Hyccin/FAM126A deficiency reduces glial enrichment and axonal sheath, which are rescued by overexpression of a plasma membrane-targeting PI4KIIIα in Drosophila.

Hyccin/FAM126A mutations are linked to hypomyelination and congenital cataract disease (HCC), but whether and how Hyccin/FAM126A deficiency causes hypomyelination remains undetermined. This study shows Hyccin/FAM126A expression was necessary for the expression of other components of the PI4KIIIα complex in Drosophila. Knockdown of Hyccin/FAM126A in glia reduced the enrichment of glial cells, disrupted axonal sheaths and visual ability in the visual system, and these defects could be fully rescued by overexpressing either human FAM126A or FAM126B, and partially rescued by overexpressing a plasma membrane-targeting recombinant mouse PI4KIIIα. Additionally, PI4KIIIα knockdown in glia phenocopied Hyccin/FAM126A knockdown, and this was partially rescued by overexpressing the recombinant PI4KIIIα, but not human FAM126A or FAM126B. This study establishes an animal model of HCC and indicates that Hyccin/FAM126A plays an essential role in glial enrichment and axonal sheath in a cell-autonomous manner in the visual system via controlling the expression and stabilization of the PI4KIIIα complex at the plasma membrane.

Inhibition of phosphatidylinositol kinase-III alpha induces or facilitates lysosome exocytosis from microglia.

Besides degradation, lysosomes can also carry molecules for secretion out of the cell, such as ATP and cytokines, during unconventional secretion. Phosphatidylinositols and their metabolizing enzymes play important roles in the sorting and trafficking of lysosomal materials through the trans-Golgi network. The present study reveals a new function of phosphatidylinositol kinase-III alpha in the 'kiss-and-run' fusion of lysosomes at the plasma membrane to release ATP from microglia.

TTC7 and Hyccin Regulate Neuronal Aß42 Accumulation and its Associated Neural Deficits in Aß42-Expressing Drosophila.

Neuronal amyloid-ß (Aß) accumulation plays an important role in the pathogenesis of Alzheimer's disease (AD). The conformation and toxicity of Aß are regulated by lipids on the plasma membrane. Previously, we found downregulation of Rolling Blackout (RBO) or phosphatidylinositol-4-kinase type IIIα (PI4KIIIα) reduces neuronal Aß accumulation and associated neural deficits in a Drosophila model expressing Aß42. In mammals, the homologs of RBO and PI4KIIIα were reported to form a plasma membrane-localized complex with a scaffold protein TTC7 and cytosolic protein Hyccin/FAM126A to tightly control the plasmalemmal level of phosphatidylinositol-4-phosphate. Here, we show genetic downregulation of Drosophila TTC7 and Hyccin also reduces neuronal Aß accumulation and associated synaptic and motor defects as well as premature death in Aß42-expressing flies, while overexpression of TTC7 and Hyccin produced the opposite effect. These results, together with our previous study, demonstrate that RBO/TTC7/PI4KIIIα/Hyccin regulate neuronal Aß accumulation and associated neural deficits in the Drosophila model, further supporting the RBO/Efr3-PI4KIIIα complex as a potential therapeutic target for AD.

An Improved Method for Collection of Cerebrospinal Fluid from Anesthetized Mice.

The cerebrospinal fluid (CSF) is a valuable body fluid for analysis in neuroscience research. It is one of the fluids in closest contact with the central nervous system and thus, can be used to analyze the diseased state of the brain or spinal cord without directly accessing these tissues. However, in mice it is difficult to obtain from the cisterna magna due to its closeness to blood vessels, which often contaminate samples. The area for CSF collection in mice is also difficult to dissect to and often only small samples are obtained (maximum of 5-7 µL or less). This protocol describes in detail a technique that improves on current methods of collection to minimize contamination from blood and allow for the abundant collection of CSF (on average 10-15 µL can be collected). This technique can be used with other dissection methods for tissue collection from mice, as it does not impact any tissues during CSF extraction. Thus, the brain and spinal cord are not affected with this technique and remain intact. With greater CSF sample collection and purity, more analyses can be used with this fluid to further aid neuroscience research and better understand diseases affecting the brain and spinal cord.

An Efficient and Reliable Assay for Investigating the Effects of Hypoxia/Anoxia on Drosophila.

