Peptidylarginine deiminase and protein citrullination in prion diseases

The post-translational citrullination (deimination) process is mediated by peptidylarginine deiminases (PADs), which convert peptidylarginine into peptidylcitrulline in the presence of high calcium concentrations. Over the past decade, PADs and protein citrullination have been commonly implicated as abnormal pathological features in neurodegeneration and inflammatory responses associated with diseases such as multiple sclerosis, Alzheimer disease and rheumatoid arthritis. Based on this evidence, we investigated the roles of PADs and citrullination in the pathogenesis of prion diseases. Prion diseases (also known as transmissible spongiform encephalopathies) are fatal neurodegenerative diseases that are pathologically well characterized as the accumulation of disease-associated misfolded prion proteins, spongiform changes, glial cell activation and neuronal loss. We previously demonstrated that the upregulation of PAD2, mainly found in reactive astrocytes of infected brains, leads to excessive citrullination, which is correlated with disease progression. Further, we demonstrated that various cytoskeletal and energy metabolism-associated proteins are particularly vulnerable to citrullination. Our recent in vivo and in vitro studies elicited altered functions of enolase as the result of citrullination; these altered functions included reduced enzyme activity, increased protease sensitivity and enhanced plasminogen-binding affinity. These findings suggest that PAD2 and citrullinated proteins may play a key role in the brain pathology of prion diseases. By extension, we believe that abnormal increases in protein citrullination may be strong evidence of neurodegeneration.     

Astrocytes and neuropsychiatric symptoms in neurodegenerative diseases: Exploring the missing links

Neurodegenerative diseases (NDs) are characterized by primary symptoms, such as cognitive or motor deficits. In addition, the presence of neuropsychiatric symptoms (NPS) in patients with ND is being increasingly acknowledged as an important disease feature. Yet, their neurobiological basis remains unclear and mostly centered on neurons while overlooking astrocytes, which are crucial regulators of neuronal function underlying complex behaviors. In this opinion article, we briefly review evidence for NPS in ND and discuss their experimental assessment in preclinical models. We then present recent studies showing that astrocyte-specific dysfunctions can lead to NPS. Because many astrocyte alterations are also observed in ND, we suggest that they might underlie ND-associated NPS. We argue that there is a need for dedicated preclinical studies assessing astrocyte-based therapeutic strategies targeting NPS in the context of ND.     

TRIM family proteins: roles in proteostasis and neurodegenerative diseases

Neurodegenerative diseases (NDs) are a diverse group of disorders characterized by the progressive degeneration of the structure and function of the central or peripheral nervous systems. One of the major features of NDs, such as Alzheimer''s disease (AD), Parkinson''s disease (PD) and Huntington''s disease (HD), is the aggregation of specific misfolded proteins, which induces cellular dysfunction, neuronal death, loss of synaptic connections and eventually brain damage. By far, a great amount of evidence has suggested that TRIM family proteins play crucial roles in the turnover of normal regulatory and misfolded proteins. To maintain cellular protein quality control, cells rely on two major classes of proteostasis: molecular chaperones and the degradative systems, the latter includes the ubiquitin-proteasome system (UPS) and autophagy; and their dysfunction has been established to result in various physiological disorders including NDs. Emerging evidence has shown that TRIM proteins are key players in facilitating the clearance of misfolded protein aggregates associated with neurodegenerative disorders. Understanding the different pathways these TRIM proteins employ during episodes of neurodegenerative disorder represents a promising therapeutic target. In this review, we elucidated and summarized the diverse roles with underlying mechanisms of members of the TRIM family proteins in NDs.     

