Are lactoferrin receptors in Gram-negative bacteria viable vaccine targets?

A number of important Gram-negative pathogens that reside exclusively in the upper respiratory or genitourinary tract of their mammalian host rely on surface receptors that specifically bind host transferrin and lactoferrin as a source of iron for growth. The transferrin receptors have been targeted for vaccine development due to their critical role in acquiring iron during invasive infection and for survival on the mucosal surface. In this study, we focus on the lactoferrin receptors, determining their prevalence in pathogenic bacteria and comparing their prevalence in commensal Neisseria to other surface antigens targeted for vaccines; addressing the issue of a reservoir for vaccine escape and impact of vaccination on the microbiome. Since the selective release of the surface lipoprotein lactoferrin binding protein B by the NalP protease in Neisseria meningitidis argues against its utility as a vaccine target, we evaluated the release of outer membrane vesicles, and transferrin and lactoferrin binding in N. meningitidis and Moraxella catarrhalis. The results indicate that the presence of NalP reduces the binding of transferrin and lactoferrin by cells and native outer membrane vesicles, suggesting that NalP may impact all lipoprotein targets, thus this should not exclude lactoferrin binding protein B as a target.     

Heat shock proteins in health and disease: therapeutic targets or therapeutic agents?

For many years, heat shock or stress proteins have been regarded as intracellular molecules that have a range of housekeeping and cytoprotective functions, only being released into the extracellular environment in pathological situations such as necrotic cell death. However, evidence is now accumulating to indicate that, under certain circumstances, these proteins can be released from cells in the absence of cellular necrosis, and that extracellular heat shock proteins have a range of immunoregulatory activities. The capacity of heat shock proteins to induce pro-inflammatory responses, together with the phylogenetic similarity between prokaryotic and eukaryotic heat shock proteins, has led to the proposition that these proteins provide a link between infection and autoimmune disease. Indeed, both elevated levels of antibodies to heat shock proteins and an enhanced immune reactivity to heat shock proteins have been noted in a variety of pathogenic disease states. However, further evaluation of heat shock protein reactivity in autoimmune disease and after transplantation has shown that, rather than promoting disease, reactivity to self-heat shock proteins can downregulate the disease process. It might be that self-reactivity to heat shock proteins is a physiological response that regulates the development and progression of pro-inflammatory immunity to these ubiquitously expressed molecules. The evolving evidence that heat shock proteins are present in the extracellular environment, that reactivity to heat shock proteins does not necessarily reflect adverse, pro-inflammatory responses and that the promotion of reactivity to self-heat shock proteins can downregulate pathogenic processes all suggest a potential role for heat shock proteins as therapeutic agents, rather than as therapeutic targets.     

Mitotic mechanisms in Alzheimer's disease?

The mechanism(s) leading to widespread hyper-phosphorylation of proteins in Alzheimer's disease (AD) are unknown. We have characterized seven new monoclonal antibodies recognizing independent phospho- epitopes in the paired helical filament proteins (PHF) found in AD brain. These antibodies show pronounced immunoreactivity with cultured human neuroblastoma cells that are in the M phase of cell division, but have no discernible reactivity with interphase cells. Immunoreactivity with these antibodies does not localize to the microtubule spindles or chromosomes in M phase, but is confined to the surrounding cytoplasm. Similar staining in M phase is observed with cultured cells of various tissue types and species. Cells arrested in M phase with the microtubule depolymerizing agent, nocodazole, show marked increases in immunoreactivity with the antibodies by immunofluorescence staining, ELISA, and immunoblotting. In neuroblastoma cells, the appearance of the TG/MC phospho-epitopes coincides with activation of mitotic protein kinases, but not with the activity of the neuronal specific cyclin- dependent kinase, cdk5. These data suggest that the TG/MC epitopes are conserved mitotic phospho-epitopes produced as a result of increased mitotic kinase activity. To investigate this possibility in AD, we examined the staining of human brain tissue with MPM-2, a marker antibody for mitotic phospho-epitopes. It was found that MPM-2 reacts strongly with neurofibrillary tangles, neuritic processes, and neurons in AD but has no staining in normal human brain. Our data suggest that accumulation of phospho-epitopes in AD may result from activation of mitotic posttranslational mechanisms which do not normally operate in mature neurons of brain.     