Stroke is a leading cause of death worldwide. Up to one thousand potential drugs or interventions have been developed to treat stroke, out of which ~160 have gone on to clinical trials. However, none of them has been successful. New insights into the molecular and cellular mechanisms of ischemia-induced injury are needed for discovering new therapeutic targets. Recently, Drosophila has been used to uncover new hypoxia-related genes. In this study, we describe an efficient and reliable assay with a sophisticated apparatus for studying the effects of oxygen deprivation on flies. Using this assay, wild-type flies were exposed to an anoxic environment for varying lengths of time, then the cumulative death rate and mobility recovery were systematically analyzed. We found that anoxia for over one hour caused lethality. The cumulative death rate on day 5 after anoxia was linearly and positively correlated with the duration of anoxia, and reached 50% when the duration was 2.5 h-3 h. We also found that the mobility recovery in normoxia was slow, as the climbing ability remained largely unchanged 4 h-6 h after 2.5-h of anoxia. We suggest that 2.5 h-3 h of anoxia and 4 h-6 h of recovery before mobility analysis are appropriate for future use of the anoxia assay.

CuII(atsm) improves the neurological phenotype and survival of SOD1G93A mice and selectively increases enzymatically active SOD1 in the spinal cord.

Ubiquitous expression of mutant Cu/Zn-superoxide dismutase (SOD1) selectively affects motor neurons in the central nervous system (CNS), causing the adult-onset degenerative disease amyotrophic lateral sclerosis (ALS). The CNS-specific impact of ubiquitous mutant SOD1 expression is recapitulated in transgenic mouse models of the disease. Here we present outcomes for the metallo-complex CuII(atsm) tested for therapeutic efficacy in mice expressing SOD1G93A on a mixed genetic background. Oral administration of CuII(atsm) delayed the onset of neurological symptoms, improved locomotive capacity and extended overall survival. Although the ALS-like phenotype of SOD1G93A mice is instigated by expression of the mutant SOD1, we show the improved phenotype of the CuII(atsm)-treated animals involves an increase in mature mutant SOD1 protein in the disease-affected spinal cord, where concomitant increases in copper and SOD1 activity are also evident. In contrast to these effects in the spinal cord, treating with CuII(atsm) had no effect in liver on either mutant SOD1 protein levels or its activity, indicating a CNS-selective SOD1 response to the drug. These data provide support for CuII(atsm) as a treatment option for ALS as well as insight to the CNS-selective effects of mutant SOD1.

SH2B1 is Involved in the Accumulation of Amyloid-ß42 in Alzheimer's Disease.

Alzheimer's disease (AD) is characterized by deficits in learning and memory abilities, as well as pathological changes of amyloid-ß (Aß) plaque and neurofibrillary tangle formation in the brain. Insulin has been identified as a modulator of the neuronal pathways involved in learning and memory, and is also implicated as a modulator of Aß and tau metabolism. Disrupted insulin signaling pathways are evident in AD patients and it is understood that type 2 diabetes can increase the risk of developing AD, suggesting a possible link between metabolic disorders and neurodegeneration. SH2B1 is a key protein in the insulin signaling pathway involved in regulating the activity of the insulin receptor. To further identify the role of the insulin signaling pathway in the pathology of AD, SH2B (dSH2B homologue in flies) in neurons was partially knocked out or overexpressed in an AD Drosophila model expressing Aß42. Partial knockout of neuronal SH2B in the Aß42-expressing Drosophila had a detrimental effect on mobility and neurotransmission, and increased levels and intraneuronal accumulation of Aß42, as assessed by ELISA and immunostaining. Alternatively, partial overexpression of neuronal SH2B in the Aß42-expressing Drosophila improved lifespan, mobility, and neurotransmission, as well as decreased levels and intraneuronal accumulation of Aß42. Thus, SH2B1 may be an upstream modulator of Aß metabolism, acting to inhibit Aß accumulation, and has a role in the pathogenesis of AD. SH2B1 may therefore have potential as a therapeutic target for this common form of dementia.

Oral treatment with Cu(II)(atsm) increases mutant SOD1 in vivo but protects motor neurons and improves the phenotype of a transgenic mouse model of amyotrophic lateral sclerosis.

