Multi-Drug Cocktail Therapy Improves Survival and Neurological Function after Asphyxial Cardiac Arrest in Rodents.

BACKGROUND: Cardiac arrest (CA) can lead to neuronal degeneration and death through various pathways, including oxidative, inflammatory, and metabolic stress. However, current neuroprotective drug therapies will typically target only one of these pathways, and most single drug attempts to correct the multiple dysregulated metabolic pathways elicited following cardiac arrest have failed to demonstrate clear benefit. Many scientists have opined on the need for novel, multidimensional approaches to the multiple metabolic disturbances after cardiac arrest. In the current study, we have developed a therapeutic cocktail that includes ten drugs capable of targeting multiple pathways of ischemia-reperfusion injury after CA. We then evaluated its effectiveness in improving neurologically favorable survival through a randomized, blind, and placebo-controlled study in rats subjected to 12 min of asphyxial CA, a severe injury model. RESULTS: 14 rats were given the cocktail and 14 received the vehicle after resuscitation. At 72 h post-resuscitation, the survival rate was 78.6% among cocktail-treated rats, which was significantly higher than the 28.6% survival rate among vehicle-treated rats (log-rank test; p = 0.006). Moreover, in cocktail-treated rats, neurological deficit scores were also improved. These survival and neurological function data suggest that our multi-drug cocktail may be a potential post-CA therapy that deserves clinical translation. CONCLUSIONS: Our findings demonstrate that, with its ability to target multiple damaging pathways, a multi-drug therapeutic cocktail offers promise both as a conceptual advance and as a specific multi-drug formulation capable of combatting neuronal degeneration and death following cardiac arrest. Clinical implementation of this therapy may improve neurologically favorable survival rates and neurological deficits in patients suffering from cardiac arrest.

Aß43 levels determine the onset of pathological amyloid deposition.

About 2% of Alzheimer's disease (AD) cases have early onset (FAD) and are caused by mutations in either Presenilins (PSEN1/2) or amyloid-ß precursor protein (APP). PSEN1/2 catalyze production of Aß peptides of different length from APP. Aß peptides are the major components of amyloid plaques, a pathological lesion that characterizes AD. Analysis of mechanisms by which PSEN1/2 and APP mutations affect Aß peptide compositions lead to the implication of the absolute or relative increase in Aß42 in amyloid-ß plaques formation. Here, to elucidate the formation of pathogenic Aß cocktails leading to amyloid pathology, we utilized FAD rat knock-in models carrying the Swedish APP (Apps allele) and the PSEN1 L435F (Psen1LF allele) mutations. To accommodate the differences in the pathogenicity of rodent and human Aß, these rat models are genetically engineered to express human Aß species as both the Swedish mutant allele and the WT rat allele (called Apph) have been humanized in the Aß-coding region. Analysis of the eight possible FAD mutant permutations indicates that the CNS levels of Aß43, rather than absolute or relative increases in Aß42, determine the onset of pathological amyloid deposition in FAD knock-in rats. Notably, Aß43 was found in amyloid plaques in late onset AD and mild cognitive impairment cases, suggesting that the mechanisms initiating amyloid pathology in FAD knock-in rat reflect disease mechanisms driving amyloid pathology in late onset AD. This study helps clarifying the molecular determinants initiating amyloid pathology and supports therapeutic interventions targeting Aß43 in AD.

Oxidative stress-induced MMP- and γ-secretase-dependent VE-cadherin processing is modulated by the proteasome and BMP9/10.