Cdk5, a therapeutic target for Alzheimer's disease?

Alzheimer's disease (AD) represents the leading cause for senile dementia affecting more than 4 million people worldwide. AD patients display a triad of pathological features including brain atrophy caused by neuronal loss, beta-amyloid plaque and neurofibrillary tangles. We previously show that Cyclin-dependent kinase 5 (Cdk5) is deregulated in AD brains and may contribute to the pathogenesis of AD. In AD brains, a calpain cleavage product of its physiological regulator p35, p25 is elevated. p25 causes prolonged activation of Cdk5 and alteration of its substrate specificity. The implications of p25/Cdk5 in neurotoxicity, beta-amyloid plaque and neurofibrillary tangle pathology will be discussed.     

Conservation targets for viable species assemblages?

Estimates of minimum areas required for effective biodiversity conservation differ substantially. Scientific reserve design and placement procedures indicate that between 30 and 75% of any region may be required to sample biodiversity features. These estimates do not routinely incorporate measures for sampling viable populations of species or explore the area requirements of sampling viable populations of species assemblages. To determine the area requirements for sampling viable populations of a herbivore assemblage, spatially explicit abundance data from the Kruger National Park, South Africa, were analyzed. Area requirements were consistently above 50% and were unaffected by selected target population sizes. In addition, area requirements appeared to be insensitive to selection unit size (analytical grain), habitat quality, the coarseness of the land classification system used or the presence of low-density species. Thus, traditional conservation area targets of 10–15% appear inadequate for representing viable populations of a herbivore assemblage from African savanna regions. This suggests that conservation targets of at least 50% of land classification units may represent a more appropriate conservation rule of thumb, or alternatively, that the use of data independent conservation targets may need to be abandoned.     

Are heat shock proteins therapeutic target for Parkinson's disease?

Heat shock proteins (HSPs), known as molecular chaperone to assist protein folding, have recently become a research focus in Parkinson's disease (PD) because the pathogenesis of this disease is highlighted by the intracellular protein misfolding and inclusion body formation. The present review will focus on the functions of different HSPs and their protective roles in PD. It is postulated that HSPs may serve as protein folding machinery and work together with ubiquitin-proteasome system (UPS) to assist in decomposing aberrant proteins. Failure of UPS is thought to play a key role in the pathogenesis of PD. In addition, HSPs may possess anti-apoptotic effects and keep the homeostasis of dopaminergic neurons against stress conditions. The critical role of HSPs and recent discovery of some novel HSPs inducers suggest that HSPs may be potential therapeutic targets for PD and other neurodegenerative disorders.     

Is the mitochondrial outermembrane protein VDAC1 therapeutic target for Alzheimer's disease?

Mitochondrial dysfunction and synaptic damage have been described as early events in Alzheimer's disease (AD) pathogenesis. Recent research using AD postmortem brains, and AD mouse and cell models revealed that amyloid beta (Aβ) and tau hyperphosphorylation are involved in mitochondrial dysfunction and synaptic damage in AD. Further, recent research also revealed that the protein levels of mitochondrial outer membrane protein, voltage-dependent anion channel 1 (VDAC1), are elevated in the affected regions of AD postmortem brains and cortical tissues from APP transgenic mice. In addition, emerging research using AD postmortem brains and AD mouse models revealed that VDAC1 is linked to Aβ and phosphorylated tau, blocks the mitochondrial permeability transition (MPT) pores, disrupts the transport of mitochondrial proteins and metabolites, impairs gating of VDAC, and causes defects in oxidative phosphorylation, leading to mitochondrial dysfunction in AD neurons. The purpose of this article is to review research that has investigated the relationship between VDAC1 and the regulation of MPT pores in AD progression.     

