Altered neuronal group 1 metabotropic glutamate receptor- and endoplasmic reticulum-mediated Ca2+ signaling in two rodent models of Alzheimer's disease

Calcium mobilization from the endoplasmic reticulum (ER) induced by, for example, IP3 receptor (IP3R) stimulation, and its subsequent crosstalk with extracellular Ca2+ influx mediated through voltage-gated calcium channels (VGCCs) and neuronal store-operated calcium entry (nSOCE), is essential for normal neuronal signaling and cellular homeostasis. However, several studies suggest that chronic calcium dysregulation may play a key role in the onset and/or progression of neurodegenerative conditions, particularly Alzheimer's disease (AD). Here, using early postnatal hippocampal tissue from two transgenic murine models of AD, we provide further evidence that not only are crucial calcium signaling pathways dysregulated, but also that such dysregulation occurs at very early stages of development. Utilizing epifluorescence calcium imaging, we investigated ER-, nSOCE- and VGCC-mediated calcium signaling in cultured primary hippocampal neurons from two transgenic rodent models of AD: 3xTg-AD mice (PS1M146V/APPSWE/TauP301L) and TgF344-AD rats (APPSWE/PS1ΔE9) between 2 and 9 days old. Our results reveal that, in comparison to control hippocampal neurons, those from 3xTg-AD mice possessed significantly greater basal ER calcium levels, as measured by larger responses to I-mGluR-mediated ER Ca2+ mobilization (amplitude; 4 (0-19) vs 21(12-36) a.u., non-Tg vs 3xTg-AD; median difference (95 % Cl) = 14 a.u. (11-18); p = 0.004)) but reduced nSOCE (15 (4-22) vs 8(5-11) a.u., non-Tg vs 3xTg-AD; median difference (95 % Cl) = -7 a.u. (-3- -10 a.u.); p < 0.0001). Furthermore, unlike non-Tg neurons, where depolarization enhanced the amplitude, duration and area under the curve (A.U.C.) of I-mGluR-evoked ER-mediated calcium signals when compared with basal conditions, this was not apparent in 3xTg-AD neurons. Whilst the amplitude of depolarization-enhanced I-mGluR-evoked ER-mediated calcium signals from both non-Tg F344 and TgF344-AD neurons was significantly enhanced relative to basal conditions, the A.U.C. and duration of responses were enhanced significantly upon depolarization in non-Tg F344, but not in TgF344-AD, neurons. Overall, the nature of basal I-mGluR-mediated calcium responses did not differ significantly between non-Tg F344 and TgF344-AD neurons. In summary, our results characterizing ER- and nSOCE-mediated calcium signaling in neurons demonstrate that ER Ca2+ dyshomeostasis is an early and potentially pathogenic event in familial AD.

Repurposing of clinically proven bioactive compounds for targeted treatment of Alzheimer's disease using molecular docking approach

Neurodegenerative diseases like Alzheimer's have become a growing concern as it is difficult to cure. Tau protein is found to be playing a major role in Alzheimer's disease, and the majority of drugs that are currently on the market are not only prohibitively expensive but also come packaged with side effects that the body cannot tolerate. Repurposing existing compounds is a successful and optimistic strategy that offers reduced risk and increased possibility. We aim to retrieve the existing drugs and analyze them using in-silico techniques. We have retrieved the compounds from the Selleckchem natural product library, and the ability of the drug to cross Blood Brain Barrier (BBB) and ADMET (Absorption, Distribution, Metabolism, Excretion, and Toxicity) properties were examined using SwissADME. The structure of Tau protein (2MZ7) was then retrieved from PDB, and molecular docking of the compounds was performed using the PyRx-Virtual Screening Tool. Initially, 92 compounds passed the ADMET screening criteria, out of which the compound Ligustroflavone was found to have the most favourable binding affinity without violating Lipinski's rule of 5 of the compounds in the library.

