains give rise to the anterior choroid plexus and ciliary body. To uncover the consequences of persistent Myc expression, MYC expression was forced in multipotent neural precursors (nestin-Cre:Myc), which produced fully penetrant models of choroid plexus carcinoma and ciliary body medulloepithelioma. Nestin-mediated MYC expression in the epithelial cells of choroid plexus leads to the regionalized formation of choroid plexus carcinoma in the posterior domain of the lateral ventricle choroid plexus and the fourth ventricle choroid plexus that is accompanied by loss of multiple cilia, up-regulation of protein biosynthetic machinery, and hydrocephalus. Parallel MYC expression in the ciliary body leads also to up-regulation of protein biosynthetic machinery. Additionally, Myc expression in human choroid plexus tumors increases with aggressiveness of disease. Collectively, our findings expose a select vulnerability of the neuroepithelial lineage to postnatal tumorigenesis and provide a new mouse model for investigating the pathogenesis of these rare pediatric neoplasms.

The gut microbiome plays a key role in the pathogenesis of multiple sclerosis.

Primary cilia-based signaling provides critical infrastructure for formation of striatal neuronal networks.

Migraine-related photophobia is multifaceted and may be mediated by numerous pathways.