Publications by authors named "Kenji Sakimura"

246 Publications

Fis1 ablation in the male germline disrupts mitochondrial morphology and mitophagy, and arrests spermatid maturation.

Development 2021 Aug 12;148(16). Epub 2021 Aug 12.

Division of Biology and Biological Engineering, California Institute of Technology, Pasadena CA 91125, USA.

Male germline development involves choreographed changes to mitochondrial number, morphology and organization. Mitochondrial reorganization during spermatogenesis was recently shown to require mitochondrial fusion and fission. Mitophagy, the autophagic degradation of mitochondria, is another mechanism for controlling mitochondrial number and physiology, but its role during spermatogenesis is largely unknown. During post-meiotic spermatid development, restructuring of the mitochondrial network results in packing of mitochondria into a tight array in the sperm midpiece to fuel motility. Here, we show that disruption of mouse Fis1 in the male germline results in early spermatid arrest that is associated with increased mitochondrial content. Mutant spermatids coalesce into multinucleated giant cells that accumulate mitochondria of aberrant ultrastructure and numerous mitophagic and autophagic intermediates, suggesting a defect in mitophagy. We conclude that Fis1 regulates mitochondrial morphology and turnover to promote spermatid maturation.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1242/dev.199686DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8380467PMC
August 2021

Optical manipulation of local cerebral blood flow in the deep brain of freely moving mice.

Cell Rep 2021 Jul;36(4):109427

Department of Neuropsychiatry, Keio University School of Medicine, Tokyo 160-8582, Japan. Electronic address:

An artificial tool for manipulating local cerebral blood flow (CBF) is necessary for understanding how CBF controls brain function. Here, we generate vascular optogenetic tools whereby smooth muscle cells and endothelial cells express optical actuators in the brain. The illumination of channelrhodopsin-2 (ChR2)-expressing mice induces a local reduction in CBF. Photoactivated adenylyl cyclase (PAC) is an optical protein that increases intracellular cyclic adenosine monophosphate (cAMP), and the illumination of PAC-expressing mice induces a local increase in CBF. We target the ventral striatum, determine the temporal kinetics of CBF change, and optimize the illumination intensity to confine the effects to the ventral striatum. We demonstrate the utility of this vascular optogenetic manipulation in freely and adaptively behaving mice and validate the task- and actuator-dependent behavioral readouts. The development of vascular optogenetic animal models will help accelerate research linking vasculature, circuits, and behavior to health and disease.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.celrep.2021.109427DOI Listing
July 2021

Characterization and Stage-Dependent Lineage Analysis of Intermediate Progenitors of Cortical GABAergic Interneurons.

Front Neurosci 2021 8;15:607908. Epub 2021 Jul 8.

Department of Morphological Neural Science, Graduate School of Life Sciences, Kumamoto University, Kumamoto, Japan.

Intermediate progenitors of both excitatory and inhibitory neurons, which can replenish neurons in the adult brain, were recently identified. However, the generation of intermediate progenitors of GABAergic inhibitory neurons (IPGNs) has not been studied in detail. Here, we characterized the spatiotemporal distribution of IPGNs in mouse cerebral cortex. IPGNs generated neurons during both embryonic and postnatal stages, but the embryonic IPGNs were more proliferative. Our lineage tracing analyses showed that the embryonically proliferating IPGNs tended to localize to the superficial layers rather than the deep cortical layers at 3 weeks after birth. We also found that embryonic IPGNs derived from the medial and caudal ganglionic eminence (CGE) but more than half of the embryonic IPGNs were derived from the CGE and broadly distributed in the cerebral cortex. Taken together, our data indicate that the broadly located IPGNs during embryonic and postnatal stages exhibit a different proliferative property and layer distribution.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3389/fnins.2021.607908DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8297055PMC
July 2021

Ddx20, DEAD box helicase 20, is essential for the differentiation of oligodendrocyte and maintenance of myelin gene expression.

Glia 2021 Nov 7;69(11):2559-2574. Epub 2021 Jul 7.

Division of Neurobiology and Anatomy, Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Japan.

Oligodendrocytes form myelin sheaths that surround axons, contributing to saltatory conduction and proper central nervous system (CNS) function. Oligodendrocyte progenitor cells (OPCs) are generated during the embryonic stage and differentiate into myelinating oligodendrocytes postnatally. Ddx20 is a multifunctional, DEAD-box helicase involved in multiple cellular processes, including transcription, splicing, microRNA biogenesis, and translation. Although defects in each of these processes result in abnormal oligodendrocyte differentiation and myelination, the involvement of Ddx20 in oligodendrocyte terminal differentiation remains unknown. To address this question, we used Mbp-Cre mice to generate Ddx20 conditional knockout (cKO) mice to allow for the deletion of Ddx20 from mature oligodendrocytes. Mbp-Cre;Ddx20 cKO mice demonstrated small body sizes, behavioral abnormalities, muscle weakness, and short lifespans, with mortality by the age of 2 months old. Histological analyses demonstrated significant reductions in the number of mature oligodendrocytes and drastic reductions in the expression levels of myelin-associated mRNAs, such as Mbp and Plp at postnatal day 42. The number of OPCs did not change. A thin myelin layer was observed for large-diameter axons in Ddx20 cKO mice, based on electron microscopic analysis. A bromodeoxyuridine (BrdU) labeling experiment demonstrated that terminal differentiation was perturbed from ages 2 weeks to 7 weeks in the CNS of Mbp-Cre;Ddx20 cKO mice. The activation of mitogen-activated protein (MAP) kinase, which promotes myelination, was downregulated in the Ddx20 cKO mice based on immunohistochemical detection. These results indicate that Ddx20 is an essential factor for terminal differentiation of oligodendrocytes and maintenance of myelin gene expression.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/glia.24058DOI Listing
November 2021

PKCδ deficiency inhibits fetal development and is associated with heart elastic fiber hyperplasia and lung inflammation in adult PKCδ knockout mice.

PLoS One 2021 1;16(7):e0253912. Epub 2021 Jul 1.

Faculty of Sports and Health Science, Department of Health Science, Daito Bunka University, Higashimatsuyama, Saitama, Japan.

