Superoxide dismutase 1 modulates expression of transferrin receptor

CaSSiDI: novel single-cell "Cluster Similarity Scoring and Distinction Index" reveals critical functions for PirB and context-dependent Cebpb repression

PirB is an inhibitory cell surface receptor particularly prominent on myeloid cells. PirB curtails the phenotypes of activated macrophages during inflammation or tumorigenesis, but its functions in macrophage homeostasis are obscure. To elucidate PirB-related functions in macrophages at steady-state, we generated and compared single-cell RNA-sequencing (scRNAseq) datasets obtained from myeloid cell subsets of wild type (WT) and PirB-deficient knockout (PirB KO) mice. To facilitate this analysis, we developed a novel approach to clustering parameter optimization called "Cluster Similarity Scoring and Distinction Index" (CaSSiDI). We demonstrate that CaSSiDI is an adaptable computational framework that facilitates tandem analysis of two scRNAseq datasets by optimizing clustering parameters. We further show that CaSSiDI offers more advantages than a standard Seurat analysis because it allows direct comparison of two or more independently clustered datasets, thereby alleviating the need for batch-correction while identifying the most similar and different clusters. Using CaSSiDI, we found that PirB is a novel regulator of Cebpb expression that controls the generation of Ly6Clo patrolling monocytes and the expansion properties of peritoneal macrophages. PirB's effect on Cebpb is tissue-specific since it was not observed in splenic red pulp macrophages (RPMs). However, CaSSiDI revealed a segregation of the WT RPM population into a CD68loIrf8+ "neuronal-primed" subset and an CD68hiFtl1+ "iron-loaded" subset. Our results establish the utility of CaSSiDI for single-cell assay analyses and the determination of optimal clustering parameters. Our application of CaSSiDI in this study has revealed previously unknown roles for PirB in myeloid cell populations. In particular, we have discovered homeostatic functions for PirB that are related to Cebpb expression in distinct macrophage subsets.

The Neuroprotective Activities of the Novel Multi-Target Iron-Chelators in Models of Alzheimer's Disease, Amyotrophic Lateral Sclerosis and Aging

The concept of chelation therapy as a valuable therapeutic approach in neurological disorders led us to develop multi-target, non-toxic, lipophilic, brain-permeable compounds with iron chelation and anti-apoptotic properties for neurodegenerative diseases, such as Parkinson's disease (PD), Alzheimer's disease (AD), age-related dementia and amyotrophic lateral sclerosis (ALS). Herein, we reviewed our two most effective such compounds, M30 and HLA20, based on a multimodal drug design paradigm. The compounds have been tested for their mechanisms of action using animal and cellular models such as APP/PS1 AD transgenic (Tg) mice, G93A-SOD1 mutant ALS Tg mice, C57BL/6 mice, Neuroblastoma × Spinal Cord-34 (NSC-34) hybrid cells, a battery of behavior tests, and various immunohistochemical and biochemical techniques. These novel iron chelators exhibit neuroprotective activities by attenuating relevant neurodegenerative pathology, promoting positive behavior changes, and up-regulating neuroprotective signaling pathways. Taken together, these results suggest that our multifunctional iron-chelating compounds can upregulate several neuroprotective-adaptive mechanisms and pro-survival signaling pathways in the brain and might function as ideal drugs for neurodegenerative disorders, such as PD, AD, ALS, and aging-related cognitive decline, in which oxidative stress and iron-mediated toxicity and dysregulation of iron homeostasis have been implicated.

Taking Advantages of Blood–Brain or Spinal Cord Barrier Alterations or Restoring Them to Optimize Therapy in ALS?

Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disorder that still lacks an efficient therapy. The barriers between the central nervous system (CNS) and the blood represent a major limiting factor to the development of drugs for CNS diseases, including ALS. Alterations of the blood–brain barrier (BBB) or blood–spinal cord barrier (BSCB) have been reported in this disease but still require further investigations. Interestingly, these alterations might be involved in the complex etiology and pathogenesis of ALS. Moreover, they can have potential consequences on the diffusion of candidate drugs across the brain. The development of techniques to bypass these barriers is continuously evolving and might open the door for personalized medical approaches. Therefore, identifying robust and non-invasive markers of BBB and BSCB alterations can help distinguish different subgroups of patients, such as those in whom barrier disruption can negatively affect the delivery of drugs to their CNS targets. The restoration of CNS barriers using innovative therapies could consequently present the advantage of both alleviating the disease progression and optimizing the safety and efficiency of ALS-specific therapies.

