metallothionein and Neurodegenerative-Diseases

According to the United States Centers for Disease Control and Prevention (CDC), as of July 11, 2016, the reported average incidence of children diagnosed with an autism spectrum disorder (ASD) was 1 in 68 (1.46%) among 8-year-old children born in 2004 and living within the 11 monitoring sites' surveillance areas in the United States of America (USA) in 2012. ASD is a multifaceted neurodevelopmental disorder that is also considered a hidden disability, as, for the most part; there are no apparent morphological differences between children with ASD and typically developing children. ASD is diagnosed based upon a triad of features including impairment in socialization, impairment in language, and repetitive and stereotypic behaviors. The increasing incidence of ASD in the pediatric population and the lack of successful curative therapies make ASD one of the most challenging disorders for medicine. ASD neurobiology is thought to be associated with oxidative stress, as shown by increased levels of reactive oxygen species and increased lipid peroxidation, as well as an increase in other indicators of oxidative stress. Children with ASD diagnosis are considered more vulnerable to oxidative stress because of their imbalance in intracellular and extracellular glutathione levels and decreased glutathione reserve capacity. Several studies have suggested that the redox imbalance and oxidative stress are integral parts of ASD pathophysiology. As such, early assessment and treatment of antioxidant status may result in a better prognosis as it could decrease the oxidative stress in the brain before it can induce more irreversible brain damage. In this review, many aspects of the role of oxidative stress in ASD are discussed, taking into account that the process of oxidative stress may be a target for therapeutic interventions.

Topics: Aerobiosis; Antioxidants; Autism Spectrum Disorder; Brain Chemistry; Central Nervous System; Child; Child, Preschool; Dysbiosis; Free Radical Scavengers; Gastrointestinal Diseases; Gastrointestinal Microbiome; Glutathione Peroxidase; Humans; Incidence; Lipid Peroxidation; Metallothionein; Mitochondria; Neurodegenerative Diseases; Oxidation-Reduction; Oxidative Stress; Selenium; Selenoproteins

Metallothionein-3 (MT-3), a member of the mammalian metallothionein (MT) family, is mainly expressed in the central nervous system (CNS). MT-3 possesses a unique neuronal growth inhibitory activity, and the levels of this intra- and extracellularly occurring metalloprotein are markedly diminished in the brain of patients affected by a number of metal-linked neurodegenerative disorders, including Alzheimer's disease (AD). In these pathologies, the redox cycling of copper, accompanied by the production of reactive oxygen species (ROS), plays a key role in the neuronal toxicity. Although MT-3 shares the metal-thiolate clusters with the well-characterized MT-1 and MT-2, it shows distinct biological, structural and chemical properties. Owing to its anti-oxidant properties and modulator function not only for Zn, but also for Cu in the extra- and intracellular space, MT-3, but not MT-1/MT-2, protects neuronal cells from the toxicity of various Cu(II)-bound amyloids. In recent years, the roles of zinc dynamics and MT-3 function in neurodegeneration are slowly emerging. This short review focuses on the recent developments regarding the chemistry and biology of MT-3.

Topics: Animals; Copper; Humans; Metallothionein; Metallothionein 3; Models, Molecular; Nerve Tissue Proteins; Neurodegenerative Diseases; Neurons; Protein Conformation; Reactive Oxygen Species; Zinc

Topics: Animals; Homeostasis; Humans; Membrane Transport Proteins; Metallothionein; Metals, Heavy; Mitochondria; Neurodegenerative Diseases

