Mitochondrial modulation with leriglitazone as a potential treatment for Rett syndrome.

BACKGROUND: Rett syndrome is a neuropediatric disease occurring due to mutations in MECP2 and characterized by a regression in the neuronal development following a normal postnatal growth, which results in the loss of acquired capabilities such as speech or purposeful usage of hands. While altered neurotransmission and brain development are the center of its pathophysiology, alterations in mitochondrial performance have been previously outlined, shaping it as an attractive target for the disease treatment. METHODS: We have thoroughly described mitochondrial performance in two Rett models, patients' primary fibroblasts and female Mecp2tm1.1Bird-/+ mice brain, discriminating between different brain areas. The characterization was made according to their bioenergetics function, oxidative stress, network dynamics or ultrastructure. Building on that, we have studied the effect of leriglitazone, a PPARγ agonist, in the modulation of mitochondrial performance. For that, we treated Rett female mice with 75 mg/kg/day leriglitazone from weaning until sacrifice at 7 months, studying both the mitochondrial performance changes and their consequences on the mice phenotype. Finally, we studied its effect on neuroinflammation based on the presence of reactive glia by immunohistochemistry and through a cytokine panel. RESULTS: We have described mitochondrial alterations in Rett fibroblasts regarding both shape and bioenergetic functions, as they displayed less interconnected and shorter mitochondria and reduced ATP production along with increased oxidative stress. The bioenergetic alterations were recalled in Rett mice models, being especially significant in cerebellum, already detectable in pre-symptomatic stages. Treatment with leriglitazone recovered the bioenergetic alterations both in Rett fibroblasts and female mice and exerted an anti-inflammatory effect in the latest, resulting in the amelioration of the mice phenotype both in general condition and exploratory activity. CONCLUSIONS: Our studies confirm the mitochondrial dysfunction in Rett syndrome, setting the differences through brain areas and disease stages. Its modulation through leriglitazone is a potential treatment for this disorder, along with other diseases with mitochondrial involvement. This work constitutes the preclinical necessary evidence to lead to a clinical trial.

Development of PPARγ Agonists for the Treatment of Neuroinflammatory and Neurodegenerative Diseases: Leriglitazone as a Promising Candidate.

Increasing evidence suggests that the peroxisome proliferator-activated receptor γ (PPARγ), a member of the nuclear receptor superfamily, plays an important role in physiological processes in the central nervous system (CNS) and is involved in cellular metabolism and repair. Cellular damage caused by acute brain injury and long-term neurodegenerative disorders is associated with alterations of these metabolic processes leading to mitochondrial dysfunction, oxidative stress, and neuroinflammation. PPARγ agonists have demonstrated the potential to be effective treatments for CNS diseases in preclinical models, but to date, most drugs have failed to show efficacy in clinical trials of neurodegenerative diseases including amyotrophic lateral sclerosis, Parkinson's disease, and Alzheimer's disease. The most likely explanation for this lack of efficacy is the insufficient brain exposure of these PPARγ agonists. Leriglitazone is a novel, blood-brain barrier (BBB)-penetrant PPARγ agonist that is being developed to treat CNS diseases. Here, we review the main roles of PPARγ in physiology and pathophysiology in the CNS, describe the mechanism of action of PPARγ agonists, and discuss the evidence supporting the use of leriglitazone to treat CNS diseases.

PPAR Gamma Agonist Leriglitazone Recovers Alterations Due to Pank2-Deficiency in hiPS-Derived Astrocytes.