50-Hz magnetic field impairs the expression of iron-related genes in the in vitro SOD1G93A model of amyotrophic lateral sclerosis

PURPOSE

We characterized the response to the extremely low frequency magnetic field (ELF-MF) in an in vitro model of familial Amyotrophic Lateral Sclerosis (fALS), carrying two mutant variants of the superoxide dismutase 1 (SOD1) gene.

MATERIALS AND METHODS

SH-SY5Y human neuroblastoma cells, stably over-expressing the wild type, the G93A or the H46R mutant SOD1 cDNA, were exposed to either the ELF-MF (50 Hz, 1 mT) or the sham control field, up to 72 h. Analysis of (i) viability, proliferation and apoptosis, (ii) reactive oxygen species generation, and (iii) assessment of the iron metabolism, were carried out in all clones in response to the MF exposure.

RESULTS

We report that 50-Hz MF exposure induces: (i) no change in proliferation and viability; (ii) no modulation of the intracellular superoxide and H₂O₂ levels; (iii) a significant deregulation in the expression of iron-related genes IRP1, MFRN1 and TfR1, this evidence being exclusive for the SOD1^G93A clone and associated with a slight (p = .0512) difference in the total iron content.

CONCLUSIONS

50-Hz MF affects iron homeostasis in the in vitro SOD1^G93A ALS model.

hmSOD1 gene mutation-induced disturbance in iron metabolism is mediated by impairment of Akt signalling pathway

BACKGROUND

Recently, skeletal muscle atrophy, impairment of iron metabolism, and insulin signalling have been reported in rats suffering from amyotrophic lateral sclerosis (ALS). However, the interrelationship between these changes has not been studied. We hypothesize that an impaired Akt-FOXO3a signalling pathway triggers changes in the iron metabolism in the muscles of transgenic animals.

METHODS

In the present study, we used transgenic rats bearing the G93A hmSOD1 gene and their non-transgenic littermates. The study was performed on the muscles taken from animals at three different stages of the disease: asymptomatic (ALS I), the onset of the disease (ALS II), and the terminal stage of the disease (ALS III). In order to study the molecular mechanism of changes in iron metabolism, we used SH-SY5Y and C2C12 cell lines stably transfected with pcDNA3.1, SOD1 WT and SOD1 G93A, or FOXO3a TM-ER.

RESULTS

A significant decrease in P-Akt level and changes in iron metabolism were observed even in the group of ALS I animals. This was accompanied by an increase in the active form of FOXO3a, up-regulation of atrogin-1, and catalase. However, significant muscle atrophy was observed in ALS II animals. An increase in ferritin L and H was accompanied by a rise in PCBP1 and APP protein levels. In SH-SY5Y cells stably expressing SOD1 or SOD1 G93A, we observed elevated levels of ferritin L and H and non-haem iron. Interestingly, insulin treatment significantly down-regulated ferritin L and H proteins in the cell. Conversely, cells transfected with small interfering RNA against Akt 1, 2, 3, respectively, showed a significant increase in the ferritin and FOXO3a levels. In order to assess the role of FOXO3a in the ferritin expression, we constructed a line of SH-SY5Y cells that expressed a fusion protein made of FOXO3a fused at the C-terminus with the ligand-binding domain of the oestrogen receptor (TM-ER) being activated by 4-hydroxytamoxifen. Treatment of the cells with 4-hydroxytamoxifen significantly up-regulated ferritin L and H proteins level.

CONCLUSIONS

Our data suggest that impairment of insulin signalling and iron metabolism in the skeletal muscle precedes muscle atrophy and is mediated by changes in Akt/FOXO3a signalling pathways.

A Summary of New Findings on the Biological Effects of Selenium in Selected Animal Species-A Critical Review

Selenium is an essential trace element important for many physiological processes, especially for the functions of immune and reproductive systems, metabolism of thyroid hormones, as well as antioxidant defense. Selenium deficiency is usually manifested by an increased incidence of retention of placenta, metritis, mastitis, aborts, lowering fertility and increased susceptibility to infections. In calves, lambs and kids, the selenium deficiency demonstrates by WMD (white muscle disease), in foals and donkey foals, it is associated with incidence of WMD and yellow fat disease, and in pigs it causes VESD (vitamin E/selenium deficiency) syndrome. The prevention of these health disorders can be achieved by an adequate selenium supplementation to the diet. The review summarizes the survey of knowledge on selenium, its biological significance in the organism, the impact of its deficiency in mammalian livestock (comparison of ruminants vs. non-ruminants, herbivore vs. omnivore) and possibilities of its peroral administration. The databases employed were as follows: Web of Science, PubMed, MEDLINE and Google Scholar.