Amyloid pathology disrupts gliotransmitter release in astrocytes

Accumulation of amyloid-beta (Aβ) is associated with synaptic dysfunction and destabilization of astrocytic calcium homeostasis. A growing body of evidence support astrocytes as active modulators of synaptic transmission via calcium-mediated gliotransmission. However, the details of mechanisms linking Aβ signaling, astrocytic calcium dynamics, and gliotransmission are not known. We developed a biophysical model that describes calcium signaling and the ensuing gliotransmitter release from a single astrocytic process when stimulated by glutamate release from hippocampal neurons. The model accurately captures the temporal dynamics of microdomain calcium signaling and glutamate release via both kiss-and-run and full-fusion exocytosis. We investigate the roles of two crucial calcium regulating machineries affected by Aβ: plasma-membrane calcium pumps (PMCA) and metabotropic glutamate receptors (mGluRs). When we implemented these Aβ-affected molecular changes in our astrocyte model, it led to an increase in the rate and synchrony of calcium events. Our model also reproduces several previous findings of Aβ associated aberrant calcium activity, such as increased intracellular calcium level and increased spontaneous calcium activity, and synchronous calcium events. The study establishes a causal link between previous observations of hyperactive astrocytes in Alzheimer’s disease (AD) and Aβ-induced modifications in mGluR and PMCA functions. Analogous to neurotransmitter release, gliotransmitter exocytosis closely tracks calcium changes in astrocyte processes, thereby guaranteeing tight control of synaptic signaling by astrocytes. However, the downstream effects of AD-related calcium changes in astrocytes on gliotransmitter release are not known. Our results show that enhanced rate of exocytosis resulting from modified calcium signaling in astrocytes leads to a rapid depletion of docked vesicles that disrupts the crucial temporal correspondence between a calcium event and vesicular release. We propose that the loss of temporal correspondence between calcium events and gliotransmission in astrocytes pathologically alters astrocytic modulation of synaptic transmission in the presence of Aβ accumulation.

Signaling by astrocytes is critical to information processing at synapses, and its aberration plays a central role in neurological diseases, especially Alzheimer’s disease (AD). A complete characterization of calcium signaling and the resulting pattern of gliotransmitter release from fine astrocytic processes are not accessible to current experimental tools. We developed a biophysical model that can quantitatively describe signaling by astrocytes in response to a wide range of synaptic activity. We show that AD-related molecular alterations disrupt the concurrence of calcium and gliotransmitter release events, a characterizing feature that enables astrocytes to influence synaptic signaling.

Mitochondrial dysfunction in neurodegenerative diseases: A focus on iPSC-derived neuronal models

Progressive neuronal loss is a hallmark of many neurodegenerative diseases, including Alzheimer's and Parkinson's disease. These pathologies exhibit clear signs of inflammation, mitochondrial dysfunction, calcium deregulation, and accumulation of aggregated or misfolded proteins. Over the last decades, a tremendous research effort has contributed to define some of the pathological mechanisms underlying neurodegenerative processes in these complex brain neurodegenerative disorders. To better understand molecular mechanisms responsible for neurodegenerative processes and find potential interventions and pharmacological treatments, it is important to have robust in vitro and pre-clinical animal models that can recapitulate both the early biological events undermining the maintenance of the nervous system and early pathological events. In this regard, it would be informative to determine how different inherited pathogenic mutations can compromise mitochondrial function, calcium signaling, and neuronal survival. Since post-mortem analyses cannot provide relevant information about the disease progression, it is crucial to develop model systems that enable the investigation of early molecular changes, which may be relevant as targets for novel therapeutic options. Thus, the use of human induced pluripotent stem cells (iPSCs) represents an exceptional complementary tool for the investigation of degenerative processes. In this review, we will focus on two neurodegenerative diseases, Alzheimer's and Parkinson's disease. We will provide examples of iPSC-derived neuronal models and how they have been used to study calcium and mitochondrial alterations during neurodegeneration.