The novel brain-penetrant peroxisome proliferator-activated receptor gamma agonist leriglitazone, previously validated for other rare neurodegenerative diseases, is a small molecule that acts as a regulator of mitochondrial function and exerts neuroprotective, anti-oxidative and anti-inflammatory effects. Herein, we tested whether leriglitazone can be effective in ameliorating the mitochondrial defects that characterize an hiPS-derived model of Pantothenate kinase-2 associated Neurodegeneration (PKAN). PKAN is caused by a genetic alteration in the mitochondrial enzyme pantothenate kinase-2, whose function is to catalyze the first reaction of the CoA biosynthetic pathway, and for which no effective cure is available. The PKAN hiPS-derived astrocytes are characterized by mitochondrial dysfunction, cytosolic iron deposition, oxidative stress and neurotoxicity. We monitored the effect of leriglitazone in comparison with CoA on hiPS-derived astrocytes from three healthy subjects and three PKAN patients. The treatment with leriglitazone did not affect the differentiation of the neuronal precursor cells into astrocytes, and it improved the viability of PKAN cells and their respiratory activity, while diminishing the iron accumulation similarly or even better than CoA. The data suggest that leriglitazone is well tolerated in this cellular model and could be considered a beneficial therapeutic approach in the treatment of PKAN.

Incorporation of hydroxytyrosol alkyl esters of different chain length as antioxidant strategy in walnut oil spray-dried microparticles with a sodium alginate outer layer.

Omega-3 rich vegetable oils, such as walnut oil, are gaining interest because of their health benefits. Synthetized homologous series of hydroxytyrosol alkyl esters (HTEs) with different alkyl chain lengths (C4-C18) were incorporated in purified walnut oil (PWO) spray-dried microparticles, designed with Capsul® (C) as encapsulating agent and sodium alginate (SA) as outer layer (PWO-C/SA). The encapsulation efficiency (>87%) and Tg of PWO-C/SA microparticles were not affected by the HTEs. The incorporation of HTE-C10 increased the melting point (185.0 ± 1.3 °C), decreasing the formation of Dimers + Polymers (1.12 ± 0.05% at day 35 of storage) and the crystallinity of the microparticles (>170 °C). The highest stability of PWO-C(HTE-C10)/SA suggests a specific location of HTE-C10 at the oil:water interface. The SA layer delayed the release of fatty acids during in vitro digestion. The incorporation of HTEs of medium chain length can be a suitable strategy to protect unsaturated oils encapsulated by spray-drying.

Genomic and Experimental Analysis of the Insecticidal Factors Secreted by the Entomopathogenic Fungus Beauveria pseudobassiana RGM 2184.

The entomopathogenic fungus Beauveria pseudobassiana strain RGM 2184 can reach a maximum efficacy of 80% against the quarantine pest Lobesia botrana in field assays. In this study, the RGM 2184 genome was sequenced, and genome mining analyses were performed to predict the factors involved in its insecticidal activity. Additionally, the metabolic profiling of the RMG 2184 culture's supernatants was analyzed by mass spectrometry, and the insecticidal activity from one of these extracts was evaluated in Galleria mellonella larvae. The genome analysis resulted in 114 genes encoding for extracellular enzymes, four biosynthetic gene clusters reported as producers of insecticidal and bactericidal factors (oosporein, beauvericin, desmethylbassianin, and beauveriolide), 20 toxins, and at least 40 undescribed potential biocontrol factors (polyketides and nonribosomal peptides). Comparative genomic analysis revealed that 65-95% of these genes are Beauveria genus-specific. Metabolic profiling of supernatant extracts from RGM 2184 cultures exhibited secondary metabolites such as beauveriolide, oosporein, inflatin C, and bassiatin. However, a number of detected metabolites still remain undescribed. The metabolite extract caused 79% mortality of Galleria mellonella larvae at 28 days. The results of this research lay the groundwork for the study of new insecticidal molecules.

Recovery of Bioactive Compounds from Pomegranate (Punica granatum L.) Peel Using Pressurized Liquid Extraction.