[Effect of iron nanoparticles on free radical oxidation process in blood of rats with Pliss lymphosarcoma]

The use of metal nanoparticles (NPs) for cancer treatment requires careful examination of their biological effects. The aim of this study was to determine parameters of oxidative processes in the blood of tumor-bearing animals treated with metallic iron NPs only. The markers of antioxidant status and accumulation of lipid peroxidation products were measured in erythrocytes and blood plasma of rats with Pliss lymphosarcoma (PLS) and intact rats. PLS animals were treated eight times with iron NPs (at a dose of 1.25 mg/kg bw (main group), rats of the control group received saline (0.3 ml). In control animals, an increase in malondialdehyde (MDA) was observed in red blood cells (RBC) by 45%; this was accompanied by compensatory increase in reduced glutathione (GSH) and catalase by 24% and 14.3%, respectively (p<0.05). In plasma an increase in MDA by 167.4% (p<0.01) and a decrease in oxidase activity of ceruloplasmin (CP) by 36.8% (p<0.001) were found. In the main group there was a decrease of accumulation of lipid peroxidation products in the blood. Intensity of detected changes depended on the antitumor effect: rats with growing LSP showed a tendency to the decrease in the RBC MDA level and normalization of plasma MDA; in animals with LSP regression this marker did not differ from normal values. In all animals of the main group the CP content was basically the same as in intact rats while GSH increased in the group without therapeutic effect (by 218.6%) and in the group with the effect by 69% (versus normal values; p<0.01). SOD activity in the rats with LSP growth significantly increased (by 42%), in the rats with regression decreased (by 30%) with subsequent normalization. Thus, administration of iron NPs caused activation of the antioxidant system in blood and a significant decrease in the manifestations of oxidative stress associated with tumor growth.

Mice Overexpressing Both Non-Mutated Human SOD1 and Mutated SOD1(G93A) Genes: A Competent Experimental Model for Studying Iron Metabolism in Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease characterized by degeneration and loss of motor neurons in the spinal cord, brainstem and motor cortex. Up to 10% of ALS cases are inherited (familial, fALS) and associated with mutations, frequently in the superoxide dismutase 1 (SOD1) gene. Rodent transgenic models of ALS are often used to elucidate a complex pathogenesis of this disease. Of importance, both ALS patients and animals carrying mutated human SOD1 gene show symptoms of oxidative stress and iron metabolism misregulation. The aim of our study was to characterize changes in iron metabolism in one of the most commonly used models of ALS – transgenic mice overexpressing human mutated SOD1^G93A gene. We analyzed the expression of iron-related genes in asymptomatic, 2-month-old and symptomatic, 4-month-old SOD1^G93A mice. In parallel, respective age-matched mice overexpressing human non-mutated SOD1 transgene and control mice were analyzed. We demonstrate that the overexpression of both SOD1 and SOD1^G93A genes account for a substantial increase in SOD1 protein levels and activity in selected tissues and that not all the changes in iron metabolism genes expression are specific for the overexpression of the mutated form of SOD1.

Serum ferritin is elevated in amyotrophic lateral sclerosis patients

Our objective was to measure serum ferritin levels, which reflect iron metabolism, in ALS patients versus healthy and disease controls, and determine whether serum ferritin levels correlate with survival. We retrospectively analyzed data from 138 ALS patients, 152 healthy controls, and 82 disease controls. Gender, age, site of onset, and dates of symptom onset and death were recorded. Survival was defined as the time from symptom onset to death. Serum ferritin levels were measured using immunoassay. ANOVA and Pearson's correlation were used to compare ferritin levels between groups and test the association between ferritin levels and age and survival. Ferritin levels were categorized into high and low groups, and Kaplan-Meier analysis performed. Results showed that gender proportions differed between ALS patients versus healthy and disease controls, and gender affected serum ferritin levels. Ferritin comparisons were stratified for gender. In both males and females, ferritin levels were higher in ALS patients versus healthy and disease controls. However, ferritin levels were unrelated to survival in either gender, by tests of association or survival analysis. In conclusion, ALS patients have altered iron metabolism that is not simply due to the presence of neurological disease. Serum ferritin levels alone are not sufficient to predict survival.

