The 7q11.23 Protein DNAJC30 Interacts with ATP Synthase and Links Mitochondria to Brain Development.

Despite the known causality of copy-number variations (CNVs) to human neurodevelopmental disorders, the mechanisms behind each gene's contribution to the constellation of neural phenotypes remain elusive. Here, we investigated the 7q11.23 CNV, whose hemideletion causes Williams syndrome (WS), and uncovered that mitochondrial dysfunction participates in WS pathogenesis. Dysfunction is facilitated in part by the 7q11.23 protein DNAJC30, which interacts with mitochondrial ATP-synthase machinery. Removal of Dnajc30 in mice resulted in hypofunctional mitochondria, diminished morphological features of neocortical pyramidal neurons, and altered behaviors reminiscent of WS. The mitochondrial features are consistent with our observations of decreased integrity of oxidative phosphorylation supercomplexes and ATP-synthase dimers in WS. Thus, we identify DNAJC30 as an auxiliary component of ATP-synthase machinery and reveal mitochondrial maladies as underlying certain defects in brain development and function associated with WS.

Vaginal Exposure to Zika Virus during Pregnancy Leads to Fetal Brain Infection.

Zika virus (ZIKV) can be transmitted sexually between humans. However, it is unknown whether ZIKV replicates in the vagina and impacts the unborn fetus. Here, we establish a mouse model of vaginal ZIKV infection and demonstrate that, unlike other routes, ZIKV replicates within the genital mucosa even in wild-type (WT) mice. Mice lacking RNA sensors or transcription factors IRF3 and IRF7 resulted in higher levels of local viral replication. Furthermore, mice lacking the type I interferon (IFN) receptor (IFNAR) became viremic and died of infection after a high-dose vaginal ZIKV challenge. Notably, vaginal infection of pregnant dams during early pregnancy led to fetal growth restriction and infection of the fetal brain in WT mice. This was exacerbated in mice deficient in IFN pathways, leading to abortion. Our study highlights the vaginal tract as a highly susceptible site of ZIKV replication and illustrates the dire disease consequences during pregnancy.

Astrocytic Insulin Signaling Couples Brain Glucose Uptake with Nutrient Availability.

We report that astrocytic insulin signaling co-regulates hypothalamic glucose sensing and systemic glucose metabolism. Postnatal ablation of insulin receptors (IRs) in glial fibrillary acidic protein (GFAP)-expressing cells affects hypothalamic astrocyte morphology, mitochondrial function, and circuit connectivity. Accordingly, astrocytic IR ablation reduces glucose-induced activation of hypothalamic pro-opio-melanocortin (POMC) neurons and impairs physiological responses to changes in glucose availability. Hypothalamus-specific knockout of astrocytic IRs, as well as postnatal ablation by targeting glutamate aspartate transporter (GLAST)-expressing cells, replicates such alterations. A normal response to altering directly CNS glucose levels in mice lacking astrocytic IRs indicates a role in glucose transport across the blood-brain barrier (BBB). This was confirmed in vivo in GFAP-IR KO mice by using positron emission tomography and glucose monitoring in cerebral spinal fluid. We conclude that insulin signaling in hypothalamic astrocytes co-controls CNS glucose sensing and systemic glucose metabolism via regulation of glucose uptake across the BBB.

Single-cell longitudinal analysis of SARS-CoV-2 infection in human airway epithelium identifies target cells, alterations in gene expression, and cell state changes.

There are currently limited Food and Drug Administration (FDA)-approved drugs and vaccines for the treatment or prevention of Coronavirus Disease 2019 (COVID-19). Enhanced understanding of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection and pathogenesis is critical for the development of therapeutics. To provide insight into viral replication, cell tropism, and host-viral interactions of SARS-CoV-2, we performed single-cell (sc) RNA sequencing (RNA-seq) of experimentally infected human bronchial epithelial cells (HBECs) in air-liquid interface (ALI) cultures over a time course. This revealed novel polyadenylated viral transcripts and highlighted ciliated cells as a major target at the onset of infection, which we confirmed by electron and immunofluorescence microscopy. Over the course of infection, the cell tropism of SARS-CoV-2 expands to other epithelial cell types including basal and club cells. Infection induces cell-intrinsic expression of type I and type III interferons (IFNs) and interleukin (IL)-6 but not IL-1. This results in expression of interferon-stimulated genes (ISGs) in both infected and bystander cells. This provides a detailed characterization of genes, cell types, and cell state changes associated with SARS-CoV-2 infection in the human airway.