Potential Enzymatic Targets in Alzheimer's: A Comprehensive Review

Alzheimer's, a degenerative cause of the brain cells, is called as a progressive neurodegenerative disease and appears to have a heterogeneous etiology with main emphasis on amyloid-cascade and hyperphosphorylated tau-cascade hypotheses, that are directly linked with macromolecules called enzymes such as β- & γ-secretases, colinesterases, transglutaminases, and glycogen synthase kinase (GSK-3), cyclin-dependent kinase (cdk-5), microtubule affinity-regulating kinase (MARK). The catalytic activity of the above enzymes is the result of cognitive deficits, memory impairment and synaptic dysfunction and loss, and ultimately neuronal death. However, some other enzymes also lead to these dysfunctional events when reduced to their normal activities and levels in the brain, such as α- secretase, protein kinase C, phosphatases etc; metabolized to neurotransmitters, enzymes like monoamine oxidase (MAO), catechol-O-methyltransferase (COMT) etc. or these abnormalities can occur when enzymes act by other mechanisms such as phosphodiesterase reduces brain nucleotides (cGMP and cAMP) levels, phospholipase A2: PLA2 is associated with reactive oxygen species (ROS) production etc. On therapeutic fronts, several significant clinical trials are underway by targeting different enzymes for development of new therapeutics to treat Alzheimer's, such as inhibitors for β-secretase, GSK-3, MAO, phosphodiesterase, PLA2, cholinesterases etc, modulators of α- & γ-secretase activities and activators for protein kinase C, sirtuins etc. The last decades have perceived an increasing focus on findings and search for new putative and novel enzymatic targets for Alzheimer's. Here, we review the functions, pathological roles, and worth of almost all the Alzheimer's associated enzymes that address to therapeutic strategies and preventive approaches for treatment of Alzheimer's.

Transport of Glucose by the Plasma Membrane Affects the Removal and Concentration of Ca2+ at Rest in Neurons - Implications of a Condition Prior to Alzheimer's Disease?

Alzheimer's disease (AD) is classically characterized by two major markers: extracellular development of senile plaques and intracellular formation of neurofibrillary tangles. Nonetheless, neuronal glucose hypometabolism and Ca²⁺ deregulation have been separately implied in the genesis and progress of the neurodegenerative process. In this sense, the goal of this study was to investigate if modifications in the glucose transport would influence the cellular viability and would be involved with the activity of Ca²⁺ removal from the neuron. The total levels of plasma membrane Ca²⁺-ATPase (PMCA) and glucose transporters (GLUT1 and 3), as well as glucose entry and intracellular Ca²⁺ dynamics were quantified in neurons maintained at different glucose concentrations or submitted to GLUT3 mRNA interference. The results showed that reduced extracellular glucose impaired neuronal viability from day 8, but didn't change the total protein levels of GLUT1, GLUT3 and PMCA before the onset of the cell death. Conversely, the rate of glucose transport and Ca²⁺ concentration was already altered since the 4th day of external glucose reduction. Interestingly, reduction of GLUT3 on plasma membrane led to lower glucose transport and intracellular Ca²⁺ accumulation. It was observed that the reduction of glucose transport directed the neuron to decrease the removal and increase of intracellular Ca²⁺ at rest. Therefore, we concluded that reduced glucose transport impairs neuronal viability and compromise the activity of Ca²⁺ removal from the neuron. Thus, it is expected that changes in glucose transport may lead to a more susceptible condition or trigger a neurodegenerative condition resulting in accumulation of intracellular Ca²⁺.

Inosine protects against impairment of memory induced by experimental model of Alzheimer disease: a nucleoside with multitarget brain actions

RATIONALE

Inosine is a naturally occurring purine nucleoside formed by adenosine breakdown. This nucleoside is reported to exert potent effects on memory and learning, possibly through its antioxidant and anti-inflammatory actions.