Aging is an inevitable biological process, associated with gradual and spontaneous biochemical and physiological changes, and increased susceptibility to diseases. Chronic inflammation and oxidative stress are hallmarks of aging. Metallothioneins (MTs) are low molecular weight, zinc-binding, anti-inflammatory, and antioxidant proteins that provide neuroprotection in the aging brain through zinc-mediated transcriptional regulation of genes involved in cell growth, proliferation, and differentiation. In addition to Zn(2+) homeostasis, antioxidant role of MTs is routed through -SH moieties on cysteine residues. MTs are induced in aging brain as a defensive mechanism to attenuate oxidative and nitrative stress implicated in broadly classified neurodegenerative α-synucleinopathies. In addition, MTs as free radical scavengers inhibit Charnoly body (CB) formation to provide mitochondrial neuroprotection in the aging brain. In general, MT-1 and MT-2 induce cell growth and differentiation, whereas MT-3 is a growth inhibitory factor, which is reduced in Alzheimer's disease. MTs are down-regulated in homozygous weaver (wv/wv) mice exhibiting progressive neurodegeneration, early aging, morbidity, and mortality. These neurodegenerative changes are attenuated in MTs over-expressing wv/wv mice, suggesting the neuroprotective role of MTs in aging. This report provides recent knowledge regarding the therapeutic potential of MTs in neurodegenerative disorders of aging such as Parkinson's disease and Alzheimer's disease.

Topics: Aging; Animals; Brain; Humans; Metallothionein; Metallothionein 3; Mitochondria; Neurodegenerative Diseases; Oxidative Stress

Metallothioneins (MT) are a family of proteins actively involved in metal detoxification and storage as well as in prevention of free-radical damage. Changes in the levels of MT have been described in a number of neurodegenerative diseases including Alzheimer's disease, Parkinson's disease, prion protein disease, Binswanger type of subcortical vascular dementia, and amyotrophic lateral sclerosis. This suggests that MT functions might be more complex and vast than what was initially thought. In this review, we summarize the current knowledge on the potential involvement of MT in the mentioned neurodegenerative diseases while also discussing the emerging evidence proposing MT modulation as a feasible therapeutic approach. Enhancing repair mechanisms after neurological damage and/or protection against oxidative stress through a proper modulation of this family of protein might indeed represent an important avenue to cope neurodegeneration.

Topics: Animals; Brain; Humans; Metallothionein; Neurodegenerative Diseases

Metallothionein (MT) is a small molecular and multi-functional protein containing four atoms of copper (Cu) and three atoms of zinc (Zn) per molecule. It was isolated from the horse kidney in 1957 and half a century has passed since then. Although MT was found to work as a modulator of Zn and induce anti-oxidant reaction, the precise functions and its functional mechanisms remain to be elucidated. Over the years, a new isoform of MT, MT-III (also called growth inhibitory factor (GIF)), has been found in the brain, which was markedly diminished in the brain of Alzheimer's disease (AD). Many new findings on MT have been discovered in neurodegenerative diseases other than AD such as amyotrophic lateral sclerosis (ALS), Parkinson's disease (PD), prion disease, brain trauma, brain ischemia, and psychiatric diseases. In ALS in particular, MTs were markedly diminished in the spinal cord of patients with ALS. Initially, MT, which easily binds to cadmium (Cd) and copper (Cu), was considered to be toxic to our bodies. Molecular biological technologies enabled the production of recombinant MT saturated with zinc (Zn). MT has a high potential for the treatment of neurodegenerative diseases such as ALS, AD, and PD owing to its various functions including anti-oxidant properties and modulators not only for Zn but for Cu in the extra- and intracellular spaces. On the other hand, there are still various problems on MT to be elucidated in detail, including their binding proteins and functional mechanisms.

Topics: Animals; Antioxidants; Brain; Humans; Metallothionein; Neurodegenerative Diseases

Metallothioneins (MTs) are a family of universal, small proteins, sharing a high cysteine content and an optimal capacity for metal ion coordination. They take part in a plethora of metal ion-related events (from detoxification to homeostasis, storage, and delivery), in a wide range of stress responses, and in different pathological processes (tumorigenesis, neurodegeneration, and inflammation). The information on both intracellular and extracellular interactions of MTs with other proteins is here comprehensively reviewed. In mammalian kidney, MT1/MT2 interact with megalin and related receptors, and with the transporter transthyretin. Most of the mammalian MT partners identified concern interactions with central nervous system (mainly brain) proteins, both through physical contact or metal exchange reactions. Physical interactions mainly involve neuronal secretion multimers. Regarding metal swap events, brain MT3 appears to control the metal ion load in peptides whose aggregation leads to neurodegenerative disorders, such as Aβ peptide, α-synuclein, and prion proteins (Alzheimer's and Parkinson's diseases, and spongiform encephalopathies, respectively). Interaction with ferritin and bovine serum albumin are also documented. The intercourse of MTs with zinc-dependent enzymes and transcription factors is capable to activate/deactivate them, thus conferring MTs the role of metabolic and gene expression regulators. As some of these proteins are involved in cell cycle and proliferation control (p53, nuclear factor κB, and PKCμ), they are considered in the context of oncogenesis and tumor progression. Only one non-mammalian MT interaction, involving Drosophila MtnA and MtnB major isoforms and peroxiredoxins, has been reported. The prospective use for biomedical applications of the MT-interaction information is finally discussed.