TDP-43 modification in the hSOD1(G93A) amyotrophic lateral sclerosis mouse model

Amyotrophic lateral sclerosis (ALS) is an adult onset disease that produces gradual motor neuron cell death in the spinal cord (SP). Recently, transactive response DNA-binding protein 43 kDa (TDP-43), a critical component of insoluble ubiquitinated inclusions, has received attention in the treatment of neurodegenerative disorders, including frontotemporal lobar degeneration (FTLD) and ALS. TDP-43 modifications, including hyperphosphorylation, truncation, and ubiquitination, have been reported in the pathogenesis of neurodegenerative diseases (NDs). However, the pathogenic mechanism of TDP-43 in ALS is unclear. To determine the association between TDP-43 and neurotoxicity in an ALS model, we characterized TDP-43 expression in hSOD1(G93A) transgenic mice (Tg) as an ALS animal model. TDP-43 was expressed by astrocytes and microglial cells in the SP of hSOD1(G93A) transgenic mice. In addition, the expression of phosphorylated and truncated TDP-43 increased in the SP of ALS mice compared with age-matched non-Tg. Furthermore, the serum iron concentration and expression of transferrin, a homeostasis-related iron protein, in the SP were increased relative to non-Tg. The protein expression level of HO-1 related to oxidative stress was increased in the SP of hSOD1(G93A) Tg relative to non-Tg. We show that an increase of TDP-43 modification, including phosphorylation or truncation, associates with dysfunctional iron homeostasis and an increase in oxidative stress in the SP of symptomatic hSOD1(G93A) Tg. These findings suggest that modified TDP-43 may be involved in motor neuron death in the SP of a SOD1(G93A)-expressing familial ALS (fALS) animal model.

Changes in skeletal muscle iron metabolism outpace amyotrophic lateral sclerosis onset in transgenic rats bearing the G93A hmSOD1 gene mutation

OBJECTIVE

Recently, iron and the adaptor protein "p66Shc" have been shown to play an important role in the development of amyotrophic lateral sclerosis (ALS) in rats. We hypothesized that changes in muscle p66Shc activity and iron metabolism would appear before visible symptoms of the disease occurred.

METHODS

In the present study, we used transgenic rats bearing the G93A hmSOD1 gene mutation and their non-transgenic littermates to test this hypothesis. We examined muscle p66Shc phosphorylation and iron metabolism in relation to oxidative stress in animals at three disease stages: asymptomatic (ALS I), disease onset (ALS II), and end-stage disease (ALS III).

RESULTS

Significant changes in iron metabolism and markers of lipid and protein oxidation were detected in ALS I animals, which manifested as decreased levels of ferritin H and ferroportin 1 (Fpn1) and increased levels of ferritin L levels. Muscles of ALS I rats possessed increased levels of p66Shc phosphorylated at Ser(36) compared with muscles of control rats. During disease progression, level of ferritin H significantly increased and was accompanied by iron accumulation.

CONCLUSIONS

This study showed that multiple mechanisms may underlie iron accumulation in muscles of ALS transgenic rats, which include changes in blood hepcidin and muscle Fpn1 and increased level of muscle ferritin H. These data suggest that impaired iron metabolism is not a result of changes in motor activity.

Shared mechanisms of neurodegeneration in Alzheimer's disease and Parkinson's disease

Alzheimer's disease (AD) and Parkinson's disease (PD) have markedly different clinical and pathological features, but these two diseases are the most common neurodegenerative disorders. Previous studies have showed that there are common mechanisms in AD and PD. Several genetic studies have revealed mutations in genes associated with the risk of AD and PD. Circumstantial evidences have shown that dysregulation of brain iron homeostasis leads to abnormal iron accumulation and results in AD as well as PD. α-Synuclein and tau take part in the mechanisms of these diseases by oxidative stress and mitochondrial dysfunction. Some studies indicated that the loss of LC noradrenergic neurons may occur early in the progression of AD and PD. Nicotinic acetylcholine receptors (nAChRs) are members of the Cys-loop superfamily of pentameric ligand-gated ion channels; some evidence showed that nicotinic receptors may be associated with AD and PD. These experimental and clinical studies may provide a scientific foundation for common shared mechanisms in AD and PD.

Amyotrophic lateral sclerosis: new insights into underlying molecular mechanisms and opportunities for therapeutic intervention

Recent years have witnessed a renewed interest in the pathogenic mechanisms of amyotrophic lateral sclerosis (ALS), a late-onset progressive degeneration of motor neurons. The discovery of new genes associated with the familial form of the disease, along with a deeper insight into pathways already described for this disease, has led scientists to reconsider previous postulates. While protein misfolding, mitochondrial dysfunction, oxidative damage, defective axonal transport, and excitotoxicity have not been dismissed, they need to be re-examined as contributors to the onset or progression of ALS in the light of the current knowledge that the mutations of proteins involved in RNA processing, apparently unrelated to the previous "old partners," are causative of the same phenotype. Thus, newly envisaged models and tools may offer unforeseen clues on the etiology of this disease and hopefully provide the key to treatment.