OBJECTIVE

The objective is to evaluate the effects of inosine on the behavioral and neurochemical parameters in a rat model of Alzheimer's disease (AD) induced by streptozotocin (STZ).

METHODS

Adult male rats were divided into four groups: control (saline), STZ, STZ plus inosine (50 mg/kg), and STZ plus inosine (100 mg/kg). STZ (3 mg/kg) was administered by bilateral intracerebroventricular injection. The animals were treated intraperitoneally with inosine for 25 days. Memory, oxidative stress, ion pump activities, acetylcholinesterase (AChE), and choline acetyltransferase (ChAT) activities and expression were evaluated in the cerebral cortex and hippocampus.

RESULTS

The memory impairment induced by STZ was prevented by inosine. An increase in the Na⁺, K⁺-ATPase, and Mg-ATPase activities and a decrease in the Ca²⁺-ATPase activity were induced by STZ in the hippocampus and cerebral cortex, and inosine could prevent these alterations in ion pump activities. Inosine also prevented the increase in AChE activity and the alterations in AChE and ChAT expression induced by STZ. STZ increased the reactive oxygen species, nitrite levels, and superoxide dismutase activity and decreased the catalase and glutathione peroxidase activities. Inosine treatment conferred protection from these oxidative alterations in the brain.

CONCLUSIONS

Our findings demonstrate that inosine affects brain multiple targets suggesting that this molecule may have therapeutic potential against cognitive deficit and tissue damage in AD.

coMethDMR: accurate identification of co-methylated and differentially methylated regions in epigenome-wide association studies with continuous phenotypes

Recent technology has made it possible to measure DNA methylation profiles in a cost-effective and comprehensive genome-wide manner using array-based technology for epigenome-wide association studies. However, identifying differentially methylated regions (DMRs) remains a challenging task because of the complexities in DNA methylation data. Supervised methods typically focus on the regions that contain consecutive highly significantly differentially methylated CpGs in the genome, but may lack power for detecting small but consistent changes when few CpGs pass stringent significance threshold after multiple comparison. Unsupervised methods group CpGs based on genomic annotations first and then test them against phenotype, but may lack specificity because the regional boundaries of methylation are often not well defined. We present coMethDMR, a flexible, powerful, and accurate tool for identifying DMRs. Instead of testing all CpGs within a genomic region, coMethDMR carries out an additional step that selects co-methylated sub-regions first. Next, coMethDMR tests association between methylation levels within the sub-region and phenotype via a random coefficient mixed effects model that models both variations between CpG sites within the region and differential methylation simultaneously. coMethDMR offers well-controlled Type I error rate, improved specificity, focused testing of targeted genomic regions, and is available as an open-source R package.

cindr, the Drosophila Homolog of the CD2AP Alzheimer's Disease Risk Gene, Is Required for Synaptic Transmission and Proteostasis

The Alzheimer's disease (AD) susceptibility gene, CD2-associated protein (CD2AP), encodes an actin binding adaptor protein, but its function in the nervous system is largely unknown. Loss of the Drosophila ortholog cindr enhances neurotoxicity of human Tau, which forms neurofibrillary tangle pathology in AD. We show that Cindr is expressed in neurons and present at synaptic terminals. cindr mutants show impairments in synapse maturation and both synaptic vesicle recycling and release. Cindr associates and genetically interacts with 14-3-3ζ, regulates the ubiquitin-proteasome system, and affects turnover of Synapsin and the plasma membrane calcium ATPase (PMCA). Loss of cindr elevates PMCA levels and reduces cytosolic calcium. Studies of Cd2ap null mice support a conserved role in synaptic proteostasis, and CD2AP protein levels are inversely related to Synapsin abundance in human postmortem brains. Our results reveal CD2AP neuronal requirements with relevance to AD susceptibility, including for proteostasis, calcium handling, and synaptic structure and function.

