There is a widespread notion, both within the sciences and among the general public, that mental deterioration can rob individuals of their identity. Yet there have been no systematic investigations of what types of cognitive damage lead people to appear to no longer be themselves. We measured perceived identity change in patients with three kinds of neurodegenerative disease: frontotemporal dementia, Alzheimer’s disease, and amyotrophic lateral sclerosis. Structural equation models revealed that injury to the moral faculty plays the primary role in (...) identity discontinuity. Other cognitive deficits, including amnesia, have no measurable impact on identity persistence. Accordingly, frontotemporal dementia has the greatest effect on perceived identity, and amyotrophic lateral sclerosis has the least. We further demonstrated that perceived identity change fully mediates the impact of neurodegenerative disease on relationship deterioration between patient and caregiver. Our results mark a departure from theories that ground personal identity in memory, distinctiveness, dispositional emotion, or global mental function. (shrink)

Dysregulation of genes that control cell‐cycle progression and DNA repair is a hallmark of tumorigenesis. It is becoming increasingly apparent, however, that these defects also contribute to degeneration of post‐mitotic neurons under certain conditions. The gene for ataxia‐telangiectasia mutated (ATM) is a prototype for this dual mechanism of action, with loss‐of‐function mutations causing not only selective degeneration of cerebellar neurons but also increased susceptibility to breast cancer and hematologic malignancy. Increased dosage of amyloid precursor protein in Down syndrome (trisomy 21) (...) predisposes to dementia of Alzheimer type and may also contribute to acute leukemia and transient myeloproliferative disorder. The gene parkin, loss‐of‐function mutations in which account for about half of cases of early‐onset Parkinson disease, has been identified as a candidate tumor suppressor gene by several groups. Parkin is deleted or downregulated in several tumor types, and its re‐expression sensitizes derivative cell lines to inhibitors of cell‐cycle progression. The overlap of molecular pathways implicated in cancer and neurodegeneration challenges long‐held notions about differentiated cellular states and may open the door to novel therapeutic approaches to both groups of disorders. BioEssays 30:719–727, 2008. © 2008 Wiley Periodicals, Inc. (shrink)

Fibrillar protein aggregates are the pathological hallmark of a group of age‐dependent neurodegenerative conditions, including Alzheimer's and Parkinson's disease. Aggregates of the microtubule‐associated protein Tau are observed in Alzheimer's disease and primary tauopathies. Tau pathology propagates from cell to cell in a prion‐like process that is likely subject to modulation by extracellular chaperones such as Clusterin. We recently reported that Clusterin delayed Tau fibril formation but enhanced the activity of Tau oligomers to seed aggregation of endogenous Tau in a cellular (...) model. In contrast, Clusterin inhibited the propagation of α‐Synuclein aggregates associated with Parkinson's disease. These findings raise the possibility of a mechanistic link between Clusterin upregulation observed in Alzheimer's disease and the progression of Tau pathology. Here we review the diverse functions of Clusterin in the pathogenesis of neurodegenerative diseases, focusing on evidence that Clusterin may act either as a suppressor or enhancer of pathology. (shrink)

Glutamine repeat expansion has been established as the mutation underlying five inherited neurodegenerative diseases. The mechanism by which this apparently universal mutation, in ubiquitously expressed proteins, causes highly selective neurodegeneration is unknown. The proteins containing the glutamine expansions are otherwise unrelated and likely to have different functions. Two recently published papers(1,2) provide evidence of a conformational change occurring in polyglutamine expansions, which may allow novel interactions and is consistent with a toxic gain‐of‐function hypothesis. HAP1, a protein that interacts with (...) huntingtin (Huntington's disease protein), has an expression profile that intriguingly mirrors the selective neurodegeneration seen in Huntington's disease(2). (shrink)

Background: The research community has a mandate to discover effective treatments for neurodegenerative disorders. The ethics landscape surrounding this mandate is in a constant state of flux, and ongoing challenges place ever greater demands on investigators to be accountable to the public and to answer questions about the implications of their work for health care, society, and policy. Methods: We surveyed US-based investigators involved in neurodegenerative diseases research about how they value ethics-related issues, what motivates them to give consideration to (...) those issues, and the barriers to doing so. Using the NIH CRISP database we identified 1,034 researchers with relevant, active grants and invited them to complete an online questionnaire. We received 193 responses. We used exploratory factor analysis to transform individual survey questions into a smaller set of factors, and linear regression to understand the effect of key variables of interest on the factor scores. Results: Ethics-related issues clustered into two groups: research ethics and external influences. Heads of research groups viewed issues of research ethics to be more important than the other respondents. Concern about external influences was related to overall interest in ethics. Motivators clustered into five groups: ensuring public understanding, external forces, requirements, values, and press and public. Heads of research groups were more motivated to ensure public understanding of research than the other respondents. Barriers clustered into four groups: lack of resources, administrative burden, relevance to the research, and lack of interest. Perceived lack of ethics resources was a particular barrier for investigators working in drug discovery. Conclusions: The data suggest that senior level neuroscientists working in the field of neurodegeneration (ND), and drug discovery specifically, are motivated to consider ethics issues related to their work, but the perceived lack of ethics resources thwarts their efforts. With bioethics centres at more than 50% of the institutions at which these respondents reside, the neuroscience and bioethics communities appear to be disconnected. Dedicated ethical, legal and social implications (ELSI) programs, such as those fully integrated into genetics and regenerative medicine, provide models for achieving meaningful partnerships not yet adequately realized for scholars and trainees interested in drug discovery for ND. (shrink)

