Metallothionein-3 deficient mice exhibit abnormalities of psychological behaviors

From periphery to center stage: 50 years of advancements in innate immunity

Over the past 50 years in the field of immunology, something of a Copernican revolution has happened. For a long time, immunologists were mainly concerned with what is termed adaptive immunity, which involves the exquisitely specific activities of lymphocytes. But the other arm of immunity, so-called "innate immunity," had been neglected. To celebrate Cell's 50th anniversary, we have put together a review of the processes and components of innate immunity and trace the seminal contributions leading to the modern state of this field. Innate immunity has joined adaptive immunity in the center of interest for all those who study the body's defenses, as well as homeostasis and pathology. We are now entering the era where therapeutic targeting of innate immune receptors and downstream signals hold substantial promise for infectious and inflammatory diseases and cancer.

Metallothionein 3 promotes osteoclast differentiation and survival by regulating the intracellular Zn2+ concentration and NRF2 pathway

In osteoclastogenesis, the metabolism of metal ions plays an essential role in controlling reactive oxygen species (ROS) production, mitochondrial biogenesis, and survival, and differentiation. However, the mechanism regulating metal ions during osteoclast differentiation remains unclear. The metal-binding protein metallothionein (MT) detoxifies heavy metals, maintains metal ion homeostasis, especially zinc, and manages cellular redox levels. We carried out tests using murine osteoclast precursors to examine the function of MT in osteoclastogenesis and evaluated their potential as targets for future osteoporosis treatments. MT genes were significantly upregulated upon differentiation from osteoclast precursors to mature osteoclasts in response to receptor activators of nuclear factor-κB (NF-κB) ligand (RANKL) stimulation, and MT3 expression was particularly pronounced in mature osteoclasts among MT genes. The knockdown of MT3 in osteoclast precursors demonstrated a remarkable inhibition of differentiation into mature osteoclasts. In preosteoclasts, MT3 knockdown suppressed the activity of mitogen-activated protein kinase (MAPK) and NF-κB signaling pathways upon RANKL stimulation, leading to affect cell survival through elevated cleaved Caspase 3 and poly (ADP-ribose) polymerase (PARP) levels. Additionally, ROS levels were decreased, and nuclear factor erythroid 2-related factor 2 (NRF2) (a suppressor of ROS) and the downstream antioxidant proteins, such as catalase (CAT) and heme oxygenase 1 (HO-1), were more highly expressed in the MT3 preosteoclast knockdowns. mitochondrial ROS, which is involved in mitochondrial biogenesis and the production of reactive oxygen species, were similarly decreased because cAMP response element-binding (CREB) and peroxisome proliferator-activated receptor γ coactivator 1β (PGC-1β) were less activated due to MT3 depletion. Thus, by modulating ROS through the NRF2 pathway, MT3 plays a crucial role in regulating osteoclast differentiation and survival, acting as a metabolic modulator of intracellular zinc ions.

Hair zinc levels and psychosis risk among adolescents

Recent meta-analyses have shown lower zinc and higher copper levels in the serum of people with schizophrenia than in healthy controls. However, the relationship between trace elements (TEs) and the pathophysiology of psychosis, including schizophrenia, remains unclear due to the antipsychotic effects on mineral levels. In this study, we aimed to determine the relationship between zinc and copper levels in hair and psychosis risk among drug-naïve adolescents. This study was conducted as a part of a population-based biomarker subsample study of the Tokyo Teen Cohort Study, including 252 community-dwelling 14-year-old drug-naïve adolescents. Zinc and copper levels in hair were measured using inductively coupled plasma mass spectrometry. The thought problems (TP) scale from the Child Behavior Checklist was used to evaluate psychosis risk. Regression analysis showed that hair zinc levels were negatively correlated with the TP scale (T-score) (β = -0.176, P = 0.005). This result remained significant after adjusting for age and sex (β = -0.175, P = 0.005). In contrast, hair copper levels were not associated with the TP scale (T-score) (β = 0.026, P = 0.687). These findings suggest that lower zinc levels could be involved in the pathophysiology of psychosis, independent of antipsychotics. Further longitudinal studies are required to investigate whether hair zinc level is a useful new biomarker for assessing psychosis risk.

