scholarly journals Pharmacological Modulators of Tau Aggregation and Spreading

2020 ◽  
Vol 10 (11) ◽  
pp. 858
Author(s):  
Antonio Dominguez-Meijide ◽  
Eftychia Vasili ◽  
Tiago Fleming Outeiro
Keyword(s):  
Tau Protein ◽  
Neurodegenerative Disorders ◽  
Molecular Mechanisms ◽  
Mechanisms Of Action ◽  
Tau Aggregation ◽  
The Brain ◽  
Pharmacological Modulators

Tauopathies are neurodegenerative disorders characterized by the deposition of aggregates composed of abnormal tau protein in the brain. Additionally, misfolded forms of tau can propagate from cell to cell and throughout the brain. This process is thought to lead to the templated misfolding of the native forms of tau, and thereby, to the formation of newer toxic aggregates, thereby propagating the disease. Therefore, modulation of the processes that lead to tau aggregation and spreading is of utmost importance in the fight against tauopathies. In recent years, several molecules have been developed for the modulation of tau aggregation and spreading. In this review, we discuss the processes of tau aggregation and spreading and highlight selected chemicals developed for the modulation of these processes, their usefulness, and putative mechanisms of action. Ultimately, a stronger understanding of the molecular mechanisms involved, and the properties of the substances developed to modulate them, will lead to the development of safer and better strategies for the treatment of tauopathies.

Age-related changes in microglial physiology: the role for healthy brain ageing and neurodegenerative disorders

e-Neuroforum ◽  
2017 ◽  
Vol 23 (4) ◽  
Author(s):  
Olga Garaschuk
Keyword(s):  
Neurodegenerative Disorders ◽  
Healthy Aging ◽  
Molecular Mechanisms ◽  
Brain Parenchyma ◽  
Immune Defense ◽  
Synaptic Activity ◽  
Mammalian Brain ◽  
Age Related ◽  
Brain Ageing ◽  
The Brain

AbstractMicroglia are the main immune cells of the brain contributing, however, not only to brain’s immune defense but also to many basic housekeeping functions such as development and maintenance of functional neural networks, provision of trophic support for surrounding neurons, monitoring and modulating the levels of synaptic activity, cleaning of accumulating extracellular debris and repairing microdamages of the brain parenchyma. As a consequence, age-related alterations in microglial function likely have a manifold impact on brain’s physiology. In this review, I discuss the recent data about physiological properties of microglia in the adult mammalian brain; changes observed in the brain innate immune system during healthy aging and the probable biological mechanisms responsible for them as well as changes occurring in humans and mice during age-related neurodegenerative disorders along with underlying cellular/molecular mechanisms. Together these data provide a new conceptual framework for thinking about the role of microglia in the context of age-mediated brain dysfunction.

scholarly journals Tau Accumulation via Reduced BAG3-mediated Autophagy Is Required for GGGGCC Repeat Expansion-Induced Neurodegeneration

2019 ◽  
Author(s):  
Xue Wen ◽  
Ping An ◽  
Hexuan Li ◽  
Zijian Zhou ◽  
Yimin Sun ◽  
...  
Keyword(s):  
Tau Protein ◽  
Neurodegenerative Disorders ◽  
Motor Performance ◽  
Molecular Mechanisms ◽  
Repeat Expansion ◽  
Cag Repeats ◽  
Reduced Activity ◽  
Lateral Sclerosis

SUMMARYExpansions of trinucleotide or hexanucleotide repeats lead to several neurodegenerative disorders including Huntington disease (HD, caused by the expanded CAG repeats (CAGr) in the HTT gene) and amyotrophic lateral sclerosis (ALS, could be caused by the expanded GGGGCC repeats (G4C2r) in the C9ORF72 gene), of which the molecular mechanisms remain unclear. Here we demonstrate that loss of the Drosophila orthologue of tau protein (dtau) significantly rescued in vivo neurodegeneration, motor performance impairments, and shortened life-span in Drosophila models expressing mutant HTT protein with expanded CAGr or the expanded G4C2r. Importantly, expression of human tau (htau4R) restored the disease-relevant phenotypes that were mitigated by the loss of dtau, suggesting a conserved role of tau in neurodegeneration. We further discovered that G4C2r expression increased dtau accumulation, possibly due to reduced activity of BAG3-mediated autophagy. Our study reveals a conserved role of tau in G4C2r-induced neurotoxicity in Drosophila models, providing mechanistic insights and potential therapeutic targets.