Emerging evidence supports the role for the intracellular domains of amyloid precursor protein (APP) in the physiology and function of APP. In this short report, I discuss the hypothesis that mutation of Tyr682 on the Y682ENPTY687 C‐terminal motif of APP may be directly or indirectly associated with alterations in APP functioning and activity, leading to neuronal defects and deficits. Mutation of Tyr682 induces an early and progressive age‐dependent cognitive and locomotor decline that is associated with a loss of synaptic connections, (...) a decrease in cholinergic tone, and defects in NGF signaling. These findings support a model in which APP‐C‐terminal domain exerts a pathogenic function in neuronal development and decline, and suggest that Tyr682 potentially could modulate the properties of APP metabolites in humans. (shrink)

TPPP/p25 is a recently discovered, unstructured protein involved in brain function. It is found predominantly in oligodendrocytes in normal brain but is enriched in neuronal and glial inclusions of Parkinson's disease and other synucleinopathies. Its physiological function seems to be the dynamic stabilization of microtubular ultrastructures, as well as the projections of mature oligodendrocytes and ciliary structures. We reappraise the earlier belief that TPPP/p25 is a brain‐specific protein. We have identified and cloned two shorter (N‐terminal‐free) homologs of TPPP/p25 that behave (...) differently from each other and from TPPP/p25. Two unique cell models have been established and used to study the effect of the unstructured protein on the energy metabolism and the formation of pathological aggregates. Our data suggest that the intracellular level of TPPP/p25 influences the cell differentiation, proliferation and the formation of protein aggregates, and consequently, the etiology of central nervous system diseases. (shrink)

Neurodegenerative syndromes present as proteinopathies – does ribosomal infidelity contribute to the protein toxicity that is the driving force for neuronal cell loss? Intracellular and extracellular protein aggregates overwhelm the clearance capacity of cells and tissues. Proteins aggregate when hydrophobic residues are exposed. Hydrophobic residues become exposed when proteins are misfolded. Protein misfolding can originate from translational errors at the ribosome. Indeed, the most error‐prone process in gene expression is translation at the ribosome. Recent evidence indicates that manipulating the ribosomal (...) accuracy impacts on the lifespan of model organisms and a reduced translational accuracy is accompanied by neurodegeneration. The first hit in aging‐associated neurodegenerative disease may be the well‐documented decline of cellular buffering capacity by aging. A second hit that impacts on the quality of protein synthesis could be the driving force for the observed loss of proteostasis in neurodegeneration. This hypothesis provides an explanation for the late onset of most neurodegenerative diseases. (shrink)

The nucleolus may represent a key stress response organelle in the nucleus following proteotoxic stress by serving as a platform for protein aggregates. Aggregation of proteins often results from insufficient protein degradation by the ubiquitin‐proteasome system (UPS), occurring in inclusion diseases, upon treatment by proteasome inhibitors (PIs) or due to various forms of stress. As the nucleolar inclusions resemble cytoplasmic aggresomes in gathering ubiquitin and numerous UPS components and targets, including cancer‐related transcription factors and cell cycle regulators (e.g. p53 and (...) cyclin D) and proteins involved in neurodegenerative diseases (e.g. ataxin‐1, Malin), these organelles are termed herein as nucleolar aggresomes. These nucleolar aggresomes contain polyadenylated RNA, and seem to be linked to defects in nuclear export. Nucleolar aggresomes have been identified in non‐neuronal cells, but prominent similarities with nuclear ubiquitin and/or ribonuclear foci detected in triplet and other repeat disease pathologies are revealed here, creating a common interest between research in cancer and neurodegeneration. (shrink)

Alzheimer's disease (AD) is a neurodegenerative disease exhibiting amyloid beta (Aβ) peptide accumulation as a key characteristic. Autophagy, which is dysregulated in AD, participates in the metabolism of Aβ. Unexpectedly, we recently found that autophagy, in addition to its degradative function, also mediates the secretion of Aβ. This finding adds Aβ to an increasing number of biomolecules, the secretion of which is mediated by autophagy. We also showed that inhibition of Aβ secretion through genetic deletion of autophagy leads to intracellular (...) Aβ accumulation, which enhanced neurodegeneration induced by autophagy deficiency. Hence, autophagy may play a central role in two pathological hallmarks of AD: Aβ amyloidosis and neurodegeneration. Herein, we summarize the role of autophagy in AD with focus on Aβ metabolism in light of the recently established role of autophagy in protein secretion. We discuss potential routes for autophagy‐mediated Aβ secretion and suggest experimental approaches to further elucidate its mechanisms. (shrink)

Recently opposing effects of cysteine protease inhibitors, the human cystatins, on neurodegeneration have been reported. Human cystatin C is a risk factor for late‐onset Alzheimer's disease (AD), whereas human stefin B (cystatin B) has no direct involvement in AD. Conflicting data show that their target protease, cathepsin B, might be anti‐amyloidogenic, helping in amyloid‐beta (Aβ) clearance or, instead, might be involved in Aβ production. Some reports claim that cystatin C binds soluble Aβ, making transgenic animals healthier, others, in contrast, (...) that deleting cystatins genes may contribute to amyloid pathology in animal models of AD. (shrink)