Protein kinase C-delta (PKCδ) has a caspase-3 recognition sequence in its structure, suggesting its involvement in apoptosis. In addition, PKCδ was recently reported to function as an anti-cancer factor. The generation of a PKCδ knockout mouse model indicated that PKCδ plays a role in B cell homeostasis. However, the Pkcrd gene, which is regulated through complex transcription, produces multiple proteins via alternative splicing. Since gene mutations can result in the loss of function of molecular species required for each tissue, in the present study, conditional PKCδ knockout mice lacking PKCδI, II, IV, V, VI, and VII were generated to enable tissue-specific deletion of PKCδ using a suitable Cre mouse. We generated PKCδ-null mice that lacked whole-body expression of PKCδ. PKCδ+/- parental mice gave birth to only 3.4% PKCδ-/- offsprings that deviated significantly from the expected Mendelian ratio (χ2(2) = 101.7, P < 0.001). Examination of mice on embryonic day 11.5 (E11.5) showed the proportion of PKCδ-/- mice implanted in the uterus in accordance with Mendelian rules; however, approximately 70% of the fetuses did not survive at E11.5. PKCδ-/- mice that survived until adulthood showed enlarged spleens, with some having cardiac and pulmonary abnormalities. Our findings suggest that the lack of PKCδ may have harmful effects on fetal development, and heart and lung functions after birth. Furthermore, our study provides a reference for future studies on PKCδ deficient mice that would elucidate the effects of the multiple protein variants in mice and decipher the roles of PKCδ in various diseases.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0253912PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8248728PMC
July 2021

Resting-state dopaminergic cell firing in the ventral tegmental area negatively regulates affiliative social interactions in a developmental animal model of schizophrenia.

Transl Psychiatry 2021 04 22;11(1):236. Epub 2021 Apr 22.

Department of Molecular Neurobiology, Brain Research Institute, Niigata University, Niigata, 951-8585, Japan.

Hyperdopaminergic activities are often linked to positive symptoms of schizophrenia, but their neuropathological implications on negative symptoms are rather controversial among reports. Here, we explored the regulatory role of the resting state-neural activity of dopaminergic neurons in the ventral tegmental area (VTA) on social interaction using a developmental rat model for schizophrenia. We prepared the model by administering an ammonitic cytokine, epidermal growth factor (EGF), to rat pups, which later exhibit the deficits of social interaction as monitored with same-gender affiliative sniffing. In vivo single-unit recording and microdialysis revealed that the baseline firing frequency of and dopamine release from VTA dopaminergic neurons were chronically increased in EGF model rats, and their social interaction was concomitantly reduced. Subchronic treatment with risperidone ameliorated both the social interaction deficits and higher frequency of dopaminergic cell firing in this model. Sustained suppression of hyperdopaminergic cell firing in EGF model rats by DREADD chemogenetic intervention restored the event-triggered dopamine release and their social behaviors. These observations suggest that the higher resting-state activity of VTA dopaminergic neurons is responsible for the reduced social interaction of this schizophrenia model.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41398-021-01346-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8062445PMC
April 2021

CAPS2 Deficiency Impairs the Release of the Social Peptide Oxytocin, as Well as Oxytocin-Associated Social Behavior.

J Neurosci 2021 May 12;41(20):4524-4535. Epub 2021 Apr 12.

Department of Applied Biological Science, Faculty of Science and Technology, Tokyo University of Science, Chiba 278-8510, Japan

Ca-dependent activator protein for secretion 2 (CAPS2) regulates dense-core vesicle (DCV) exocytosis to facilitate peptidergic and catecholaminergic transmitter release. CAPS2 deficiency in mice has mild neuronal effects but markedly impairs social behavior. Rare alterations also occur in autism spectrum disorder, although whether CAPS2-mediated release influences social behavior remains unclear. Here, we demonstrate that CAPS2 is associated with DCV exocytosis-mediated release of the social interaction modulatory peptide oxytocin (OXT). CAPS2 is expressed in hypothalamic OXT neurons and localizes to OXT nerve projection and OXT release sites, such as the pituitary. KO mice exhibited reduced plasma albeit increased hypothalamic and pituitary OXT levels, indicating insufficient release. OXT neuron-specific conditional KO supported CAPS2 function in pituitary OXT release, also affording impaired social interaction and recognition behavior that could be ameliorated by exogenous OXT administered intranasally. Thus, CAPS2 appears critical for OXT release, thereby being associated with social behavior. The role of the neuropeptide oxytocin in enhancing social interaction and social bonding behavior has attracted considerable public and neuroscientific attention. A central issue in oxytocin biology concerns how oxytocin release is regulated. Our study provides an important insight into the understanding of oxytocin-dependent social behavior from the perspective of the CAPS2-regulated release mechanism.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1523/JNEUROSCI.3240-20.2021DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8152601PMC
May 2021

Activity-induced secretion of semaphorin 3A mediates learning.

Eur J Neurosci 2021 05 5;53(10):3279-3293. Epub 2021 Apr 5.

Department of Physiology, Yokohama City University Graduate School of Medicine, Yokohama, Japan.

The semaphorin family is a well-characterized family of secreted or membrane-bound proteins that are involved in activity-independent neurodevelopmental processes, such as axon guidance, cell migration, and immune functions. Although semaphorins have recently been demonstrated to regulate activity-dependent synaptic scaling, their roles in Hebbian synaptic plasticity as well as learning and memory remain poorly understood. Here, using a rodent model, we found that an inhibitory avoidance task, a hippocampus-dependent contextual learning paradigm, increased secretion of semaphorin 3A in the hippocampus. Furthermore, the secreted semaphorin 3A in the hippocampus mediated contextual memory formation likely by driving AMPA receptors into hippocampal synapses via the neuropilin1-plexin A4-semaphorin receptor complex. This signaling process involves alteration of the phosphorylation status of collapsin response mediator protein 2, which has been characterized as a downstream molecule in semaphorin signaling. These findings implicate semaphorin family as a regulator of Hebbian synaptic plasticity and learning.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/ejn.15210DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8252788PMC
May 2021

Ezh1 regulates expression of Cpg15/Neuritin in mouse cortical neurons.

Drug Discov Ther 2021 May 8;15(2):55-65. Epub 2021 Mar 8.

Neuroscience 2, Laboratory for Drug Discovery and Disease Research, Shionogi & Co. Ltd., Toyonaka, Osaka, Japan.