Pressurized liquid extraction (PLE) is a clean and environmentally friendly alternative for the recovery of bioactive compounds from fruit by-products. Herein we focused on PLE for the extraction of bioactive compounds from pomegranate peel using a combination of pressurized water and ethanol. The main aim was to determine the optimal PLE conditions, i.e., ethanol percentage and process temperature, to obtain a pomegranate peel extract (PPE) with maximum total phenolic content (TPC), punicalagin content, and antimicrobial activity (AMA). The experimental design was conducted using a central composite design with axial points. Response surface methodology was applied to optimize the response variables using the desirability function. Multiple response optimization indicated a process temperature of 200 °C and ethanol of 77% as optimal conditions. The TPC and the punicalagin content of PPE-PLE obtained under optimal conditions were 164.3 ± 10.7 mg GAE/g DW and 17 ± 3.6 mg/g DW, respectively. Our findings support the efficacy of PLE on TPC recovery but not in punicalagin recovery. The AMA against S. aureus was 14 mm. The efficacy of PPE-PLE in food applications must continue to be studied in order to achieve adequate information on its potential for developing new food additives.

PPAR gamma agonist leriglitazone improves frataxin-loss impairments in cellular and animal models of Friedreich Ataxia.

Friedreich ataxia (FRDA), the most common autosomal recessive ataxia, is characterized by degeneration of the large sensory neurons and spinocerebellar tracts, cardiomyopathy, and increased incidence in diabetes. The underlying pathophysiological mechanism of FRDA, driven by a significantly decreased expression of frataxin (FXN), involves increased oxidative stress, reduced activity of enzymes containing iron­sulfur clusters (ISC), defective energy production, calcium dyshomeostasis, and impaired mitochondrial biogenesis, leading to mitochondrial dysfunction. The peroxisome proliferator-activated receptor gamma (PPARγ) is a ligand-activated transcriptional factor playing a key role in mitochondrial function and biogenesis, fatty acid storage, energy metabolism, and antioxidant defence. It has been previously shown that the PPARγ/PPARγ coactivator 1 alpha (PGC-1α) pathway is dysregulated when there is frataxin deficiency, thus contributing to FRDA pathogenesis and supporting the PPARγ pathway as a potential therapeutic target. Here we assess whether MIN-102 (INN: leriglitazone), a novel brain penetrant and orally bioavailable PPARγ agonist with an improved profile for central nervous system (CNS) diseases, rescues phenotypic features in cellular and animal models of FRDA. In frataxin-deficient dorsal root ganglia (DRG) neurons, leriglitazone increased frataxin protein levels, reduced neurite degeneration and α-fodrin cleavage mediated by calpain and caspase 3, and increased survival. Leriglitazone also restored mitochondrial membrane potential and partially reversed decreased levels of mitochondrial Na+/Ca2+ exchanger (NCLX), resulting in an improvement of mitochondrial functions and calcium homeostasis. In frataxin-deficient primary neonatal cardiomyocytes, leriglitazone prevented lipid droplet accumulation without increases in frataxin levels. Furthermore, leriglitazone improved motor function deficit in YG8sR mice, a FRDA mouse model. In agreement with the role of PPARγ in mitochondrial biogenesis, leriglitazone significantly increased markers of mitochondrial biogenesis in FRDA patient cells. Overall, these results suggest that targeting the PPARγ pathway by leriglitazone may provide an efficacious therapy for FRDA increasing the mitochondrial function and biogenesis that could increase frataxin levels in compromised frataxin-deficient DRG neurons. Alternately, leriglitazone improved the energy metabolism by increasing the fatty acid ß-oxidation in frataxin-deficient cardiomyocytes without elevation of frataxin levels. This could be linked to a lack of significant mitochondrial biogenesis and cardiac hypertrophy. The results reinforced the different tissue requirement in FRDA and the pleiotropic effects of leriglitazone that could be a promising therapy for FRDA.

Influence of the Location of Ascorbic Acid in Walnut Oil Spray-Dried Microparticles with Outer Layer on the Physical Characteristics and Oxidative Stability.