Topics: Animals; Brain; Gene Expression Regulation; Humans; Kidney; Metallothionein; Neoplasms; Neurodegenerative Diseases; Protein Aggregates; Protein Binding; Protein Conformation; Reactive Oxygen Species; Synaptic Transmission

Metallothioneins (MTs) are a class of ubiquitously occurring low molecular mass, cysteine- and metal-rich proteins containing sulfur-based metal clusters formed with Zn(II), Cd(II), and Cu(I) ions. In mammals, four distinct MT isoforms designated MT-1 through MT-4 exist. The first discovered MT-1/MT-2 are widely expressed isoforms, whose biosynthesis is inducible by a wide range of stimuli, including metals, drugs, and inflammatory mediators. In contrast, MT-3 and MT-4 are noninducible proteins, with their expression primarily confined to the central nervous system and certain squamous epithelia, respectively. MT-1 through MT-3 have been reported to be secreted, suggesting that they may play different biological roles in the intracellular and extracellular space. Recent reports established that these isoforms play an important protective role in brain injury and metal-linked neurodegenerative diseases. In the postgenomic era, it is becoming increasingly clear that MTs fulfill multiple functions, including the involvement in zinc and copper homeostasis, protection against heavy metal toxicity, and oxidative damage. All mammalian MTs are monomeric proteins, containing two metal-thiolate clusters. In this review, after a brief summary of the historical milestones of the MT-1/MT-2 research, the recent advances in the structure, chemistry, and biological function of MT-3 and MT-4 are discussed.

Topics: Amino Acid Sequence; Animals; Humans; Mammals; Metallothionein; Metals; Molecular Sequence Data; Neurodegenerative Diseases

Metallothioneins (MTs) constitutes a superfamily of highly conserved, low molecular weight polypeptides, which are characterized by high contents of cysteine (sulphur) and metals. As intracellular metal-binding proteins they play a significant role in the regulation of essential metals. The major isoforms of the protein (MT-I and MT-II) are induced by numerous stimuli and pathogens but most importantly their induction by metals is closely linked to the physiological metabolism of zinc and protection from the toxic affects following heavy metal exposure. Although the preservation of their genetic expression across animal phyla suggests that MTs may play an important physiological role, MT-I, II knock out (KO) mice survive to adulthood. In both central and peripheral nervous tissues, MT-I, II have neuroprotective roles, which are also induced by exogenous MT-I and/or MT-II treatment. Hence, MT-I, II may provide neurotherapeutic targets offering protection against neuronal injury and degeneration.

Topics: Animals; Central Nervous System; Humans; Metallothionein; Mice; Mice, Knockout; Models, Biological; Models, Molecular; Neurodegenerative Diseases; Neuroprotective Agents; Protein Isoforms; Protein Structure, Tertiary; Rabbits; RNA, Messenger