Immature neurons undergo morphological and physiological maturation in order to establish neuronal networks. During neuronal maturation, a large number of genes change their transcriptional levels, and these changes may be mediated by chromatin modifiers. In this study, we found that the level of Ezh1, a component of Polycomb repressive complex 2 (PRC2), increases during neuronal maturation in mouse neocortical culture. In addition, conditional knockout of Ezh1 in post-mitotic excitatory neurons leads to downregulation of a set of genes related to neuronal maturation. Moreover, the locus encoding Cpg15/Neuritin (Nrn1), which is regulated by neuronal activity and implicated in stabilization and maturation of excitatory synapses, is a direct target of Ezh1 in cortical neurons. Together, these results suggest that elevated expression of Ezh1 contributes to maturation of cortical neurons.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.5582/ddt.2021.01017DOI Listing
May 2021

A comparative analysis of kainate receptor GluK2 and GluK5 knockout mice in a pure genetic background.

Behav Brain Res 2021 05 22;405:113194. Epub 2021 Feb 22.

Division of Oral Biochemistry, Faculty of Dentistry & Graduate School of Medical and Dental Sciences, Niigata University, Niigata 951-8514, Japan. Electronic address:

Kainate receptors (KARs) are members of the glutamate receptor family that regulate synaptic function in the brain. Although they are known to be associated with psychiatric disorders, how they are involved in these disorders remains unclear. KARs are tetrameric channels assembled from a combination of GluK1-5 subunits. Among these, GluK2 and GluK5 subunits are the major heteromeric subunits in the brain. To determine the functional similarities and differences between GluK2 and GluK5 subunits, we generated GluK2 KO and GluK5 KO mice on a C57BL/6N background, a well-characterized inbred strain, and compared their behavioral phenotypes. We found that GluK2 KO and GluK5 KO mice exhibited the same phenotypes in many tests, such as reduced locomotor activity, impaired motor function, and enhanced depressive-like behavior. No change was observed in motor learning, anxiety-like behavior, or sociability. Additionally, we identified subunit-specific phenotypes, such as reduced motivation toward their environment in GluK2 KO mice and an enhancement in the contextual memory in GluK5 KO mice. These results revealed that GluK2 and GluK5 subunits not only function in a coordinated manner but also have a subunit-specific role in regulating behavior. To summarize, we demonstrated subunit-specific and common behavioral effects of GluK2 and GluK5 subunits for the first time. Moreover, to the best of our knowledge, this is the first evidence of the involvement of the GluK5 subunit in the expression of depressive-like behavior and contextual memory, which strongly indicates its role in psychiatric disorders.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.bbr.2021.113194DOI Listing
May 2021

Dysregulation of sphingolipid metabolic enzymes leads to high levels of sphingosine-1-phosphate and ceramide in human hepatocellular carcinoma.

Hepatol Res 2021 May 9;51(5):614-626. Epub 2021 Mar 9.

Division of Digestive and General Surgery, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Niigata, Japan.

Aim: Sphingosine-1-phosphate (S1P) and ceramide are bioactive sphingolipids known to be important in regulating numerous processes involved in cancer progression. The aim of this study was to determine the absolute levels of sphingolipids in hepatocellular carcinoma (HCC) utilizing data obtained from surgical specimens. In addition, we explored the clinical significance of S1P in patients with HCC and the biological role of S1P in HCC cells.

Methods: Tumors and normal liver tissues were collected from 20 patients with HCC, and sphingolipids were measured by mass spectrometry. The Cancer Genome Atlas (TCGA) cohort was utilized to evaluate gene expression of enzymes related to sphingolipid metabolism. Immunohistochemistry of phospho-sphingosine kinase 1 (SphK1), an S1P-producing enzyme, was performed for 61 surgical specimens. CRISPR/Cas9-mediated SphK1 knockout cells were used to examine HCC cell biology.

Results: S1P levels were substantially higher in HCC tissue compared with normal liver tissue. Levels of other sphingolipids upstream of S1P in the metabolic cascade, such as sphingomyelin, monohexosylceramide and ceramide, were also considerably higher in HCC tissue. Enzymes involved in generating S1P and its precursor, ceramide, were found in higher levels in HCC compared with normal liver tissue. Immunohistochemical analysis found that phospho-SphK1 expression was associated with tumor size. Finally, in vitro assays indicated that S1P is involved in the aggressiveness of HCC cells.

Conclusions: Sphingolipid levels, including S1P and ceramide, were elevated in HCC compared with surrounding normal liver tissue. Our findings suggest S1P plays an important role in HCC tumor progression, and further examination is warranted.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/hepr.13625DOI Listing
May 2021

Induction of Mutant Allele in Neurons in Late Infancy Increases Sleep Need.

J Neurosci 2021 03 8;41(12):2733-2746. Epub 2021 Feb 8.

International Institute for Integrative Sleep Medicine, University of Tsukuba, Tsukuba, Ibaraki 305-8575, Japan

Sleep is regulated in a homeostatic manner. Sleep deprivation increases sleep need, which is compensated mainly by increased EEG δ power during non-rapid eye movement sleep (NREMS) and, to a lesser extent, by increased sleep amount. Although genetic factors determine the constitutive level of sleep need and sleep amount in mice and humans, the molecular entity behind sleep need remains unknown. Recently, we found that a gain-of-function () mutation in the () gene, which produces the mutant SIK3(SLP) protein, leads to an increase in NREMS EEG δ power and sleep amount. Since mice express SIK3(SLP) in various types of cells in the brain as well as multiple peripheral tissues from the embryonic stage, the cell type and developmental stage responsible for the sleep phenotype in mice remain to be elucidated. Here, we generated two mouse lines, and mice, which enable inducible Cre-mediated, conditional expression of SIK3(SLP) in neurons on tamoxifen administration. Administration of tamoxifen to mice during late infancy resulted in higher recombination efficiency than administration during adolescence. SIK3(SLP) expression after late infancy increased NREMS and NREMS δ power in male mice. The expression of SIK3(SLP) after adolescence led to a higher NREMS δ power without a significant change in NREMS amounts. Thus, neuron-specific expression of SIK3(SLP) after late infancy is sufficient to increase sleep. The propensity to accumulate sleep need during wakefulness and to dissipate it during sleep underlies the homeostatic regulation of sleep. However, little is known about the developmental stage and cell types involved in determining the homeostatic regulation of sleep. Here, we show that allele induction in mature neurons in late infancy is sufficient to increase non-rapid eye movement sleep amount and non-rapid eye movement sleep δ power. SIK3 signaling in neurons constitutes an intracellular mechanism to increase sleep.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1523/JNEUROSCI.1004-20.2020DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8018738PMC
March 2021

Activin a Receptor Type 2A Mutation Affects the Tumor Biology of Microsatellite Instability-High Gastric Cancer.