Classical cadherins, including vascular endothelial (VE)-cadherin, are targeted by matrix metalloproteinases (MMPs) and γ-secretase during adherens junction (AJ) disassembly, a mechanism that might have relevance for endothelial cell (EC) integrity and vascular homeostasis. Here, we show that oxidative stress triggered by H2O2 exposure induced efficient VE-cadherin proteolysis by MMPs and γ-secretase in human umbilical endothelial cells (HUVECs). The cytoplasmic domain of VE-cadherin produced by γ-secretase, VE-Cad/CTF2-a fragment that has eluded identification so far-could readily be detected after H2O2 treatment. VE-Cad/CTF2, released into the cytosol, was tightly regulated by proteasomal degradation and was sequentially produced from an ADAM10/17-generated C-terminal fragment, VE-Cad/CTF1. Interestingly, BMP9 and BMP10, two circulating ligands critically involved in vascular maintenance, significantly reduced VE-Cad/CTF2 levels during H2O2 challenge, as well as mitigated H2O2-mediated actin cytoskeleton disassembly during VE-cadherin processing. Notably, BMP9/10 pretreatments efficiently reduced apoptosis induced by H2O2, favoring endothelial cell recovery. Thus, oxidative stress is a trigger of MMP- and γ-secretase-mediated endoproteolysis of VE-cadherin and AJ disassembly from the cytoskeleton in ECs, a mechanism that is negatively controlled by the EC quiescence factors, BMP9 and BMP10.

Significance of Blood and Cerebrospinal Fluid Biomarkers for Alzheimer's Disease: Sensitivity, Specificity and Potential for Clinical Use.

Alzheimer's disease (AD) is the most common type of dementia, affecting more than 5 million Americans, with steadily increasing mortality and incredible socio-economic burden. Not only have therapeutic efforts so far failed to reach significant efficacy, but the real pathogenesis of the disease is still obscure. The current theories are based on pathological findings of amyloid plaques and tau neurofibrillary tangles that accumulate in the brain parenchyma of affected patients. These findings have defined, together with the extensive neurodegeneration, the diagnostic criteria of the disease. The ability to detect changes in the levels of amyloid and tau in cerebrospinal fluid (CSF) first, and more recently in blood, has allowed us to use these biomarkers for the specific in-vivo diagnosis of AD in humans. Furthermore, other pathological elements of AD, such as the loss of neurons, inflammation and metabolic derangement, have translated to the definition of other CSF and blood biomarkers, which are not specific of the disease but, when combined with amyloid and tau, correlate with the progression from mild cognitive impairment to AD dementia, or identify patients who will develop AD pathology. In this review, we discuss the role of current and hypothetical biomarkers of Alzheimer's disease, their specificity, and the caveats of current high-sensitivity platforms for their peripheral detection.

Intramuscular injection of vectorized-scFvMC1 reduces pathological tau in two different tau transgenic models.

With evidence supporting the prion-like spreading of extracellular tau as a mechanism for the initiation and progression of Alzheimer's disease (AD), immunotherapy has emerged as a potential disease-modifying strategy to target tau. Many studies have proven effective to clear pathological tau species in animal models of AD, and several clinical trials using conventional immunotherapy with anti-tau native antibodies are currently active. We have previously generated a vectorized scFv derived from the conformation-dependent anti-tau antibody MC1, scFvMC1, and demonstrated that its intracranial injection was able to prevent tau pathology in adult tau mice. Here, we show that, in a prevention paradigm and in two different tau transgenic models (JNPL3 and P301S), a one-time intramuscular injection of AAV1-scFvMC1 generated a long-lasting peripheral source of anti-tau scFvMC1 and significantly reduced insoluble and soluble tau species in the brain. Moreover, our data showed that scFvMC1 was internalized by the microglia, in the absence of overt inflammation. This study demonstrates the efficacy of intramuscular delivery of vectorized scFv to target tau, and suggests a new potential application to treat AD and the other tauopathies.

Endogenous retroviruses are associated with hippocampus-based memory impairment.