Two research groups produced metallothionein (MT)-I/II knockout mice with null mutation of MT-I and MT-II genes. In 1993, Choo et al. produced MT-I/II knockout mice with a mixed genetic background of 129 Ola and C57BL/6 strains. Palmiter et al. also produced MT-I/II knockout mice with a genetic background of 129/Sv strain in 1994. Subsequently, MT-I/II knockout mice have been used to clarify the biological function and physiological role of MT by many research groups. We were also provided MT-I/II knockout mice from Dr. Choo (Australia). F1 hybrid mice were mated with C57BL/6, and their offspring were back-crossed to C57BL/6 for ten generations. MT-I/II knockout (MT(-/-)) mice and wild-type (MT(+/+)) mice were obtained by mating of those heterozygous (MT(+/-)) mice. We have been investigating the susceptibility of MT-I/II knockout mice to toxicity of harmful factors and some diseases. Our present studies found that MT-I/II knockout mice have an increased sensitivity to harmful metals such as cadmium, mercury, and arsenic, oxidative stress, chemical carcinogenesis and neurodegenerative diseases. These results clearly indicate that MT plays an important role in defense of these toxicities. In this review, we present our findings and summarize recent reports with MT-I/II knockout mice concerning the role of MT as a biological protective factor.

Topics: Animals; Metallothionein; Metals, Heavy; Mice; Mice, Inbred C57BL; Mice, Knockout; Neoplasms; Neurodegenerative Diseases; Oxidative Stress

In recent years metallothionein (MT) biology has moved from investigation of its ability to protect against environmental heavy metals to a wider appreciation of its role in responding to cellular stress, whether as a consequence of normal function, or following injury and disease. This is exemplified by recent investigation of MT in the mammalian brain where plausible roles for MT action have been described, including zinc metabolism, free radical scavenging, and protection and regeneration following neurological injury. Along with other laboratories we have used several models of central nervous system (CNS) injury to investigate possible parallels between injury-dependent changes in MT expression and those observed in the ageing and/or degenerating brain. Therefore, this brief review aims to summarise existing information on MT expression during CNS ageing, and to examine the possible involvement of this protein in the course of human neurodegenerative disease, as exemplified by Alzheimer's disease.

Topics: Aging; Brain; Humans; Metallothionein; Neurodegenerative Diseases

Actual fields of research in neurobiology are not only aimed at understanding the different aspects of brain aging but also at developing strategies useful to preserve brain compensatory capacity and to prevent the onset of neurodegenerative diseases. Consistent with this trend much attention has been addressed to zinc metabolism. In fact, zinc acts as a neuromodulator at excitatory synapses and has a considerable role in the stress response and in the functionality of zinc-dependent enzymes contributing to maintaining brain compensatory capacity. In particular, the mechanisms that modulate the free zinc pool are pivotal for safeguarding brain health and performance. Alterations in zinc homeostasis have been reported in Parkinson's and Alzheimer's disease as well as in transient forebrain ischemia, seizures and traumatic brain injury, but little is known regarding aged brain. There is much evidence that that age-related changes, frequently associated to a decline in brain functions and impaired cognitive performances, could be related to dysfunctions affecting the intracellular zinc ion availability. A general agreement emerges from studies of humans' and rodents' old brains about an increased expression of metallothionein (MT) isoforms I and II, but dyshomogenous results are reported for MT-III, and it is still uncertain whether these proteins maintain in aging the protective role, as it occurs in adult/young age. At the same time, there is considerable evidence that amyloid-beta deposition in Alzheimer's disease is induced by zinc, but the pathological significance and the causes of this phenomenon are still an open question. The scientific debate on the role of zinc and of some zinc-binding proteins in aging and neurodegenerative disorders, as well as on the beneficial effect of zinc supplementation in aged brain and neurodegeneration, is extensively discussed in this review.

Topics: Aging; Amyloid beta-Peptides; Animals; Brain; Dietary Supplements; Humans; Metallothionein; Neurodegenerative Diseases; Neurons; Zinc

An increasing body of evidence suggests that high intracellular free zinc promotes neuronal death by inhibiting cellular energy production. A number of targets have been postulated, including complexes of the mitochondrial electron transport chain, components of the tricarboxylic acid cycle, and enzymes of glycolysis. Consequences of cellular zinc overload may include increased cellular reactive oxygen species (ROS) production, loss of mitochondrial membrane potential, and reduced cellular ATP levels. Additionally, zinc toxicity might involve zinc uptake by mitochondria and zinc induction of mitochondrial permeability transition. The present review discusses these processes with special emphasis on their potential involvement in brain injury.