J Gastrointest Surg 2021 Jan 8. Epub 2021 Jan 8.

Division of Digestive and General Surgery, Niigata University Graduate School of Medical and Dental Sciences, 1-757 Asahimachi-dori, Chuo-ku, Niigata, Niigata, 951-8510, Japan.

Background: Activin A receptor type 2A (ACVR2A) is one of the most frequently mutated genes in microsatellite instability-high (MSI-H) gastric cancer. However, the clinical relevance of the ACVR2A mutation in MSI-H gastric cancer patients remains unclear. The aims of this study were to explore the effect of ACVR2A mutation on the tumor behavior and to identify the clinicopathological characteristics of gastric cancer patients with ACVR2A mutations.

Methods: An in vitro study was performed to investigate the biological role of ACVR2A via CRISPR/Cas9-mediated ACVR2A knockout MKN74 human gastric cancer cells. One hundred twenty-four patients with gastric cancer were retrospectively analyzed, and relations between MSI status, ACVR2A mutations, and clinicopathological factors were evaluated.

Results: ACVR2A knockout cells showed less aggressive tumor biology than mock-transfected cells, displaying reduced proliferation, migration, and invasion (P < 0.05). MSI mutations were found in 10% (13/124) of gastric cancer patients, and ACVR2A mutations were found in 8.1% (10/124) of patients. All ACVR2A mutations were accompanied by MSI. The 5-year overall survival rates of ACVR2A wild-type patients and ACVR2A-mutated patients were 57% and 90%, respectively (P = 0.048). Multivariate analysis revealed that older age (P = 0.015), distant metastasis (P < 0.001), and ACVR2A wild-type status (P = 0.040) were independent prognostic factors for overall survival.

Conclusions: Our study demonstrated that gastric cancer patients with ACVR2A mutation have a significantly better prognosis than those without. Dysfunction of ACVR2A in MKN74 human gastric cancer cells caused less aggressive tumor biology, indicating the importance of ACVR2A in the progression of MSI-H tumors.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s11605-020-04889-9DOI Listing
January 2021

Deletion of the gene encoding prostamide/prostaglandin F synthase reveals an important role in regulating intraocular pressure.

Prostaglandins Leukot Essent Fatty Acids 2021 02 5;165:102235. Epub 2021 Jan 5.

Dept. of Bioengineering, Imperial College London, Prince Consort Road, South Kensington, London, SW7 2AZ, United Kingdom.

Prostamide/prostaglandin F synthase (PM/PGFS) is an enzyme with very narrow substrate specificity and is dedicated to the biosynthesis of prostamide F and prostaglandin F (PGF). The importance of this enzyme, relative to the aldo-keto reductase (AKR) series, in providing functional tissue prostamide F levels was determined by creating a line of PM/PGFS gene deleted mice. Deletion of the gene encoding PM/PGFS (Fam213b / Prxl2b) was accomplished by a two exon disruption. Prostamide F levels in wild type (WT) and PM/PGFS knock-out (KO) mice were determined by LC/MS/MS. Deletion of Fam213b (Prxl2b) had no observed effect on behavior, appetite, or fertility. In contrast, tonometrically measured intraocular pressure was significantly elevated by approximately 4 mmHg in PM/PGFS KO mice compared to littermate WT mice. Outflow facility was measured in enucleated mouse eyes using the iPerfusion system. No effect on pressure dependent outflow facility occurred, which is consistent with the effects of prostamide F and PGF increasing outflow through the unconventional pathway. The elevation of intraocular pressure caused by deletion of the gene encoding the PM/PGFS enzyme likely results from a diversion of the endoperoxide precursor pathway to provide increased levels of those prostanoids known to raise intraocular pressure, namely prostaglandin D (PGD) and thromboxane A (TxA). It follows that PM/PGFS may serve an important regulatory role in the eye by providing PGF and prostamide F to constrain the influence of those prostanoids that raise intraocular pressure.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.plefa.2020.102235DOI Listing
February 2021

Global knockdown of glutamate decarboxylase 67 elicits emotional abnormality in mice.

Mol Brain 2021 01 7;14(1). Epub 2021 Jan 7.

Department of Genetic and Behavioral Neuroscience, Gunma University Graduate School of Medicine, Maebashi, 371-8511, Japan.

Reduced expression of glutamate decarboxylase 67 (GAD67), encoded by the Gad1 gene, is a consistent finding in postmortem brains of patients with several psychiatric disorders, including schizophrenia, bipolar disorder and major depressive disorder. The dysfunction of GAD67 in the brain is implicated in the pathophysiology of these psychiatric disorders; however, the neurobiological consequences of GAD67 dysfunction in mature brains are not fully understood because the homozygous Gad1 knockout is lethal in newborn mice. We hypothesized that the tetracycline-controlled gene expression/suppression system could be applied to develop global GAD67 knockdown mice that would survive into adulthood. In addition, GAD67 knockdown mice would provide new insights into the neurobiological impact of GAD67 dysfunction. Here, we developed Gad1 biallelic knock-in mice using Gad1 and Gad1 knock-in mice, and compared them with Gad1 mice. The expression level of GAD67 protein in brains of Gad1 mice treated with doxycycline (Dox) was decreased by approximately 90%. The GABA content was also decreased in the brains of Dox-treated Gad1 mice. In the open-field test, Dox-treated Gad1 mice exhibited hyper-locomotor activity and decreased duration spent in the center region. In addition, acoustic startle responses were impaired in Dox-treated Gad1 mice. These results suggest that global reduction in GAD67 elicits emotional abnormalities in mice. These GAD67 knockdown mice will be useful for elucidating the neurobiological mechanisms of emotional abnormalities, such as anxiety symptoms associated with psychiatric disorders.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1186/s13041-020-00713-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7789591PMC
January 2021

Heterogeneity of microglial proton channel in different brain regions and its relationship with aging.

J Neurochem 2021 05 20;157(3):624-641. Epub 2021 Jan 20.

Integrative Physiology, Graduate School of Medicine & Frontier Biosciences, Osaka University, Suita, Japan.