Animal Models of Neurodegenerative Diseases

2016 ◽  
Author(s):  
David Baglietto-Vargas ◽  
Rahasson R. Ager ◽  
Rodrigo Medeiros ◽  
Frank M. LaFerla
Keyword(s):  
Animal Models ◽  
Life Expectancy ◽  
Neurodegenerative Diseases ◽  
Neurodegenerative Disorders ◽  
Human Disease ◽  
Molecular Mechanisms ◽  
Preclinical Studies ◽  
Pathological Features ◽  
The Past ◽  
The Brain

The incidence and prevalence of neurodegenerative disorders (e.g., Alzheimer’s disease (AD), Parkinson’s disease (PD), and Huntington’s disease (HD), etc.) are growing rapidly due to increasing life expectancy. Researchers over the past two decades have focused their efforts on the development of animal models to dissect the molecular mechanisms underlying neurodegenerative disorders. Existing models, however, do not fully replicate the symptomatic and pathological features of human diseases. This chapter focuses on animal models of AD, as this disorder is the most prevalent of the brain degenerative conditions afflicting society. In particular, it briefly discusses the current leading animal models, the translational relevance of the preclinical studies using such models, and the limitations and shortcomings of using animals to model human disease. It concludes with a discussion of potential means to improve future models to better recapitulate human conditions.

scholarly journals What Are the Molecular Mechanisms by Which Functional Bacterial Amyloids Influence Amyloid Beta Deposition and Neuroinflammation in Neurodegenerative Disorders?

2020 ◽  
Vol 21 (5) ◽  
pp. 1652 ◽  
Author(s):  
Robert P. Friedland ◽  
Joseph D. McMillan ◽  
Zimple Kurlawala
Keyword(s):  
Amyloid Beta ◽  
Neurodegenerative Disorders ◽  
Innate Immune System ◽  
Molecular Mechanisms ◽  
Innate Immune ◽  
Know How ◽  
Unique Distribution ◽  
The Brain

Despite the enormous literature documenting the importance of amyloid beta (Ab) protein in Alzheimer's disease, we do not know how Ab aggregation is initiated and why it has its unique distribution in the brain. In vivo and in vitro evidence has been developed to suggest that functional microbial amyloid proteins produced in the gut may cross-seed Ab aggregation and prime the innate immune system to have an enhanced and pathogenic response to neuronal amyloids. In this commentary, we summarize the molecular mechanisms by which the microbiota may initiate and sustain the pathogenic processes of neurodegeneration in aging.

scholarly journals Mechanisms of secretion and spreading of pathological tau protein

2019 ◽  
Vol 77 (9) ◽  
pp. 1721-1744 ◽  
Author(s):  
Cecilia A. Brunello ◽  
Maria Merezhko ◽  
Riikka-Liisa Uronen ◽  
Henri J. Huttunen
Keyword(s):  
Tau Protein ◽  
Molecular Mechanisms ◽  
Recent Literature ◽  
General Mechanism ◽  
Cell Transfer ◽  
Tau Pathology ◽  
Cellular Mechanisms ◽  
Brain Areas ◽  
Cell To Cell Transfer ◽  
The Brain

Abstract Accumulation of misfolded and aggregated forms of tau protein in the brain is a neuropathological hallmark of tauopathies, such as Alzheimer’s disease and frontotemporal lobar degeneration. Tau aggregates have the ability to transfer from one cell to another and to induce templated misfolding and aggregation of healthy tau molecules in previously healthy cells, thereby propagating tau pathology across different brain areas in a prion-like manner. The molecular mechanisms involved in cell-to-cell transfer of tau aggregates are diverse, not mutually exclusive and only partially understood. Intracellular accumulation of misfolded tau induces several mechanisms that aim to reduce the cellular burden of aggregated proteins and also promote secretion of tau aggregates. However, tau may also be released from cells physiologically unrelated to protein aggregation. Tau secretion involves multiple vesicular and non-vesicle-mediated pathways, including secretion directly through the plasma membrane. Consequently, extracellular tau can be found in various forms, both as a free protein and in vesicles, such as exosomes and ectosomes. Once in the extracellular space, tau aggregates can be internalized by neighboring cells, both neurons and glial cells, via endocytic, pinocytic and phagocytic mechanisms. Importantly, accumulating evidence suggests that prion-like propagation of misfolding protein pathology could provide a general mechanism for disease progression in tauopathies and other related neurodegenerative diseases. Here, we review the recent literature on cellular mechanisms involved in cell-to-cell transfer of tau, with a particular focus in tau secretion.