Multifunctional roles of enolase in Alzheimer's disease brain: beyond altered glucose metabolism

Enolase enzymes are abundantly expressed, cytosolic carbon-oxygen lyases known for their role in glucose metabolism. Recently, enolase has been shown to possess a variety of different regulatory functions, beyond glycolysis and gluconeogenesis, associated with hypoxia, ischemia, and Alzheimer's disease (AD). AD is an age-associated neurodegenerative disorder characterized pathologically by elevated oxidative stress and subsequent damage to proteins, lipids, and nucleic acids, appearance of neurofibrillary tangles and senile plaques, and loss of synapse and neuronal cells. It is unclear if development of a hypometabolic environment is a consequence of or contributes to AD pathology, as there is not only a significant decline in brain glucose levels in AD, but also there is an increase in proteomics identified oxidatively modified glycolytic enzymes that are rendered inactive, including enolase. Previously, our laboratory identified α-enolase as one the most frequently up-regulated and oxidatively modified proteins in amnestic mild cognitive impairment (MCI), early-onset AD, and AD. However, the glycolytic conversion of 2-phosphoglycerate to phosphoenolpyruvate catalyzed by enolase does not directly produce ATP or NADH; therefore it is surprising that, among all glycolytic enzymes, α-enolase was one of only two glycolytic enzymes consistently up-regulated from MCI to AD. These findings suggest enolase is involved with more than glucose metabolism in AD brain, but may possess other functions, normally necessary to preserve brain function. This review examines potential altered function(s) of brain enolase in MCI, early-onset AD, and AD, alterations that may contribute to the biochemical, pathological, clinical characteristics, and progression of this dementing disorder.     

Peptidylarginine deiminase of the mouse. Distribution, properties, and immunocytochemical localization

Peptidylarginine deiminase (protein-L-arginine iminohydrolase, EC 3.5.3.15) is widely distributed in various organs of the mouse. Activity in salivary glands, pancreas, and uterus is higher than that in the other organs. In submandibular gland and uterus, sex- and estrous cycle-related differences were observed, respectively. The activity in the submandibular gland from females was approximately four times higher than that in the male. In the uterus, the activity increased in proportion to the hyperplasia of the tissues. Peptidylarginine deiminase from the murine skeletal muscle resembles the enzyme obtained from other animal species with respect to enzymatic and chemical properties. Double immunodiffusion tests and immunoblotting analyses showed that the enzymes present in each murine tissue have the same molecular weight (81,000) and are immunologically indistinguishable. Immunohistochemical analyses of salivary glands and pancreas revealed an intense staining only of the exocrine cells. In uterus, the staining was restricted to the luminal and glandular epithelia of endometrium; the intensity of the staining changed during the course of the estrous cycle. Furthermore, immunoelectron microscopy showed that the enzyme is distributed diffusely in the cytoplasm of the exocrine cell. These observations indicate the general importance of peptidylarginine deiminase, presumably in a cytoplasmic secretory process of the exocrine cells.     

From autophagy to mitophagy: the roles of P62 in neurodegenerative diseases

P62, also called sequestosome1 (SQSTM1), is the selective cargo receptor for autophagy to degenerate misfolded proteins. It has also been found to assist and connect parkin in pink1/parkin mitophagy pathway. Previous studies showed that p62 was in association with neurodegenerative diseases, and one of the diseases pathogenesis is P62 induced autophagy and mitophagy dysfunction. Autophagy is an important process to eliminate misfolded proteins. Intracellular aggregation including α-synuclein, Huntingtin, tau protein and ß-amyloid (Aß) protein are the misfolded proteins found in PD, HD and AD, respectively. P62 induced autophagy failure significantly accelerates misfolded protein aggregation. Mitophagy is the special autophagy, functions as the selective scavenger towards the impaired mitochondria. Mitochondrial dysfunction was confirmed greatly contribute to the occurrence of neurodegenerative diseases. Through assistance and connection with parkin, P62 is vital for regulating mitophagy, thus, aberrant P62 could influence the balance of mitophagy, and further disturb mitochondrial quality control. Therefore, accumulation of misfolded proteins leads to the aberrant P62 expression, aberrant P62 influence the balance of mitophagy, forming a vicious circle afterwards. In this review, we summarize the observations on the function of P62 relevant to autophagy and mitophagy in neurodegenerative diseases, hoping to give some clear and objective opinions to further study.     