Modulating metals as a therapeutic strategy for Alzheimer's disease

In 1906, Alois Alzheimer first characterized the disease that bears his name. Despite intensive research, which has led to a better understanding of the pathology, there is no effective treatment for this disease. Of the drugs approved by the US FDA, none are disease modifying, only symptomatic. Unfortunately, there have been a number of failed clinical trials in the past 10 years where studies show either no cognitive improvement or, worse, serious side effects associated with treatment. Hence, there is a need for the field to look at alternative approaches to therapy. In this review, we will discuss how metal dyshomeostasis occurs in aging and Alzheimer's disease. Concomitantly, we will discuss how targeting this dyshomeostasis offers an effective and novel therapeutic approach. Thus far, compounds that mediate these effects have shown great potential in both preclinical animal studies as well as in early-stage clinical trials.

Dysregulation of iron metabolism in Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis

Dysregulation of iron metabolism has been observed in patients with neurodegenerative diseases (NDs). Utilization of several importers and exporters for iron transport in brain cells helps maintain iron homeostasis. Dysregulation of iron homeostasis leads to the production of neurotoxic substances and reactive oxygen species, resulting in iron-induced oxidative stress. In Alzheimer's disease (AD) and Parkinson's disease (PD), circumstantial evidence has shown that dysregulation of brain iron homeostasis leads to abnormal iron accumulation. Several genetic studies have revealed mutations in genes associated with increased iron uptake, increased oxidative stress, and an altered inflammatory response in amyotrophic lateral sclerosis (ALS). Here, we review the recent findings on brain iron metabolism in common NDs, such as AD, PD, and ALS. We also summarize the conventional and novel types of iron chelators, which can successfully decrease excess iron accumulation in brain lesions. For example, iron-chelating drugs have neuroprotective effects, preventing neural apoptosis, and activate cellular protective pathways against oxidative stress. Glial cells also protect neurons by secreting antioxidants and antiapoptotic substances. These new findings of experimental and clinical studies may provide a scientific foundation for advances in drug development for NDs.

Iron insufficiency compromises motor neurons and their mitochondrial function in Irp2-null mice

Genetic ablation of Iron Regulatory Protein 2 (Irp2, Ireb2), which post-transcriptionally regulates iron metabolism genes, causes a gait disorder in mice that progresses to hind-limb paralysis. Here we have demonstrated that misregulation of iron metabolism from loss of Irp2 causes lower motor neuronal degeneration with significant spinal cord axonopathy. Mitochondria in the lumbar spinal cord showed significantly decreased Complex I and II activities, and abnormal morphology. Lower motor neurons appeared to be the most adversely affected neurons, and we show that functional iron starvation due to misregulation of iron import and storage proteins, including transferrin receptor 1 and ferritin, may have a causal role in disease. We demonstrated that two therapeutic approaches were beneficial for motor neuron survival. First, we activated a homologous protein, IRP1, by oral Tempol treatment and found that axons were partially spared from degeneration. Secondly, we genetically decreased expression of the iron storage protein, ferritin, to diminish functional iron starvation. These data suggest that functional iron deficiency may constitute a previously unrecognized molecular basis for degeneration of motor neurons in mice.

Association between divalent metal transport 1 encoding gene (SLC11A2) and disease duration in amyotrophic lateral sclerosis

BACKGROUND

Dysregulation of iron homeostasis is one possible pathophysiological mechanism involved in motor neuron degeneration in amyotrophic lateral sclerosis (ALS). SLC11A2 gene encodes the divalent metal transport 1 (DMT1) mediating iron transport in cerebral endosomal compartments. The objective of the study was to analyze DMT1 as a possible risk or modulating factor in sporadic ALS (SALS).

METHODS

We performed a case-control association study on an intronic polymorphism (rs407135) previously analyzed in another neurodegenerative disease, Alzheimer's disease. This polymorphism was studied by DNA sequencing in 579 French patients with SALS and 517 healthy matched individuals. The clinical characteristics of patients were analyzed in relation to their genotypes.

RESULTS

We observed that the C allele of rs407135 in SLC11A2 was associated with a shorter disease duration in SALS patients with onset in the legs [Hazard ratio: 1.5 [1.1-2.1] (p=0.02)]. These results are in line with previous observations suggesting that bulbar and spinal motor neurons have different metabolic regulation and gene expression profiles.

CONCLUSIONS

Our findings support an implication for iron metabolism in ALS and suggest that the genotype of the SLC11A2 gene could modulate the duration of the disease in French SALS patients.

