Use of Anti-phospho-girdin Antibodies to Visualize Intestinal Tuft Cells in Free-Floating Mouse Jejunum Cryosections

The actin binding protein girdin is a cytosolic protein that is required for actin remodeling to trigger cell migration in various tissues. Girdin is ...

Aichi Human Service Center

Schnurri-2 (Shn-2), an nuclear factor-κB site-binding protein, tightly binds to the enhancers of major histocompatibility complex class I genes and inflammatory cytokines, which have been shown to harbor common variant single-nucleotide polymorphisms associated with schizophrenia. Although genes related to immunity are implicated in schizophrenia, there has been no study showing that their mutation or knockout (KO) results in schizophrenia. Here, we show that Shn-2 KO mice have behavioral abnormalities that resemble those of schizophrenics. The mutant brain demonstrated multiple schizophrenia-related phenotypes, including transcriptome/proteome changes similar to those of postmortem schizophrenia patients, decreased parvalbumin and GAD67 levels, increased theta power on electroencephalograms, and a thinner cortex. Dentate gyrus granule cells failed to mature in mutants, a previously proposed endophenotype of schizophrenia. Shn-2 KO mice also exhibited mild chronic inflammation of the brain, as evidenced by increased inflammation markers (including GFAP and NADH/NADPH oxidase p22 phox), and genome-wide gene expression patterns similar to various inflammatory conditions. Chronic administration of anti-inflammatory drugs reduced hippocampal GFAP expression, and reversed deficits in working memory and nest-building behaviors in Shn-2 KO mice. These results suggest that genetically induced changes in immune system can be a predisposing factor in schizophrenia.

Deficiency of schnurri-2, an MHC enhancer binding protein, induces mild chronic inflammation in the brain and confers molecular, neuronal, and behavioral phenotypes related to schizophrenia.

A loss of function of SIP1 (Smad interacting protein 1) in the mouse as well as in human of Mowat-Wilson syndrome results in severe and multiple defects in neural tissue development, especially in the brain. However, no detailed expression analysis of SIP1 during brain development has been previously reported. In this study, we describe the generation of an EGFP knock-in reporter mouse for the Sip1 locus and our subsequent analysis of SIP1-EGFP fusion protein expression during brain development. SIP1-EGFP expression was observed in the pyramidal neurons of the hippocampus, the dentate gyrus, and the postmitotic neurons in the cerebral cortex. In layer 5 of the cerebral cortex, SIP1-EGFP expression was complementary to the Ctip2-expressing neurons, most of which are thought to be the cortico-spinal neurons. This suggested that SIP1-EGFP expressing cells might have the specific trajectory targets other than the spinal region. We further observed SIP1-EGFP expression in oligodendrocytes of the corpus callosum and fimbria, Bergmann glial cells of the cerebellum, the olfactory bulb, and in the serotonergic and dopaminergic neurons of the raphe nuclei in the brainstem. These findings may help to clarify the unknown roles of SIP1 in these cells and the pathoetiology of Mowat-Wilson syndrome.

SIP1 expression patterns in brain investigated by generating a SIP1-EGFP reporter knock-in mouse.

Mowat-Wilson syndrome (MOWS) is caused by de novo heterozygous mutation at ZEB2 (SIP1, ZFHX1B) gene, and exhibit moderate to severe intellectual disability (ID), a characteristic facial appearance, epilepsy and other congenital anomalies. Establishing a murine MOWS model is important, not only for investigating the pathogenesis of this disease, but also for identifying compounds that may improve the symptoms. However, because the heterozygous Zeb2 knockout mouse could not be maintained as a mouse line with the inbred C57BL/6 background, it was difficult to use those mice for the study of MOWS. Here, we systematically generated de novo Zeb2 Δex7/+ mice by inducing the Zeb2 mutation in the germ cells using conditional recombination system. The de novo Zeb2 Δex7/+ mice with C57BL/6 background developed multiple defects relevant to MOWS, including craniofacial abnormalities, defective corpus callosum formation and the decreased number of parvalbumin interneurons in the cortex. In behavioral analyses, these mice showed reduced motor activity, increased anxiety and impaired sociability. Notably, during the Barnes maze test, immobile Zeb2 mutant mice were observed over repeated trials. In contrast, neither the mouse line nor the de novo Zeb2 Δex7/+ mice with the closed colony ICR background showed cranial abnormalities or reduced motor activities. These results demonstrate the advantages of using de novo Zeb2 Δex7/+ mice with the C57BL/6 background as the MOWS model. To our knowledge, this is the first time an inducible de novo mutation system has been applied to murine germline cells to produce an animal model of a human congenital disease.

De novo inbred heterozygous Zeb2/Sip1 mutant mice uniquely generated by germ-line conditional knockout exhibit craniofacial, callosal and behavioral defects associated with Mowat-Wilson syndrome.

Schnurri-2 (Shn-2) knockout (KO) mice have been proposed as a preclinical neuroinflammatory schizophrenia model. We used behavioral studies and imaging markers that can be readily translated to human populations to explore brain effects of inflammation. Shn-2 KO mice and their littermate control mice were imaged with two novel PET ligands; an inflammation marker [(11)C]PBR28 and the mGluR5 ligand [(18)F]FPEB. Locomotor activity was measured using open field exploration with saline, methamphetamine or amphetamine challenge. A significantly increased accumulation of [(11)C]PBR28 was found in the cortex, striatum, hippocampus and olfactory bulb of Shn-2 KO mice. Increased mGluR5 binding was also observed in the cortex and hippocampus of the Shn-2 KO mice. Open field locomotor testing revealed a large increase in novelty-induced hyperlocomotion in Shn-2 KO mice with abnormal (decreased) responses to either methamphetamine or amphetamine. These data provide additional support to demonstrate that the Shn-2 KO mouse model exhibits several behavioral and pathological markers resembling human schizophrenia making it an attractive translational model for the disease.