The tricarboxylic acid (TCA) or Krebs cycle, which takes place in prokaryotic cells and in the mitochondria of eukaryotic cells, is central to life on Earth and participates in key events such as energy production and anabolic processes. Despite its relevance, it is not perceived as tightly regulated compared to other key metabolisms such as glycolysis/gluconeogenesis. A better understanding of the functioning of the TCA cycle is crucial due to mitochondrial function impairment in several diseases, especially those that occur with (...) neurodegeneration. This article revisits what is known about the regulation of the Krebs cycle and hypothesizes the need for large‐scale, rapid regulation of TCA cycle enzyme activity. Evidence of mitochondrial enzyme activity regulation by activation/deactivation of protein kinases and phosphatases exists in the literature. Apart from indirect regulation via G protein‐coupled receptors (GPCRs) at the cell surface, signaling upon activation of GPCRs in mitochondrial membranes may lead to a direct regulation of the enzymes of the Krebs cycle. Hormonal‐like regulation by posttranscriptional events mediated by activable kinases and phosphatases deserve proper assessment using isolated mitochondria. Also see the video abstract here: https://youtu.be/aBpDSWiMQyI. (shrink)

AMP‐activated protein kinase (AMPK) is an evolutionarily conserved cellular switch that activates catabolic pathways and turns off anabolic processes. In this way, AMPK activation can restore the perturbation of cellular energy levels. In physiological situations, AMPK senses energy deficiency (in the form of an increased AMP/ATP ratio), but it is also activated by metabolic insults, such as glucose or oxygen deprivation. Metformin, one of the most widely prescribed anti‐diabetic drugs, exerts its actions by AMPK activation. However, while the functions of (...) AMPK as a metabolic regulator are fairly well understood, its actions in neuronal cells only recently gained attention. This review will discuss newly emerged functions of AMPK in neuroprotection and neurodegeneration. Additionally, recent views on the role of AMPK in autophagy, an important catabolic process that is also involved in neurodegeneration and cancer, will be highlighted. (shrink)

Humans can recollect past events in details and/or know that an object, person, or place has been encountered before. During the last two decades, there has been intense debate about how recollection and familiarity are organized in the brain. Here, we propose an integrative memory model which describes the distributed and interactive neurocognitive architecture of representations and operations underlying recollection and familiarity. In this architecture, the subjective experience of recollection and familiarity arises from the interaction between core systems and an (...) attribution system. By integrating principles from current theoretical views about memory functioning, we provide a testable framework to refine the prediction of deficient versus preserved mechanisms in memory-impaired populations. The case of Alzheimer's disease is considered as an example because it entails progressive lesions starting with limited damage to core systems before invading step-by-step most parts of the model-related network. We suggest a chronological scheme of cognitive impairments along the course of AD, where the inaugurating deficit would relate early neurodegeneration of the perirhinal/anterolateral entorhinal cortex to impaired familiarity for items that need to be discriminated as viewpoint-invariant conjunctive entities. The integrative memory model can guide future neuropsychological and neuroimaging studies aiming to understand how such a network allows humans to remember past events, to project into the future, and possibly also to share experiences. (shrink)

The question of what makes someone the same person through time and change has long been a preoccupation of philosophers. In recent years, the question of what makes ordinary or lay people judge that someone is—or isn’t—the same person has caught the interest of experimental psychologists. These latter, empirically oriented researchers have sought to understand the cognitive processes and eliciting factors that shape ordinary people’s judgments about personal identity and the self. Still more recently, practitioners within an emerging discipline, experimental (...) philosophical bioethics or “bioxphi”—the focus of this chapter—have adopted a similar aim and employed similar methodologies, but with two distinctive features: (a) a special concern for enhanced ecological validity in the examples and populations studied; and (b) an interest in contributing to substantive normative debates within the wider field of bioethics. Our aim in this chapter is to sample illustrative work on personal identity in bioxphi, explore how it relates to studies in psychology covering similar terrain, and draw out the implications of this work for matters of bioethical concern. In pursuing these issues, we highlight recent work in bioxphi that includes the perceived validity of advance directives following neurodegeneration, the right of psychologically altered study participants to withdraw from research, how drug addiction may cause one to be regarded by others as “a completely different person,” the effect of deep-brain stimulation on perceptions of the self, and the potential influence of moral enhancement interventions on intuitive impressions of a person’s character. (shrink)

The evolution of a relevant nosological concept reflects changes in the distinction between what is recognized and defined as normal and pathologic. Attention is directed to the rationale and value of detecting subclinical aging-related modifications in cognitive performance. The position that different kinds of dementias may have precedents in etiological-specific kinds of early or mild cognitive impairments (MCI) supports targeting people earlier for study of these subclinical symptoms. Because heterogeneous disorders can be expected to have multiple patterns of cognitive and (...) behavioral changes, useful conceptual nosologies should be flexible. Yet clinical research primarily restricts its focus to a single pathway where MCI leads to Alzheimer's disease (AD), and uses selective recruitment, washout screenings, repeated trialing of similar compounds, and other methods that bank the published evidence in favor of the existing therapies and their modest efficacy. This focus on AD recursively colors MCI, not as a flexible "human kind" in need of more careful research, but like AD, as an essential "natural kind." Early determination of MCI targets a potential pharmaceutical market of a quarter to a half of the population over sixty-five and the individual experiencing cognitive decline in its early stages is aware and sensitive to their surroundings, to a linked sociodegeneration with neurodegeneration. This paper examines how classifying people changes both the classifier and the subject of classification. The potential for conflict of interest is raised regarding what new causal knowledge and techniques for ascertainment are selected. Reading evidence from epidemiology, neurology, and clinical studies through science studies and bioethics lenses, we explore the possibility of a pluralistic model of cognitive impairment nosology where biological/pathologic processes respond and interrelate with a normal healthy state. (shrink)