Hypothalamic POMC neurons promote cannabinoid-induced feeding.

Hypothalamic pro-opiomelanocortin (POMC) neurons promote satiety. Cannabinoid receptor 1 (CB1R) is critical for the central regulation of food intake. Here we test whether CB1R-controlled feeding in sated mice is paralleled by decreased activity of POMC neurons. We show that chemical promotion of CB1R activity increases feeding, and notably, CB1R activation also promotes neuronal activity of POMC cells. This paradoxical increase in POMC activity was crucial for CB1R-induced feeding, because designer-receptors-exclusively-activated-by-designer-drugs (DREADD)-mediated inhibition of POMC neurons diminishes, whereas DREADD-mediated activation of POMC neurons enhances CB1R-driven feeding. The Pomc gene encodes both the anorexigenic peptide α-melanocyte-stimulating hormone, and the opioid peptide ß-endorphin. CB1R activation selectively increases ß-endorphin but not α-melanocyte-stimulating hormone release in the hypothalamus, and systemic or hypothalamic administration of the opioid receptor antagonist naloxone blocks acute CB1R-induced feeding. These processes involve mitochondrial adaptations that, when blocked, abolish CB1R-induced cellular responses and feeding. Together, these results uncover a previously unsuspected role of POMC neurons in the promotion of feeding by cannabinoids.

Intranasal epidermal growth factor treatment rescues neonatal brain injury.

There are no clinically relevant treatments available that improve function in the growing population of very preterm infants (less than 32 weeks' gestation) with neonatal brain injury. Diffuse white matter injury (DWMI) is a common finding in these children and results in chronic neurodevelopmental impairments. As shown recently, failure in oligodendrocyte progenitor cell maturation contributes to DWMI. We demonstrated previously that the epidermal growth factor receptor (EGFR) has an important role in oligodendrocyte development. Here we examine whether enhanced EGFR signalling stimulates the endogenous response of EGFR-expressing progenitor cells during a critical period after brain injury, and promotes cellular and behavioural recovery in the developing brain. Using an established mouse model of very preterm brain injury, we demonstrate that selective overexpression of human EGFR in oligodendrocyte lineage cells or the administration of intranasal heparin-binding EGF immediately after injury decreases oligodendroglia death, enhances generation of new oligodendrocytes from progenitor cells and promotes functional recovery. Furthermore, these interventions diminish ultrastructural abnormalities and alleviate behavioural deficits on white-matter-specific paradigms. Inhibition of EGFR signalling with a molecularly targeted agent used for cancer therapy demonstrates that EGFR activation is an important contributor to oligodendrocyte regeneration and functional recovery after DWMI. Thus, our study provides direct evidence that targeting EGFR in oligodendrocyte progenitor cells at a specific time after injury is clinically feasible and potentially applicable to the treatment of premature children with white matter injury.

Prokaryotic SPHINX replication sequences are conserved in mammalian brain and participate in neurodegeneration.