Is Alzheimer's disease a systemic disease?

Although Alzheimer's disease (AD) is the most common neurodegenerative disease, the etiology of AD is not well understood. In some cases, genetic factors explain AD risk, but a high percentage of late-onset AD is unexplained. The fact that AD is associated with a number of physical and systemic manifestations suggests that AD is a multifactorial disease that affects both the CNS and periphery. Interestingly, a common feature of many systemic processes linked to AD is involvement in energy metabolism. The goals of this review are to 1) explore the evidence that peripheral processes contribute to AD risk, 2) explore ways that AD modulates whole-body changes, and 3) discuss the role of genetics, mitochondria, and vascular mechanisms as underlying factors that could mediate both central and peripheral manifestations of AD. Despite efforts to strictly define AD as a homogeneous CNS disease, there may be no single etiologic pathway leading to the syndrome of AD dementia. Rather, the neurodegenerative process may involve some degree of baseline genetic risk that is modified by external risk factors. Continued research into the diverse but related processes linked to AD risk is necessary for successful development of disease-modifying therapies.     

Is ammonia a pathogenetic factor in Alzheimer's disease?

An attempt was made to review experimental evidence in favor of the idea that ammonia plays a role in dementia of the Alzheimer type (DAT). Hyperammonemia causes biochemical and cellular dysfunctions in the brain, which can be found in brains of DAT patients. The most conspicuous among these findings are astrocytosis, impairment of glucose utilization, and a decreased rate of energy metabolism, and the impairment of neurotransmission, with a net increase in excitability and glutamate release. The derangement of lysosomal processing of proteins is another potential site of ammonia action. This aspect is especially important in view of the growing evidence for the role of the endosomal-lysosomal system in the formation of amyloidogenic fragments from -amyloid precursor protein. Ammonia is not considered a primary factor of the disease. However, since hyperammonemia and release of ammonia from the brains of DAT patients is well supported by published observations, ammonia should be taken into account as a factor that contributes to manifestations and the progression of DAT. If elevated ammonia concentrations turn out to be indeed as important in DAT, as is suggested in this review, rational therapeutic avenues can be envisaged that lead to the amelioration of symptoms and progression of the disease.Abbreviations -AP -amyloid protein - -APP -amyloid precursor protein - CNS central nervous system - DAT dementia of the Alzheimer type - GABA -aminobutyrate - MAO monoamine oxidase - NAD nicotinamide adenine dinucleotide This paper is dedicated to Rudi Vrba, a pioneer of the neurochemistry of ammonia, and a friend, at the occasion of his 68th birthday.     

MMPs as therapeutic targets--still a viable option?

Matrix metalloproteinases (MMPs) appear to be ideal drug targets--they are disease-associated, extracellular enzymes with a dependence on zinc for activity. This apparently straightforward target, however, is much more complex than initially realized. Although disease associated, the roles for particular enzymes may be healing rather than harmful making broad-spectrum inhibition unwise; targeting the catalytic zinc with specificity is difficult, since other related proteases as well as non-related proteins can be affected by some chelating groups. While the failure of early-generation MMP inhibitors dampened enthusiasm for this type of drug, there has recently been a wealth of studies examining the basic biology of MMPs which will greatly inform new drug trials in this field.     