Analytical Strategy to Prioritize Alzheimer's Disease Candidate Genes in Gene Regulatory Networks Using Public Expression Data

Alzheimer’s disease (AD) progressively destroys cognitive abilities in the aging population with tremendous effects on memory. Despite recent progress in understanding the underlying mechanisms, high drug attrition rates have put a question mark behind our knowledge about its etiology. Re-evaluation of past studies could help us to elucidate molecular-level details of this disease. Several methods to infer such networks exist, but most of them do not elaborate on context specificity and completeness of the generated networks, missing out on lesser-known candidates. In this study, we present a novel strategy that corroborates common mechanistic patterns across large scale AD gene expression studies and further prioritizes potential biomarker candidates. To infer gene regulatory networks (GRNs), we applied an optimized version of the BC3Net algorithm, named BC3Net10, capable of deriving robust and coherent patterns. In principle, this approach initially leverages the power of literature knowledge to extract AD specific genes for generating viable networks. Our findings suggest that AD GRNs show significant enrichment for key signaling mechanisms involved in neurotransmission. Among the prioritized genes, well-known AD genes were prominent in synaptic transmission, implicated in cognitive deficits. Moreover, less intensive studied AD candidates (STX2, HLA-F, HLA-C, RAB11FIP4, ARAP3, AP2A2, ATP2B4, ITPR2, and ATP2A3) are also involved in neurotransmission, providing new insights into the underlying mechanism. To our knowledge, this is the first study to generate knowledge-instructed GRNs that demonstrates an effective way of combining literature-based knowledge and data-driven analysis to identify lesser known candidates embedded in stable and robust functional patterns across disparate datasets.

BARHL1 Is Downregulated in Alzheimer's Disease and May Regulate Cognitive Functions through ESR1 and Multiple Pathways

The Transcription factor BarH like homeobox 1 (BARHL1) is overexpressed in medulloblastoma and plays a role in neurogenesis. However, much about the BARHL1 regulatory networks and their functions in neurodegenerative and neoplastic disorders is not yet known. In this study, using a tissue microarray (TMA), we report for the first time that BARHL1 is downregulated in hormone-negative breast cancers and Alzheimer’s disease (AD). Furthermore, using an integrative bioinformatics approach and mining knockout mouse data, we show that: (i) BARHL1 and Estrogen Receptor 1 (ESR1) may constitute a network that regulates Neurotrophin 3 (NTF3)- and Brain Derived Neurotrophic Factor (BDNF)-mediated neurogenesis and neural survival; (ii) this is probably linked to AD pathways affecting aberrant post-translational modifications including SUMOylation and ubiquitination; (iii) the BARHL1-ESR1 network possibly regulates β-amyloid metabolism and memory; and (iv) hsa-mir-18a, having common key targets in the BARHL1-ESR1 network and AD pathway, may modulate neuron death, reduce β-amyloid processing and might also be involved in hearing and cognitive decline associated with AD. We have also hypothesized why estrogen replacement therapy improves AD condition. In addition, we have provided a feasible new mechanism to explain the abnormal function of mossy fibers and cerebellar granule cells related to memory and cognitive decline in AD apart from the Tau and amyloid pathogenesis through our BARHL1-ESR1 axis.

Neuroplastin deletion in glutamatergic neurons impairs selective brain functions and calcium regulation: implication for cognitive deterioration