Retrotransposons compose a staggering 40% of the mammalian genome. Among them, endogenous retroviruses (ERV) represent sequences that closely resemble the proviruses created from exogenous retroviral infection. ERVs make up 8 to 10% of human and mouse genomes and range from evolutionarily ancient sequences to recent acquisitions. Studies in Drosophila have provided a causal link between genomic retroviral elements and cognitive decline; however, in mammals, the role of ERVs in learning and memory remains unclear. Here we studied 2 independent murine models for ERV activation: muMT strain (lacking B cells and antibody production) and intracerebroventricular injection of streptozotocin (ICVI-STZ). We conducted behavioral assessments (contextual fear memory and spatial learning), as well as gene and protein analysis (RNA sequencing, PCR, immunohistochemistry, and western blot assays). Mice lacking mitochondrial antiviral-signaling protein (MAVS) and mice lacking stimulator of IFN genes protein (STING), 2 downstream sensors of ERV activation, provided confirmation of ERV impact. We found that muMT mice and ICVI-STZ mice induced hippocampal ERV activation, as shown by increased gene and protein expression of the Gag sequence of the transposable element intracisternal A-particle. ERV activation was accompanied by significant hippocampus-related memory impairment in both models. Notably, the deficiency of the MAVS pathway was protective against ICVI-STZ-induced cognitive pathology. Overall, our results demonstrate that ERV activation is associated with cognitive impairment in mice. Moreover, they provide a molecular target for strategies aimed at attenuating retroviral element sensing, via MAVS, to treat dementia and neuropsychiatric disorders.

Anti-tau conformational scFv MC1 antibody efficiently reduces pathological tau species in adult JNPL3 mice.

Tau, the main component of the neurofibrillary tangles (NFTs), is an attractive target for immunotherapy in Alzheimer's disease (AD) and other tauopathies. MC1/Alz50 are currently the only antibodies targeting a disease-specific conformational modification of tau. Passive immunization experiments using intra-peritoneal injections have previously shown that MC1 is effective at reducing tau pathology in the forebrain of tau transgenic JNPL3 mice. In order to reach a long-term and sustained brain delivery, and avoid multiple injection protocols, we tested the efficacy of the single-chain variable fragment of MC1 (scFv-MC1) to reduce tau pathology in the same animal model, with focus on brain regional differences. ScFv-MC1 was cloned into an AAV delivery system and was directly injected into the hippocampus of adult JNPL3 mice. Specific promoters were employed to selectively target neurons or astrocytes for scFv-MC1 expression. ScFv-MC1 was able to decrease soluble, oligomeric and insoluble tau species, in our model. The effect was evident in the cortex, hippocampus and hindbrain. The astrocytic machinery appeared more efficient than the neuronal, with significant reduction of pathology in areas distant from the site of injection. To our knowledge, this is the first evidence that an anti-tau conformational scFv antibody, delivered directly into the mouse adult brain, is able to reduce pathological tau, providing further insight into the nature of immunotherapy strategies.

Detecting tau in serum of transgenic animal models after tau immunotherapy treatment.

In the attempt to elucidate if the "peripheral sink hypothesis" could be a potential mechanism of action for tau removal in passive immunotherapy experiments, we have examined tau levels in serum of chronically injected JNPL3 and Tg4510 transgenic animals. Measurement of tau in serum of mice treated with tau antibodies is challenging because of the antibody interference in sandwich enzyme-linked immunosorbent assays. To address this issue, we have developed a heat-treatment protocol at acidic pH to remove interfering molecules from serum, with excellent recovery of tau. The present data show that pan-tau and conformational antibodies do increase tau in mouse sera. However, these concentrations in serum do not consistently correlate with reductions of tau pathology in brain, suggesting that large elevations of tau species measured in serum are not predictive of efficacy. Here, we describe a reliable method to detect tau in serum of transgenic animals that have undergone tau immunotherapy. Levels of tau in human serum are less than the sensitivity of current assays, although artifactual signals are common. The method may be useful in similarly treated humans, a situation in which false positive signals are likely.

Passive Immunization in JNPL3 Transgenic Mice Using an Array of Phospho-Tau Specific Antibodies.

Recent work from our lab and few others have strongly suggested that immunotherapy could be an effective means of preventing the development of tau accumulation in JNPL3 transgenic mice, carrying the human P301L mutation. The aim of this study was to test the efficacy of a variety of specific tau monoclonal antibodies in JNPL3. Starting at 3 months of age, mice were treated for 4 months with weekly intraperitoneal injections of saline or purified tau monoclonal antibodies (10 mg/Kg) different in specificity for pathological tau: CP13 (pSer202), RZ3 (pThr231) and PG5 (pSer409). As expected, not all the antibodies tested showed efficacy at preventing the development of tau pathology at the described dose, with some of them even worsening the pathological scenario. Only by targeting the pSer202 epitope with CP13 was a conspicuous reduction of insoluble or soluble tau in cortex and hindbrain obtained. Here we report about the importance of screening in vivo multiple tau antibodies in order to select the antibodies to direct into future clinical studies.