A new class of viral mammalian Slow Progressive Hidden INfections of variable (X) latency ("SPHINX") DNAs, represented by the 1.8 and 2.4 kb nuclease-protected circular elements, were discovered in highly infectious cytoplasmic particles isolated from Creutzfeldt-Jakob Disease (CJD) and scrapie samples. These DNAs contained replication initiation sequences (REPs) with approximately 70% homology to those of environmental Acinetobacter phage. Antibodies against REP peptides from the 1.8 kb DNA highlighted a 41 kDa protein (spx) on Western blots, and in situ studies previously revealed its peripheral tissue expression, for example, in pancreatic islet cells, keratinocytes, kidney tubules, and oocytes but not pancreatic exocrine cells, alveoli, and striated muscle. To determine if spx concentrated in specific neurons and synapses, and also maintained a conserved pattern of architectural organization in mammalian brains, we evaluated mouse, rat, hamster, guinea pig (GP), and human samples. Most outstanding was the cross-species concentration of spx in huge excitatory synapses of mossy fibers and small internal granule neuron synapses, the only excitatory neuron within the cerebellum. Spx also localized to excitatory glutamate type synapses in the hippocampus, and both cerebellar and hippocampal synaptic spx was demonstrable ultrastructurally. Studies of two well-characterized models of sporadic CJD (sCJD) revealed novel spx pathology. Vacuolar loss of cerebellar synaptic complexes, thinning of the internal granule cell layer, and fibrillar spx accumulations within Purkinje neurons were prominent in sCJD GP brains. In rats, comparable spx fibrillar changes appeared in hippocampal pyramidal neurons, and they preceded prion protein misfolding. Hence, spx is an integral player in progressive neurodegeneration. The evolutionary origin, spread, and neuropathology of SPHINX 1.8 REP sequences opens another unanticipated chapter for mammalian symbiotic interactions with environmental microbes.

Fetal Growth Restriction Caused by Sexual Transmission of Zika Virus in Mice.

Zika virus (ZIKV) can be transmitted by mosquito bite or sexual contact. Using mice that lack the type I interferon receptor, we examined sexual transmission of ZIKV. Electron microscopy analyses showed association of virions with developing sperm within testes as well as with mature sperm within epididymis. When ZIKV-infected male mice were mated with naive female mice, the weight of fetuses at embryonic day 18.5 was significantly reduced compared with the control group. Additionally, we found ocular deformities in a minority of the fetuses. These results suggest that ZIKV causes fetal abnormalities after female mating with an infected male.

Prevention of paclitaxel-induced peripheral neuropathy by lithium pretreatment.

Chemotherapy-induced peripheral neuropathy (CIPN) is a debilitating side effect that occurs in many patients undergoing chemotherapy. It is often irreversible and frequently leads to early termination of treatment. In this study, we have identified two compounds, lithium and ibudilast, that when administered as a single prophylactic injection prior to paclitaxel treatment, prevent the development of CIPN in mice at the sensory-motor and cellular level. The prevention of neuropathy was not observed in paclitaxel-treated mice that were only prophylactically treated with a vehicle injection. The coadministration of lithium with paclitaxel also allows for administration of higher doses of paclitaxel (survival increases by 60%), protects against paclitaxel-induced cardiac abnormalities, and, notably, does not interfere with the antitumor effects of paclitaxel. Moreover, we have determined a mechanism by which CIPN develops and have discovered that lithium and ibudilast inhibit development of peripheral neuropathy by disrupting the interaction between paclitaxel, neuronal calcium sensor 1 (NCS-1), and the inositol 1,4,5-trisphosphate receptor (InsP3R) to prevent treatment-induced decreases in intracellular calcium signaling. This study shows that lithium and ibudilast are candidate therapeutics for the prevention of paclitaxel-induced neuropathy and could enable patients to tolerate more aggressive treatment regimens.

LINE-1 activation in the cerebellum drives ataxia.

Dysregulation of long interspersed nuclear element 1 (LINE-1, L1), a dominant class of transposable elements in the human genome, has been linked to neurodegenerative diseases, but whether elevated L1 expression is sufficient to cause neurodegeneration has not been directly tested. Here, we show that the cerebellar expression of L1 is significantly elevated in ataxia telangiectasia patients and strongly anti-correlated with the expression of epigenetic silencers. To examine the role of L1 in the disease etiology, we developed an approach for direct targeting of the L1 promoter for overexpression in mice. We demonstrated that L1 activation in the cerebellum led to Purkinje cell dysfunctions and degeneration and was sufficient to cause ataxia. Treatment with a nucleoside reverse transcriptase inhibitor blunted ataxia progression by reducing DNA damage, attenuating gliosis, and reversing deficits of molecular regulators for calcium homeostasis in Purkinje cells. Our study provides the first direct evidence that L1 activation can drive neurodegeneration.