Neuroprotective multifunctional iron chelators: from redox-sensitive process to novel therapeutic opportunities

Accumulating evidence suggests that many cytotoxic signals occurring in the neurodegenerative brain can initiate neuronal death processes, including oxidative stress, inflammation, and accumulation of iron at the sites of the neuronal deterioration. Neuroprotection by iron chelators has been widely recognized with respect to their ability to prevent hydroxyl radical formation in the Fenton reaction by sequestering redox-active iron. An additional neuroprotective mechanism of iron chelators is associated with their ability to upregulate or stabilize the transcriptional activator, hypoxia-inducible factor-1alpha (HIF-1alpha). HIF-1alpha stability within the cells is under the control of a class of iron-dependent and oxygen-sensor enzymes, HIF prolyl-4-hydroxylases (PHDs) that target HIF-1alpha for degradation. Thus, an emerging novel target for neuroprotection is associated with the HIF system to promote stabilization of HIF-1alpha and increase transcription of HIF-1-related survival genes, which have been reported to be regulated in patient's brains afflicted with diverse neurodegenerative diseases. In accordance, a new potential therapeutic strategy for neurodegenerative diseases is explored, by which iron chelators would inhibit PHDs, target the HIF-1-signaling pathway and ultimately activate HIF-1-dependent neuroprotective genes. This review discusses two interrelated approaches concerning therapy targets in neurodegeneration, sharing in common the implementation of iron chelation activity: antioxidation and HIF-1-pathway activation.

Recent advances in amyotrophic lateral sclerosis research: perspectives for personalized clinical application

Treatment of amyotrophic lateral sclerosis (ALS) has been fueled, in part, by frustration over the shortcomings of the symptomatic drugs available, since these do not impede the progression of this disease. Currently, over 150 different potential therapeutic agents or strategies have been tested in preclinical models of ALS. Unfortunately, therapeutic modifiers of murine ALS have failed to be successfully translated into strategies for patients, probably because of differences in pharmacokinetics of the therapeutic agents, route of delivery, inefficiency of the agents to affect the distinct pathologies of the disease or inherent limitations of the available animal models. Given the multiplicity of the pathological mechanisms implicated in ALS, new therapies should consider the simultaneous manipulation of multiple targets. Additionally, a better management of ALS therapy should include understanding the interactions between potential risk factors, biomarkers and heterogeneous clinical features of the patients, aiming to manage their adverse events or personalize the safety profile of these agents. This review will discuss novel pharmacological approaches concerning adjusted therapy for ALS patients: iron-binding brain permeable multimodal compounds, genetic manipulation and cell-based treatment.

Flightless flies: Drosophila models of neuromuscular disease

The fruit fly, Drosophila melanogaster, has a long and rich history as an important model organism for biologists. In particular, study of the fruit fly has been essential to much of our fundamental understanding of the development and function of the nervous system. In recent years, studies using fruit flies have provided important insights into the pathogenesis of neurodegenerative and neuromuscular diseases. Fly models of spinal muscular atrophy, spinobulbar muscular atrophy,myotonic dystrophy, dystrophinopathies and other inherited neuromuscular diseases recapitulate many of the key pathologic features of the human disease. The ability to perform genetic screens holds promise for uncovering the molecular mechanisms of disease, and indeed, for identifying novel therapeutic targets. This review will summarize recent progress in developing fly models of neuromuscular diseases and will emphasize the contribution that Drosophila has made to our understanding of these diseases.

Up-regulation of ferritin ubiquitination in skeletal muscle of transgenic rats bearing the G93A hmSOD1 gene mutation

In the present study we measured the levels of protein carbolnyls and the H and L subunits of ferritin in three hind limb muscles, [Extensor digitorum longus, Tibialis anterior and Soleus] of transgenic rats bearing the G93A hmSOD1 gene and of their non-transgenic littermates. All of the muscles from the transgenic animals showed significantly higher protein carbonyl levels, compared to the respective muscles from control non-transgenic animals. In two muscles (Tibialis anterior and Soleus) from transgenic rats, both L and H subunits of ferritin were upregulated. Moreover, we observed that the electrophoretic mobility of both ferritin subunits was retarded which indicates their post-translational modification. Ferritin immunoprecipitation experiments show an increased ubiquitination of both H and L ferritin in all muscles from the transgenic animals. Our data show for the first time that ferritin ubiquitination could be responsible for oxidative stress in muscles of rats bearing the G93A hmSOD1, consequently ferritin is not able to control the labile iron pool.