Coronavirus disease 2019 (COVID-19) is likely to have long-term mental health effects on individuals who have recovered from COVID-19. Rightly, there is a global response for recognition and planning on how to deal with mental health problems for everyone impacted by the global pandemic. This does not just include COVID-19 patients but the general public and health care workers as well. There is also a need to understand the role of the virus itself in the pathophysiology of mental health disorders (...) and longer-term mental health sequelae. Emerging evidence suggests that COVID-19 patients develop neurological symptoms such as headache, altered consciousness, and paraesthesia. Brain tissue oedema and partial neurodegeneration have also been observed in an autopsy. In addition, there are reports that the virus has the potential to cause nervous system damage. Together, these findings point to a possible role of the virus in the development of acute psychiatric symptoms and long-term neuropsychiatric sequelae of COVID-19. The brain pathologies associated with COVID-19 infection is likely to have a long-term impact on cognitive processes. Evidence from other viral respiratory infections, such as severe acute respiratory syndrome (SARS), suggests a potential development of psychiatric disorders, long-term neuropsychiatric disorders, and cognitive problems. In this paper, we will review and evaluate the available evidence of acute and possible long-term neuropsychiatric manifestations of COVID-19. We will discuss possible pathophysiological mechanisms and the implications this will have on preparing a long-term strategy to monitor and manage such patients. (shrink)

The extracellular‐signal regulated kinases 1/2 (ERK or ERKs) are involved in the regulation of important neuronal functions, including neuronal plasticity in normal and pathological conditions. We present findings that support the notion that the kinetics and localization of ERK are intrinsically linked, in that the duration of ERK activation dictates its subcellular compartmentalization and/or trafficking. The latter, in turn, dictates whether ERK‐expressing cells would enter a program of cell death, survival or differentiation. We summarize experimental data showing that chronic activation (...) of ERK plays a role in the mechanisms that trigger neurodegeneration. We also discuss how MKPs, members of the subclass of dual specificity phosphatases, might be the link between ERK kinetics and its subcellular localization. BioEssays 25:1085–1095, 2003. © 2003 Wiley Periodicals, Inc. (shrink)

The Golgi apparatus in vertebrate cells consists of individual Golgi stacks fused together in a continuous ribbon structure. The ribbon structure per se is not required to mediate the classical functions of this organelle and the relevance of the “ribbon” structure has been a mystery since first identified ultrastructurally in the 1950s. Recent advances recognize a role for the Golgi apparatus in a range of cellular processes, some mediated by signaling networks which are regulated at the Golgi. Here we review (...) the cellular processes and signaling events regulated by the Golgi apparatus and, in particular, explore an emerging theme that the ribbon structure of the Golgi contributes directly to the regulation of these higher order functions. The Golgi apparatus has recently emerged as a signaling hub for co-ordinating cellular processes. Here we explore the concept that the Golgi ribbon structure is critical in regulating higher order processes. Changes in Golgi ribbon morphology, that is, fragmentation into mini-stacks, modulate cellular processes, and are associated with diseases including neurodegeneration and cancer. (shrink)

It might seem counterintuitive to think transhumanists, who are typically characterized by extreme techno-optimism and hope for radical life-extension, would be interested in assisted dying. Because the technological enhancements they long for will probably not be available during their natural lifetimes, many transhumanists at least entertain the idea of having themselves cryonically preserved to buy some additional time for real-world technology to catch up to their dreams. However, since an ideal preservation would take place before serious cellular deterioration sets in, (...) controlling the time and manner of death would be very attractive for transhumanist cryonicists. This chapter identifies some circumstances under which they might be justified in seeking assistance in dying (even though they would describe it as something more akin to hibernating). After providing a fundamental overview of both transhumanism and cryonics, and then making my case for what some scholars have called “cryothanasia” (i.e. assisted dying for the purpose of improved preservation quality), I proceed to consider some scenarios meant to test the limits of this justification. While things are admittedly murkier when considering the possibility of cryothanasia outside the context of imminent medical collapse, I can see no insurmountable criticisms of cryothanasia as a last resort in cases of (currently) terminal and irreparable neurodegeneration or other forms of progressive brain damage. (shrink)

Hedgehog is an important morphogenic signal that directs pattern formation during embryogenesis, but its activity also remains present through adult life. It is now becoming increasingly clear that during the reproductive phase of life and beyond it continues to direct cell renewal (which is essential to combat the chronic environmental stress to which the body is constantly exposed) and counteracts vascular, osteolytic and sometimes oncological insults to the body. Conversely, down‐regulation of hedgehog signalling is associated with ageing‐related diseases such as (...) type 2 diabetes, neurodegeneration, atherosclerosis and osteoporosis. Hence, in this essay we argue that hedgehog signalling is not only important at the start of life, but also constitutes an important anti‐geriatric influence, and that enhanced understanding of its properties may contribute to developing rational strategies for healthy ageing and prevention of ageing‐related diseases.Also watch the Video Abstract. (shrink)