Synaptic roles of Cdk5: implications in higher cognitive functions and neurodegenerative diseases

Accumulating evidence indicates that cyclin dependent kinase 5 (Cdk5), through phosphorylating a plethora of pre- and postsynaptic proteins, functions as an essential modulator of synaptic transmission. Recent advances in the field of Cdk5 research have not only consolidated the in vivo importance of Cdk5 in neurotransmission but also suggest a pivotal role of Cdk5 in the regulation of higher cognitive functions and neurodegenerative diseases. In this review, we will discuss the recent findings on the emanating role of Cdk5 as a regulator of synaptic functions and plasticity.     

Impaired autophagy: a link between neurodegenerative and neuropsychiatric diseases

Protein misfolding, and subsequent aggregation have been proven as the leading cause of most known dementias. Many of these, in addition to neurodegeneration, show profound changes in behaviour and thinking, thus, psychiatric symptoms. On the basis of the observation that progressive myoclonic epilepsies and neurodegenerative diseases share some common features of neurodegeneration, we proposed autophagy as a possible common impairment in these diseases. Here, we argue along similar lines for some neuropsychiatric conditions, among them depression and schizophrenia. We propose that existing and new therapies for these seemingly different diseases could be augmented with drugs used for neurodegenerative or neuropsychiatric diseases, respectively, among them some which modulate or augment autophagy.     

TGF-β in the central nervous system: Potential roles in ischemic injury and neurodegenerative diseases

The Transforming Growth Factor-βs (TGF-β) are a group of multifunctional proteins whose cellular sites of production and action are widely distributed throughout the body, including the central nervous system (CNS). Within the CNS, various isoforms of TGF-β are produced by both glial and neural cells. When evaluated in either cell culture or in vivo models, the various isoforms of TGF-β have been shown to have potent effects on the proliferation, function, or survival of both neurons and all three glial cell types, astrocytes, microglia and oligodendrocytes. TGF-β has also been shown to play a role in several forms of acute CNS pathology including ischemia, excitotoxicity and several forms of neurodegenerative diseases including multiple sclerosis, Parkinson's disease, AIDS dementia and Alzheimer's disease.     

Linkage between the proteasome pathway and neurodegenerative diseases and aging

During aging, the production of free radicals increases. This can result in damage to protein, the accumulation of which is characteristic of the aging process. This questions the efficacy of proteolytic systems. Among these systems, the proteasome and the adenosine triphosphate-ubiquitin-dependent pathway have been shown to play an important role in the elimination of abnormal proteins. There are two major steps in the ubiquitin-proteasome pathway: the conjugation of a polyubiquitin degradation signal to the substrate and the subsequent degradation of the tagged protein by the 26S proteasome. The 26S proteasome is build-up from the 20S proteasome, which is a cylinder-shaped multimeric complex, and two additional 19S complexes. The 20S proteasome can also bind to 11S regulator and is then implicated in antigen presentation. These regulators confer a high adaptability on proteasome. With advancing age, predisposition to neurodegenerative diseases increases. These diseases are also characterized by protein aggregation. Several findings such as the presence of ubiquinated proteins, usually broken down by proteasomes, and genetic anomalies involving the ubiquitinproteasome system (parkin, UCH-L1) suggest a link between the ubiquitin-proteasome pathway and the genesis of these diseases.     

Theoretical insights into the protonation states of active site cysteine and citrullination mechanism of Porphyromonas gingivalis peptidylarginine deiminase

Porphyromonas gingivalis peptidylarginine deiminase (PPAD) catalyzes the citrullination of peptidylarginine, which plays a critical role in the rheumatoid arthritis (RA) and gene regulation. For a better understanding of citrullination mechanism of PPAD, it is required to establish the protonation states of active site cysteine, which is still a controversial issue for the members of guanidino‐group‐modifying enzyme superfamily. In this work, we first explored the transformation between the two states: State N (both C351 and H236 are neutral) and State I (both residues exist as a thiolate–imidazolium ion pair), and then investigated the citrullination reaction of peptidylarginine, using a combined QM/MM approach. State N is calculated to be more stable than State I by 8.46 kcal/mol, and State N can transform to State I via two steps of substrate‐assisted proton transfer. Citrullination of the peptidylarginine contains deamination and hydrolysis. Starting from State N, the deamination reaction corresponds to an energy barrier of 18.82 kcal/mol. The deprotonated C351 initiates the nucleophilic attack to the substrate, which is the key step for deamination reaction. The hydrolysis reaction contains two chemical steps. Both the deprotonated D238 and H236 can act as the bases to activate the hydrolytic water, which correspond to similar energy barriers (～17 kcal/mol). On the basis of our calculations, C351, D238, and H236 constitute a catalytic triad, and their protonation states are critical for both the deamination and hydrolysis processes. In view of the sequence similarity, these findings may be shared with human PAD1–PAD4 and other guanidino‐group‐modifying enzymes. Proteins 2017; 85:1518–1528. © 2017 Wiley Periodicals, Inc.     