The cell adhesion molecule neuroplastin (Np) is a novel candidate to influence human intelligence. Np-deficient mice display complex cognitive deficits and reduced levels of Plasma Membrane Ca²⁺ ATPases (PMCAs), an essential regulator of the intracellular Ca²⁺ concentration ([iCa²⁺]) and neuronal activity. We show abundant expression and conserved cellular and molecular features of Np in glutamatergic neurons in human hippocampal-cortical pathways as characterized for the rodent brain. In Nptn^{lox/loxEmx1Cre} mice, glutamatergic neuron-selective Np ablation resulted in behavioral deficits indicating hippocampal, striatal, and sensorimotor dysfunction paralleled by highly altered activities in hippocampal CA1 area, sensorimotor cortex layers I-III/IV, and the striatal sensorimotor domain detected by single-photon emission computed tomography. Altered hippocampal and cortical activities correlated with reduction of distinct PMCA paralogs in Nptn^{lox/loxEmx1Cre} mice and increased [iCa²⁺] in cultured mutant neurons. Human and rodent Np enhanced the post-transcriptional expression of and co-localized with PMCA paralogs in the plasma membrane of transfected cells. Our results indicate Np as essential for PMCA expression in glutamatergic neurons allowing proper [iCa²⁺] regulation and normal circuit activity. Neuron-type-specific Np ablation empowers the investigation of circuit-coded learning and memory and identification of causal mechanisms leading to cognitive deterioration.

Presynaptic control of glycine transporter 2 (GlyT2) by physical and functional association with plasma membrane Ca2+-ATPase (PMCA) and Na+-Ca2+ exchanger (NCX)

Fast inhibitory glycinergic transmission occurs in spinal cord, brainstem, and retina to modulate the processing of motor and sensory information. After synaptic vesicle fusion, glycine is recovered back to the presynaptic terminal by the neuronal glycine transporter 2 (GlyT2) to maintain quantal glycine content in synaptic vesicles. The loss of presynaptic GlyT2 drastically impairs the refilling of glycinergic synaptic vesicles and severely disrupts neurotransmission. Indeed, mutations in the gene encoding GlyT2 are the main presynaptic cause of hyperekplexia in humans. Here, we show a novel endogenous regulatory mechanism that can modulate GlyT2 activity based on a compartmentalized interaction between GlyT2, neuronal plasma membrane Ca(2+)-ATPase (PMCA) isoforms 2 and 3, and Na(+)/Ca(2+)-exchanger 1 (NCX1). This GlyT2·PMCA2,3·NCX1 complex is found in lipid raft subdomains where GlyT2 has been previously found to be fully active. We show that endogenous PMCA and NCX activities are necessary for GlyT2 activity and that this modulation depends on lipid raft integrity. Besides, we propose a model in which GlyT2·PMCA2-3·NCX complex would help Na(+)/K(+)-ATPase in controlling local Na(+) increases derived from GlyT2 activity after neurotransmitter release.

Quantification of the brain proteome in Alzheimer's disease using multiplexed mass spectrometry

We have compared the brain proteome in the temporal neocortex between Alzheimer's disease (AD) patients and non-AD individuals by using shotgun mass spectrometry based on a stable isotope dimethyl labeling. A total of 827 unique proteins were identified and quantitated. Of these, 227 proteins were found in at least 9 out of 10 AD/control pairs and were further subjected to statistical analysis. A total of 69 proteins showed different levels (p-value < 0.05) in AD versus control brain samples. Of these proteins, 37 were increased and 32 were decreased as compared to the non-AD subjects. Twenty-three proteins comprise novel proteins that have not previously been reported as related to AD, e.g., neuronal-specific septin-3, septin-2, septin-5, dihydropteridine reductase, and clathrin heavy chain 1. The proteins with altered levels in the AD brain represent a wide variety of pathways suggested to be involved in the disease pathogenesis, including energy metabolism, glycolysis, oxidative stress, apoptosis, signal transduction, and synaptic functioning. Apart from leading to new insights into the molecular mechanisms in AD, the findings provide us with possible novel candidates for future diagnostic and prognostic disease markers.