Neuroprotective and neuritogenic activities of novel multimodal iron-chelating drugs in motor-neuron-like NSC-34 cells and transgenic mouse model of amyotrophic lateral sclerosis

Novel therapeutic approaches for the treatment of neurodegenerative disorders comprise drug candidates designed specifically to act on multiple central nervous system targets. We have recently synthesized multifunctional, nontoxic, brain-permeable iron-chelating drugs, M30 and HLA20, possessing the N-propargylamine neuroprotective moiety of rasagiline (Azilect) and the iron-chelating moiety of VK28. The present study demonstrates that M30 and HLA20 possess a wide range of pharmacological activities in mouse NSC-34 motor neuron cells, including neuroprotective effects against hydrogen peroxide- and 3-morpholinosydnonimine-induced neurotoxicity, induction of differentiation, and up-regulation of hypoxia-inducible factor (HIF)-1alpha and HIF-target genes (enolase1 and vascular endothelial growth factor). Both compounds induced NSC-34 neuritogenesis, accompanied by a marked increase in the expression of brain-derived neurotrophic factor and growth-associated protein-43, which was inhibited by PD98059 and GF109203X, indicating the involvement of mitogen-activated protein kinase and protein kinase C pathways. A major finding was the ability of M30 to significantly extend the survival of G93A-SOD1 amyotrophic lateral sclerosis mice and delay the onset of the disease. These properties of the novel multimodal iron-chelating drugs possessing neuroprotective/neuritogenic activities may offer future therapeutic possibilities for motor neurodegenerative diseases.

Dysregulation of iron homeostasis in the CNS contributes to disease progression in a mouse model of amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS), characterized by degeneration of spinal motor neurons, consists of sporadic and familial forms. One cause of familial ALS is missense mutations in the superoxide dismutase 1 (SOD1) gene. Iron accumulation occurs in the CNS of both forms of ALS; however, its contribution to the pathogenesis of ALS is not known. We examined the role of iron in a transgenic mouse line overexpressing the human SOD1(G37R) mutant. We show that multiple mechanisms may underlie the iron accumulation in neurons and glia in SOD1(G37R) transgenic mice. These include dysregulation of proteins involved in iron influx and sensing of intracellular iron; iron accumulation in ventral motor neurons secondary to blockage of anterograde axonal transport; and increased mitochondrial iron load in neurons and glia. We also show that treatment of SOD1(G37R) mice with an iron chelator extends life span by 5 weeks, accompanied by increased survival of spinal motor neurons and improved locomotor function. These data suggest that iron chelator therapy might be useful for the treatment of ALS.

The effect of different zwitterionic buffers and PBS used for out-of-incubator procedures during standard in vitro embryo production on development, morphology and gene expression of bovine embryos

The effect of the zwitterionic buffers HEPES, TES and MOPS and of PBS used for out-of-incubator procedures during standard in vitro embryo production on bovine oocytes and embryo development, morphology and on the expression patterns of eight selected genes: Fgf-4, Lama1, Ube2a, Gsta4, Il6, Sod1, Prss11 and Hspb1, was evaluated. All buffers were prepared at a concentration of 10 mM in TALP medium, with the exception of PBS. The total time of oocyte/embryo exposure to each buffer was approximately 41 min. The cleavage rates and number of embryos that developed to > or =8 cells at day 4 were no different among the buffers tested, however, more blastocysts developed at day 7, 8 and 9 in HEPES and MOPS treatments than in PBS and TES (P<0.05). No difference between buffers in total and apoptotic cell number was found. Except for Hspb1 and Ube2a genes, the levels of expression of the six remaining transcripts were higher in in vivo than in in vitro embryos irrespective of buffer used (P<0.05). In addition, higher expression of Hspb1 and lower expression of Ube2a and Lama1 were observed in PBS and TES than in MOPS and HEPES treatments (P<0.05). Expression of Fgf-4 and Gsta4 in the in vitro embryos was lower in PBS than in the remaining three buffers (P<0.05) and the level of expression of the Il6 gene was not affected by any buffer tested but was lower in in vitro than in in vivo derived embryos. Expression of both Sod1 and Prss11 genes in MOPS were at the level of the in vivo embryos. These results showed that the choice of buffer and short exposure time of approximately 41 min, affects mRNA expression of in vitro produced bovine embryos.