Emerging links between initiation of translation and human diseases

Some diseases are caused by mutations that perturb the initiation step of translation by changing the context around the AUG(START) codon or introducing upstream AUG codons. The scanning mechanism provides a framework for understanding the effects of these and other structural changes in mRNAs derived from oncogenes, tumor suppressor genes, and other key regulatory genes. In mRNAs from mutated as well as normal genes, translation sometimes initiates from an internal AUG codon. Sanctioned mechanisms that allow this, including leaky scanning and reinitiation, are discussed. Thrombopoietin mRNA is an example in which translation normally initiates from an internal position via an inefficient reinitiation mechanism. Mutations that restructure this mRNA in ways that elevate production of thrombopoietin cause hereditary thrombocythemia, demonstrating that some mRNAs are designed deliberately with upstream AUG codons to preclude efficient translation and thus to prevent harmful overproduction of potent proteins. While upstream AUG codons in certain mRNAs thus play an important regulatory role, the frequency of upstream AUG codons tends to be exaggerated when cDNA sequences are compiled and analyzed. Because the discovery of mutations that perturb translation usually begins with cDNA analysis, some misunderstandings vis-a-vis the interpretation of cDNA sequences are discussed.     

Impaired autophagy: a link between neurodegenerative diseases and progressive myoclonus epilepsies

In recent years, research into the molecular bases of neurodegenerative diseases has progressed, and therapies have been developed to combat the causative agents. Based on the observation that progressive myoclonus epilepsies (PMEs) and neurodegenerative diseases share common features of neurodegeneration, we propose that the two pathologies share common underlying molecular characteristics. It is well documented that autophagy is overloaded or impaired in neurodegenerative conditions, and it is also impaired in some PMEs, the clearest example being EPM2 (Lafora disease). Although more research into this connection is warranted, we propose that existing therapies for PMEs could be augmented with similar drugs as those used for neurodegenerative diseases.     

Genetic tests: between risks and opportunities. The case of neurodegenerative diseases