CB2 receptor deficiency increases amyloid pathology and alters tau processing in a transgenic mouse model of Alzheimer's disease.

The endocannabinoid CB2 receptor system has been implicated in the neuropathology of Alzheimer's disease (AD). In order to investigate the impact of the CB2 receptor system on AD pathology, a colony of mice with a deleted CB2 receptor gene, CNR2, was established on a transgenic human mutant APP background for pathological comparison with CB2 receptor-sufficient transgenic mice. J20 APP (PDGFB-APPSwInd) mice were bred over two generations with CNR2(-/-) (Cnr2(tm1Dgen)/J) mice to produce a colony of J20 CNR2(+/+) and J20 CNR2(-/-) mice. Seventeen J20 CNR2(+/+) mice (12 females, 5 males) and 16 J20 CNR2(-/-) mice (11 females, 5 males) were killed at 12 months, and their brains were interrogated for AD-related pathology with both biochemistry and immunocytochemistry (ICC). In addition to amyloid-dependent endpoints such as soluble Aß production and plaque deposition quantified with 6E10 staining, the effect of CB2 receptor deletion on total soluble mouse tau production was assayed by using a recently developed high-sensitivity assay. Results revealed that soluble Aß42 and plaque deposition were significantly increased in J20 CNR2(-/-) mice relative to CNR2(+/+) mice. Microgliosis, quantified with ionized calcium-binding adapter molecule 1 (Iba-1) staining, did not differ between groups, whereas plaque associated microglia was more abundant in J20 CNR2(-/-) mice. Total tau was significantly suppressed in J20 CNR2(-/-) mice relative to J20 CNR2(+/+) mice. The results confirm the constitutive role of the CB2 receptor system both in reducing amyloid plaque pathology in AD and also support tehpotential of cannabinoid therapies targeting CB2 to reduce Aß; however, the results suggest that interventions may have a divergent effect on tau pathology.

Tau passive immunotherapy in mutant P301L mice: antibody affinity versus specificity.

The use of antibodies to treat neurodegenerative diseases has undergone rapid development in the past decade. To date, immunotherapeutic approaches to Alzheimer's disease have mostly targeted amyloid beta as it is a secreted protein that can be found in plasma and CSF and is consequently accessible to circulating antibodies. Few recent publications have suggested the utility of treatment of tau pathology with monoclonal antibodies to tau. Our laboratory has begun a systematic study of different classes of tau monoclonal antibodies using mutant P301L mice. Three or seven months old mutant tau mice were inoculated weekly with tau monoclonal antibodies at a dose of 10 mg/Kg, until seven or ten months of age were reached respectively. Our data strongly support the notion that in P301L animals treated with MC1, a conformational monoclonal antibody specific for PHF-tau, the rate of development of tau pathology is effectively reduced, while injecting DA31, a high affinity tau sequence antibody, does not exert such benefit. MC1 appears superior to DA31 in overall effects, suggesting that specificity is more important than affinity in therapeutic applications. Unfortunately the survival rate of the P301L treated mice was not improved when immunizing either with MC1 or PHF1, a high affinity phospho-tau antibody previously reported to be efficacious in reducing pathological tau. These data demonstrate that passive immunotherapy in mutant tau models may be efficacious in reducing the development of tau pathology, but a great deal of work remains to be done to carefully select the tau epitopes to target.

CB2 receptor deficiency increases amyloid pathology and alters tau processing in a transgenic mouse model of Alzheimer's disease.