Iron and ferritin concentrations in exhaled breath condensate of children with asthma

Maintenance of iron homeostasis is of utmost importance for the respiratory system physiology and pathophysiology. Local iron deficiency or accumulation may result in particular respiratory function impairment. The aim of the present study was to find out whether iron and ferritin could be determined in exhaled breath condensate (EBC) of healthy children and children with asthma. Oxidative stress was verified by determination of EBC superoxide dismutase (SOD) activity, and the airway inflammatory process by determination of exhaled nitric oxide (F(E)NO). EBC was collected from 39 children (22 healthy children as a control group and 17 asthmatics) using an EcoScreen condenser. Iron, ferritin, and SOD were determined on optimization and validation for low concentrations. In comparison with a control group, asthma patients had a statistically significantly lower iron concentration (p = 0.0001) and higher SOD catalytic activity (p = 0.0160), with no significant difference in ferritin levels (p = 0.5252), although percentile values indicated elevated ferritin concentration in about half of asthma patients. F(E)NO values were significantly higher in the asthma group (p = 0.0047). This preliminary study demonstrated the possibility of determining iron and ferritin concentrations and SOD activity in EBC, and a significant difference in EBC iron and SOD between asthma patients and healthy children.

Serum ferritin and metal levels as risk factors for amyotrophic lateral sclerosis

Metal toxicity has been identified as a possible risk factor for amyotrophic lateral sclerosis (ALS) and other neurodegenerative disorders. We conducted a retrospective chart review of urinary, hair and blood metal levels and serum ferritin in 321 people with ALS seen over a ten-year period at the Massachusetts General Hospital (MGH). We found that hair lead levels and serum ferritin levels were elevated in ALS patients compared to published normal values. Metal levels of arsenic, lead, mercury, cadmium, thallium, cobalt and aluminum in 24-hour urine specimens and lead, mercury and arsenic in serum were within the normal range. We conclude that twenty-four hour urine or blood testing for metals is not warranted as part of the evaluation of ALS. Elevated levels of serum ferritin in ALS population could reflect an underlying perturbation in iron metabolism.

Increased serum ferritin levels in amyotrophic lateral sclerosis (ALS) patients

Iron misregulation promotes oxidative stress, a proposed pathological mechanism in neurodegenerative disease. The aim of this study was to evaluate serum iron metabolism indicators in 60 amyotrophic lateral sclerosis (ALS) patients and 44 age matched controls. Serum ferritin levels were significantly increased in ALS patients compared to controls (p < 0.001), while no differences in the levels of serum iron, transferrin, iron saturation or total iron binding capacity were found. Likewise no differences in C reactive protein (CRP) or caeruloplasmin were detected, suggesting that the elevated ferritin levels in ALS did not merely indicate an acute phase response. The increased ferritin level may reflect a general increase in stored iron or be a consequence of ongoing muscle degeneration.

Amyotrophic lateral sclerosis: from current developments in the laboratory to clinical implications

Amyotrophic lateral sclerosis (ALS) is a late-onset progressive degeneration of motor neurons occurring both as a sporadic and a familial disease. The etiology of ALS remains unknown, but one fifth of instances are due to specific gene defects, the best characterized of which is point mutations in the gene coding for Cu/Zn superoxide dismutase (SOD1). Because sporadic and familial ALS affect the same neurons with similar pathology, it is hoped that understanding these gene defects will help in devising therapies effective in both forms. A wealth of evidence has been collected in rodents made transgenic for mutant SOD1, which represent the best available models for familial ALS. Mutant SOD1 likely induces selective vulnerability of motor neurons through a combination of several mechanisms, including protein misfolding, mitochondrial dysfunction, oxidative damage, cytoskeletal abnormalities and defective axonal transport, excitotoxicity, inadequate growth factor signaling, and inflammation. Damage within motor neurons is enhanced by noxious signals originating from nonneuronal neighboring cells, where mutant SOD1 induces an inflammatory response that accelerates disease progression. The clinical implication of these findings is that promising therapeutic approaches can be derived from multidrug treatments aimed at the simultaneous interception of damage in both motor neurons and nonmotor neuronal cells.

Role of iron in neurodegenerative disorders

Although the pathophysiology underlying a number of neurodegenerative diseases is complex and, in many aspects, only partly understood, increased iron levels in pathologically relevant brain areas and iron-mediated oxidative stress seem to play a central role in many of them. Much has been learned from monogenetically caused disturbances of brain iron metabolism including pantothenate kinase-associated neurodegeneration type 2, hereditary ferritinopathies affecting the basal ganglia, and aceruloplasminemia that may well be applied to the most common neurodegenerative disorders associated with brain iron accumulation including Parkinson disease and Alzheimer disease. Iron-mediated oxidative stress in neurodegenerative diseases caused by other genetic pathways like Huntington disease and Friedreich ataxia underscore the complex interaction of this trace metal and genetic variations. Therapeutical strategies derived from application of iron chelators in monogenetically caused disturbances of brain iron metabolism and new iron and oxidative stress diminishing substances in animal models of Parkinson disease are promising and warrant further investigational effort.