Commercial genetic testing challenges traditional medical practice and the doctor–patient relationship. Neurodegenerative diseases may serve as the practical and ethical testing ground for the application of genomics to medicine.In the age of the Internet, a wealth of information lies at your fingertips—even your genetic ancestry and your fate in terms of health and sickness. A Google search for ‘genetic testing'' immediately comes up with a list of companies offering quick, direct-to-consumer genetic tests (DCGT) for relatively little money. “Claim your kit, spit into the tube and send it to the lab,” states the website of 23andMe—the company whose Personal Genome Service was named the ‘2008 Invention of the Year'' by Time magazine. Six to eight weeks after sending in a sample, customers can log on to the company website and learn about their genetic origins and ancestry if they opted for the ‘Fill in Your Family Tree'' option, or can explore their genetic profile under the “Health Edition” and what it says about personal disease risks and drug responses.The availability of next-generation high-throughput DNA sequencers has enabled companies to sequence the genes of a large number of customers at a low costs and with few personnel23andMe is one of several companies that offer predictive genetic tests covering a range of multifactorial and monogenic disorders (STOA, 2008). This is clearly a revolutionary approach to personalized medicine; it not only allows individuals to learn about genetic risk factors for a variety of diseases, but also does so outside the established medical system. Before the advent of DCGTs, genetic tests were only carried out at specialized medical institutions under controlled conditions, and only on referral from a physician. The decreasing price of DNA sequencing, new technologies for high-throughput sequencing and the growth of the Internet have all helped to reduce the technical, financial and access barriers to genetic testing. It is therefore not surprising that private enterprises moved into this fast-developing market.The availability of next-generation high-throughput DNA sequencers enables companies to sequence the genes of a large number of customers at a low cost and with few personnel. They can therefore offer this service at attractive prices, in the range of a few hundred dollars. The Internet conversely enables accessibility: a few mouse clicks are enough, while completely bypassing the usual checks and balances of organized healthcare. This means that expert advice is often lacking for patients about results that predict inherited risks for diabetes, cancer, neurological disorders and drug response (STOA, 2008).The simple, affordable and rapid service offered by these companies raises concerns about the clinical validity and utility of the tests, as well as the information and support that they offer to properly interpret the results. In June this year, the US Food and Drug Administration (FDA) contacted five companies that sell genetic tests directly to consumers and asked them to prove the validity of their products (Pollack, 2010). The FDA argues that genetic tests are diagnostic tools that must obtain regulatory approval before they can be marketed, but it did not order the companies to stop selling their tests. 23andMe—one of the five companies that were contacted—replied: “We are sensitive to the FDA''s concerns, but we believe that people have the right to know as much about their genes and their bodies as they choose” (Pollack, 2010). Last year, researchers from the J. Craig Venter Institute (San Diego, CA, USA) and the Scripps Translational Science Institute (La Jolla, CA, USA) reported inconsistencies between results obtained from two DCGT companies in an opinion article in Nature and made recommendations for improving predictions (Ng et al, 2009).A balance must be struck between consumer choice, consumer benefit and consumer protection. On one side is the individual''s right to have access to information about his or her health condition and health risks, so as to be able to take preventive measures. On the other side, serious questions have emerged about the lack of proper counselling in a professional setting. Are customers able to correctly understand, interpret and manage the information gained from a genetic test? Are they prepared to deal with the health risk information such a test provides? Are the scientific community and society as a whole ready to change the focus in medicine from morphological and physiological factors to molecular and genetic information?A balance must be struck between consumer choice, benefit and protectionThese concerns become more complicated when companies offer genetic tests for neurodegenerative disorders for which there are no preventive measures or treatments, such as Alzheimer, Parkinson or Huntington diseases. Most of these diseases are severe, debilitating and can lead to stigmatization and possible discrimination for patients. Brain disorders that cause progressive mental decline affect not only the health of the individual, but also their identity, self-consciousness and role within the family and society. As Judit Sándor, Director of the Centre for Ethics and Law in Biomedicine at the Central European University (Budapest, Hungary) put it: “The stigmatization of hereditary diseases in society may lead to ethical and legal consequences that are difficult to grasp. The stigma associated with neurodegenerative diseases would be even harder to bear if the disease is proven to be hereditary by some form of genetic testing.”In this context, 60 experts from a range of disciplines—scientists, clinicians, philosophers, sociologists, jurists, journalists and patients—from Europe, Canada and the USA met at the 2010 workshop ‘Brains In Dialogue On Genetic Testing'' in Trieste, Italy. The meeting was organized by the International School for Advanced Studies, as part of the European project ‘Brains in Dialogue'', which aims to foster dialogue among key stakeholders in neuroscience (www.neuromedia.eu). The use of predictive genetic testing for neurodegenerative diseases was the main focus of the meeting and represents an interesting model for discussing the risks and benefits of DCGTs.Very few neurodegenerative disorders have a typical Mendelian inheritance. The most (in)famous is Huntington disease, which typically becomes noticeable in middle age. Symptoms include progressive choreiform movements, cognitive impairment, mood disorders and behavioural changes. Huntington disease is caused by an increase in the number of CAG repeats in the gene Huntingtin, which can be tested for easily and reliably (Myers, 2004) in order to confirm a diagnosis or predict the disease, in at-risk groups or