The endocannabinoid CB2 receptor system has been implicated in the neuropathology of Alzheimer's disease (AD). In order to investigate the impact of the CB2 receptor system on AD pathology, a colony of mice with a deleted CB2 receptor gene, CNR2, was established on a transgenic human mutant APP background for pathological comparison with CB2 receptor-sufficient transgenic mice. J20 APP (PDGFB-APPSwInd) mice were bred over two generations with CNR2⁻/⁻ (Cnr2(tm1Dgen)/J) mice to produce a colony of J20 CNR2⁺/⁺ and J20 CNR2⁻/⁻ mice. Seventeen J20 CNR2⁺/⁺ mice (12 females, 5 males) and 16 J20 CNR2⁻/⁻ mice (11 females, 5 males) were killed at 12 months, and their brains were interrogated for AD-related pathology with both biochemistry and immunocytochemistry (ICC). In addition to amyloid-dependent endpoints such as soluble Aß production and plaque deposition quantified with 6E10 staining, the effect of CB2 receptor deletion on total soluble mouse tau production was assayed by using a recently developed high-sensitivity assay. Results revealed that soluble Aß42 and plaque deposition were significantly increased in J20 CNR2⁻/⁻ mice relative to CNR2⁺/⁺ mice. Microgliosis, quantified with ionized calcium-binding adapter molecule 1 (Iba-1) staining, did not differ between groups, whereas plaque associated microglia was more abundant in J20 CNR2⁻/⁻ mice. Total tau was significantly suppressed in J20 CNR2⁻/⁻ mice relative to J20 CNR2⁺/⁺ mice. The results confirm the constitutive role of the CB2 receptor system both in reducing amyloid plaque pathology in AD and also support tehpotential of cannabinoid therapies targeting CB2 to reduce Aß; however, the results suggest that interventions may have a divergent effect on tau pathology.

Methods for measuring tau pathology in transgenic mouse models.

In Alzheimer's disease (AD) and tauopathies, tau becomes hyperphosphorylated, undergoes a conformational change, and becomes aggregated and insoluble. There are three methods commonly used to study the insoluble tau fraction, two that utilize detergents (Sarkosyl and RIPA) and another that does not (insoluble). However, these methods require large amounts of homogenate for a relatively low yield of the insoluble fraction, which can be problematic when dealing with small tissue samples. Furthermore, the most common way of analyzing this material is through densitometry of immunoblots, offering only semiquantitative measurements. We provide a comparison of the three methods commonly used (Sarksoyl, RIPA, and insoluble) through immunoblot and ELISA analyses. Finally, we tested a new method to determine aggregated tau levels, utilizing a monoantibody tau ELISA. The insoluble fractions of four different mouse models (P301 L, htau, wild type, and knockout) as well as human AD and control brains were examined. There were significant correlations between the three insoluble methods for both total tau and pS396/404 tau measured by immunoblot or ELISA analyses. Additionally, the results from the ELISA method correlated significantly with those from immunoblot analyses. Finally, the monoantibody assay on the lysate significantly correlated with the total tau ELISAs performed on the three insoluble preparations. Taken together, these results suggest that all three insoluble preparation methods offer similar results for measuring insoluble tau in either mouse or human brains. In addition the new monoantibody ELISA offers a simple quantitative method to measure the amount of aggregated tau in both human and mouse brains.

Sensitive quantitative assays for tau and phospho-tau in transgenic mouse models.

Transgenic mouse models have been an invaluable resource in elucidating the complex roles of ß-amyloid and tau in Alzheimer's disease. Although many laboratories rely on qualitative or semiquantitative techniques when investigating tau pathology, we have developed 4 Low-Tau, Sandwich enzyme-linked immunosorbent assays (ELISAs) that quantitatively assess different epitopes of tau relevant to Alzheimer's disease: total tau, pSer-202, pThr-231, and pSer-396/404. In this study, after comparing our assays with commercially available ELISAs, we demonstrate our assay's high specificity and quantitative capabilities using brain homogenates from tau transgenic mice, htau, JNPL3, and tau knockout. All 4 ELISAs show excellent specificity for mouse and human tau, with no reactivity to tau knockout animals. An age-dependent increase of serum tau in both tau transgenic models was also seen. Taken together, these assays are valuable methods to quantify tau and phospho-tau levels in transgenic animals, by examining tau levels in brain and measuring tau as a potential serum biomarker.