scholarly journals Non-Canonical Roles of Tau and Their Contribution to Synaptic Dysfunction

2021 ◽  
Vol 22 (18) ◽  
pp. 10145
Author(s):  
Giacomo Siano ◽  
Chiara Falcicchia ◽  
Nicola Origlia ◽  
Antonino Cattaneo ◽  
Cristina Di Primio
Keyword(s):  
Tau Protein ◽  
Neurodegenerative Disorders ◽  
Neuronal Degeneration ◽  
Synaptic Dysfunction ◽  
Cell Soma ◽  
Post Translational Modifications ◽  
Synaptic Homeostasis ◽  
Wide Range ◽  
And Function ◽  
Tau Aggregation

Tau plays a central role in a group of neurodegenerative disorders collectively named tauopathies. Despite the wide range of diverse symptoms at the onset and during the progression of the pathology, all tauopathies share two common hallmarks, namely the misfolding and aggregation of Tau protein and progressive synaptic dysfunctions. Tau aggregation correlates with cognitive decline and behavioural impairment. The mechanistic link between Tau misfolding and the synaptic dysfunction is still unknown, but this correlation is well established in the human brain and also in tauopathy mouse models. At the onset of the pathology, Tau undergoes post-translational modifications (PTMs) inducing the detachment from the cytoskeleton and its release in the cytoplasm as a soluble monomer. In this condition, the physiological enrichment in the axon is definitely disrupted, resulting in Tau relocalization in the cell soma and in dendrites. Subsequently, Tau aggregates into toxic oligomers and amyloidogenic forms that disrupt synaptic homeostasis and function, resulting in neuronal degeneration. The involvement of Tau in synaptic transmission alteration in tauopathies has been extensively reviewed. Here, we will focus on non-canonical Tau functions mediating synapse dysfunction.

scholarly journals First person – Mariana Castro Dias

2021 ◽  
Vol 134 (8) ◽  
Keyword(s):  
Neurodegenerative Disorders ◽  
Molecular Mechanisms ◽  
Early Career ◽  
First Person ◽  
Early Career Researchers ◽  
University Of Bern ◽  
Theodor Kocher ◽  
Roche Diagnostics ◽  
The Brain ◽  
Selection Of

ABSTRACT First Person is a series of interviews with the first authors of a selection of papers published in Journal of Cell Science, helping early-career researchers promote themselves alongside their papers. Mariana Castro Dias is first author on ‘Brain endothelial tricellular junctions as novel sites for T cell diapedesis across the blood–brain barrier’, published in JCS. Mariana conducted the research described in this article while a PhD student in Britta Engelhardt's lab at the Theodor Kocher Institute, University of Bern, Switzerland. She is now an Associate Scientific Communications Manager working for Roche Diagnostics International. She is utterly fascinated by the brain, particularly the molecular mechanisms underlying the pathology of neurodegenerative disorders.

scholarly journals Braiding Braak and Braak: Staging patterns and model selection in network neurodegeneration

2021 ◽  
Author(s):  
Prama Putra ◽  
Travis Thompson ◽  
Alain Goriely
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Tau Protein ◽  
Tau Proteins ◽  
Histopathological Analysis ◽  
Braak Staging ◽  
New Methods ◽  
Tau Aggregation ◽  
The Brain ◽  
And Diffusion

AbstractA hallmark of Alzheimer’s disease is the aggregation of insoluble amyloid-beta plaques and tau protein neurofibrillary tangles. A key histopathological observation is that tau protein aggregates follow a clear progression pattern through the brain; characterized by six distinct stages. This so-called ‘Braak staging pattern’ has become the gold standard for Alzheimer’s disease progression. It has also been suggested, via a histopathological analysis, that soluble seed-competent tau seeding precedes tau aggregation in the same manner. Mathematical models such as prion-like propagation on networks have the ability to capture key feature of the dynamics. Here, we study the staging of tau proteins using a model of proteopathy that include both local growth due to autocatalytic effects and diffusion along axonal pathways. We develop new methods to capture the staging patterns and use these as a qualitative criterion to identify the best model for diffusion process on networks and to identify possible parameter regimes. Our analysis provides a systematic way to study Braak staging in neurodegenerative processes.