prenatally. The results have psychological and ethical implications that affect individuals and their families. According to the STOA report on DCGTs, only one company offers a test for Huntington disease.Most neurodegenerative disorders have a more complex set of genetic and environmental risk factors that make it difficult—if not impossible—to predict the risk of disease at a certain age. A small percentage of cases of Alzheimer and Parkinson diseases—usually early-onset—carry specific mutations with a Mendelian inheritance, but genetic factors are also involved in the most common late-onset forms of these diseases (Avramopoulos, 2009; Klein & Schlossmacher, 2006). Nicholas Wood of University College London, UK, commented that: “[t]here has been a revolution in our molecular genetic understanding of Parkinson''s disease. Twenty years ago Parkinson''s disease perhaps was considered the archetype of non-genetic disease. It is now clear that a growing list of genes is primarily responsible for Mendelian forms of Parkinson''s disease. It is also clear from recent studies that, due to reduced penetrance, some of these ‘Mendelian genes'' play a role in the so-called sporadic disease.” Nevertheless, a genetic test based on susceptibility genes would not enable a clear diagnosis—as in the case of Huntington disease—but only an estimate of the individual''s risk of developing the disease later in life, with varying reliability.For Alzheimer disease, genetic testing is usually only recommended for individuals with a family history of early-onset or with immediate relatives who already have the disease. The most common form of late-onset Alzheimer disease has a complex inheritance pattern. The medical establishment does not therefore recommend genetic testing for it, although a polymorphism in the Apolipoprotein E (APOE) gene has been unequivocally associated with Alzheimer disease (Avramopoulos, 2009). The identification of such risk factors through epidemiological studies provides valuable information about the molecular basis of the disease, but the management of this information at the individual level seems difficult for clinicians and patients. Agnes Allansdottir of the University of Siena, Italy, explained these difficulties stating that “research on decision-making processes demonstrates that we humans have severe problems dealing with probabilities.”Sándor expressed concerns that these difficulties could lead to additional discrimination. “Most people know what to do if they have high blood pressure, for instance. However, information coming from a genetic test is much more complex—their reading and interpretation require special expertise,” she said. She pointed out that some groups might be unable to access that expertise, while others might be unable to understand the information. “As a consequence, they will suffer an additional form of discrimination that is the ‘discrimination in the accessibility'' of sensitive and complex medical data, and that affects […] the right to privacy, as well.”…“research on decision-making processes demonstrates that we humans have severe problems dealing with probabilities”It is certainly possible that individuals who do not understand what probabilistic estimates of risk mean will be upset to find out they have a higher risk of developing a certain disorder, even though in absolute terms this risk is marginal. Avoiding this situation is what genetic counselling tries to achieve: to inform patients and help them to interpret the results of genetic tests. For the same reason, genetic testing for most common forms of late-onset Alzheimer or Parkinson disease—both of which are multifactorial—is not recommended, precisely because of the limited predictive value of these tests and the lack of proven preventive measures. However, various companies including deCODEme offer to identify your APOE variant and calculate “your risk of developing late-onset Alzheimer''s Disease” as part of their service.Research has demonstrated that genetic testing may be a useful coping strategy for some at-risk individuals (Gooding et al, 2006), a conclusion that was also reached by the Risk Evaluation and Education for Alzheimer''s Disease (REVEAL) study (Green et al, 2009). Some results showed that knowledge of their APOE genotype and numerical lifetime risk influenced the health-related behaviour of asymptomatic adult children of Alzheimer disease patients. The discovery of increased risk of disease through an education-and-disclosure protocol was associated with a stronger motivation to engage in behaviours that reduce risk, such as changes in medications or vitamin intake, even if their effectiveness is still unclear (Chao et al, 2008). Genotype disclosure did not result in short-term psychological problems, despite the frightening nature of the disease and the lack of therapies for it (Green et al, 2009). These studies highlight the importance of education and counselling in understanding risk and evaluating the means of counteracting it.Yet the ease with which DCGT companies offer tests over the Internet creates a new kind of autonomy for patients. “Genetic information serves often as a key to future decisions. Based on the information, they may rearrange the priorities in their life or change their lifestyle in order to fight against the manifestation of the disease, to decrease its symptoms or simply delay its progress,” Sándor said. “For many people, nothing else is worse than the lack of certainty and thus knowledge, in itself, can be a value.”To know or not to know: that is the question—particularly for neurodegenerative diseases. In addition to the opinions of the experts at the meeting, the public round table, ‘Health and DNA: my life, my genes'', showed that the choice whether to take a test should be a personal decision; certainly nobody should be forced in one direction or another. During the discussion, different opinions and experiences regarding the use of genetic testing were presented by members of the panel and the public. Verena Schmocker, a Swiss woman affected by Parkinson disease, explained why she refused to be tested, despite a strong family history of early-onset Parkinson disease. “I knew already that the disease was in my family, but I didn''t want to take any genetic test. I chose to live my life day by day and live what is there for me to live.” Another woman in the audience explained that she wanted to know her destiny: “[w]hen 15 years ago I was diagnosed with Huntington''s disease I woke up from a nightmare of doubts. I started organizing my life, I got married and got prepared for the future.”In many ways, Huntington disease is an unrepresentative example—not only because it is an untreatable, debilitating Mendelian disease, but also because patients typically receive mandatory and sophisticated patient counselling. Most importantly, as Marina Frontali from the National Research Council (Rome, Italy) highlighted, counselling should enable and respect autonomous decisions by the person at risk, even in light of third-party pressure to take the test, not just by employers or insurance companies, but also by family members. The counselling service for Huntington disease—through a tight collaboration between laypeople and professionals—is a valuable example of the management of genetic testing.