Novel synthetic small-molecule activators of AMPK as enhancers of autophagy and amyloid-ß peptide degradation.

AMP-activated protein kinase (AMPK) is a metabolic sensor involved in intracellular energy metabolism through the control of several homeostatic mechanisms, which include autophagy and protein degradation. Recently, we reported that AMPK activation by resveratrol promotes autophagy-dependent degradation of the amyloid-ß (Aß) peptides, the core components of the cerebral senile plaques in Alzheimer's disease. To identify more potent enhancers of Aß degradation, we screened a library of synthetic small molecules selected for their structural similarities with resveratrol. Here, we report the identification of a series of structurally related molecules, the RSVA series, which inhibited Aß accumulation in cell lines nearly 40 times more potently than did resveratrol. Two of these molecules, RSVA314 and RSVA405, were further characterized and were found to facilitate CaMKKß-dependent activation of AMPK, to inhibit mTOR (mammalian target of rapamycin), and to promote autophagy to increase Aß degradation by the lysosomal system (apparent EC(50) ∼ 1 µM). This work identifies the RSVA compounds as promising lead molecules for the development of a new class of AMPK activating drugs controlling mTOR signaling, autophagy, and Aß clearance.

Memory deficits due to familial British dementia BRI2 mutation are caused by loss of BRI2 function rather than amyloidosis.

Familial dementias, which include Alzheimer disease (AD), familial British dementia (FBD), and familial Danish dementia (FDD), are caused by dominantly inherited autosomal mutations and are characterized by the production of amyloidogenic peptides, neurofibrillary tangles (NFTs) and neurodegeneration (St George-Hyslop and Petit, 2005; Garringer et al., 2009). The prevailing pathogenic theory, the "amyloid cascade hypothesis" (Hardy and Selkoe, 2002), posits that the accumulation of amyloidogenic peptides triggers tauopathy, neurodegeneration, and cognitive and behavioral changes. However, this hypothesis is yet to be validated, and causes of dementia may be multifaceted and involve other mechanisms, such as loss of function due to pathogenic mutations. Mouse models of human dementia invariably use transgenic expression systems (LaFerla and Oddo, 2005; McGowan et al., 2006; Vidal et al., 2009; Coomaraswamy et al., 2010) that do not reflect the genotypes of human disease and cannot replicate loss of function. Therefore, we generated a knock-in (KI) mouse model of FBD (FBD(KI)) genetically congruous with the human disease. FBD is caused by a missense mutation at the stop codon of the BRI2 gene (Vidal et al., 1999) and, like FBD patients, FBD(KI) mice carry this mutation in one of the two murine Bri2 alleles. We report that the British mutation drastically reduces expression of mature BRI2 in both KI mice and human FBD brains. This deficit is associated with severe hippocampal memory deficits in FBD(KI) mice. Remarkably, these animals showed no cerebral amyloidosis and tauopathy. Bri2(+/-) mice present memory deficits similar to those in FBD(KI) animals. Collectively, these results indicate that the British BRI2 mutation underlies abnormal memory due to loss of BRI2 function and independently of histopathological alterations typically evident in advanced neurodegenerative disease.

Transgenic expression of the amyloid-beta precursor protein-intracellular domain does not induce Alzheimer's Disease-like traits in vivo.

BACKGROUND: Regulated intramembranous proteolysis of the amyloid-beta precursor protein by the gamma-secretase yields amyloid-beta, which is the major component of the amyloid plaques found in Alzheimer's disease (AD), and the APP intracellular domain (AID). In vitro studies have involved AID in apoptosis and gene transcription. In vivo studies, which utilize transgenic mice expressing AID in the forebrain, only support a role for AID in apoptosis but not gene transcription. METHODOLOGY/PRINCIPAL FINDINGS: Here, we have further characterized several lines of AID transgenic mice by crossing them with human Tau-bearing mice, to determine whether over-expression of AID in the forebrain provokes AD-like pathologic features in this background. We have found no evidence that AID overexpression induces AD-like characteristics, such as activation of GSK-3beta, hyperphosphorylation of Tau and formation of neurofibrillary pathology. CONCLUSIONS/SIGNIFICANCE: Overall, these data suggest that AID transgenic mice do not represent a model that reproduces the overt biochemical and anatomo-pathologic lesions observed in AD patients. They can still be a valuable tool to understand the role of AID in enhancing the cell sensitivity to apoptotic stimuli, whose pathways still need to be characterized.