Bisphenol A prevents the synaptogenic response to estradiol in hippocampus and prefrontal cortex of ovariectomized nonhuman primates.

Exposure measurements from several countries indicate that humans are routinely exposed to low levels of bisphenol A (BPA), a synthetic xenoestrogen widely used in the production of polycarbonate plastics. There is considerable debate about whether this exposure represents an environmental risk, based on reports that BPA interferes with the development of many organs and that it may alter cognitive functions and mood. Consistent with these reports, we have previously demonstrated that BPA antagonizes spine synapse formation induced by estrogens and testosterone in limbic brain areas of gonadectomized female and male rats. An important limitation of these studies, however, is that they were based on rodent animal models, which may not be representative of the effects of human BPA exposure. To address this issue, we examined the influence of continuous BPA administration, at a daily dose equal to the current U.S. Environmental Protection Agency's reference safe daily limit, on estradiol-induced spine synapse formation in the hippocampus and prefrontal cortex of a nonhuman primate model. Our data indicate that even at this relatively low exposure level, BPA completely abolishes the synaptogenic response to estradiol. Because remodeling of spine synapses may play a critical role in cognition and mood, the ability of BPA to interfere with spine synapse formation has profound implications. This study is the first to demonstrate an adverse effect of BPA on the brain in a nonhuman primate model and further amplifies concerns about the widespread use of BPA in medical equipment, and in food preparation and storage.

Cerebellar Kv3.3 potassium channels activate TANK-binding kinase 1 to regulate trafficking of the cell survival protein Hax-1.

Mutations in KCNC3, which encodes the Kv3.3 potassium channel, cause degeneration of the cerebellum, but exactly how the activity of an ion channel is linked to the survival of cerebellar neurons is not understood. Here, we report that Kv3.3 channels bind and stimulate Tank Binding Kinase 1 (TBK1), an enzyme that controls trafficking of membrane proteins into multivesicular bodies, and that this stimulation is greatly increased by a disease-causing Kv3.3 mutation. TBK1 activity is required for the binding of Kv3.3 to its auxiliary subunit Hax-1, which prevents channel inactivation with depolarization. Hax-1 is also an anti-apoptotic protein required for survival of cerebellar neurons. Overactivation of TBK1 by the mutant channel leads to the loss of Hax-1 by its accumulation in multivesicular bodies and lysosomes, and also stimulates exosome release from neurons. This process is coupled to activation of caspases and increased cell death. Our studies indicate that Kv3.3 channels are directly coupled to TBK1-dependent biochemical pathways that determine the trafficking of cellular constituents and neuronal survival.

Presynaptic Kv3 channels are required for fast and slow endocytosis of synaptic vesicles.

Since their discovery decades ago, the primary physiological and pathological effects of potassium channels have been attributed to their ion conductance, which sets membrane potential and repolarizes action potentials. For example, Kv3 family channels regulate neurotransmitter release by repolarizing action potentials. Here we report a surprising but crucial function independent of potassium conductance: by organizing the F-actin cytoskeleton in mouse nerve terminals, the Kv3.3 protein facilitates slow endocytosis, rapid endocytosis, vesicle mobilization to the readily releasable pool, and recovery of synaptic depression during repetitive firing. A channel mutation that causes spinocerebellar ataxia inhibits endocytosis, vesicle mobilization, and synaptic transmission during repetitive firing by disrupting the ability of the channel to nucleate F-actin. These results unmask novel functions of potassium channels in endocytosis and vesicle mobilization crucial for sustaining synaptic transmission during repetitive firing. Potassium channel mutations that impair these "non-conducting" functions may thus contribute to generation of diverse neurological disorders.

Obesity-associated hyperleptinemia alters the gliovascular interface of the hypothalamus to promote hypertension.