Topics: Citric Acid Cycle; Electron Transport; Energy Metabolism; Glycolysis; Ion Transport; Metallothionein; Mitochondria; Neurodegenerative Diseases; Neurons; Reactive Oxygen Species; Zinc

Topics: Animals; Brain; Humans; Metallothionein; Mitochondria; Neurodegenerative Diseases; Neuroprotective Agents; Oxidative Phosphorylation; Parkinson Disease; Ubiquinone

Metallothioneins (MTs) constitute a family of proteins characterized by a high heavy metal [Zn(II), Cu(I)] content and also by an unusual cysteine abundance. Mammalian MTs are comprised of four major isoforms designated MT-1 trough MT-4. MT-1 and MT-2 are expressed in most tissues including the brain, whereas MT-3 (also called growth inhibitory factor) and MT-4 are expressed predominantly in the central nervous system and in keratinizing epithelia, respectively. All MT isoforms have been implicated in disparate physiological functions, such as zinc and copper metabolism, protection against reactive oxygen species, or adaptation to stress. In the case of MT-3, an additional involvement of this isoform in neuromodulatory events and in the pathogenesis of Alzheimer's disease has also been suggested. It is essential to gain insight into how MTs are regulated in the brain in order to characterize MT functions, both in normal brain physiology, as well as in pathophysiological states. The focus of this review concerns the biology of the MT family in the context of their expression and functional roles in the central nervous system.

Topics: Animals; Central Nervous System; Copper; Humans; Metallothionein; Neurodegenerative Diseases; Oxidative Stress; Protein Isoforms; Zinc

Genetic transfer approaches have received recent consideration as potential treatment modalities for human central and peripheral nervous system (CNS and PNS, respectively) neurodegenerative disorders, including Parkinson's disease, Alzheimer's disease, and amyotrophic lateral sclerosis. Transplantation of genetically modified cells into the brain represents a promising strategy for the delivery and expression of specific neurotrophic factors, neurotransmitter-synthesizing enzymes, and cellular regulatory proteins for intervention in neurodegenerative diseases. The use of specific regulatable promoters may also provide potential control of gene expression required for dose-specific or time-specific therapeutic strategies. In this article, we review the potential use of activated promoters in ex vivo systems for the potential genetic therapy of neurodegenerative disorders, and then describe our own studies using the zinc-inducible metallothionein promoter for the regulated expression of nerve growth factor (NGF) in rodent brain transplants.

Topics: Animals; Brain; Brain Tissue Transplantation; Carcinoembryonic Antigen; Cell Line; Endothelial Growth Factors; Fetal Tissue Transplantation; Gene Transfer Techniques; Genetic Therapy; Humans; Lac Operon; Lymphokines; Metallothionein; Nerve Growth Factor; Neurodegenerative Diseases; Promoter Regions, Genetic; Vascular Endothelial Growth Factor A; Vascular Endothelial Growth Factors

Parkinson's disease (PD) is the second most common neurodegenerative disease caused by selective degeneration of dopaminergic neurons in the substantia nigra. Metallothionein has been shown to act as a neuroprotectant in various brain injury. Thus, this study aims to identify the effects of full-length human metallothionein 2 peptide (hMT2) in paraquat-induced brain injury in the zebrafish.. A total of 80 adult zebrafish were divided into 4 groups namely control, paraquat-treated, pre-hMT2-treated, and post-hMT2-treated groups. Fish were treated with paraquat intraperitoneally every 3 days for 15 days. hMT2 were injected intracranially on day 0 (pre-treated group) and day 16 (post-treated group). Fish were sacrificed on day 22 and the brains were collected for qPCR, ELISA and immunohistochemistry analysis.. qPCR analysis showed that paraquat treatment down-regulated the expression of genes related to dopamine activity and biosynthesis (. Paraquat has been identified as one of the pesticides that can cause the death of dopaminergic neurons and affect dopamine biosynthesis. Treatment with exogenous hMT2 could reverse the effects of paraquat in the zebrafish brain.