Development and Validation of a Risk Prediction Model for Breast Cancer Prognosis Based on Depression-Related Genes

Background

Depression plays a significant role in mediating breast cancer recurrence and metastasis. However, a precise risk model is lacking to evaluate the potential impact of depression on breast cancer prognosis. In this study, we established a depression-related gene (DRG) signature that can predict overall survival (OS) and elucidate its correlation with pathological parameters and sensitivity to therapy in breast cancer.

Methods

The model training and validation assays were based on the analyses of 1,096 patients from The Cancer Genome Atlas (TCGA) database and 2,969 patients from GSE96058. A risk signature was established through univariate and multivariate Cox regression analyses.

Results

Ten DRGs were determined to construct the risk signature. Multivariate analysis revealed that the signature was an independent prognostic factor for OS. Receiver operating characteristic (ROC) curves indicated good performance of the model in predicting 1-, 3-, and 5-year OS, particularly for patients with triple-negative breast cancer (TNBC). In the high-risk group, the proportion of immunosuppressive cells, including M0 macrophages, M2 macrophages, and neutrophils, was higher than that in the low-risk group. Furthermore, low-risk patients responded better to chemotherapy and endocrine therapy. Finally, a nomogram integrating risk score, age, tumor-node-metastasis (TNM) stage, and molecular subtypes were established, and it showed good agreement between the predicted and observed OS.

Conclusion

The 10-gene risk model not only highlights the significance of depression in breast cancer prognosis but also provides a novel gene-testing tool to better prevent the potential adverse impact of depression on breast cancer prognosis.

Sensorimotor gating deficits and effects of antipsychotics on the hyperactivity in VGF-overexpressing mice

BACKGROUND

VGF nerve growth factor inducible (VGF) is a neuropeptide which is expressed in neuronal cells and endocrine cells. VGF is induced by several neurotrophic factors. The expression level of VGF in patients with schizophrenia is increased in cerebrospinal fluid (CSF) and prefrontal cortex. In our previous study, we generated mice in which the expression level of VGF in the brain was increased. VGF-overexpressing mice exhibited abnormal behaviors including hyperactivity. However, it remains unknown whether VGF-overexpressing mice exhibit the endophenotype of schizophrenia and whether abnormal behaviors in these mice can be improved by antipsychotics.

METHODS

In the present study, we investigated schizophrenia-like behaviors and the responsiveness to antipsychotics in transgenic mice.

RESULTS

VGF-overexpressing mice (1) exhibited prepulse inhibition (PPI) impairment, (2) showed normalized hyperactivity following antipsychotic drug treatment, and (3) showed abnormal responsiveness to haloperidol.

CONCLUSION

Upregulation of VGF may be implicated in the pathophysiology of schizophrenia and abnormalities of dopaminergic signaling.

Extracerebral Dysfunction in Animal Models of Autism Spectrum Disorder

Genetic factors might be largely responsible for the development of autism spectrum disorder (ASD) that alone or in combination with specific environmental risk factors trigger the pathology. Multiple mutations identified in ASD patients that impair synaptic function in the central nervous system are well studied in animal models. How these mutations might interact with other risk factors is not fully understood though. Additionally, how systems outside of the brain are altered in the context of ASD is an emerging area of research. Extracerebral influences on the physiology could begin in utero and contribute to changes in the brain and in the development of other body systems and further lead to epigenetic changes. Therefore, multiple recent studies have aimed at elucidating the role of gene-environment interactions in ASD. Here we provide an overview on the extracerebral systems that might play an important associative role in ASD and review evidence regarding the potential roles of inflammation, trace metals, metabolism, genetic susceptibility, enteric nervous system function and the microbiota of the gastrointestinal (GI) tract on the development of endophenotypes in animal models of ASD. By influencing environmental conditions, it might be possible to reduce or limit the severity of ASD pathology.

Significance of synaptic Zn2+ signaling in zincergic and non-zincergic synapses in the hippocampus in cognition

