Accumulation Of Hyperphosphorylated Tau Protein Research Articles

Therapeutic Potential of Ferulic Acid in Alzheimer's Disease.

Alzheimer's Disease (AD) is one of the most important neurodegenerative diseases, accounting for 60% of all dementia cases. AD is a progressive neurodegenerative disease that occurs due to the production of β-amyloid (Aβ) protein and accumulation of hyper-phosphorylated tau protein; it causes breakage in the synaptic bonds and neuronal deaths to a large extent. Millions of people worldwide suffer from AD because there is no definitive drug for disease prevention, treatment, or slowing down its progression. Over the last decade, multiple target applications have been developed for AD treatments. These targets include Aβ accumulations, hyper-phosphorylated tau proteins, mitochondrial dysfunction, and oxidative stress, resulting in toxicity. Various natural or semisynthetic antioxidant formulations have been shown to protect brain cells from Aβ-induced toxicity and provide promising potentials for AD treatment. Ferulic acid (FA), a high-capacity antioxidant molecule, is naturally synthesized from certain plants. FA has been shown to have different substantial biological properties, such as anticancer, antidiabetic, antimicrobial, anti-inflammatory, hepatoprotective, and cardioprotective actions, etc. Furthermore, FA exerts neuroprotection via preventing Aβ-fibril formation, acting as an anti-inflammatory agent, and inhibiting free radical generation and acetylcholinesterase (AChE) enzyme activity. In this review, we present key biological roles of FA and several FA derivatives in preventing Aβ-induced neurotoxicity, protecting against free radical attacks, and exhibiting enzyme inhibitions and evaluate them as possible therapeutic agents for the treatment of AD.

BAG1 Overexpression Stabilizes High Molecular Tau Protein – a Crucial Role of the Co-chaperone in Tau Pathology

The Bcl-2-associated athanogene-1 (BAG1) exerts neuroprotective properties which has been shown in several studies of neurodegenerative disease models like Parkinson’s disease, Huntington’s disease and even cerebral ischemia. On the basis of the well-known neuroprotective function of the co-chaperone, we wanted to examine its properties in a model for Alzheimer’s disease, a neurological disorder of great significance. One of the hallmarks of Alzheimer’s disease, besides extracellular plaque formation, is the intra-neuronal accumulation of hyper-phosphorylated tau protein that leads to tau aggregation. When overexpressed together with a tau mutant with high propensity for aggregation, BAG1 led to the stabilization of high-molecular tau fragments in rat CSM 14.1 cells compared to wild-type cells. Deletion of the domain in BAG1 that is responsible for binding to Hsp70 (BAGΔC) abolished this effect, which could be confirmed by immunocytochemistry. In fact, BAG1 does not only increase mutant tau aggregation but also prevents its degradation by the proteasome. Immunochemistry revealed that overexpression of the Bcl-2-associated athanogene-1 gives rise to large tau aggregates surrounded by lysosomes. Furthermore, toxicity assays indicated increased tau toxicity in BAG1 overexpressing cells. Hence, in contrast to other neurodegenerative diseases, BAG1 seems to enhance Alzheimer´s pathology and to promote cell death due to the stabilization of aggregation-prone tau species that evade proteasomal clearance. To conclude, this analysis provides a new sight of the co-chaperone BAG1 and yet again demonstrates its complex influence in a model of Alzheimer’s disease.

Neuroprotective effects of resveratrol in Alzheimer's disease.

Alzheimer's disease (AD) is a neurodegenerative disorder, which is commonly seen in older individuals. This is characterized by cognitive dysfunction, which leads to dementia. Pharmacological treatments for AD are mainly targeted on its symptoms like memory loss and cognitive impairment. The pathophysiology involved in AD is intra-neuronal accumulation of hyper-phosphorylated tau protein as neurofibrillary tangle and extra cellular beta amyloid plaque deposition, which is due to oxidative stress. Here we review the neuro-protective effects of Resveratrol (RSV) and its treatment efficacy in AD. RSV is a naturally available polyphenolic compound, which has antioxidant, anti-cancerous, anti-inflammatory and anti-aging properties. RSV crosses blood brain barrier and exerts its antioxidant effect by enhancing the anti-oxidant enzymes. RSV is involved in Sirtuin (SIRT1) mediated lifespan extension activity. RSV has reduced glial activation and helped in increasing the hippocampal neurogenesis. RSV was able to decrease the expression of amyloid precursor protein, along with improvement of spatial working memory. Since RSV acts as an antioxidant, it can be safely used as oral drug.

Encefalopatía traumática crónica, definición, diagnóstico y prevención. Revisión de la literatura

La encefalopatía traumática crónica (ETC) es una enfermedad neurodegenerativa que se produce como consecuencia traumatismoscerebrales repetitivos; concusiones, que son un síndrome clínico que se caracteriza por una alteración de la función cerebral5. Una concusión, bajo su estricta definición, no debiese causar cambios estructurales en el cerebro por lo que no sería visible a través de imágenes, sí existen cambios a nivel microscópicos, bioquímicos y biomecánicos1. La mayoría de los pacientes tienen completa resolución de sus síntomas dentro de 10 días (90%), pero existe un pequeño porcentaje que persiste con estos8, pudiendo presentarse como un síndrome postconcusional, síndrome de segundo impacto o una encefalopatía traumática crónica3. La ETC se caracteriza por la acumulación de prot-tau hiperfosforilada en neuronas y astrocitos2. Estas se van a presentar en forma de ovillos o hilos neurofibrilares. En etapas iniciales las encontraremos de forma focalizada en la corteza frontal y en las formas más severas su distribución será más generalizada, distribuyéndose en la mayoría de las regiones del cerebro9. Su diagnóstico se realiza a través de histopatología, por lo que hasta el momento sólo se ha logrado post-mortem. Se está trabajando en nuevas tecnologías asociadas a biomarcadores y PET para lograr una diagnostico premortem. El mayor énfasis en el manejo de esta taupatía es la prevención y adecuado manejo de las concusiones.

Antibody-mediated clearance of tau in primary mouse microglial cultures requires Fc\u03b3-receptor binding and functional lysosomes

Neurodegenerative diseases such as Alzheimer’s disease are characterized by the progressive spreading and accumulation of hyper-phosphorylated tau protein in the brain. Anti-tau antibodies have been shown to reduce tau pathology in in vivo models and antibody-mediated clearance of tau exerted by microglia has been proposed as a contributing factor. By subjecting primary microglia cultured in vitro to anti-phospho-tau antibodies in complex with pathological tau, we show that microglia internalise and degrade tau in a manner that is dependent on FcγR interaction and functional lysosomes. It has recently been discussed if anti-tau antibody effector-functions are required for induction of tau clearance. Using antibodies with compromised FcγR binding and non-compromised control antibodies we show that antibody effector functions are required for induction of microglial clearance of tau. Understanding the inflammatory consequences of targeting microglia using therapeutic antibodies is important when developing these molecules for clinical use. Using RNA sequencing, we show that treatment with anti-tau antibodies increases transcription of mRNA encoding pro-inflammatory markers, but that the mRNA expression profile of antibody-treated cells differ from the profile of LPS activated microglia. We further demonstrate that microglia activation alone is not sufficient to induce significant tau clearance.