Purified walnut oil (PWO) microparticles with Capsul® (C, encapsulating agent), sodium alginate (SA) as outer layer and ascorbic acid (AA) as oxygen scavenger were obtained by spray drying using a three-fluid nozzle. AA was incorporated in the inner infeed (PWO-C(AA)/SA), in the outer infeed (PWO-C/SA(AA)) and in both infeed (PWO-C(AA)/SA(AA)). PWO-C(AA)/SA (4.56 h) and POW-C(AA)/SA(AA) (2.60 h) microparticles showed higher induction period than POW-C/SA(AA) (1.17 h), and lower formation of triacylglycerol dimers and polymers during storage (40 °C). Therefore, AA located in the inner infeed improved the oxidative stability of encapsulated PWO by removing the residual oxygen. AA in the SA outer layer did not improve the oxidative stability of encapsulated PWO since oxygen diffusion through the microparticles was limited and/or AA weakened the SA layer structure. The specific-location of AA (inner infeed) is a strategy to obtain stable spray-dried polyunsaturated oil-based microparticles for the design of foods enriched with omega-3 fatty acids.

Tau Protein as a New Regulator of Cellular Prion Protein Transcription.

Cellular prion protein (PrPC) is largely responsible for transmissible spongiform encephalopathies (TSEs) when it becomes the abnormally processed and protease resistant form PrPSC. Physiological functions of PrPC include protective roles against oxidative stress and excitotoxicity. Relevantly, PrPC downregulates tau levels, whose accumulation and modification are a hallmark in the advance of Alzheimer's disease (AD). In addition to the accumulation of misfolded proteins, in the initial stages of AD-affected brains display both increased reactive oxygen species (ROS) markers and levels of PrPC. However, the factors responsible for the upregulation of PrPC are unknown. Thus, the aim of this study was to uncover the different molecular actors promoting PrPC overexpression. In order to mimic early stages of AD, we used ß-amyloid-derived diffusible ligands (ADDLs) and tau cellular treatments, as well as ROS generation, to elucidate their particular roles in human PRNP promoter activity. In addition, we used specific chemical inhibitors and site-specific mutations of the PRNP promoter sequence to analyze the contribution of the main transcription factors involved in PRNP transcription under the analyzed conditions. Our results revealed that tau is a new modulator of PrPC expression independently of ADDL treatment and ROS levels. Lastly, we discovered that the JNK/c-jun-AP-1 pathway is involved in increased PRNP transcription activity by tau but not in the promoter response to ROS.

Microencapsulation of Anthocyanin Extracted from Purple Flesh Cultivated Potatoes by Spray Drying and Its Effects on In Vitro Gastrointestinal Digestion.

Purple flesh cultivated potato (PP) is a foodstuff scarcely cultivated in the world but with high potential because of its anthocyanin content. Moreover, it has been little explored as a source of anthocyanins (AT) for further applications in formulated food products. The main goal of this research was to study the effect of maltodextrin (MD) and spray drying conditions on the encapsulation efficiency (EE) and bioaccesibility of AT from purple flesh cultivated potato extract (PPE). The anthocyanin-rich extract was obtained from PP and microencapsulated by spray-drying, using MD as the encapsulating agent. A statistical optimization approach was used to obtain optimal microencapsulation conditions. The PPE microparticles obtained under optimal conditions showed 86% of EE. The protector effect of microencapsulation on AT was observed to be stable during storage and in vitro digestion. The AT degradation rate constant was significantly lower for the PPE-MD than for the PPE. The assessed bioaccesibility of AT from the PPE-MD was 20% higher than that of the PPE, which could be explained by the protective effect of encapsulation against environmental conditions. In conclusion, microencapsulation is an effective strategy to protect AT from PP, suggesting that AT may be an alternative as a stable colorant for use in the food industry.

Influence of gelation on the retention of purple cactus pear extract in microencapsulated double emulsions.