A portion of zinc concentrates in the synaptic vesicles in the brain and is released from glutamatergic (zincergic) neuron terminals. It serves as a signaling factor (in a form of free Zn²⁺). Both extracellular Zn²⁺ signaling, which predominantly originates in Zn²⁺ release from zincergic neuron terminals, and intracellular Zn²⁺ signaling, which is often linked to extracellular Zn²⁺ signaling, are involved in hippocampus-dependent memory. At mossy fiber-CA3 pyramidal cell synapses and Schaffer collateral-CA1 pyramidal cell synapses, which are zincergic, extracellular Zn²⁺ signaling leads to intracellular Zn²⁺ signaling and is involved in learning and memory. At medial perforant pathway-dentate granule cell synapses, which are non-zincergic, intracellular Zn²⁺ signaling, which originates in the internal stores containing Zn²⁺, is involved in learning and memory. The blockade of Zn²⁺ signaling with Zn²⁺ chelators induces memory deficit, while the optimal amount range of Zn²⁺ signaling is unknown. It is possible that the degree and frequency of Zn²⁺ signaling, which determine the increased Zn²⁺ levels, modulates learning and memory as well as intracellular Ca²⁺ signaling. To understand the precise role of synaptic Zn²⁺ signaling in the hippocampus, the present paper summarizes the current knowledge on Zn²⁺ signaling at zincergic and non-zincergic synapses in the hippocampus in cognition and involvement of zinc transporters and zinc-binding proteins in synaptic Zn²⁺ signaling.

Behavioral impairments in animal models for zinc deficiency

Apart from teratogenic and pathological effects of zinc deficiency such as the occurrence of skin lesions, anorexia, growth retardation, depressed wound healing, altered immune function, impaired night vision, and alterations in taste and smell acuity, characteristic behavioral changes in animal models and human patients suffering from zinc deficiency have been observed. Given that it is estimated that about 17% of the worldwide population are at risk for zinc deficiency and that zinc deficiency is associated with a variety of brain disorders and disease states in humans, it is of major interest to investigate, how these behavioral changes will affect the individual and a putative course of a disease. Thus, here, we provide a state of the art overview about the behavioral phenotypes observed in various models of zinc deficiency, among them environmentally produced zinc deficient animals as well as animal models based on a genetic alteration of a particular zinc homeostasis gene. Finally, we compare the behavioral phenotypes to the human condition of mild to severe zinc deficiency and provide a model, how zinc deficiency that is associated with many neurodegenerative and neuropsychological disorders might modify the disease pathologies.

Absence of metallothionein-3 produces changes on MT-1/2 regulation in basal conditions and alters hypothalamic-pituitary-adrenal (HPA) axis

Metallothioneins (MTs) are multipurpose proteins with clear antioxidant, anti-inflammatory and metal homeostasis properties. The roles of brain MT-1 and MT-2 are similar to those described in the periphery, and are inducible by metals, inflammatory and stress stimuli. MT-3, originally named growth inhibitory factor, exists mainly in the central nervous system, is hardly ever inducible and its functional role and regulation are poorly understood and controversial. In the present study we examined how absence of MT-3 affects phenotypic characteristics and its effects on MT1/2 expression in basal situation and after induction. Hyperactive behavior was found only in young male Mt-3 KO mice and disappeared in the older ones. Absence of MT-3 was associated with a significant increase of MT-1/2 protein levels in several brain areas but decreased MT-1 mRNA levels, which might be related to lower corticosterone levels. The response to stress or inflammation on corticosterone plasma levels was similar in wild type and Mt-3 KO mice, suggesting that the relevant MT-3 role as MT-1/2 regulator in basal conditions is lost when other important regulatory factors such as glucocorticoids or cytokines appear.

A role for synaptic zinc in ProSAP/Shank PSD scaffold malformation in autism spectrum disorders

The establishment and maintenance of synaptic contacts as well as synaptic plasticity are crucial factors for normal brain function. The functional properties of a synapse are largely dependent on the molecular setup of synaptic proteins. Multidomain proteins of the ProSAP/Shank family act as major organizing scaffolding elements of the postsynaptic density (PSD). Interestingly, ProSAP/Shank proteins at glutamatergic synapses have been linked to a variety of Autism Spectrum Disorders (ASDs) including Phelan McDermid Syndrome, and deregulation of ProSAP/Shank has been reported in Alzheimer's disease. Although the precise molecular mechanism of the dysfunction of these proteins remains unclear, an emerging model is that mutations or deletions impair neuronal circuitry by disrupting the formation, plasticity and maturation of glutamatergic synapses. Several PSD proteins associated with ASDs are part of a complex centered around ProSAP/Shank proteins and many ProSAP/Shank interaction partners play a role in signaling within dendritic spines. Interfering with any one of the members of this signaling complex might change the output and drive the system towards synaptic dysfunction. Based on recent data, it is possible that the concerted action of ProSAP/Shank and Zn²⁺ is essential for the structural integrity of the PSD. This interplay might regulate postsynaptic receptor composition, but also transsynaptic signaling. It might be possible that environmental factors like nutritional Zn²⁺ status or metal ion homeostasis in general intersect with this distinct pathway centered around ProSAP/Shank proteins and the deregulation of any of these two factors may lead to ASDs.

