Pros and cons of inhibiting cholesteryl ester transfer protein

Whether or not it is desirable to inhibit cholesteryl ester transfer protein (CETP) has been an important question for over fifteen years since genetic CETP deficiency was found. Recently, some epidemiological studies which have been reported in Japan as well as Western countries help to clarify the atherogenicity of human subjects with mutations or polymorphisms in the CETP gene. In addition, some experimental atherosclerosis studies, in which CETP was inhibited in rabbits with different approaches, have been reported. There was a considerable difference in the atherogenicity of human CETP deficiency and CETP-inhibited rabbits. In this review, we summarize the recent advances in this field as well as discussing the significance of CETP in reverse cholesterol transport, a major protective system against atherosclerosis.     

Alpha-synuclein and the pathogenesis of Parkinson's disease

Lesions known as Lewy bodies (LBs) and Lewy neurites (LNs) characterise brains of Parkinson's disease (PD) patients. Intracellular aggregation of alpha-synuclein (alpha-syn) appears to play a key role in the generation of LBs and LNs. Such aggregation in the presence of redox metals may initiate Fenton reaction-mediated generation of reactive oxygen species (ROS). ROS thus generated may result in cytotoxic mechanisms such as the induction of DNA single-strand breaks.     

自噬在帕金森病发病中的作用

自噬是广泛存在于真核细胞内的一种溶酶体依赖性的降解途径,主要起着调节性的作用以保护细胞免遭感染、癌症、神经变性、老化,以及心脏疾病等在内的各种病理性损伤,与细胞的存活、分化、发育和内环境稳态的维持密切相关.近来的研究表明,自噬在清除与神经变性疾病相关的错误折叠蛋白和易聚集蛋白方面起关键作用,尤其在帕金森病的发生、发展过程中发挥重要作用.     

Gene dosage and pathogenesis of Parkinson's disease

Four recent papers related specifically to the familial form of Parkinson's disease reinforce the idea that endogenous levels of alpha-synuclein can strongly influence disease phenotype. Two recent publications of alpha-synuclein-duplication mutations show that the severity of familial Parkinsonian phenotype is dependent upon SNCA gene dosage and corresponding protein levels. Familial point mutations in SNCA were found to impair the efficient lysosomal degradation of alpha-synuclein, potentially resulting in elevated levels of alpha-synuclein. Conversely, the complete knockout of SNCA has little effect on transgenic mice. It is now clear that the regulation of alpha-synuclein levels has potential significance in the pathogenesis and treatment of sporadic PD.     

Progress in the pathogenesis and genetics of Parkinson's disease

Recent progresses in the pathogenesis of sporadic Parkinson's disease (PD) and genetics of familial PD are reviewed. There are common molecular events between sporadic and familial PD, particularly between sporadic PD and PARK1-linked PD due to alpha-synuclein (SNCA) mutations. In sporadic form, interaction of genetic predisposition and environmental factors is probably a primary event inducing mitochondrial dysfunction and oxidative damage resulting in oligomer and aggregate formations of alpha-synuclein. In PARK1-linked PD, mutant alpha-synuclein proteins initiate the disease process as they have increased tendency for self-aggregation. As highly phosphorylated aggregated proteins are deposited in nigral neurons in PD, dysfunctions of proteolytic systems, i.e. the ubiquitin-proteasome system and autophagy-lysosomal pathway, seem to be contributing to the final neurodegenerative process. Studies on the molecular mechanisms of nigral neuronal death in familial forms of PD will contribute further on the understanding of the pathogenesis of sporadic PD.     

Pros and cons: on-line versus off-line analysis of fermentations

A fermenter is a complex system consisting of metabolically active cells suspended in a medium which is often aerated. Since the behaviour of such systems is not determined by the initial conditions fermentations must be subject to closed loop control. Closed loop control can be applied using either on-line or off-line methods.     

Pros and cons of external swabbing of amphibians for genetic analyses

Non-invasive DNA sampling is an important tool in amphibian conservation. Buccal swabs are nowadays replacing the wounding toe-clipping method. Skin and cloaca swabbing are even less invasive and easier to handle than buccal swabbing, but could result in contaminations of genetic material. Therefore, we test if external skin and cloaca swabs are as reliable as buccal swabs for genetic analysis of amphibians. We analysed eight microsatellite loci for the common frog (Rana temporaria, Linnaeus 1758) and compared genotyping results for buccal, skin and cloaca swabs regarding allelic dropouts and false alleles. Furthermore, we compared two DNA extraction methods regarding efficiency and cost. DNA quality and quantity (amplification success, genotyping error rate, in nanogram per microlitre) were comparable among DNA sources and extraction methods. However, skin and cloaca samples exhibited high degrees of contamination with foreign individuals, which was due to sample collection during mating season. Here, we established a simple low budget procedure to receive DNA of amphibians avoiding stressful buccal swabbing or harmful toe clipping. However, the possibility of contaminations of external swabs has to be considered.     