Topics: Animals; Brain Injuries; Dopamine; Dopaminergic Neurons; Humans; Metallothionein; Mice; Mice, Inbred C57BL; Neurodegenerative Diseases; Neuroprotective Agents; Paraquat; Parkinson Disease; Substantia Nigra; Zebrafish

Parkinson's disease (PD) is a progressive neurodegenerative disease of both the central and peripheral / enteric nervous systems. Oxidative stress and neuroinflammation are associated with the pathogenesis of PD, suggesting that anti-oxidative and anti-inflammatory compounds could be neuroprotective agents for PD. Eucommia ulmoides (EU) is a traditional herbal medicine which exerts neuroprotective effects by anti-inflammatory and anti-oxidative properties. Our previous study showed that treatment with chlorogenic acid, a component of EU, protected against neurodegeneration in the central and enteric nervous systems in a PD model. In this study, we examined the effects of EU extract (EUE) administration on dopaminergic neurodegeneration, glial response and α-synuclein expression in the substantia nigra pars compacta (SNpc), and intestinal enteric neurodegeneration in low-dose rotenone-induced PD model mice. Daily oral administration of EUE ameliorated dopaminergic neurodegeneration and α-synuclein accumulation in the SNpc. EUE treatment inhibited rotenone-induced decreases in the number of total astrocytes and in those expressing the antioxidant molecule metallothionein. EUE also prevented rotenone-induced microglial activation. Furthermore, EUE treatment exerted protective effects against intestinal neuronal loss in the PD model. These results suggest that EU exerts neuroprotective effects in the central and enteric nervous systems of rotenone-induced parkinsonism mice, in part by glial modification.

Topics: alpha-Synuclein; Animals; Antioxidants; Chlorogenic Acid; Dopamine; Dopaminergic Neurons; Eucommiaceae; Metallothionein; Mice; Neurodegenerative Diseases; Neuroprotective Agents; Plant Extracts; Rotenone

Simultaneous determination of proteins with micrometric resolution is a significant challenge. In this study, laser ablation (LA) inductively coupled plasma - mass spectrometry (ICP-MS) was employed to quantify the distribution of proteins associated to the eye disease age-related macular degeneration (AMD) using antibodies labelled with three different metal nanoclusters (MNCs). PtNCs, AuNCs and AgNCs contain hundreds of metal atoms and were used to detect metallothionein 1/2 (MT1/2), complement factor H (CFH) and amyloid precursor protein (APP) in retina, ciliary body, retinal pigment epithelium (RPE), choroid and sclera from human cadaveric eye sections. First, the labelling of MNCs bioconjugated primary antibodies (Ab) was optimised following an immunolabelling protocol to avoid the non-specific interaction of MNCs with the tissue. Then, the LA and ICP-MS conditions were studied to obtain high-resolution images for the simultaneous detection of the three labels at the same tissue section. A significant signal amplification was found when using AuNCs, AgNCs and PtNCs labelled Ab of 310, 723 and 1194 respectively. After the characterisation of MNCs labelled immunoprobes, the Ab labelling was used for determination of MT1/2, CFH and APP in the RPE-choroid-sclera, where accumulation of extracellular deposits related to AMD was observed. Experimental results suggest that this method is fully suitable for the simultaneous detection of at least three different proteins.

Topics: Eye; Eye Proteins; Humans; Laser Therapy; Mass Spectrometry; Metallothionein; Metals; Neurodegenerative Diseases

In the last decade, the budding yeast Saccharomyces cerevisiae has been used as a model system to study the mechanisms of the human aging process and of age-associated neurodegenerative disorders such as Parkinson's, Huntington's, Alzheimer's, and amyotrophic lateral sclerosis. S. cerevisiae is a facultative aerobic, unicellular yeast, and despite their simplicity, yeast cells possess most of the same basic cellular machinery as neurons in the brain, including pathways required for protein homeostasis and energy metabolism. The power of yeast genetics and the use of high-throughput screening technologies have provided important clues concerning the pathophysiology of these disorders and the identification of candidate therapeutic targets and drugs. The yeast models are based on the expression of human disease proteins in yeast and recapitulate some of the cytotoxic features observed in patients. However, the currently available models mostly suffer from high-level protein expression that results in acute cytotoxicity, and from metabolic constraints when the models are based on extensively used, strong, galactose-inducible promoters. The models would increase their significance if they were based on continuous and tightly regulated gene expression systems for both activation and levels of expression. This would allow for more chronic cytotoxicity that better simulates the timing of events that occur during disease progression. Additionally, the use of metabolism-independent inducers would allow for the study of cell toxicities under conditions where the cells are forced to exclusively respire, thus more reliably modeling the highly oxidative neuronal metabolism. Here we have constructed yeast models of Huntington's disease based on the expression, under the control of different promoters, of the first exon of the huntingtin-containing polyglutamine tracts of both wild-type and mutant lengths. The different models are compared and evaluated.