Mutations in the metallo-protein Cu/Zn-superoxide dismutase (SOD1) cause amyotrophic lateral sclerosis (ALS) in humans and an expression level-dependent phenotype in transgenic rodents. We show that oral treatment with the therapeutic agent diacetyl-bis(4-methylthiosemicarbazonato)copper(II) [Cu(II)(atsm)] increased the concentration of mutant SOD1 (SOD1G37R) in ALS model mice, but paradoxically improved locomotor function and survival of the mice. To determine why the mice with increased levels of mutant SOD1 had an improved phenotype, we analyzed tissues by mass spectrometry. These analyses revealed most SOD1 in the spinal cord tissue of the SOD1G37R mice was Cu deficient. Treating with Cu(II)(atsm) decreased the pool of Cu-deficient SOD1 and increased the pool of fully metallated (holo) SOD1. Tracking isotopically enriched (65)Cu(II)(atsm) confirmed the increase in holo-SOD1 involved transfer of Cu from Cu(II)(atsm) to SOD1, suggesting the improved locomotor function and survival of the Cu(II)(atsm)-treated SOD1G37R mice involved, at least in part, the ability of the compound to improve the Cu content of the mutant SOD1. This was supported by improved survival of SOD1G37R mice that expressed the human gene for the Cu uptake protein CTR1. Improving the metal content of mutant SOD1 in vivo with Cu(II)(atsm) did not decrease levels of misfolded SOD1. These outcomes indicate the metal content of SOD1 may be a greater determinant of the toxicity of the protein in mutant SOD1-associated forms of ALS than the mutations themselves. Improving the metal content of SOD1 therefore represents a valid therapeutic strategy for treating ALS caused by SOD1.

Localized changes to glycogen synthase kinase-3 and collapsin response mediator protein-2 in the Huntington's disease affected brain.

All cases of Huntington's disease (HD) are caused by mutant huntingtin protein (mhtt), yet the molecular mechanisms that link mhtt to disease symptoms are not fully elucidated. Given glycogen synthase kinase-3 (GSK3) is implicated in several neurodegenerative diseases as a molecular mediator of neuronal decline and widely touted as a therapeutic target, we investigated GSK3 in cells expressing mhtt, brains of R6/1 HD mice and post-mortem human brain samples. Consistency in data across the two models and the human brain samples indicate decreased GSK3 signalling contributes to neuronal dysfunction in HD. Inhibitory phosphorylation of GSK3 (pGSK3) was elevated in mhtt cells and this appeared related to an overall energy metabolism deficit as the mhtt cells had less ATP and inhibiting ATP production in control cells expressing non-pathogenic htt with paraquat also increased pGSK3. pGSK3 was increased and ATP levels decreased in the frontal cortex and striatum of R6/1 mice and levels of cortical pGSK3 inversely correlated with cognitive function of the mice. Consistent with decreased GSK3 activity in the R6/1 mouse brain, ß-catenin levels were increased and phosphorylation of collapsin response mediator protein-2 (CRMP2) decreased in the frontal cortex where inhibitory phosphorylation of GSK3 was the greatest. pGSK3 was predominantly undetectable in HD and healthy control human brain samples, but levels of total GSK3 were decreased in the HD-affected frontal cortex and this correlated with decreased pCRMP2. Thus, disruptions to cortical GSK3 signalling, possibly due to localized energy metabolism deficits, appear to contribute to the cognitive symptoms of HD.

Increased metal content in the TDP-43(A315T) transgenic mouse model of frontotemporal lobar degeneration and amyotrophic lateral sclerosis.

Disrupted metal homeostasis is a consistent feature of neurodegenerative disease in humans and is recapitulated in mouse models of Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis (ALS) and neuronal ceriod lipofuscinosis. While the definitive pathogenesis of neurodegenerative disease in humans remains to be fully elucidated, disease-like symptoms in the mouse models are all driven by the presence or over-expression of a putative pathogenic protein, indicating an in vivo relationship between expression of these proteins, disrupted metal homeostasis and the symptoms of neuronal failure. Recently it was established that mutant TAR DNA binding protein-43 (TDP-43) is associated with the development of frontotemporal lobar degeneration and ALS. Subsequent development of transgenic mice that express human TDP-43 carrying the disease-causing A315T mutation has provided new opportunity to study the underlying mechanisms of TDP-43-related neurodegenerative disease. We assessed the cognitive and locomotive phenotype of TDP-43 (A315T) mice and their wild-type littermates and also assessed bulk metal content of brain and spinal cord tissues. Metal levels in the brain were not affected by the expression of mutant TDP-43, but zinc, copper, and manganese levels were all increased in the spinal cords of TDP-43 (A315T) mice when compared to wild-type littermates. Performance of the TDP-43 (A315T) mice in the Y-maze test for cognitive function was not significantly different to wild-type mice. By contrast, performance of the TDP-43 (A315T) in the rotarod test for locomotive function was consistently worse than wild-type mice. These preliminary in vivo data are the first to show that expression of a disease-causing form of TDP-43 is sufficient to disrupt metal ion homeostasis in the central nervous system. Disrupted metal ion homeostasis in the spinal cord but not the brain may explain why the TDP-43 (A315T) mice show symptoms of locomotive decline and not cognitive decline.