A new therapeutic approach is being developed for the treatment of Alzheimer's disease (AD). This approach involves the deliberate induction of an autoimmune response to amyloid‐β (Aβ) peptide, the constituent of neuritic plaques that is thought to cause the neurodegeneration and dementia in AD. If this approach is to be effective, antibodies must be produced that can selectively target the toxic forms of Aβ, while leaving the functionally‐relevant forms of Aβ and its precursor protein untouched. Furthermore, an approach needs (...) to be found that avoids provoking an acute neuroinflammatory response. The situation is made even more challenging by uncertainty regarding which isoforms of Aβ contribute to the pathogenesis of AD. BioEssays 25:283–288, 2003. © 2003 Wiley Periodicals, Inc. (shrink)

Substantial evidence implicates fast axonal transport (FAT) defects in neurodegeneration. In Alzheimer's disease (AD), it is controversial whether transport defects cause or arise from amyloid‐β (Aβ)‐induced toxicity. Using a novel, unbiased genetic screen, Morihara et al. identified kinesin light chain‐1 splice variant E (KLC1vE) as a modifier of Aβ accumulation. Here, we propose three mechanisms to explain this causal role. First, KLC1vE reduces APP transport, leading to Aβ accumulation. Second, reduced transport of APP by KLC1vE triggers an ER stress (...) response that activates the amyloidogenic pathway. Third, KLC1vE impairs transport of other KLC1 cargos that regulate amyloidogenesis, promoting Aβ retention within the secretory pathway. Collectively, KLC1vE perpetuates a vicious cycle of Aβ generation, kinase dysregulation, and global FAT impairment that inevitably leads to cellular toxicity. These concepts implicate alternative splicing of KLC1 in AD and suggest that the reciprocal influence of transport mechanisms on disease states contributes to neurodegeneration. (shrink)

A new therapeutic approach is being developed for the treatment of Alzheimer's disease (AD). This approach involves the deliberate induction of an autoimmune response to amyloid‐β (Aβ) peptide, the constituent of neuritic plaques that is thought to cause the neurodegeneration and dementia in AD. If this approach is to be effective, antibodies must be produced that can selectively target the toxic forms of Aβ, while leaving the functionally‐relevant forms of Aβ and its precursor protein untouched. Furthermore, an approach needs (...) to be found that avoids provoking an acute neuroinflammatory response. The situation is made even more challenging by uncertainty regarding which isoforms of Aβ contribute to the pathogenesis of AD. BioEssays 25:283–288, 2003. © 2003 Wiley Periodicals, Inc. (shrink)

The choroid plexuses (CPs) are involved in the most-basic aspects of neural function including maintaining the extracellular milieu of the brain by actively modulating chemical exchange between the CSF and brain parenchyma, surveying the chemical and immunological status of the brain, detoxifying the brain, secreting a nutritive “cocktail” of polypeptides and participating in repair processes following trauma. This diversity of functions may mean that even modest changes in the CP can have far-reaching effects. Indeed, changes in the anatomy and physiology (...) of the CP have been linked to aging and several CNS diseases. It is also possible that replacing diseased or transplanting healthy CP might be useful for treating acute and chronic brain diseases. This review focuses on the wide-ranging and under-appreciated functions of the CP, alterations of these functions in aging and neurodegeneration, and recent demonstrations of the therapeutic potential of transplanted CP for neural trauma. BioEssays 27:262–274, 2005. © 2005 Wiley Periodicals, Inc. (shrink)

Ghosn, Mariam Huntington's disease (HD) is an inherited disorder. Sufferers usually develop symptoms in midlife between the ages of 30 and 50 years. HD causes neurodegeneration resulting in the progressive development of physical, cognitive and emotional symptoms. The impact on sufferers worsens over time with the final stage of the disease resulting in the need for professional assistance in a long-term care facility. More rarely HD develops in children and young adults, with less than 5% of HD sufferers being (...) affected by Juvenile HD. This article considers the ethical aspects of such testing. (shrink)

The World Health Organisation recently listed air pollution as the most significant threat to human health. Air pollution comprises particulate matter (PM), metals, black carbon and gases such as ozone (O3), nitrogen dioxide (NO2) and carbon monoxide (CO). In addition to respiratory and cardiovascular disease, PM exposure is linked with increased risk of neurodegeneration as well as neurodevelopmental impairments. Critically, studies suggest that PM crosses the placenta, making direct in utero exposure a reality. Rodent models reveal that neuroinflammation, neurotransmitter (...) imbalance and oxidative stress are triggered following gestational/early life exposure to PM, and may be exacerbated by concomitant mitochondrial dysfunction. Gestational PM exposure (potentiated by mitochondrial impairment in the metabolically active neonatal brain) not only impacts neurodevelopment but may sensitise the brain to subsequent cognitive impairment. Having reviewed this field, we conclude that strategies are urgently required to reduce exposure to PM during this sensitive developmental period. (shrink)

IntroductionThis study aimed to evaluate, in adults with mild cognitive impairment, the brain atrophy that may distinguish between three AT biomarker-based profiles, and to determine its clinical value.MethodsStructural MRI was employed to evaluate the volume and cortical thickness differences in MCI patients with different AT profiles, namely, A−T−−: normal AD biomarkers; A+T−−: AD pathologic change; and A+T++: prodromal AD. Sensitivity and specificity of these changes were also estimated.ResultsAn initial atrophy in medial temporal lobe areas was found in the A+T−− and (...) A+T++ groups, spreading toward the parietal and frontal regions in A+T++ patients. These structural changes allowed distinguishing AT profiles within the AD continuum; however, the profiles and their pattern of neurodegeneration were unsuccessful to determine the current clinical status.ConclusionsMRI is useful in the determination of the specific brain structural changes of AT profiles along the AD continuum, allowing differentiation between MCI adults with or without pathological AD biomarkers. (shrink)