The properties of microglia largely differ depending on aging as well as on brain regions. However, there are few studies that investigated the functional importance of such heterogeneous properties of microglia at the molecular level. Voltage-gated proton channel, Hv1/VSOP, could be one of the candidates which confers functional heterogeneity among microglia since it regulates brain oxidative stress in age-dependent manner. In this study, we found that Hv1/VSOP shows brain region-dependent heterogeneity of gene expression with the highest level in the striatum. We studied the importance of Hv1/VSOP in two different brain regions, the cerebral cortex and striatum, and examined their relationship with aging (using mice of different ages). In the cortex, we observed the age-dependent impact of Hv1/VSOP on oxidative stress, microglial morphology, and gene expression profile. On the other hand, we found that the age-dependent significance of Hv1/VSOP was less obvious in the striatum than the cortex. Finally, we performed a battery of behavioral experiments on Hv1/VSOP-deficient mice both at young and aged stages to examine the effect of aging on Hv1/VSOP function. Hv1/VSOP-deficient mice specifically showed a marked difference in behavior in light/dark transition test only at aged stages, indicating that anxiety state is altered in aged Hv1/VSOP mice. This study suggests that a combination of brain region heterogeneity and animal aging underscores the functional importance of Hv1/VSOP in microglia.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/jnc.15292DOI Listing
May 2021

p62/SQSTM1-droplet serves as a platform for autophagosome formation and anti-oxidative stress response.

Nat Commun 2021 01 4;12(1):16. Epub 2021 Jan 4.

Department of Physiology, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo, 113-8421, Japan.

Autophagy contributes to the selective degradation of liquid droplets, including the P-Granule, Ape1-complex and p62/SQSTM1-body, although the molecular mechanisms and physiological relevance of selective degradation remain unclear. In this report, we describe the properties of endogenous p62-bodies, the effect of autophagosome biogenesis on these bodies, and the in vivo significance of their turnover. p62-bodies are low-liquidity gels containing ubiquitin and core autophagy-related proteins. Multiple autophagosomes form on the p62-gels, and the interaction of autophagosome-localizing Atg8-proteins with p62 directs autophagosome formation toward the p62-gel. Keap1 also reversibly translocates to the p62-gels in a p62-binding dependent fashion to activate the transcription factor Nrf2. Mice deficient for Atg8-interaction-dependent selective autophagy show that impaired turnover of p62-gels leads to Nrf2 hyperactivation in vivo. These results indicate that p62-gels are not simple substrates for autophagy but serve as platforms for both autophagosome formation and anti-oxidative stress.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41467-020-20185-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7782522PMC
January 2021

Cav3.1 t-type calcium channel is critical for cell proliferation and survival in newly generated cells of the adult hippocampus.

Acta Physiol (Oxf) 2021 05 12;232(1):e13613. Epub 2021 Jan 12.

Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Japan.

Aims: Adult hippocampal neurogenesis plays an important role in neuronal plasticity and maintenance in mammals. Low-threshold voltage-gated T-type calcium channels produce calcium spikes that increase fast action potentials in newborn cells in the hippocampal dentate gyrus (DG); however, their role in adult hippocampal neurogenesis remains unclear. Here, we demonstrate impaired adult hippocampal neurogenesis in Cav3.1T-type calcium channel knockout mice.

Methods And Results: Cav3.1T-type calcium channel was predominantly localized in neuronal progenitor cells of the mouse hippocampal DG. By counting the number of 5-bromo-2'-deoxyuridine-labeled cells, decreased proliferation and survival of newly generated cells were observed in the adult hippocampal DG in Cav3.1 knockout mice as compared to wild-type (WT) mice. Moreover, the degree of maturation of doublecortin-positive cells in Cav3.1 knockout mice was lower than that in WT mice, suggesting that Cav3.1 deletion may impair neuronal differentiation. Consistent with impaired hippocampal neurogenesis, Cav3.1 knockout mice showed decreased social interaction. Reduced phosphorylation levels of calcium/calmodulin-dependent protein kinase II and protein kinase B were closely associated with impaired hippocampal neurogenesis in Cav3.1 knockout mice. Moreover, the mRNA and protein expression levels of brain-derived neurotrophic factor, important for neurogenesis, were significantly decreased in Cav3.1 knockout mice. Finally, gene ontology analysis revealed alterations in genes related to the promotion of cell death/apoptosis and suppression of cell proliferation/neuronal differentiation pathways, including Bdnf.

Conclusion: These results suggest that the Cav3.1T-type calcium channel may be a key molecule required for cell proliferation, survival and neuronal differentiation in newly generated cells of the adult mouse hippocampus.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/apha.13613DOI Listing
May 2021

Generation of Thyroid Tissues From Embryonic Stem Cells Blastocyst Complementation .

Front Endocrinol (Lausanne) 2020 14;11:609697. Epub 2020 Dec 14.

Department of Medical Oncology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan.

The generation of mature, functional, thyroid follicular cells from pluripotent stem cells would potentially provide a therapeutic benefit for patients with hypothyroidism, but differentiation remains difficult. We earlier reported the generation of lung organs blastocyst complementation in fibroblast growth factor 10 (), compound, heterozygous mutant ( Ex1/Ex3) mice. Fgf10 also plays an essential role in thyroid development and branching morphogenesis, but any role thereof in thyroid organogenesis remains unclear. Here, we report that the thyroids of Ex1/Ex3 mice exhibit severe hypoplasia, and we generate thyroid tissues from mouse embryonic stem cells (ESCs) in Ex1/Ex3 mice blastocyst complementation. The tissues were morphologically normal and physiologically functional. The thyroid follicular cells of Ex1/Ex3 chimeric mice were derived largely from GFP-positive mouse ESCs although the recipient cells were mixed. Thyroid generation blastocyst complementation will aid functional thyroid regeneration.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3389/fendo.2020.609697DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7767966PMC
May 2021

A Discrete Glycinergic Neuronal Population in the Ventromedial Medulla That Induces Muscle Atonia during REM Sleep and Cataplexy in Mice.

J Neurosci 2021 02 28;41(7):1582-1596. Epub 2020 Dec 28.

Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki 305-8575, Japan

During rapid eye movement (REM) sleep, anti-gravity muscle tone and bodily movements are mostly absent, because somatic motoneurons are inhibited by descending inhibitory pathways. Recent studies showed that glycine/GABA neurons in the ventromedial medulla (VMM; Gly neurons) play an important role in generating muscle atonia during REM sleep (REM-atonia). However, how these REM-atonia-inducing neurons interconnect with other neuronal populations has been unknown. In the present study, we first identified a specific subpopulation of Gly neurons that play an important role in induction of REM-atonia by virus vector-mediated tracing in male mice in which glycinergic neurons expressed Cre recombinase. We found these neurons receive direct synaptic input from neurons in several brain stem regions, including glutamatergic neurons in the sublaterodorsal tegmental nucleus (SLD; Glu neurons). Silencing this circuit by specifically expressing tetanus toxin light chain (TeTNLC) resulted in REM sleep without atonia. This manipulation also caused a marked decrease in time spent in cataplexy-like episodes (CLEs) when applied to narcoleptic mice. We also showed that Gly neurons play an important role in maintenance of sleep. This present study identified a population of glycinergic neurons in the VMM that are commonly involved in REM-atonia and cataplexy. We identified a population of glycinergic neurons in the ventral medulla that plays an important role in inducing muscle atonia during rapid eye movement (REM) sleep. It sends axonal projections almost exclusively to motoneurons in the spinal cord and brain stem except to those that innervate extraocular muscles, while other glycinergic neurons in the same region also send projections to other regions including monoaminergic nuclei. Furthermore, these neurons receive direct inputs from several brainstem regions including glutamatergic neurons in the sublaterodorsal tegmental nucleus (SLD). Genetic silencing of this pathway resulted in REM sleep without atonia and a decrease of cataplexy when applied to narcoleptic mice. This work identified a neural population involved in generating muscle atonia during REM sleep and cataplexy.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1523/JNEUROSCI.0688-20.2020DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7896014PMC
February 2021

Specific Neuroligin3-αNeurexin1 signaling regulates GABAergic synaptic function in mouse hippocampus.

Elife 2020 12 23;9. Epub 2020 Dec 23.

Brudnick Neuropsychiatric Research Institute, Department of Neurobiology, University of Massachusetts Medical School, Worcester, United States.

Synapse formation and regulation require signaling interactions between pre- and postsynaptic proteins, notably cell adhesion molecules (CAMs). It has been proposed that the functions of neuroligins (Nlgns), postsynaptic CAMs, rely on the formation of trans-synaptic complexes with neurexins (Nrxns), presynaptic CAMs. Nlgn3 is a unique Nlgn isoform that localizes at both excitatory and inhibitory synapses. However, Nlgn3 function mediated via Nrxn interactions is unknown. Here we demonstrate that Nlgn3 localizes at postsynaptic sites apposing vesicular glutamate transporter 3-expressing (VGT3+) inhibitory terminals and regulates VGT3+ inhibitory interneuron-mediated synaptic transmission in mouse organotypic slice cultures. Gene expression analysis of interneurons revealed that the αNrxn1+AS4 splice isoform is highly expressed in VGT3+ interneurons as compared with other interneurons. Most importantly, postsynaptic Nlgn3 requires presynaptic αNrxn1+AS4 expressed in VGT3+ interneurons to regulate inhibitory synaptic transmission. Our results indicate that specific Nlgn-Nrxn signaling generates distinct functional properties at synapses.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.7554/eLife.59545DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7758064PMC
December 2020

Central dopamine D receptors regulate plasma glucose levels in mice through autonomic nerves.

Sci Rep 2020 12 18;10(1):22347. Epub 2020 Dec 18.

Department of Pathophysiology and Therapeutics, Hoshi University School of Pharmacy and Pharmaceutical Sciences, 2-4-41 Ebara, Shinagawa-ku, Tokyo, 142-8501, Japan.

Recent evidence suggests that the central nervous system (CNS) regulates plasma glucose levels, but the underlying mechanism is unclear. The present study investigated the role of dopaminergic function in the CNS in regulation of plasma glucose levels in mice. I.c.v. injection of neither the dopamine D receptor agonist SKF 38393 nor the antagonist SCH 23390 influenced plasma glucose levels. In contrast, i.c.v. injection of both the dopamine D receptor agonist quinpirole and the antagonist l-sulpiride increased plasma glucose levels. Hyperglycemia induced by quinpirole and l-sulpiride was absent in dopamine D receptor knockout mice. I.c.v. injection of quinpirole and l-sulpiride each increased mRNA levels of hepatic glucose-6-phosphatase and phosphoenolpyruvate carboxykinase, which are the key enzymes for hepatic gluconeogenesis. Systemic injection of the β adrenoceptor antagonist ICI 118,551 inhibited hyperglycemia induced by l-sulpiride, but not by quinpirole. In contrast, hyperglycemia induced by quinpirole, but not by l-sulpiride, was inhibited by hepatic vagotomy. These results suggest that stimulation of central dopamine D receptors increases plasma glucose level by increasing hepatic glucose production through parasympathetic nerves, whereas inhibition of central dopamine D receptors increases plasma glucose level by increasing hepatic glucose production through sympathetic nerves.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41598-020-79292-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7749102PMC
December 2020

Decreased Proliferation in the Neurogenic Niche, Disorganized Neuroblast Migration, and Increased Oligodendrogenesis in Adult Netrin-5-Deficient Mice.

Front Neurosci 2020 26;14:570974. Epub 2020 Nov 26.

Department of Organ and Tissue Anatomy, Hamamatsu University School of Medicine, Hamamatsu, Japan.

In the adult mouse brain, neurogenesis occurs mainly in the ventricular-subventricular zone (V-SVZ) and the subgranular zone of the hippocampal dentate gyrus. Neuroblasts generated in the V-SVZ migrate to the olfactory bulb via the rostral migratory stream (RMS) in response to guidance molecules, such as netrin-1. We previously showed that the related netrin-5 (NTN5) is expressed in Mash1-positive transit-amplifying cells and doublecortin-positive neuroblasts in the granule cell layer of the olfactory bulb, the RMS, and the subgranular zone of the adult mouse brain. However, the precise role of NTN5 in adult neurogenesis has not been investigated. In this study, we show that proliferation in the neurogenic niche is impaired in NTN5 knockout mice. The number of proliferating (EdU-labeled) cells in NTN5 KO mice was significantly lower in the V-SVZ, whereas the number of Ki67-positive proliferating cells was unchanged, suggesting a longer cell cycle and decreased cell division in NTN5 KO mice. The number of EdU-labeled cells in the RMS and olfactory bulb was unchanged. By contrast, the numbers of EdU-labeled cells in the cortex, basal ganglia/lateral septal nucleus, and corpus callosum/anterior commissure were increased, which largely represented oligodendrocyte lineage cells. Lastly, we found that chain migration in the RMS of NTN5 KO mice was disorganized. These findings suggest that NTN5 may play important roles in promoting proliferation in the V-SVZ niche, organizing proper chain migration in the RMS, and suppressing oligodendrogenesis in the brain.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3389/fnins.2020.570974DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7726356PMC
November 2020

AUTS2 Governs Cerebellar Development, Purkinje Cell Maturation, Motor Function and Social Communication.

iScience 2020 Dec 18;23(12):101820. Epub 2020 Nov 18.