Mitochondrial β-amyloid in Alzheimer's disease

It is well established that the intracellular accumulation of Aβ (amyloid β-peptide) is associated with AD (Alzheimer's disease) and that this accumulation is toxic to neurons. The precise mechanism by which this toxicity occurs is not well understood; however, identifying the causes of this toxicity is an essential step towards developing treatments for AD. One intracellular location where the accumulation of Aβ can have a major effect is within mitochondria, where mitochondrial proteins have been identified that act as binding sites for Aβ, and when binding occurs, a toxic response results. At one of these identified sites, an enzyme known as ABAD (amyloid-binding alcohol dehydrogenase), we have identified changes in gene expression in the brain cortex, following Aβ accumulation within mitochondria. Specifically, we have identified two proteins that are up-regulated not only in the brains of transgenic animal models of AD but also in those of human sufferers. The increased expression of these proteins demonstrates the complex and counteracting pathways that are activated in AD. Previous studies have identified approximate contact sites between ABAD and Aβ; on basis of these observations, we have shown that by using a modified peptide approach it is possible to reverse the expression of these two proteins in living transgenic animals and also to recover mitochondrial and behavioural deficits. This indicates that the ABAD-Aβ interaction is potentially an interesting target for therapeutic intervention. To explore this further we used a fluorescing substrate mimic to measure the activity of ABAD within living cells, and in addition we have identified chemical fragments that bind to ABAD, using a thermal shift assay.     

Are formal oxidation states above one viable in cyclopentadienylcopper cyanides?

Recent experiments have led to the discovery of the thermally unstable organocopper compounds (η(3)-C(3)H(5))CuMe(2), [(η(3)-C(3)H(5))CuMe(3)](-), and CuMe (4)(-) in which the copper atom is in the +3 formal oxidation state. In a quest for more stable organocopper compounds with copper in formal oxidation states above one, the binuclear cyclopentadienylcopper cyanides Cp(2)Cu(2)(CN)(n) (Cp = η(5)-C(5)H(5); n = 1, 2, 3) have been studied using density functional theory (DFT). The lowest energy structures are found to have terminal Cp rings and bridging cyanide ligands up to a maximum of two bridges. Higher-energy Cp(2)Cu(2)(CN)(n) (n = 1, 2, 3) structures are found with bridging Cp rings. The Cp(2)Cu(2)(CN)(3) derivatives, with the copper atoms in an average +2.5 oxidation state, are clearly thermodynamically disfavored with respect to cyanogen loss. However, Cp(2)Cu(2)(CN)(2) and Cp(2)Cu(2)(CN), with the copper atoms in the average oxidation states +1.5 and +2, respectively, are predicted to have marginal viability. The prospects for the copper(II) derivative Cp(2)Cu(2)(CN)(2) contrast with that of the "simple" Cu(CN)(2), which is shown both experimentally and theoretically to be unstable with respect to cyanogen loss to give CuCN.     

Heat shock proteins in oncology: Diagnostic biomarkers or therapeutic targets?

Heat shock proteins (HSP) are a family of proteins induced in cells exposed to different insults. This induction of HSPs allows cells to survive stress conditions. Mammalian HSPs have been classified into six families according to their molecular size: HSP100, HSP90, HSP70, HSP60, HSP40 and small HSPs (15 to 30kDa) including HSP27. These proteins act as molecular chaperones either helping in the refolding of misfolded proteins or assisting in their elimination if they become irreversibly damaged. In recent years, proteomic studies have characterized several different HSPs in various tumor types which may be putative clinical biomarkers or molecular targets for cancer therapy. This has led to the development of a series of molecules capable of inhibiting HSPs. Numerous studies speculated that over-expression of HSP is in part responsible for resistance to many anti-tumor agents and chemotherapeutics. Hence, from a pharmacological point of view, the co-administration of HSP inhibitors together with other anti-tumor agents is of major importance in overcoming therapeutic resistance. In this review, we provide an overview of the current status of HSPs in autoimmune, cardiovascular, and neurodegenerative diseases with special emphasis on cancer.     

Network dysfunction in Alzheimer's disease: does synaptic scaling drive disease progression?

Accumulation of beta-amyloid protein (Abeta) in the brain is a key feature of Alzheimer's disease (AD). The build-up of aggregated forms of Abeta leads to synaptic loss and to cognitive dysfunction. Although the pathways controlling production and aggregation of Abeta are well studied, the mechanisms that drive the spread of neurodegeneration in the brain are unclear. Here, the idea is presented that AD progresses as a consequence of synaptic scaling, a type of neuronal plasticity that helps maintain synaptic signal strength. Recent studies indicate that brain-derived neurotrophic factor, tumour necrosis factor-alpha and alpha7 nicotinic acetylcholine receptors (alpha7 nAChRs) regulate synaptic scaling in the AD brain. It is suggested that further studies on synaptic scaling in AD could reveal new targets for therapeutic drug development.     