scholarly journals Synapse formation: from cellular and molecular mechanisms to neurodevelopmental and neurodegenerative disorders

2019 ◽  
Vol 121 (4) ◽  
pp. 1381-1397 ◽  
Author(s):  
Shadab Batool ◽  
Hussain Raza ◽  
Jawwad Zaidi ◽  
Saba Riaz ◽  
Sean Hasan ◽  
...  
Keyword(s):  
Neurodegenerative Disorders ◽  
Structural Changes ◽  
Molecular Mechanisms ◽  
Synapse Formation ◽  
Brain Functions ◽  
Mature Brain ◽  
Behavioral Needs ◽  
Neuronal Assembly ◽  
The Brain ◽  
Shed Light

The precise patterns of neuronal assembly during development determine all functional outputs of a nervous system; these may range from simple reflexes to learning, memory, cognition, etc. To understand how brain functions and how best to repair it after injury, disease, or trauma, it is imperative that we first seek to define fundamental steps mediating this neuronal assembly. To acquire the sophisticated ensemble of highly specialized networks seen in a mature brain, all proliferated and migrated neurons must extend their axonal and dendritic processes toward targets, which are often located at some distance. Upon contact with potential partners, neurons must undergo dramatic structural changes to become either a pre- or a postsynaptic neuron. This connectivity is cemented through specialized structures termed synapses. Both structurally and functionally, the newly formed synapses are, however, not static as they undergo consistent changes in order for an animal to meet its behavioral needs in a changing environment. These changes may be either in the form of new synapses or an enhancement of their synaptic efficacy, referred to as synaptic plasticity. Thus, synapse formation is not restricted to neurodevelopment; it is a process that remains active throughout life. As the brain ages, either the lack of neuronal activity or cell death render synapses dysfunctional, thus giving rise to neurodegenerative disorders. This review seeks to highlight salient steps that are involved in a neuron’s journey, starting with the establishment, maturation, and consolidation of synapses; we particularly focus on identifying key players involved in the synaptogenic program. We hope that this endeavor will not only help the beginners in this field to understand how brain networks are assembled in the first place but also shed light on various neurodevelopmental, neurological, neurodegenerative, and neuropsychiatric disorders that involve synaptic inactivity or dysfunction.

scholarly journals The Blood–Brain Barrier and Its Intercellular Junctions in Age-Related Brain Disorders

2019 ◽  
Vol 20 (21) ◽  
pp. 5472 ◽  
Author(s):  
Laura Costea ◽  
Ádám Mészáros ◽  
Hannelore Bauer ◽  
Hans-Christian Bauer ◽  
Andreas Traweger ◽  
...  
Keyword(s):  
Blood Brain Barrier ◽  
Neurodegenerative Disorders ◽  
Neurological Disorders ◽  
Barrier Function ◽  
Molecular Mechanisms ◽  
Brain Barrier ◽  
Common Denominator ◽  
Blood Brain ◽  
Age Related ◽  
The Brain

With age, our cognitive skills and abilities decline. Maybe starting as an annoyance, this decline can become a major impediment to normal daily life. Recent research shows that the neurodegenerative disorders responsible for age associated cognitive dysfunction are mechanistically linked to the state of the microvasculature in the brain. When the microvasculature does not function properly, ischemia, hypoxia, oxidative stress and related pathologic processes ensue, further damaging vascular and neural function. One of the most important and specialized functions of the brain microvasculature is the blood–brain barrier (BBB), which controls the movement of molecules between blood circulation and the brain parenchyma. In this review, we are focusing on tight junctions (TJs), the multiprotein complexes that play an important role in establishing and maintaining barrier function. After a short introduction of the cell types that modulate barrier function via intercellular communication, we examine how age, age related pathologies and the aging of the immune system affects TJs. Then, we review how the TJs are affected in age associated neurodegenerative disorders: Alzheimer’s disease and Parkinson’s disease. Lastly, we summarize the TJ aspects of Huntington’s disease and schizophrenia. Barrier dysfunction appears to be a common denominator in neurological disorders, warranting detailed research into the molecular mechanisms behind it. Learning the commonalities and differences in the pathomechanism of the BBB injury in different neurological disorders will predictably lead to development of new therapeutics that improve our life as we age.

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