In vitro effect of PPAR-gamma2 Pro12Ala polymorphism on the deposition of Alzheimer's amyloid-beta peptides.

Mounting evidence suggests that peroxisome proliferator-activated receptor-gamma (PPAR-gamma) is involved in the modulation of pathogenic events related to Alzheimer's disease (AD). Such events would include the cerebral deposition of amyloid-beta (Abeta) and the consequent local inflammatory response. PPAR-gamma has been shown to act on both fronts, reducing either the secretion of Abeta or the expression of pro-inflammatory cytokines. Recently, the relatively common Pro12Ala polymorphism in exon 2 of PPAR-gamma has been associated with higher risk for late onset AD. Here, we compare the effect of PPAR-gamma and its genetic variant on the secretion of Abeta. Our results indicate that, in neuronal cultured cells, the Pro12Ala substitution does not affect the anti-amyloidogenic capacity of PPAR-gamma. Additional factors, PPAR-gamma related, may therefore predispose aged subjects, carrying the Ala allele, to develop the neurodegenerative disease.

Downregulation of myosin II-B by siRNA alters the subcellular localization of the amyloid precursor protein and increases amyloid-beta deposition in N2a cells.

The Alzheimer's disease (AD) brain pathology is characterized by extracellular deposits of amyloid-beta (Abeta) peptides and intraneuronal fibrillar structures. These pathological features may be functionally linked, but the mechanism by which Abeta accumulation relates to neuronal degeneration is still poorly understood. Abeta peptides are fragments cleaved from the amyloid precursor protein (APP), a transmembrane protein ubiquitously expressed in the nervous system. Although the proteolytic processing of APP has been implicated in AD, the physiological function of APP and the subcellular site of APP cleavages remain unknown. The overall structure of the protein and its fast anterograde transport along the axon support the idea that APP functions as a vesicular receptor for cytoskeletal motor proteins. In the current study, we test the hypothesis that myosin II, important contributor to the cytoskeleton of neuronal cells, may influence the trafficking and/or the processing of APP. Our results demonstrate that downregulation of myosin II-B, the major myosin isoform in neurons, is able to increase Abeta deposition, concomitantly altering the subcellular localization of APP. These new insights might be important for the understanding of the function of APP and provide a novel conceptual framework in which to analyze its pathological role.

Troglitazone, a peroxisome proliferator-activated receptor-gamma agonist, decreases tau phosphorylation in CHOtau4R cells.

Peroxisome proliferator-activated receptor-gamma (PPARgamma), a member of the nuclear receptor superfamily, is activated by several compounds including the thiazolidinediones. In addition to being a target for diabetes, PPARgamma activation state has recently been shown to modulate beta-amyloid peptide (Abeta) production in cellular models relevant to Alzheimer's disease. Here, we report the effect of troglitazone, a thiazolidinedione, in cells expressing 4-repeat tau. A 24 h treatment with troglitazone significantly reduced phosphorylation of tau at Ser202 and Ser396/404, residues of early and later stages of neurofibrillary tangle accumulation in Alzheimer's disease and other neurodegenerative disorders. Under the same experimental conditions the level of tau did not change. In our cellular model, troglitazone appeared to enhance 3'-phosphoinositide-dependent protein kinase 1 (PDK1) nuclear translocation, resulting in a decrease in cytosolic phosphorylated 70 kDa ribosomal protein kinase (p70S6) and phosphorylated mammalian target of rapamycin (mTor). Furthermore, PPARgamma transcriptional activity did not appear to be responsible for decreased phosphorylation of tau. Thus, we believe that the thiazolidinedione regulates tau phosphorylation through a PPARgamma-dependent/independent mechanism involving an Akt/glycogen synthase kinase-3(GSK-3beta)-independent signalling cascade: PDK1/p70S6K/mTor.