Topics: Carrier Proteins; Galactokinase; Gene Expression Regulation; Humans; Huntington Disease; Metallothionein; Models, Biological; Neurodegenerative Diseases; Promoter Regions, Genetic; Saccharomyces cerevisiae; Saccharomyces cerevisiae Proteins

Neonatal Borna disease (NBD) virus infection in the Lewis rat results in life-long viral persistence and causes behavioral and neurodevelopmental abnormalities. A hallmark of the disorder is progressive loss of cerebellar Purkinje and dentate gyrus granule cells. Findings of increased brain metallothionein-I and -II (MT-I/-II) mRNA expression in cDNA microarray experiments led us to investigate MT isoforms and their relationship to brain zinc metabolism, cellular toxicity, and neurodevelopmental abnormalities in this model. Real-time PCR confirmed marked induction of MT-I/-II mRNA expression in the brains of NBD rats (40.5-fold increase in cerebellum, p<0.0001; 6.8-fold increase in hippocampus, p=0.003; and 9.5-fold increase in striatum, p=0.0012), whereas a trend toward decreased MT-III mRNA was found in hippocampus (1.25-fold decrease, p=0.0841). Double label immunofluorescence revealed prominent MT-I/-II expression in astrocytes throughout the brain; MT-III protein was decreased in granule cell neurons and increased in astrocytes, with differential subcellular distribution from cytoplasmic to nuclear compartments in NBD rat hippocampus. Modified Timm staining of hippocampus revealed reduced zinc in mossy fiber projections to the hilus and CA3, accumulation of zinc in glial cells and degenerating granule cell somata, and robust mossy fiber sprouting into the inner molecular layer of the dentate gyrus. Zinc Transporter 3 (ZnT-3) mRNA expression was decreased in hippocampus (2.3-fold decrease, p= 0.0065); staining for its correlate protein was reduced in hippocampal mossy fibers. Furthermore, 2 molecules implicated in axonal pathfinding and mossy fiber sprouting, the extracellular matrix glycoprotein, tenascin-R (TN-R), and the hyaluronan receptor CD44, were increased in NBD hippocampal neuropil. Abnormal zinc metabolism and mechanisms of neuroplasticity may contribute to the pathogenesis of disease in this model, raising more general implications for neurodevelopmental damage following viral infections in early life.

Topics: Animals; Astrocytes; Blotting, Western; Borna Disease; Borna disease virus; Extracellular Matrix Proteins; Fluorescent Antibody Technique; Metallothionein; Mossy Fibers, Hippocampal; Nerve Tissue Proteins; Neurodegenerative Diseases; Neurons; Oligonucleotide Array Sequence Analysis; Rats; Rats, Inbred Lew; Reverse Transcriptase Polymerase Chain Reaction; RNA; Zinc