Tau phosphorylation in Alzheimer's disease: pathogen or protector?

During the past decade, hypotheses concerning the pathogenesis of most neurodegenerative diseases have been dominated by the notion that the aggregation of specific proteins and subsequent formation of cytoplasmic and extracellular lesions represent a harbinger of neuronal dysfunction and death. As such, in Alzheimer's disease, phosphorylated tau protein, the major component of neurofibrillary tangles, is considered a central mediator of disease pathogenesis. We challenge this classic notion by proposing that tau phosphorylation represents a compensatory response mounted by neurons against oxidative stress and serves a protective function. This novel concept, which can also be applied to protein aggregates in other neurodegenerative diseases, opens a new window of knowledge with broad implications for both the understanding of mechanisms underlying disease pathophysiology and the design of new therapeutic strategies.     

Do phospholipases, key enzymes in sperm physiology, represent therapeutic challenges?

The spermatozoon is one of the most differentiated cells in mammals and its production requires an extremely complex machinery. Subtle but critical molecular changes take place during capacitation, which comprises the last series of maturation steps that naturally occur between the cauda epididymidis where spermatozoa are stored and their ultimate destination inside the oocyte. Phospholipases, by hydrolyzing various phospholipids, have been found to be critical in sperm processes such as 1) the control of flagellum beats, 2) capacitation - the molecular transformations preparing the sperm for fertilization, 3) acrosome reaction and 4) oocyte activation by eliciting calcium oscillations. The emerging important role of phospholipases is also emphasized by the fact that alterations of sperm lipids can lead to infertility. Phospholipases may represent valuable targets to develop anti- and pro-fertility drugs. Results obtained in mice are encouraging, since treatment of sperm with recombinant sPLA(2) of group X, known to be involved in capacitation, improves fertilization in vitro, while co-injection of PLCζ RNA with infertile sperm restores oocyte activation.     

Histone methyltransferases: a new class of therapeutic targets in cancer treatment?

Epigenetic gene regulation contributes, together with genetic alterations, to cancer development and progression. In contrast to genetic disorders, the possibility of reversing epigenetic alterations has provided original targets for therapeutic application. In the last years, work has been focused on the pharmacological restoration of epigenetic regulation balance using epidrugs which yield hopes for novel strategy in cancer therapy. Histone acetylation and DNA methylation are epigenetic modifications which have been closely linked to the pathology of human cancers, and inhibitors of both enzyme classes for clinical use are at hands. Novel findings accumulated during the last years both in chemistry and biomedical applications give rise to new targeted treatments against cancer. Since their links with pathogenesis and progression of cancer were recognized, histone methyltransferases emerge as promising therapeutic targets in cancer treatment.     

Apoptosis in Alzheimer's disease—an update

Alzheimer's disease (AD) is the most common human neurodegenerative disorder characterized by the progressive deterioration of cognition and memory in association with the presence of senile plaques, neurofibrillary tangles, and massive loss of neurons. Most cases of AD are late-onset and sporadic, but in some cases the disease is inherited as an autosomal dominant trait. Four different genes, the amyloid precursor protein, apolipoprotein E, and presenilins 1 and 2 have been implicated in the etiology of familial AD. It is now generally accepted that massive neuronal death due to apoptosis is a commmon characteristic in the brains of patients suffering from neurodegenerative diseases, and apoptotic cell death has been found in neurons and glial cells in AD. This review summarizes the current findings regarding the evidence for apoptosis in AD and discusses the possible involvement of apoptosis-regulating factors in the pathology of AD. Modification of the apoptotic cascade could be considered as a primary therapeutic strategy for the disease.