Department of Biochemistry and Cellular Biology, National Institute of Neuroscience, National Center of Neurology and Psychiatry (NCNP), Tokyo 187-8502, Japan.

(), a risk gene for autism spectrum disorders (ASDs), is implicated in telencephalon development. Because AUTS2 is also expressed in the cerebellum where defects have been linked to ASDs, we investigated AUTS2 functions in the cerebellum. AUTS2 is specifically localized in Purkinje cells (PCs) and Golgi cells during postnatal development. conditional knockout (cKO) mice exhibited smaller and deformed cerebella containing immature-shaped PCs with reduced expression of . cKO and knock-down experiments implicated AUTS2 participation in elimination and translocation of climbing fiber synapses and restriction of parallel fiber synapse numbers. cKO mice exhibited behavioral impairments in motor learning and vocal communications. Because is known to regulate synapse development in PCs, it suggests that AUTS2 is required for PC maturation to elicit normal development of PC synapses and thus the impairment of may cause cerebellar dysfunction related to psychiatric illnesses such as ASDs.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.isci.2020.101820DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7708818PMC
December 2020

Kv11 (ether-à-go-go-related gene) voltage-dependent K channels promote resonance and oscillation of subthreshold membrane potentials.

J Physiol 2021 01 18;599(2):547-569. Epub 2020 Nov 18.

Department of Neurophysiology, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan.

Key Points: Some ion channels are known to behave as inductors and make up the parallel resonant circuit in the plasma membrane of neurons, which enables neurons to respond to current inputs with a specific frequency (so-called 'resonant properties'). Here, we report that heterologous expression of mouse Kv11 voltage-dependent K channels generate resonance and oscillation at depolarized membrane potentials in HEK293 cells; expressions of individual Kv11 subtypes generate resonance and oscillation with different frequency properties. Kv11.3-expressing HEK293 cells exhibited transient conductance changes that opposed the current changes induced by voltage steps; this probably enables Kv11 channels to behave like an inductor. The resonance and oscillation of inferior olivary neurons were impaired at the resting membrane potential in Kv11.3 knockout mice. This study helps to elucidate basic ion channel properties that are crucial for the frequency responses of neurons.

Abstract: The plasma membranes of some neurons preferentially respond to current inputs with a specific frequency, and output as large voltage changes. This property is called resonance, and is thought to be mediated by ion channels that show inductor-like behaviour. However, details of the candidate ion channels remain unclear. In this study, we mainly focused on the functional roles of Kv11 potassium (K ) channels, encoded by ether-á-go-go-related genes, in resonance in mouse inferior olivary (IO) neurons. We transfected HEK293 cells with long or short splice variants of Kv11.1 (Merg1a and Merg1b) or Kv11.3, and examined membrane properties using whole-cell recording. Transfection with Kv11 channels reproduced resonance at membrane potentials depolarized from the resting state. Frequency ranges of Kv11.3-, Kv11.1(Merg1b)- and Kv11.1(Merg1a)-expressing cells were 2-6 Hz, 2-4 Hz, and 0.6-0.8 Hz, respectively. Responses of Kv11.3 currents to step voltage changes were essentially similar to those of inductor currents in the resistor-inductor-capacitor circuit. Furthermore, Kv11 transfections generated membrane potential oscillations. We also confirmed the contribution of HCN1 channels as a major mediator of resonance at more hyperpolarized potentials by transfection into HEK293 cells. The Kv11 current kinetics and properties of Kv11-dependent resonance suggested that Kv11.3 mediated resonance in IO neurons. This finding was confirmed by the impairment of resonance and oscillation at -30 to -60 mV in Kcnh7 (Kv11.3) knockout mice. These results suggest that Kv11 channels have important roles in inducing frequency-dependent responses in a subtype-dependent manner from resting to depolarized membrane potentials.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1113/JP280342DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7839749PMC
January 2021

Regulation of hepatic oxidative stress by voltage-gated proton channels (Hv1/VSOP) in Kupffer cells and its potential relationship with glucose metabolism.

FASEB J 2020 12 11;34(12):15805-15821. Epub 2020 Oct 11.

Integrative Physiology, Graduate School of Medicine & Frontier Biosciences, Osaka University, Suita, Japan.

Voltage-gated proton channels (Hv1/VSOP), encoded by Hvcn1, are important regulator of reactive oxygen species (ROS) production in many types of immune cells. While in vitro studies indicate that Hv1/VSOP regulates ROS production by maintaining pH homeostasis, there are few studies investigating the functional importance of Hv1/VSOP in vivo. In the present study, we first show that Hv1/VSOP is functionally expressed in liver resident macrophage, Kupffer cells, regulating the hepatic oxidative stress in vivo. Our immunocytochemistry and electrophysiology data showed that Hvcn1 is specifically expressed in Kupffer cells, but not in hepatocytes. Furthermore, Hvcn1-deficiency drastically altered the hepatic oxidative stress. The Hvcn1-deficient mice showed high blood glucose and serum insulin but normal insulin sensitivity, indicating that these phenotypes were not linked to insulin resistance. Transcriptome analysis indicated that the gene expression of glycogen phosphorylase (Pygl) and Glucose-6-phosphatase, catalytic subunit (G6pc) were upregulated in Hvcn1-deficient liver tissues, and quantitative PCR confirmed the result for Pygl. Furthermore, we observed higher amount of glucose-6-phosphate, a key sugar intermediate for glucose in Hvcn1-deficient liver than WT, suggesting that glucose production in liver is accelerated in Hvcn1-deficient mice. The present study sheds light on the functional importance of Kupffer cells in hepatic oxidative stress and its potential relationship with glucose metabolism.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1096/fj.202001056RRRDOI Listing
December 2020

Activation of proprotein convertase in the mouse habenula causes depressive-like behaviors through remodeling of extracellular matrix.