We examined metallothionein (MT)-induced neuroprotection during kainic acid (KA)-induced excitotoxicity by studying transgenic mice with MT-I overexpression (TgMT mice). KA induces epileptic seizures and hippocampal excitotoxicity, followed by inflammation and delayed brain damage. We show for the first time that even though TgMT mice were more susceptible to KA, the cerebral MT-I overexpression decreases the hippocampal inflammation and delayed neuronal degeneration and cell death as measured 3 days after KA administration. Hence, the proinflammatory responses of microglia/macrophages and lymphocytes and their expression of interleukin (IL)-1, IL-6, IL-12, tumor necrosis factor-alpha and matrix metalloproteinases (MMP-3, MMP-9) were significantly reduced in hippocampi of TgMT mice relative to wild-type mice. Also by 3 days after KA, the TgMT mice showed significantly less delayed damage, such as oxidative stress (formation of nitrotyrosine, malondialdehyde, and 8-oxoguanine), neurodegeneration (neuronal accumulation of abnormal proteins), and apoptotic cell death (judged by TUNEL and activated caspase-3). This reduced bystander damage in TgMT mice could be due to antiinflammatory and antioxidant actions of MT-I but also to direct MT-I effects on the neurons, in that significant extracellular MT presence was detected. Furthermore, MT-I overexpression stimulated astroglia and increased immunostaining of antiinflammatory IL-10, growth factors, and neurotrophins (basic fibroblastic growth factor, transforming growth factor-beta, nerve growth factor, brain-derived neurotrophic factor, glial-derived neurotrophic factor) in hippocampus. Accordingly, MT-I has different functions that likely contribute to the increased neuron survival and improved CNS condition of TgMT mice. The data presented here add new insight into MT-induced neuroprotection and indicate that MT-I therapy could be used against neurological disorders.

Topics: Amyloid beta-Peptides; Analysis of Variance; Animals; Astrocytes; Cell Count; Cell Death; Central Nervous System Diseases; Epilepsy; Gene Expression Regulation; Glial Fibrillary Acidic Protein; Growth Substances; Guanine; Hippocampus; Immunohistochemistry; In Situ Nick-End Labeling; Interleukins; Kainic Acid; Matrix Metalloproteinase 3; Matrix Metalloproteinase 9; Metallothionein; Mice; Mice, Inbred C57BL; Mice, Transgenic; Neurodegenerative Diseases; Neurofibrillary Tangles; Staining and Labeling; Tyrosine

The 20th biennial meeting of the International Society for Neurochemistry was recently held in Innsbruck, Austria. This meeting gave an overview of the latest findings in the field of molecular mechanisms and diagnosis of neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, and prion disease. There was a focus on the molecular pathogenesis of protein misfolding in these disorders as well as on the association between oxidative metabolism and neurological diseases. RNA interference, metal chelators, and the use of metallopeptidases were discussed as possible therapeutic strategies.

Topics: Amyloid; Homeostasis; Humans; Metallothionein; Metals; Neurochemistry; Neurodegenerative Diseases

Metallothioneins (MTs) are ubiquitous low molecular weight proteins characterized by their abundance of the thiol (SH)-containing amino acid, cysteine. To date four MT isoforms have been identified and cloned in mammals. MT-I and MT-II, the most widely expressed isoforms are generally coordinately regulated in all mammalian tissues; MT-III, is predominantly expressed in zinc (Zn)-containing neurons of the hippocampus; MT-IV is not expressed in brain tissue. The MT proteins have been implicated in gene expression regulation, homeostatic control of cellular metabolism of metals, and cellular adaptation to stress, including oxidative stress. MTs therefore impact on transcription, replication, protein synthesis, metabolism, and numerous other Zn-dependent biological processes. Disordered MT homeostasis leads to changes in brain concentrations of Zn. Since intracellular concentration of Zn are mediated by complexing with apothionein to form MT, there has been great interest in ascertaining whether disordered MT regulation plays a role in the etiology of neurodegenerative disorders. Though abnormalities in MT and/or Zn homeostasis have been reported in multiple neurological disorders a definitive link between MTs and the above disorders remains to be established. The chapter will commence with a brief discussion on the various MT isoforms, their structure and abundance (in brain), followed by a survey on the ability of MTs to potentiate or attenuate neurodegenerative process, with major emphasis on the role of MTs in the etiology of Alzheimer disease (AD).

Topics: Alzheimer Disease; Brain; Homeostasis; Humans; Metallothionein; Neurodegenerative Diseases; Protein Isoforms; Zinc

Topics: Animals; Brain; Brain Injuries; Cytokines; Disease Models, Animal; Encephalomyelitis, Autoimmune, Experimental; Gene Expression; Humans; Inflammation Mediators; Metallothionein; Mice; Mice, Knockout; Multiple Sclerosis; Neurodegenerative Diseases; Oxidative Stress; Rats; RNA, Messenger