Characterization of the role of metallothionein-3 in an animal model of Alzheimer's disease

Among the dementias, Alzheimer's disease (AD) is the most commonly diagnosed, but there are still no effective drugs available for its treatment. It has been suggested that metallothionein-3 (MT-3) could be somehow involved in the etiology of AD, and in fact very promising results have been found in in vitro studies, but the role of MT-3 in vivo needs further analysis. In this study, we analyzed the role of MT-3 in a mouse model of AD, Tg2576 mice, which overexpress human Amyloid Precursor Protein (hAPP) with the Swedish mutation. MT-3 deficiency partially rescued the APP-induced mortality of females, and mildly affected APP-induced changes in behavior assessed in the hole-board and plus-maze tests in a gender-dependent manner. Amyloid plaque burden and/or hAPP expression were decreased in the cortex and hippocampus of MT-3-deficient females. Interestingly, exogenously administered Zn(7)MT-3 increased soluble Aβ40 and Aβ42 and amyloid plaques and gliosis, particularly in the cortex, and changed several behavioral traits (increased deambulation and exploration and decreased anxiety). These results highlight that the control of the endogenous production and/or action of MT-3 could represent a powerful therapeutic target in AD.

The molecular basis of memory

We propose a tripartite biochemical mechanism for memory. Three physiologic components are involved, namely, the neuron (individual and circuit), the surrounding neural extracellular matrix, and the various trace metals distributed within the matrix. The binding of a metal cation affects a corresponding nanostructure (shrinking, twisting, expansion) and dielectric sensibility of the chelating node (address) within the matrix lattice, sensed by the neuron. The neural extracellular matrix serves as an electro-elastic lattice, wherein neurons manipulate multiple trace metals (n > 10) to encode, store, and decode coginive information. The proposed mechanism explains brains low energy requirements and high rates of storage capacity described in multiples of Avogadro number (N(A) = 6 × 10(23)). Supportive evidence correlates memory loss to trace metal toxicity or deficiency, or breakdown in the delivery/transport of metals to the matrix, or its degradation. Inherited diseases revolving around dysfunctional trace metal metabolism and memory dysfunction, include Alzheimer's disease (Al, Zn, Fe), Wilson's disease (Cu), thalassemia (Fe), and autism (metallothionein). The tripartite mechanism points to the electro-elastic interactions of neurons with trace metals distributed within the neural extracellular matrix, as the molecular underpinning of "synaptic plasticity" affecting short-term memory, long-term memory, and forgetting.

Mammalian metallothioneins: properties and functions

Metallothioneins (MT) are a family of ubiquitous proteins, whose role is still discussed in numerous papers, but their affinity to some metal ions is undisputable. These cysteine-rich proteins are connected with antioxidant activity and protective effects on biomolecules against free radicals, especially reactive oxygen species. In this review, the connection between zinc(II) ions, reactive oxygen species, heavy metal ions and metallothioneins is demonstrated with respect to effect of these proteins on cell proliferation and a possible negative role in resistance to heavy metal-based and non-heavy metal-based drugs.

Genetic models of sensorimotor gating: relevance to neuropsychiatric disorders

Sensorimotor gating, or the ability of a sensory event to suppress a motor response, can be measured operationally via prepulse inhibition (PPI) of the startle response. PPI is deficient in schizophrenia patients as well as other neuropsychiatric disorders, can be measured across species, and has been used widely as a translational tool in preclinical neuropharmacological and genetic research. First developed to assess drug effects in pharmacological and developmental models, PPI has become one of the standard behavioral measures in genetic models of schizophrenia and other neuropsychiatric disorders that exhibit PPI deficits. In this chapter we review the literature on genetic models of sensorimotor gating and discuss the utility of PPI as a tool in phenotyping mutant mouse models. We highlight the approaches to genetic mouse models of neuropsychiatric disease, discuss some of the important caveats to these approaches, and provide a comprehensive table covering the more recent genetic models that have evaluated PPI.