Neuroprotective effect of anthocyanins on acetylcholinesterase activity and attenuation of scopolamine-induced amnesia in rats

Anthocyanins are a group of natural phenolic compounds responsible for the color to plants and fruits. These compounds might have beneficial effects on memory and have antioxidant properties. In the present study we have investigated the therapeutic efficacy of anthocyanins in an animal model of cognitive deficits, associated to Alzheimer's disease, induced by scopolamine. We evaluated whether anthocyanins protect the effects caused by SCO on nitrite/nitrate (NOx) levels and Na(+),K(+)-ATPase and Ca(2+)-ATPase and acetylcholinesterase (AChE) activities in the cerebral cortex and hippocampus (of rats. We used 4 different groups of animals: control (CTRL), anthocyanins treated (ANT), scopolamine-challenged (SCO), and scopolamine+anthocyanins (SCO+ANT). After seven days of treatment with ANT (200mgkg(-1); oral), the animals were SCO injected (1mgkg(-1); IP) and were performed the behavior tests, and submitted to euthanasia. A memory deficit was found in SCO group, but ANT treatment prevented this impairment of memory (P<0.05). The ANT treatment per se had an anxiolytic effect. AChE activity was increased in both in cortex and hippocampus of SCO group, this effect was significantly attenuated by ANT (P<0.05). SCO decreased Na(+),K(+)-ATPase and Ca(2+)-ATPase activities in hippocampus, and ANT was able to significantly (P<0.05) prevent these effects. No significant alteration was found on NOx levels among the groups. In conclusion, the ANT is able to regulate cholinergic neurotransmission and restore the Na(+),K(+)-ATPase and Ca(2+)-ATPase activities, and also prevented memory deficits caused by scopolamine administration.

Downregulation of PMCA2 increases the vulnerability of midbrain neurons to mitochondrial complex I inhibition

Parkinson's disease is an age-associated disorder characterized by selective degeneration of dopaminergic neurons. The molecular mechanisms underlying the selective vulnerability of this subset of neurons are, however, not fully understood. Employing SH-SY5Y neuroblastoma cells and primary mesencephalic neurons, we here demonstrate a significant increase in cytosolic calcium after inhibition of mitochondrial complex I by means of MPP(+), which is a well-established environmental toxin-based in vitro model of Parkinson's disease. This increase in calcium is correlated with a downregulation of the neuron-specific plasma membrane Ca(2+)-ATPase isoform 2 (PMCA2). Interestingly, two other important mediators of calcium efflux, sarcoplasmic reticulum Ca(2+)-ATPase (SERCA), and Na(+)-Ca(2+)-exchanger (NCX), remained unaltered, indicating a specific role of PMCA2 in maintaining calcium homeostasis in neurons. The observed PMCA2 downregulation was accompanied by reduced levels of phosphorylated CREB protein, an intracellular signaling molecule and transcriptional regulator. In order to investigate the potential influence of PMCA2 on neuronal vulnerability, experimental downregulation of PMCA2 by means of siRNA was performed. The results demonstrate a significant impairment of cell survival under conditions of PMCA2 suppression. Hence, in our cell models increased cytosolic calcium levels as a consequence of insufficient calcium efflux lead to an increased vulnerability of neuronal cells. Moreover, overexpression of PMCA2 rendered the neurons significantly resistant to complex I inhibition. Our findings point toward a dysregulation of calcium homeostasis in Parkinson's disease and suggest a potential molecular mechanism of neurodegeneration via PMCA2.

Recent advances in Membrane Biochemistry

This Biochemical Society Annual Symposium on Recent Advances in Membrane Biochemistry was organized to bring together experts from across the spectrum of biomembrane disciplines from the biological to the biophysical/structural, with the intention of promoting interactions and collaborations across the field. We were keen that the potential for improving human health that stems from a deeper understanding of membrane structure/function should be acknowledged, especially in the light of the increasing numbers of membrane protein structures that continue to be made available to the biomembrane community. This foreword provides an idea of what was communicated in the various sessions and, we hope, gives an impression of the excitement generated by the speakers and delegates at this over-subscribed Symposium.