Inflammatory responses are essential for the clearance of pathogens and the repair of injured tissues; however, if these responses are not properly controlled chronic inflammation can occur. Chronic inflammation is now recognized as a contributing factor to many age‐associated diseases including metabolic disorders, arthritis, neurodegeneration, and cardiovascular disease. Due to the connection between chronic inflammation and these diseases, it is essential to understand underlying mechanisms behind this process. In this review, factors that contribute to chronic inflammation are discussed. Further, (...) we emphasize the emerging roles of microRNAs (miRNAs) and other noncoding RNAs (ncRNA) in regulating chronic inflammatory states, making them important future diagnostic markers and therapeutic targets. Copyright Line: © 2015 The Authors BioEssays Published by Wiley‐VCH Verlag GmbH & Co. KGaA. (shrink)

Over the past two decades, research on neural transplantation in animal models of neurodegeneration has provided provocative in sights into the therapeutic use of grafted tissue for various neurological diseases. Although great strides have been made and functional benefits gained in these animal models, much information is still needed with regard to transplantation in human patients. Several factors are unique to human disease, for example, age of the recipient, duration of disease, and drug interaction with grafted cells; these need (...) to be explored before grafting can be considered a safe and effective therapeutic tool. (shrink)

Recently, βIII spectrins have been recognized as ataxia disease genes, with the identification by Ikeda and co‐workers of pathogenic mutations in the SPTBN2 gene in three large (and mapped) SCA5 families of American and European origin.(1) With their discovery, the large “Lincoln” family has been traced back to the underlying genetic defect for the slowly progressive cerebellar ataxia. In addition, the involvement of this component of the cytoskeleton directs attention towards the possible role of organelle stability during neurodegeneration. The (...) findings suggest that the mechanical properties of neurons and their dynamics may be as important as altered Ca2+ homeostasis, transcriptional dysregulation, and impaired protein degradation in neurodegeneration conditions. BioEssays 28: 785–787, 2006. © 2006 Wiley Periodicals, Inc. (shrink)

The personal identity relation is of great interest to philosophers, who often consider fictional scenarios to test what features seem to make persons persist through time. But often real examples of neuroscientific interest also provide important tests of personal identity. One such example is the case of Phineas Gage – or at least the story often told about Phineas Gage. Many cite Gage’s story as example of severed personal identity; Phineas underwent such a tremendous change that Gage “survived as a (...) different man.” I discuss a recent empirical finding about judgments about this hypothetical. It is not just the magnitude of the change that affects identity judgment; it is also the negative direction of the change. I present an experiment suggesting that direction of change also affects neuroethical judgments. I conclude we should consider carefully the way in which improvements and deteriorations affect attributions of personal identity. This is particularly important since a number of the most crucial neuroethical decisions involve varieties of cognitive enhancements or deteriorations. (shrink)

Brain function depends on the cooperation between highly specialized cells. Neurons generate electrical signals and glial cells provide structural and metabolic support. Here, I propose a new kind of job‐sharing between neurons and astrocytes. Recent studies on primary cultures of highly purified neurons from the rodent central nervous system (CNS) suggest that, during development, neurons reduce or even abandon cholesterol synthesis to save energy and import cholesterol from astrocytes via lipoproteins. The cholesterol shuttle may be restricted to compartments distant from (...) the soma including synapses and may be regulated by electrical activity. Testing these hypotheses will help to improve our still insufficient understanding of brain cholesterol metabolism and its role in neurodegeneration. BioEssays 25:72–78, 2003. © 2002 Wiley Periodicals, Inc. (shrink)

Polyglutamine (polyQ) diseases are genetically inherited neurodegenerative disorders. They are caused by mutations that result in polyQ expansions of particular proteins. Mutant proteins form intranuclear aggregates, induce cytotoxicity and cause neuronal cell death. Protein interaction data suggest that polyQ regions modulate interactions between coiled‐coil (CC) domains. In the case of the polyQ disease spinocerebellar ataxia type‐1 (SCA1), interacting proteins with CC domains further enhance aggregation and toxicity of mutant ataxin‐1 (ATXN1). Here, we suggest that CC partners interacting with the polyQ (...) region of a mutant protein, increase its aggregation while partners that interact with a different region reduce the formation of aggregates. Computational analysis of genetic screens revealed that CC‐rich proteins are highly enriched among genes that enhance pathogenicity of polyQ proteins, supporting our hypothesis. We therefore suggest that blocking interactions between mutant polyQ proteins and their CC partners might constitute a promising preventive strategy against neurodegeneration. (shrink)