Climbing the scaffolds of Parkinson's disease pathogenesis

Several neurodegenerative disorders, including Parkinson's and Alzheimer's diseases, are characterized neuropathologically by accumulation of misfolded proteins such as alpha-synuclein that disrupts scaffold molecules in the caveolae. A new study by Ihara et al. in this issue of Neuron shows that a novel scaffold protein, Sept4, may be an important player in modulating the pathological alterations of alpha-synuclein in models of Parkinson's disease, suggesting that gene therapies targeting scaffold proteins might be effective in the treatment of neurodegenerative disorders.     

Pros and cons of using a standard protocol to test germination of alpine species

Plant Ecology - Storing seeds in seed banks is an effective way to preserve plant diversity and conserve species. An essential step towards a valuable conservation is the validation of germination....     

Assessing protein-DNA interactions: Pros and cons of classic and emerging techniques

正Investigation of protein-DNA interactions provides important information for understanding gene function and regulation,but identification and validation of specific interactions remain major challenges in the post-genomics era.Therefore,effective and economical methods to assess protein-DNA interactions are highly sought-after by molecular biologists.Choosing the appropriate method to examine a specific protein-DNA interaction also remains a crucial challenge     

Mitochondrial dysfunction in the limelight of Parkinson's disease pathogenesis

Parkinson's disease (PD) is a progressive neurodegenerative movement disorder with unknown etiology. It is marked by widespread neurodegeneration in the brain with profound loss of A9 midbrain dopaminergic neurons in substantia nigra pars compacta. Several theories of biochemical abnormalities have been linked to pathogenesis of PD of which mitochondrial dysfunction due to an impairment of mitochondrial complex I and subsequent oxidative stress seems to take the center stage in experimental models of PD and in postmortem tissues of sporadic forms of illness. Recent identification of specific gene mutations and their influence on mitochondrial functions has further reinforced the relevance of mitochondrial abnormalities in disease pathogenesis. In both sporadic and familial forms of PD abnormal mitochondrial paradigms associated with disease include impaired functioning of the mitochondrial electron transport chain, aging associated damage to mitochondrial DNA, impaired calcium buffering, and anomalies in mitochondrial morphology and dynamics. Here we provide an overview of specific mitochondrial functions affected in sporadic and familial PD that play a role in disease pathogenesis. We propose to utilize these gained insights to further streamline and focus the research to better understand mitochondria's role in disease development and exploit potential mitochondrial targets for therapeutic interventions in PD pathogenesis.     

The relevance of iron in the pathogenesis of Parkinson's disease

Alterations of iron levels in the brain has been observed and documented in a number of neurodegenerative disorders including Parkinson's disease (PD). The elevated nigral iron levels observed in PD may reflect a dysfunction of brain iron homeostasis. Under normal physiological conditions excess iron can be sequestrated in ferritin and neuromelanin. Alternatively, the excess iron may represent a component of brain iron deposition associated with ageing. The aetiology of idiopathic PD largely remains an enigma. However, intensive investigations have provided a host of putative mechanisms that might contribute to the pathogenesis underlying the characteristic degeneration of the dopaminergic neurons in the substantia nigra (SN). The mechanisms proposed include oxidative (and nitrative) stress, inflammation, excitotoxicity, mitochondrial dysfunction, altered proteolysis and finally apoptotic induced cell death. Iron-mediated cellular destruction is mediated primarily via reactive oxygen or/and nitrogen species induced oxidative stress. Furthermore, these pathogenic mechanisms appear to be closely interlinked to the cascade of events leading to cellular death. There are conflicting reports about the stage during disease progression at which nigral iron change occurs in PD. Some have found that there are no changes in iron content SN in asymptomatic incidental Lewy body disease, suggesting it may represent a secondary event in the cascade of neuronal degeneration. In contrast, others have found an elevation of iron in SN in pre-clinical stages. These discrepancies may be attributed to the occurrence of different sub-groups of the disease. This concurs with the notion that PD represents a group of related diseases with a number of potential pathogenic pathways.     