…the ease with which DCGT companies offer tests over the Internet creates a new kind of autonomy for patientsThe Eurobarometer 2005 survey showed that EU citizens are generally supportive of the use of genetic data for diagnosis and research, and 64% of the respondents said that they would take a genetic test to detect potential diseases (EC, 2006). In reality, however, attitudes vary between countries: in most cases, people would be willing to take a test only in exceptional circumstances or only if it was highly regulated and controlled. Interestingly, those countries in which people expressed more concern and negative attitudes towards testing were those with higher levels of education and scientific literacy, where the mass media is more attentive to science and technology and where the public and political debate is more advanced. It shows, again, that increasing scientific literacy is not enough to overcome people''s fears and objections to genetic testing; the more they understand the issues, the less likely people are to be enthusiastic about new technologies.These concerns notwithstanding, the number of tests that are available is growing, and genetic testing—whether as part of the healthcare system or through DCGT companies—is becoming a model for preventive medicine and discussions about the impact of genetics on public health (Brand et al, 2008). The advances brought about by genomics will lead to more targeted health promotion messages and disease prevention programmes specifically directed at susceptible individuals and families, or at subgroups of the population, based on their genomic risk profile.The controversial nature of the political discourse concerning science and health often raises controversy, and the integration of genomics into public healthcare, research and policy might therefore be challenging. According to Brand et al (2008), the question is not whether the use of genomics in public health is dangerous, but whether excluding genomic information from public health interventions and withholding the potential of evidence-based prevention might do more harm. The next decade will provide a window of opportunity in which to prepare and educate clinicians, public health professionals, policy-makers and the public for the integration of genomics into healthcare. Brand et al (2008) argue that there is an ethical obligation to meet this challenge and make the best use of the opportunities provided by scientific progress.This, inevitably, requires a legal and regulatory framework to ensure that the benefits are made widely available to the population and, in particular, to protect consumers—today, DCGT by private companies remains a largely unregulated market. In 2008, the Committee of Ministers of the 47 Member States of the Council of Europe adopted the first international legally binding document concerning genetic testing for health purposes (Lwoff, 2009). The Additional Protocol to The Convention on Human Rights and Biomedicine about Genetic Testing for Health Purposes addresses some of the issues raised by genetic testing, from quality and clinical utility, to public information and genetic screening programmes for health purposes (Council of Europe, 2008). According to the Protocol, a health-screening programme that uses genetic tests can only be implemented if approved by the competent body, after independent evaluation of its ethical acceptability and fulfilment of specific conditions. These include the health relevance, scientific validity and effectiveness, availability of appropriate preventive or treatment measures, equitable access to the programme and availability of adequate measures to inform the population about the existence, purpose and accessibility of the screening programme, as well as the voluntary nature of participation in it.Two particular issues were discussed during the development of the Protocol: direct access to tests by individuals; and information and genetic counselling (Lwoff, 2009). The Protocol includes some debated restrictions to DCGT (Borry, 2008), to guarantee the proper interpretation of predictive test results and appropriate counselling to understand their implications. According to Article 7, with few exceptions “[a] genetic test for health purposes may only be performed under individualized medical supervision.” In order to assure quality of information and support for the patient, Article 8 states that “the person concerned shall be provided with prior appropriate information in particular on the purpose and the nature of the test, as well as the implications of its results.” Moreover, for tests for monogenic diseases, tests that aim to detect a genetic predisposition or genetic susceptibility to a disease, or tests to identify the subject as a healthy carrier of a gene responsible for a disease, appropriate genetic counselling should be available. It states that “the form and extent of this genetic counselling shall be defined according to the implications of the results of the test and their significance for the person or the members of his or her family, including possible implications concerning procreation choices.” According to this document, genetic counselling could thus go from being a “very heavy and long” procedure to a “lighter” one, but should be guaranteed in any case. The Protocol has already influenced legislation, but it will apply only in countries that have ratified it, which, so far, is only Slovenia.Companies that offer DCGTs are harbingers of change for personalized medicine. Their increasing popularity—owing not least to the ease with which their services can be obtained over the Internet—shows that the public is willing to pay for this kind of personal information. Nevertheless, healthcare systems and regulators must ensure that developments in this area benefit patients. Experience from genetic testing for neurological diseases—given their particularly severe impact on patients and their families—highlights both the current lack of proper regulation and oversight, as well as the potential health benefits that can be reaped from genetic tests.? Open in a separate windowDonato RamaniOpen in a separate windowChiara Saviane     