A purple cactus pear (Opuntia ficus-indica) extract (CP) was encapsulated in double emulsions (DE) gelled with gelatin (DE-CP-G) and with gelatin and transglutaminase (DE-CP-GT), as well as in a DE with a liquid external aqueous phase (DE-CP), in order to study the retention of betanin as colorant agent. Both gelled DEs showed a predominantly elastic behavior, in contrast with DE-CP. The degradation rate constant of betanin was significantly higher in DE-CP-GT (90.2 x 10-3 days-1) than in DE-CP-G (11.0 x 10-3 days-1) and DE-CP (14.6 x 10-3 days-1) during cold-storage (4 °C). A shift towards yellow color was found in all the systems during cold-storage (4 °C) and after thermal treatment (70°C/30 min), especially in DE-CP-GT, denoting a higher degradation of betanin. Betalamic acid, cyclo-Dopa 5-O-ß-glucoside, 17-decarboxy-betanin and neobetanin were identified by UHPLC-MS/MS as degradation products of betanin.

Picalm reduction exacerbates tau pathology in a murine tauopathy model.

Genome-wide association studies (GWAS) have identified PICALM as one of the most significant susceptibility loci for late-onset Alzheimer's disease (AD) after APOE and BIN1. PICALM is a clathrin-adaptor protein and plays critical roles in clathrin-mediated endocytosis and in autophagy. PICALM modulates brain amyloid ß (Aß) pathology and tau accumulation. We have previously reported that soluble PICALM protein level is reduced in correlation with abnormalities of autophagy markers in the affected brain areas of neurodegenerative diseases including AD, sporadic tauopathies and familial cases of frontotemporal lobar degeneration with tau-immunoreactive inclusions (FTLD-tau) with mutations in the microtubule-associated protein tau (MAPT) gene. It remains unclarified whether in vivo PICALM reduction could either trigger or influence tau pathology progression in the brain. In this study, we confirmed a significant reduction of soluble PICALM protein and autophagy deficits in the post-mortem human brains of FTLD-tau-MAPT (P301L, S364S and L266V). We generated a novel transgenic mouse line named Tg30xPicalm+/- by crossing Tg30 tau transgenic mice with Picalm-haploinsufficient mice to test whether Picalm reduction may modulate tau pathology. While Picalm haploinsufficiency did not lead to any motor phenotype or detectable tau pathology in mouse brains, Tg30xPicalm+/- mice developed markedly more severe motor deficits than Tg30 by the age of 9 months. Tg30xPicalm+/- had significantly higher pathological tau levels in the brain, an increased density of neurofibrillary tangles compared to Tg30 mice and increased abnormalities of autophagy markers. Our results demonstrate that Picalm haploinsufficiency in transgenic Tg30 mice significantly aggravated tau pathologies and tau-mediated neurodegeneration, supporting a role for changes in Picalm expression as a risk/sensitizing factor for development of tau pathology and as a mechanism underlying the AD risk associated to PICALM.

A 4R tauopathy develops without amyloid deposits in aged cat brains.

Human tauopathies are neurodegenerative diseases with accumulation of abnormally phosphorylated and aggregated tau proteins forming neurofibrillary tangles. We investigated the development of tau pathology in aged cat brains as a model of neurofibrillary tangle formation occurring spontaneously during aging. In 4 of 6 cats aged between 18 and 21 years, we found a somatodendritic accumulation of phosphorylated and aggregated tau in neurons and oligodendrocytes. Two of these 4 cats had no amyloid immunoreactivity. These tau inclusions were mainly composed of 4R tau isoforms and straight filaments and colocalized with the active form of the glycogen synthase kinase-3 (GSK3). Cat brains with a tau pathology showed a significant cortical atrophy and neuronal loss. We demonstrate in this study the presence of a tau pathology in aged cat brains that develop independently of amyloid deposits. The colocalization of the active form of the GSK3 with tau inclusions as observed in human tauopathies suggests that this kinase could be responsible for the abnormal tau phosphorylation observed in aged cat brains, representing a mechanism of tau pathology development shared between a naturally occurring tauopathy in aged cats and human tauopathies.

Amyloid-ß pathology enhances pathological fibrillary tau seeding induced by Alzheimer PHF in vivo.