The ubiquitin–proteasome system (UPS) is the major proteolytic pathway that degrades intracellular proteins in a regulated manner. Deregulation of the UPS has been implicated in the pathogenesis of many neurodegenerative disorders like Alzheimer's disease, Parkinson's diseases, Huntington disease, Prion‐like lethal disorders, in the pathogenesis of several genetic diseases including cystic fibrosis, Angelman's syndrome and Liddle syndrome and in many cancers. Multiple lines of evidence have already proved that UPS has the potential to be an exciting novel therapeutic target for the (...) treatment of these diseases. Here I review how aberrant functions of various genes have implicated UPS in many human disorders including neurodegeneration and cancers. I also discuss the finding that some proteasome inhibitors possess a therapeutic potential as drugs against many such diseases. BioEssays 30:1172–1184, 2008. © 2008 Wiley Periodicals, Inc. (shrink)

Apoptosis‐inducing factor (AIF) is expelled from mitochondria after some apoptotic stimuli and translocates to the nucleus, which may contribute to DNA and nuclear fragmentation in some non‐physiological mammalian cell deaths. Conversely, the requirement for mitochondrial AIF in oxidative phosphorylation and energy generation provides a plausible explanation for the embryonic lethality or neurodegeneration that has been found in different AIF‐deficient mouse models. These findings may help illuminate the ability of mitochondrial AIF to suppress cytoplasmic stress granule formation and to promote (...) the tumorigenic growth of cancer cells. AIF is ideally located in the mitochondrion to perform a vital normal function in energy production. Once it translocates to the nucleus, however, the cell might die either of energy failure or nuclear fragmentation (or both). We propose that the main function of AIF is to support energy production in both normal and transformed cell physiology, whereas nuclear‐translocated AIF might contribute to stress‐induced or pathological cell death in certain scenarios. BioEssays 28: 834–843, 2006. © 2006 Wiley Periodicals, Inc. (shrink)

The transcription factor Nrf2 is the master regulator of cellular stress response, facilitating the expression of cytoprotective genes, including those responsible for drug detoxification, immunomodulation, and iron metabolism. FDA‐approved Nrf2 activators, Tecfidera and Skyclarys for patients with multiple sclerosis and Friedreich's ataxia, respectively, are non‐specific alkylating agents exerting side effects. Nrf2 is under feedback regulation through its target gene, transcriptional repressor Bach1. Specifically, in Parkinson's disease and other neurodegenerative diseases with Bach1 dysregulation, excessive Bach1 accumulation interferes with Nrf2 activation. Bach1 (...) is a heme sensor protein, which, upon heme binding, is targeted for proteasomal degradation, relieving the repression of Nrf2 target genes. Ideally, a combination of Nrf2 stabilization and Bach1 inhibition is necessary to achieve the full therapeutic benefits of Nrf2 activation. Here, we discuss recent advances and future perspectives in developing small molecule inhibitors of Bach1, highlighting the significance of the Bach1/Nrf2 signaling pathway as a promising neurotherapeutic strategy. (shrink)

Lysosomal positioning is an important factor in regulating cellular responses, including autophagy. Because proteins encoded by disease‐responsible genes are involved in lysosomal trafficking, proper intracellular lysosomal trafficking is thought to be essential for cellular homeostasis. In the past few years, the mechanisms of lysosomal trafficking have been elucidated with a focus on adapter proteins linking motor proteins to lysosomes. Here, we outline recent findings on the mechanisms of lysosomal trafficking by focusing on adapter protein c‐Jun NH2‐terminal kinase‐interacting protein (JIP) 4, (...) which plays a central role in this process, and other JIP4 functions and JIP family proteins. Additionally, we discuss neuronal diseases associated with aberrance in the JIP family protein. Accumulating evidence suggests that chemical manipulation of lysosomal positioning may be a therapeutic approach for these neuronal diseases. (shrink)

Ageing is associated with a decline in autophagy and elevated reactive oxygen species (ROS), which can breach the capacity of antioxidant systems. Resulting oxidative stress can cause further cellular damage, including DNA breaks and protein misfolding. This poses a challenge for longevous organisms, including humans. In this review, we hypothesise that in the course of human evolution selective autophagy receptors (SARs) acquired the ability to sense and respond to localised oxidative stress. We posit that in the vicinity of protein aggregates (...) and dysfunctional mitochondria oxidation of key cysteine residues in SARs induces their oligomerisation which initiates autophagy. The degradation of damaged cellular components thus could reduce ROS production and restore redox homeostasis. This evolutionarily acquired function of SARs may represent one of the biological adaptations that contributed to longer lifespan. Inversely, loss of this mechanism can lead to age‐related diseases associated with impaired autophagy and oxidative stress. (shrink)

No overarching hypotheses tie the basic mechanisms of mitochondrial reactive oxygen species (ROS) production to activity dependent synapse pruning—a fundamental biological process in health and disease. Neuronal activity divergently regulates mitochondrial ROS: activity decreases whereas inactivity increases their production, respectively. Placing mitochondrial ROS as innate synaptic activity sentinels informs the novel hypothesis that: (1) at an inactive synapse, increased mitochondrial ROS production initiates intrinsic apoptosis dependent pruning; and (2) at an active synapse, decreased mitochondrial ROS production masks intrinsic apoptosis dependent (...) pruning. Immature antioxidant defense may enable the developing brain to harness mitochondrial ROS to prune weak synapses. Beyond development, endogenous antioxidant defense constrains mitochondrial (ROS) to mask pruning. Unwanted age‐related synapse loss may arise when mitochondrial ROS aberrantly recapitulate developmental pruning. Placing mitochondrial ROS with their hands on the shears is beneficial in early but deleterious in later life. (shrink)