Apoptosis in neurodegenerative diseases: the role of mitochondria

Nerve cell death is the central feature of the human neurodegenerative diseases. It has long been thought that nerve cell death in these disorders occurs by way of necrosis, a process characterized by massive transmembrane ion currents, compromise of mitochondrial ATP production, and the formation of high levels of reactive oxygen species combining to induce rapid disruption of organelles, cell swelling, and plasma membrane rupture with a secondary inflammatory response. Nuclear DNA is relatively preserved. Recent evidence now indicates that the process of apoptosis rather than necrosis primarily contributes to nerve cell death in neurodegeneration. This has opened up new avenues for understanding the pathogenesis of neurodegeneration and may lead to new and more effective therapeutic approaches to these diseases.     

The roles of NADPH oxidase and phospholipases A2 in oxidative and inflammatory responses in neurodegenerative diseases

Reactive oxygen species (ROS) are produced in mammalian cells through enzymic and non-enzymic mechanisms. Although some ROS production pathways are needed for specific physiological functions, excessive production is detrimental and is regarded as the basis of numerous neurodegenerative diseases. Among enzymes producing superoxide anions, NADPH oxidase is widespread in mammalian cells and is an important source of ROS in mediating physiological and pathological processes in the cardiovascular and the CNS. ROS production is linked to the alteration of intracellular calcium homeostasis, activation of Ca(2+)-dependent enzymes, alteration of cytoskeletal proteins, and degradation of membrane glycerophospholipids. There is evolving evidence that ROS produced by NADPH oxidase regulate neuronal functions and degrade membrane phospholipids through activation of phospholipases A(2) (PLA(2)). This review is intended to cover recent studies describing ROS generation from NADPH oxidase in the CNS and its downstream activation of PLA(2), namely, the group IV cytosolic cPLA(2) and the group II secretory sPLA(2). A major focus is to elaborate the dual role of NADPH oxidase and PLA(2) in mediating the oxidative and inflammatory responses in neurodegenerative diseases, including cerebral ischemia and Alzheimer's disease. Elucidation of the signaling pathways linking NADPH oxidase with the multiple forms of PLA(2) will be important in understanding the oxidative and degradative mechanisms that underline neuronal damage and glial activation and will facilitate development of therapeutic intervention for prevention and treatment of these and other neurodegenerative diseases.