Neuropathological analysis in Alzheimer's disease (AD) and experimental evidence in transgenic models overexpressing frontotemporal dementia with Parkinsonism linked to chromosome 17 (FTDP-17) mutant tau suggest that amyloid-ß pathology enhances the development of tau pathology. In this work, we analyzed this interaction independently of the overexpression of an FTDP-17 mutant tau, by analyzing tau pathology in wild-type (WT), 5xFAD, APP-/- and tau-/- mice after stereotaxic injection in the somatosensory cortex of short-length native human AD-PHF. Gallyas and phosphotau-positive tau inclusions developed in WT, 5xFAD, and APP-/- but not in tau-/- mice. Ultrastructural analysis demonstrated their intracellular localization and that they were composed of straight filaments. These seeded tau inclusions were composed only of endogenous murine tau exhibiting a tau antigenic profile similar to tau aggregates in AD. Insoluble tau level was higher and ipsilateral anteroposterior and contralateral cortical spreading of tau inclusions was more important in AD-PHF-injected 5xFAD mice than in WT mice. The formation of large plaque-associated dystrophic neurites positive for oligomeric and phosphotau was observed in 5xFAD mice injected with AD-PHF but never in control-injected or in non-injected 5xFAD mice. An increased level of the p25 activator of CDK5 kinase was found in AD-PHF-injected 5xFAD mice. These data demonstrate in vivo that the presence of Aß pathology enhances experimentally induced tau seeding of endogenous, wild-type tau expressed at physiological level, and demonstrate the fibrillar nature of heterotopically seeded endogenous tau. These observations further support the hypothesis that Aß enhances tau pathology development in AD through increased pathological tau spreading.

Effect of spray-drying with organic solvents on the encapsulation, release and stability of fish oil.

Fish-oil (FO) was encapsulated with hydroxypropylcelullose (HPC) by conventional spray-drying with water (FO-water) and solvent spray-drying with ethanol (FO-EtOH), methanol (FO-MeOH) and acetone (FO-Acet) in order to study the effect of the solvent on the encapsulation efficiency (EE), microparticle properties and stability of FO during storage at 40 °C. Results showed that FO-Acet presented the highest EE of FO (92.0%), followed by FO-EtOH (80.4%), FO-MeOH (75.0%) and FO-water (71.1%). A decrease of the dielectric constant increased the EE of FO, promoting triglyceride-polymer interactions instead of oil-in-water emulsion retention. FO release profile in aqueous model was similar for all FO-microparticles, releasing only the surface FO, according to Higuchi model. Oxidative stability of FO significantly improved by spray-drying with MeOH, both in surface and encapsulated oil fractions. In conclusion, encapsulation of FO by solvent spray-drying can be proposed as an alternative technology for encapsulation of hydrophobic molecules.

Effect of salinity on locomotor performance and thermal extremes of metamorphic Andean Toads (Rhinella spinulosa) from Monte Desert, Argentina.

Rhinella spinulosa is distributed from Peru to Argentina (from 1200 to 5000 m elevation), inhabiting arid mountain valleys of the Andes, characterized by salty soils. The variations in soil salinity, caused by high evapotranspiration of water, can create an osmotic constraint and high thermal oscillations for metamorphsed Andean toad (R. spinulosa), affecting their thermoregulation and extreme thermal tolerances. We investigated the changes in thermal tolerance parameters (critical thermal maximum and crystallization temperature) of a population of metamorphosed R. spinulosa from the Monte Desert of San Juan, Argentina, under different substrate salinity conditions. Our results suggest that the locomotor performance of metamorphs of R. spinulosa is affected by increasing salinity concentrations in the environment where they develop. On the other hand, the thermal extremes of metamorphs of R. spinulosa also showed changes associated with different salinity conditions. According to other studies on different organisms, the increase of the osmolarity of the internal medium may increase the thermal tolerance of this species. More studies are needed to understand the thermo-osmolar adjustments of the metamorphs of toads to environmental variability.

iPS Cell Cultures from a Gerstmann-Sträussler-Scheinker Patient with the Y218N PRNP Mutation Recapitulate tau Pathology.