The transactivation response‐DNA binding protein of 43 kDa (TDP‐43) is an aggregation‐prone nucleic acid‐binding protein linked to the etiology of Amyotrophic Lateral Sclerosis (ALS) and Frontotemporal Lobar Degeneration (FTLD). These conditions feature the accumulation of insoluble TDP‐43 aggregates in the neuronal cytoplasm that lead to cell death. The dynamics between cytoplasmic and nuclear TDP‐43 are altered in the disease state where TDP‐43 mislocalizes to the cytoplasm, disrupting Nuclear Pore Complexes (NPCs), and ultimately forming large fibrils stabilized by the C‐terminal prion‐like (...) domain. Here, we review three emerging and poorly understood aspects of TDP‐43 biology linked to its aggregation. First, how post‐translational modifications in the proximity of TDP‐43 N‐terminal domain (NTD) promote aggregation. Second, how TDP‐43 engages FG‐nucleoporins in the NPC, disrupting the pore permeability and function. Third, how the importin α/β heterodimer prevents TDP‐43 aggregation, serving both as a nuclear import transporter and a cytoplasmic chaperone. (shrink)

Amyloid fibril formation plays a central role in the pathogenesis of a number of neurodegenerative diseases, including Alzheimer and Parkinson diseases. Transient prefibrillar oligomers forming during the aggregation process, exhibiting a small size and a large hydrophobic surface, can aberrantly interact with a number of molecular targets on neurons, including the lipid bilayer of plasma membranes, resulting in a fatal outcome for the cells. By contrast, the mature fibrils, despite presenting generally a high hydrophobic surface, are endowed with a low (...) diffusion rate and poorly penetrate the interior of the lipid bilayer. However, increasing evidence shows that both intracellular α‐synuclein fibrils, as well and as extracellular amyloid‐β and β2‐microglobulin fibrils, can release oligomers over time that quickly diffuse to reach the membrane of the neighboring cells. The persistent leakage of harmful oligomers from fibrils triggers an ongoing cascade of events resulting in a sustained injury to neurons and glia and also provides aggregates with the ability to cross biological membranes and diffuse between cells or cellular compartments. (shrink)

Synthetic biology is an emerging engineering discipline that attempts to design and rewire biological components, so as to achieve new functions in a robust and predictable manner. The new tools and strategies provided by synthetic biology have the potential to improve therapeutics for neurodegenerative diseases. In particular, synthetic biology will help design small molecules, proteins, gene networks, and vectors to target disease‐related genes. Ultimately, new intelligent delivery systems will provide targeted and sustained therapeutic benefits. New treatments will arise from combining (...) ‘protect and repair’ strategies: the use of drug treatments, the promotion of neurotrophic factor synthesis, and gene targeting. Going beyond RNAi and artificial transcription factors, site‐specific genome modification is likely to play an increasing role, especially with newly available gene editing tools such as CRISPR/Cas9 systems. Taken together, these advances will help develop safe and long‐term therapies for many brain diseases in human patients. (shrink)

The etiology of Tauopathies, a diverse class of neurodegenerative diseases associated with the Microtubule Associated Protein (MAP) Tau, is usually described by a common mechanism in which Tau dysfunction results in the loss of axonal microtubule stability. Here, we reexamine and build upon the canonical disease model to encompass other Tau functions. In addition to regulating microtubule dynamics, Tau acts as a modulator of motor proteins, a signaling hub, and a scaffolding protein. This diverse array of functions is related to (...) the dynamic nature of Tau isoform expression, post‐translational modification (PTM), and conformational flexibility. Thus, there is no single mechanism that can describe Tau dysfunction. The effects of specific pathogenic mutations or aberrant PTMs need to be examined on all of the various functions of Tau in order to understand the unique etiology of each disease state. (shrink)

The conventional approach to developing disease‐modifying treatments for neurodegenerative conditions has been to identify drivers of pathology and inhibit such pathways. Here we discuss the possibility that the efficacy of such approaches may be increasingly attenuated as disease progresses. This is based on experiments using mouse models of spinocerebellar ataxia type 1 and Huntington's disease (HD), where expression of the dominantly acting mutations could be switched off, as well as studies in human HD, which suggest that the primary genetic driver (...) of age‐of‐onset of disease is a much weaker determinant of disease progression in affected individuals. The idea that one may approach a point in the disease course where such rational therapeutic strategies based on targets which determine onset of disease have minimal efficacy, suggests that one needs to consider other approaches to therapies and clinical trial design, including initiation of therapies in presymptomatic individuals. (shrink)

Parkinson's disease (PD) is generally sporadic but a number of genetic diseases have parkinsonism as a clinical feature. Two dominant genes, α‐synuclein (SNCA) and leucine‐rich repeat kinase 2 (LRRK2), are important for understanding inherited and sporadic PD. SNCA is a major component of pathologic inclusions termed Lewy bodies found in PD. LRRK2 is found in a significant proportion of PD cases. These two proteins may be linked as most LRRK2 PD cases have SNCA‐positive Lewy bodies. Mutations in both proteins are (...) associated with toxic effects in model systems although mechanisms are unclear. LRRK2 is an intracellular signaling protein possessing both GTPase and kinase activities that may contribute to pathogenicity. A third protein, tau, is implicated as a risk factor for PD. We discuss the potential relationship between these genes and suggest a model for PD pathogenesis where LRRK2 is upstream of pathogenic effects through SNCA, tau, or both proteins. (shrink)