Pros and cons of using aberrant glycosylation as companion biomarkers for therapeutics in cancer

Cancer treatment has been stratified by companion biomarker tests that serve to provide information on the genetic status of cancer patients and to identify patients who can be expected to respond to a given treatment. This stratification guarantees better efficiency and safety during treatment. Cancer patients, however, marginally benefit from the current companion biomarker-aided treatment regimens, presumably because companion biomarker tests are dependent solely on the mutation status of several genes status quo. In the true sense of the term, "personalized medicine", cancer patients are deemed to be identified individually by their molecular signatures, which are not necessarily confined to genetic mutations. Glycosylation is tremendously dynamic and shows alterations in cancer. Evidence is accumulating that aberrant glycosylation contributes to the development and progression of cancer, holding the promise for use of glycosylation status as a companion biomarker in cancer treatment. There are, however, several challenges derived from the lack of a reliable detection system for aberrant glycosylation, and a limited library of aberrant glycosylation. The challenges should be addressed if glycosylation status is to be used as a companion biomarker in cancer treatment and contribute to the fulfillment of personalized medicine.     

Dopamine complexes of iron in the etiology and pathogenesis of Parkinson's disease

Parkinson’s disease (PD) is the second most common neurodegenerative disease after Alzheimers. The main pathological hallmark of Parkinson’s is the deterioration and death of neurons that produce the neurotransmitter dopamine. Much of the neuronal damage takes place in the substantia nigra, a small region of the midbrain that contains the cell bodies of neurons that produce dopamine. The deterioration and death of dopaminergic neurons are directly associated with misfolding and aggregation of proteins, principally α-synuclein, that are natively unfolded. Present also in the substantia nigra is an unusually high concentration of vestigial iron. Protein misfolding in non-genetic (sporadic) cases of PD has been associated with reactive oxygen species formed as products of O₂ reduction by the combination of dopamine and iron. Combinations of Fe³⁺, dopamine hydrochloride (DA^H+Cl), and various ancillary ligands have been studied as a function of pH in aqueous solution to determine the optimum pH for complex formation. With ancillary ligands (L₄) derived from nitrilotriacetic acid and ethylenediamine diacetic acid spectral changes are consistent with the formation of L₄Fe(DA^H+) species that reach a maximum concentration at pH 7.2. With edta as the ancillary ligand, spectral features at pH 7 resemble those of Fe³⁺-catecholate complexes that contain catecholate ligands bonded through a single oxygen. This demonstrates the ability of the dopamine catechol functionality to penetrate the coordination sphere of even exceptionally stable iron chelates.     

Protein kinases linked to the pathogenesis of Parkinson's disease

Two papers in this issue of Neuron identify a causative gene, LRRK2, for familial parkinsonism. Several dominantly inherited missense mutations have been identified in a number of families that exhibit a broad spectrum of neuropathological features, including deposition of alpha-synuclein and tau proteins. The LRRK2 gene is predicted to encode a large protein containing leucine-rich repeats and Ras/GTPase, tyrosine kinase-like, and WD40 domains.     

Radiolabelled proteins for positron emission tomography: Pros and cons of labelling methods

Background

Dynamic biomedical research is currently yielding a wealth of information about disease-associated molecular alterations on cell surfaces and in the extracellular space. The ability to visualize and quantify these alterations in vivo could provide important diagnostic information and be used to guide individually-optimized therapy. Biotechnology can provide proteinaceous molecular probes with highly specific target recognitions. Suitably labelled, these may be used as tracers for radionuclide-based imaging of molecular disease signatures. If the labels are positron-emitting radionuclides, the superior resolution, sensitivity and quantification capability of positron emission tomography (PET) can be exploited.

Scope of review

This article discusses different approaches to labelling proteins with positron-emitting nuclides with suggestions made depending on the biological features of the tracers.

Major conclusions

Factors such as matching biological and physical half-lives, availability of the nuclide, labelling yields, and influences of labelling on targeting properties (affinity, charge and lipophilicity, cellular processing and retention of catabolites) should be considered when selecting a labelling strategy for each proteinaceous tracer.

General significance

The labelling strategy used can make all the difference between success and failure in a tracer application. This review emphasises chemical, biological and pharmacological considerations in labelling proteins with positron-emitting radionuclides.