Pathologies of the micro- and macrovascular systems are a hallmark of the metabolic syndrome, which can lead to chronically elevated blood pressure. However, the underlying pathomechanisms involved still need to be clarified. Here, we report that an obesity-associated increase in serum leptin triggers the select expansion of the micro-angioarchitecture in pre-autonomic brain centers that regulate hemodynamic homeostasis. By using a series of cell- and region-specific loss- and gain-of-function models, we show that this pathophysiological process depends on hypothalamic astroglial hypoxia-inducible factor 1α-vascular endothelial growth factor (HIF1α-VEGF) signaling downstream of leptin signaling. Importantly, several distinct models of HIF1α-VEGF pathway disruption in astrocytes are protected not only from obesity-induced hypothalamic angiopathy but also from sympathetic hyperactivity or arterial hypertension. These results suggest that hyperleptinemia promotes obesity-induced hypertension via a HIF1α-VEGF signaling cascade in hypothalamic astrocytes while establishing a novel mechanistic link that connects hypothalamic micro-angioarchitecture with control over systemic blood pressure.

Neuroinvasion of SARS-CoV-2 in human and mouse brain.

Although COVID-19 is considered to be primarily a respiratory disease, SARS-CoV-2 affects multiple organ systems including the central nervous system (CNS). Yet, there is no consensus on the consequences of CNS infections. Here, we used three independent approaches to probe the capacity of SARS-CoV-2 to infect the brain. First, using human brain organoids, we observed clear evidence of infection with accompanying metabolic changes in infected and neighboring neurons. However, no evidence for type I interferon responses was detected. We demonstrate that neuronal infection can be prevented by blocking ACE2 with antibodies or by administering cerebrospinal fluid from a COVID-19 patient. Second, using mice overexpressing human ACE2, we demonstrate SARS-CoV-2 neuroinvasion in vivo. Finally, in autopsies from patients who died of COVID-19, we detect SARS-CoV-2 in cortical neurons and note pathological features associated with infection with minimal immune cell infiltrates. These results provide evidence for the neuroinvasive capacity of SARS-CoV-2 and an unexpected consequence of direct infection of neurons by SARS-CoV-2.

Single-cell longitudinal analysis of SARS-CoV-2 infection in human airway epithelium.

SARS-CoV-2, the causative agent of COVID-19, has tragically burdened individuals and institutions around the world. There are currently no approved drugs or vaccines for the treatment or prevention of COVID-19. Enhanced understanding of SARS-CoV-2 infection and pathogenesis is critical for the development of therapeutics. To reveal insight into viral replication, cell tropism, and host-viral interactions of SARS-CoV-2 we performed single-cell RNA sequencing of experimentally infected human bronchial epithelial cells (HBECs) in air-liquid interface cultures over a time-course. This revealed novel polyadenylated viral transcripts and highlighted ciliated cells as a major target of infection, which we confirmed by electron microscopy. Over the course of infection, cell tropism of SARS-CoV-2 expands to other epithelial cell types including basal and club cells. Infection induces cell-intrinsic expression of type I and type III IFNs and IL6 but not IL1. This results in expression of interferon-stimulated genes in both infected and bystander cells. We observe similar gene expression changes from a COVID-19 patient ex vivo. In addition, we developed a new computational method termed CONditional DENSity Embedding (CONDENSE) to characterize and compare temporal gene dynamics in response to infection, which revealed genes relating to endothelin, angio-genesis, interferon, and inflammation-causing signaling pathways. In this study, we conducted an in-depth analysis of SARS-CoV-2 infection in HBECs and a COVID-19 patient and revealed genes, cell types, and cell state changes associated with infection.

Neuroinvasion of SARS-CoV-2 in human and mouse brain.

Although COVID-19 is considered to be primarily a respiratory disease, SARS-CoV-2 affects multiple organ systems including the central nervous system (CNS). Yet, there is no consensus whether the virus can infect the brain, or what the consequences of CNS infection are. Here, we used three independent approaches to probe the capacity of SARS-CoV-2 to infect the brain. First, using human brain organoids, we observed clear evidence of infection with accompanying metabolic changes in the infected and neighboring neurons. However, no evidence for the type I interferon responses was detected. We demonstrate that neuronal infection can be prevented either by blocking ACE2 with antibodies or by administering cerebrospinal fluid from a COVID-19 patient. Second, using mice overexpressing human ACE2, we demonstrate in vivo that SARS-CoV-2 neuroinvasion, but not respiratory infection, is associated with mortality. Finally, in brain autopsy from patients who died of COVID-19, we detect SARS-CoV-2 in the cortical neurons, and note pathologic features associated with infection with minimal immune cell infiltrates. These results provide evidence for the neuroinvasive capacity of SARS-CoV2, and an unexpected consequence of direct infection of neurons by SARS-CoV-2.