Therapeutic effects of CuII(atsm) in the SOD1-G37R mouse model of amyotrophic lateral sclerosis.

Our objective was to assess the copper(II) complex of diacetylbis(4-methylthiosemicarbazone) [Cu(II)(atsm)] for its preclinical potential as a novel therapeutic for ALS. Experimental paradigms used were designed to assess Cu(II)(atsm) efficacy relative to treatment with riluzole, as a function of dose administered, and when administered post symptom onset. Mice expressing human Cu/Zn superoxide dismutase harbouring the disease-causing G37R mutation (SOD1-G37R) were used and effects of Cu(II)(atsm) determined by assessing mouse survival and locomotor function (rotarod assay). Cu(II)(atsm) improved SOD1-G37R mouse survival and locomotor function in a dose-dependent manner. The highest dose tested improved survival by 26%. Riluzole had a modest effect on mouse survival (3.3%) but it did not improve locomotor function. Cotreatment with Cu(II)(atsm) did not alter the protective activity of Cu(II)(atsm) administered on its own. Commencing treatment with Cu(II)(atsm) after the onset of symptoms was less effective than treatments that commenced before symptom onset but still significantly improved locomotor function and survival. Improved locomotor function and survival of SOD1-G37R mice supports the potential for Cu(II)(atsm) as a novel treatment option for ALS.

Diacetylbis(N(4)-methylthiosemicarbazonato) copper(II) (CuII(atsm)) protects against peroxynitrite-induced nitrosative damage and prolongs survival in amyotrophic lateral sclerosis mouse model.

Amyotrophic lateral sclerosis (ALS) is a progressive paralyzing disease characterized by tissue oxidative damage and motor neuron degeneration. This study investigated the in vivo effect of diacetylbis(N(4)-methylthiosemicarbazonato) copper(II) (CuII(atsm)), which is an orally bioavailable, blood-brain barrier-permeable complex. In vitro the compound inhibits the action of peroxynitrite on Cu,Zn-superoxide dismutase (SOD1) and subsequent nitration of cellular proteins. Oral treatment of transgenic SOD1G93A mice with CuII(atsm) at presymptomatic and symptomatic ages was performed. The mice were examined for improvement in lifespan and motor function, as well as histological and biochemical changes to key disease markers. Systemic treatment of SOD1G93A mice significantly delayed onset of paralysis and prolonged lifespan, even when administered to symptomatic animals. Consistent with the properties of this compound, treated mice had reduced protein nitration and carbonylation, as well as increased antioxidant activity in spinal cord. Treatment also significantly preserved motor neurons and attenuated astrocyte and microglial activation in mice. Furthermore, CuII(atsm) prevented the accumulation of abnormally phosphorylated and fragmented TAR DNA-binding protein-43 (TDP-43) in spinal cord, a protein pivotal to the development of ALS. CuII(atsm) therefore represents a potential new class of neuroprotective agents targeting multiple major disease pathways of motor neurons with therapeutic potential for ALS.

Investigation of matrix metalloproteinases, MMP-2 and MMP-9, in plasma reveals a decrease of MMP-2 in Alzheimer's disease.

Pathological changes in the Alzheimer's disease (AD) brain include amyoid-ß (Aß) plaques, and neurofibrillary tangles, as well as neuronal death and synaptic loss. Matrix metalloproteinases MMP-2 and MMP-9 are known to degrade Aß, and their expressions are increased in the AD brain, in particular in the astrocytes surrounding amyloid plaque. To investigate a possible association between plasma metalloproteinases and AD, we quantified MMP-2 and MMP-9 activities in the plasma of healthy controls (HC, n = 56), cases with mild cognitive impairment (MCI, n = 45), and AD (n = 50). All cases had previously been imaged with Pittsburgh compound B (PiB) and had a Mini-Mental Status Examination (MMSE) assessment. MMP-2 and MMP-9 activity was determined using gelatine-zymography. There was a significant 1.5-fold decrease in MMP-2 activity in the AD group compared to HC (p < 0.001) and a 1.4-fold decrease compared to MCI (p < 0.01). There was no difference in MMP-9 levels between the three groups. A positive correlation was identified between MMP-2 plasma activity and MMSE score (r = 0.16, p < 0.05), but there was no association with PiB. This is the first report of a change in MMP-2 activity in AD plasma and these findings may provide some insight into AD pathogenesis.