Neuropsychopharmacology 2021 01 17;46(2):442-454. Epub 2020 Sep 17.

Department of Neurobiology, Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima, 734-8553, Japan.

The lateral habenula (LHb) attracts a growing interest as a regulator of monoaminergic activity which were frequently reported to be defective in depression. Here we found that chronic social defeat stress (CSDS) increased production of pro-inflammatory cytokines in LHb associated with mobilization of monocytes and remodeling of extracellular matrix by increased matrix metalloproteinase (MMP) activity. RNA-seq analysis identified proprotein convertase Pcsk5 as an upstream regulator of MMP activation, with upregulation in LHb neurons of mice with susceptibility to CSDS. PCSK5 facilitated motility of microglia in vitro by converting inactive pro-MMP14 and pro-MMP2 to their active forms, highlighting its role in mobilization of microglia and monocytes in neuroinflammation. Suppression of Pcsk5 expression via small interfering RNA (siRNA) ameliorated depressive-like behaviors and pathological mobilization of monocytes in mice with susceptibility to CSDS. PCSK5-MMPs signaling pathway could be a target for development of the antidepressants targeting the inflammatory response in specific brain regions implicated in depression.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41386-020-00843-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7852607PMC
January 2021

Hypnotic effect of thalidomide is independent of teratogenic ubiquitin/proteasome pathway.

Proc Natl Acad Sci U S A 2020 09 26;117(37):23106-23112. Epub 2020 Aug 26.

International Institute for Integrative Sleep Medicine (WPI-IIIS), University of Tsukuba, Tsukuba, Ibaraki 305-8575, Japan;

Thalidomide exerts its teratogenic and immunomodulatory effects by binding to cereblon (CRBN) and thereby inhibiting/modifying the CRBN-mediated ubiquitination pathway consisting of the Cullin4-DDB1-ROC1 E3 ligase complex. The mechanism of thalidomide's classical hypnotic effect remains largely unexplored, however. Here we examined whether CRBN is involved in the hypnotic effect of thalidomide by generating mice harboring a thalidomide-resistant mutant allele of ( knock-in mice). Thalidomide increased non-REM sleep time in knock-in homozygotes and heterozygotes to a similar degree as seen in wild-type littermates. Thalidomide similarly depressed excitatory synaptic transmission in the cortical slices obtained from wild-type and homozygous knock-in mice without affecting GABAergic inhibition. Thalidomide induced Fos expression in vasopressin-containing neurons of the supraoptic nucleus and reduced Fos expression in the tuberomammillary nuclei. Thus, thalidomide's hypnotic effect seems to share some downstream mechanisms with general anesthetics and GABA-activating sedatives but does not involve the teratogenic CRBN-mediated ubiquitin/proteasome pathway.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1073/pnas.1917701117DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7502749PMC
September 2020

TDP-43 transports ribosomal protein mRNA to regulate axonal local translation in neuronal axons.

Acta Neuropathol 2020 11 16;140(5):695-713. Epub 2020 Aug 16.

Department of Peripheral Nervous System Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan.

Mislocalization and abnormal deposition of TDP-43 into the cytoplasm (TDP-43 proteinopathy) is a hallmark in neurons of amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD). However, the pathogenic mechanism of the diseases linked to TDP-43 is largely unknown. We hypothesized that the failure of mRNA transport to neuronal axons by TDP-43 may contribute to neurodegeneration in ALS and FTLD, and sought to examine the function of TDP-43 by identifying its target mRNA for axonal transport. We found that mRNAs related to translational function including ribosomal proteins (RPs) were decreased by shRNA-based TDP-43 knock-down in neurites of cortical neurons. TDP-43 binds to and transports the RP mRNAs through their 5' untranslated region, which contains a common 5' terminal oligopyrimidine tract motif and a downstream GC-rich region. We showed by employing in vitro and in vivo models that the RP mRNAs were translated and incorporated into native ribosomes locally in axons to maintain functionality of axonal ribosomes, which is required for local protein synthesis in response to stimulation and stress to axons. We also found that RP mRNAs were reduced in the pyramidal tract of sporadic ALS cases harboring TDP-43 pathology. Our results elucidated a novel function of TDP-43 to control transport of RP mRNAs and local translation by ribosomes to maintain morphological integrity of neuronal axons, and proved the influence of this function of TDP-43 on neurodegeneration in ALS and FTLD associated with TDP-43 proteinopathy.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00401-020-02205-yDOI Listing
November 2020

Significance of Autoantibodies in Autoimmune Encephalitis in Relation to Antigen Localization: An Outline of Frequently Reported Autoantibodies with a Non-Systematic Review.

Int J Mol Sci 2020 Jul 13;21(14). Epub 2020 Jul 13.

Department of Physiology, Kanazawa Medical University, Ishikawa 920-0293, Japan.

Autoantibodies related to central nervous system (CNS) diseases propel research on paraneoplastic neurological syndrome (PNS). This syndrome develops autoantibodies in combination with certain neurological syndromes and cancers, such as anti-HuD antibodies in encephalomyelitis with small cell lung cancer and anti-Yo antibodies in cerebellar degeneration with gynecological cancer. These autoantibodies have roles in the diagnosis of neurological diseases and early detection of cancers that are usually occult. Most of these autoantibodies have no pathogenic roles in neuronal dysfunction directly. Instead, antigen-specific cytotoxic T lymphocytes are thought to have direct roles in neuronal damage. The recent discoveries of autoantibodies against neuronal synaptic receptors/channels produced in patients with autoimmune encephalomyelitis have highlighted insights into our understanding of the variable neurological symptoms in this disease. It has also improved our understanding of intractable epilepsy, atypical psychosis, and some demyelinating diseases that are ameliorated with immune therapies. The production and motility of these antibodies through the blood-brain barrier into the CNS remains unknown. Most of these recently identified autoantibodies bind to neuronal and glial cell surface synaptic receptors, potentially altering the synaptic signaling process. The clinical features differ among pathologies based on antibody targets. The investigation of these antibodies provides a deeper understanding of the background of neurological symptoms in addition to novel insights into their basic neuroscience.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/ijms21144941DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7404295PMC
July 2020
-->