SARS-CoV-2 infection of the placenta.

BACKGROUNDThe effects of the novel coronavirus disease 2019 (COVID-19) in pregnancy remain relatively unknown. We present a case of second trimester pregnancy with symptomatic COVID-19 complicated by severe preeclampsia and placental abruption.METHODSWe analyzed the placenta for the presence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) through molecular and immunohistochemical assays and by and electron microscopy and measured the maternal antibody response in the blood to this infection.RESULTSSARS-CoV-2 localized predominantly to syncytiotrophoblast cells at the materno-fetal interface of the placenta. Histological examination of the placenta revealed a dense macrophage infiltrate, but no evidence for the vasculopathy typically associated with preeclampsia.CONCLUSIONThis case demonstrates SARS-CoV-2 invasion of the placenta, highlighting the potential for severe morbidity among pregnant women with COVID-19.FUNDINGBeatrice Kleinberg Neuwirth Fund and Fast Grant Emergent Ventures funding from the Mercatus Center at George Mason University. The funding bodies did not have roles in the design of the study or data collection, analysis, and interpretation and played no role in writing the manuscript.

Neuronal calcium sensor-1 enhancement of InsP3 receptor activity is inhibited by therapeutic levels of lithium.

Regulation and dysregulation of intracellular calcium (Ca2+) signaling via the inositol 1,4,5-trisphosphate receptor (InsP3R) has been linked to many cellular processes and pathological conditions. In the present study, addition of neuronal calcium sensor-1 (NCS-1), a high-affinity, low-capacity, calcium-binding protein, to purified InsP3R type 1 (InsP3R1) increased the channel activity in both a calcium-dependent and -independent manner. In intact cells, enhanced expression of NCS-1 resulted in increased intracellular calcium release upon stimulation of the phosphoinositide signaling pathway. To determine whether InsP3R1/NCS-1 interaction could be functionally relevant in bipolar disorders, conditions in which NCS-1 is highly expressed, we tested the effect of lithium, a salt widely used for treatment of bipolar disorders. Lithium inhibited the enhancing effect of NCS-1 on InsP3R1 function, suggesting that InsP3R1/NCS-1 interaction is an essential component of the pathomechanism of bipolar disorder.

Bisphenol A prevents the synaptogenic response to testosterone in the brain of adult male rats.

Exposure measurement data from several developed countries indicate that human beings are widely exposed to low levels of the synthetic xenoestrogen, bisphenol A. We reported previously that bisphenol A, even at doses below the reference safe daily limit for human exposure, recommended by the U.S. Environmental Protection Agency, impairs the synaptogenic response to 17beta-estradiol in the hippocampus of ovariectomized rats. Recent experiments revealed that bisphenol A also interferes with androgen receptor-mediated transcriptional activities. Thus, to investigate whether bisphenol A impairs synaptogenesis in the medial prefrontal cortex (mPFC) and hippocampus of adult male rats, castrated and sham-operated animals were treated with different combinations of bisphenol A (300 microg/kg), testosterone propionate (1.5 mg/kg), and sesame oil vehicle. The brains were processed for electron microscopic stereology, and the number of asymmetric spine synapses in the mPFC and CA1 hippocampal area was estimated. In both regions analyzed, bisphenol A reduced the number of spine synapses in sham-operated, gonadally intact animals, which was accompanied by a compensatory increase in astroglia process density. In addition, bisphenol A prevented both the prefrontal and hippocampal synaptogenic response to testosterone supplementation in castrated males. These results demonstrate that bisphenol A interferes with the synaptogenic response to testosterone in the mPFC and hippocampus of adult male rats. Because the hippocampal synaptogenic action of androgens seems to be independent of androgen and estrogen receptors in males, the potential mechanisms that underlie these negative effects of bisphenol A remain the subject of further investigation.