Gerstmann-Sträussler-Scheinker (GSS) syndrome is a fatal autosomal dominant neurodegenerative prionopathy clinically characterized by ataxia, spastic paraparesis, extrapyramidal signs and dementia. In some GSS familiar cases carrying point mutations in the PRNP gene, patients also showed comorbid tauopathy leading to mixed pathologies. In this study we developed an induced pluripotent stem (iPS) cell model derived from fibroblasts of a GSS patient harboring the Y218N PRNP mutation, as well as an age-matched healthy control. This particular PRNP mutation is unique with very few described cases. One of the cases presented neurofibrillary degeneration with relevant Tau hyperphosphorylation. Y218N iPS-derived cultures showed relevant astrogliosis, increased phospho-Tau, altered microtubule-associated transport and cell death. However, they failed to generate proteinase K-resistant prion. In this study we set out to test, for the first time, whether iPS cell-derived neurons could be used to investigate the appearance of disease-related phenotypes (i.e, tauopathy) identified in the GSS patient.

Level of PICALM, a key component of clathrin-mediated endocytosis, is correlated with levels of phosphotau and autophagy-related proteins and is associated with tau inclusions in AD, PSP and Pick disease.

Single nucleotide polymorphisms in PICALM, a key component of clathrin-mediated endocytosis machinery, have been identified as genetic susceptibility loci for late onset Alzheimer's disease (LOAD). We previously reported that PICALM protein levels were decreased in AD brains and that PICALM was co-localised with neurofibrillary tangles in LOAD, familial AD with PSEN1 mutations and Down syndrome. In the present study, we analysed PICALM expression, cell localisation and association with pathological cellular inclusions in other tauopathies and in non-tau related neurodegenerative diseases. We observed that PICALM was associated with neuronal tau pathology in Pick disease and in progressive supranuclear palsy (PSP) and co-localised with both 3R and 4R tau positive inclusions unlike in corticobasal degeneration (CBD) or in frontotemporal lobar degeneration (FTLD)-MAPT P301L. PICALM immunoreactivities were not detected in tau-positive tufted astrocytes in PSP, astrocytic plaques in CBD, Lewy bodies in Lewy body disease, diffuse type (LBD) and in TDP-43-positive inclusions in FTLD. In the frontal cortex in tauopathies, the ratio of insoluble to soluble PICALM was increased while the level of soluble PICALM was decreased and was inversely correlated with the level of phosphotau. PICALM decrease was also significantly correlated with increased LC3-II and decreased Beclin-1 levels in tauopathies and in non-tau related neurodegenerative diseases. These results suggest that there is a close relationship between abnormal PICALM processing, tau pathology and impairment of autophagy in human neurodegenerative diseases.

Domain-Specific Activation of Death-Associated Intracellular Signalling Cascades by the Cellular Prion Protein in Neuroblastoma Cells.

The biological functions of the cellular prion protein remain poorly understood. In fact, numerous studies have aimed to determine specific functions for the different protein domains. Studies of cellular prion protein (PrP(C)) domains through in vivo expression of molecules carrying internal deletions in a mouse Prnp null background have provided helpful data on the implication of the protein in signalling cascades in affected neurons. Nevertheless, understanding of the mechanisms underlying the neurotoxicity induced by these PrP(C) deleted forms is far from complete. To better define the neurotoxic or neuroprotective potential of PrP(C) N-terminal domains, and to overcome the heterogeneity of results due to the lack of a standardized model, we used neuroblastoma cells to analyse the effects of overexpressing PrP(C) deleted forms. Results indicate that PrP(C) N-terminal deleted forms were properly processed through the secretory pathway. However, PrPΔF35 and PrPΔCD mutants led to death by different mechanisms sharing loss of alpha-cleavage and activation of caspase-3. Our data suggest that both gain-of-function and loss-of-function pathogenic mechanisms may be associated with N-terminal domains and may therefore contribute to neurotoxicity in prion disease. Dissecting the molecular response induced by PrPΔF35 may be the key to unravelling the physiological and pathological functions of the prion protein.