Combined behavioral studies and in vivo imaging of inflammatory response and expression of mGlu5 receptors in schnurri-2 knockout mice.

During spinal cord development, astrocyte precursors arise from neuroepithelial progenitors, delaminate from the ventricular zone, and migrate toward their final locations where they differentiate. Although the mechanisms underlying their early specification and late differentiation are being deciphered, less is known about the temporal control of their migration. Here, we show that the epithelial-mesenchymal transition regulator Zeb1 is expressed in glial precursors and report that loss of Zeb1 function specifically delays the onset of astrocyte precursor delamination from the ventricular zone, correlating with transient deregulation of the adhesion protein Cadherin-1. Consequently, astrocyte precursor invasion into the Zeb1(-/-) mutant white matter is delayed, and induction of their differentiation is postponed. These findings illustrate how fine regulation of adhesive properties influences the onset of neural precursor migration and further support the notion that duration of exposure of migrating astrocyte precursors to environmental cues and/or their correct positioning influence the timing of their differentiation.

Onset of Spinal Cord Astrocyte Precursor Emigration from the Ventricular Zone Involves the Zeb1 Transcription Factor.

Although the brains of patients with schizophrenia and bipolar disorder exhibit decreased brain pH relative to those of healthy controls upon postmortem examination, it remains controversial whether this finding reflects a primary feature of the diseases or is a result of confounding factors such as medication and agonal state. To date, systematic investigation of brain pH has not been undertaken using animal models that can be studied without confounds inherent in human studies. In the present study, we first reevaluated the pH of the postmortem brains of patients with schizophrenia and bipolar disorder by conducting a meta-analysis of existing data sets from 10 studies. We then measured pH, lactate levels, and related metabolite levels in brain homogenates from five neurodevelopmental mouse models of psychiatric disorders, including schizophrenia, bipolar disorder, and autism spectrum disorder. All mice were drug naive with the same agonal state, postmortem interval, and age within each strain. Our meta-analysis revealed that brain pH was significantly lower in patients with schizophrenia and bipolar disorder than in control participants, even when a few potential confounding factors (postmortem interval, age, and history of antipsychotic use) were considered. In animal experiments, we observed significantly lower pH and higher lactate levels in the brains of model mice relative to controls, as well as a significant negative correlation between pH and lactate levels. Our findings suggest that lower pH associated with increased lactate levels is not a mere artifact, but rather implicated in the underlying pathophysiology of schizophrenia and bipolar disorder.

Decreased Brain pH as a Shared Endophenotype of Psychiatric Disorders.

Accumulating evidence suggests that subcellular-scale structures such as dendritic spine and mitochondria may be involved in the pathogenesis/pathophysiology of schizophrenia and intellectual disability. Previously, we proposed mice lacking Schnurri-2 (Shn2; also called major histocompatibility complex [MHC]-binding protein 2 [MBP-2], or human immunodeficiency virus type I enhancer binding protein 2 [HIVEP2]) as a schizophrenia and intellectual disability model with mild chronic inflammation. In the mutants' brains, there are increases in C4b and C1q genes, which are considered to mediate synapse elimination during postnatal development. However, morphological properties of subcellular-scale structures such as dendritic spine in Shn2 knockout (KO) mice remain unknown. In this study, we conducted three-dimensional morphological analyses in subcellular-scale structures in dentate gyrus granule cells of Shn2 KO mice by serial block-face scanning electron microscopy. Shn2 KO mice showed immature dendritic spine morphology characterized by increases in spine length and decreases in spine diameter. There was a non-significant tendency toward decrease in spine density of Shn2 KO mice over wild-type mice, and spine volume was indistinguishable between genotypes. Shn2 KO mice exhibited a significant reduction in GluR1 expression and a nominally significant decrease in SV2 expression, while PSD95 expression had a non-significant tendency to decrease in Shn2 KO mice. There were significant decreases in dendrite diameter, nuclear volume, and the number of constricted mitochondria in the mutants. Additionally, neuronal density was elevated in Shn2 KO mice. These results suggest that Shn2 KO mice serve as a unique tool for investigating morphological abnormalities of subcellular-scale structures in schizophrenia, intellectual disability, and its related disorders.

Immature morphological properties in subcellular-scale structures in the dentate gyrus of Schnurri-2 knockout mice: a model for schizophrenia and intellectual disability.

Tsuyoshi Takagi

Division of Perinatology,
Institute for Developmental Research,
Division of Perinatology, Institute for Developmental Research

Aichi Human Service Center

Use of Anti-phospho-girdin Antibodies to Visualize Intestinal Tuft Cells in Free-Floating Mouse Jejunum Cryosections

Tsuyoshi Takagi

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Aichi Human Service Center

Use of Anti-phospho-girdin Antibodies to Visualize Intestinal Tuft Cells in Free-Floating Mouse Jejunum Cryosections

Division of Perinatology,
Institute for Developmental Research,
Division of Perinatology, Institute for Developmental Research