Broad proteomics analysis of seeding-induced aggregation of α-synuclein in M83 neurons reveals remodeling of proteostasis mechanisms that might contribute to Parkinson's disease pathogenesis.

Aggregation of misfolded α-synuclein (α-syn) is a key characteristic feature of Parkinson's disease (PD) and related synucleinopathies. The nature of these aggregates and their contribution to cellular dysfunction is still not clearly elucidated. We employed mass spectrometry-based total and phospho-proteomics to characterize the underlying molecular and biological changes due to α-syn aggregation using the M83 mouse primary neuronal model of PD.

Establishment of a high-content imaging assay for tau aggregation in hiPSC-derived neurons differentiated from two protocols to routinely evaluate compounds and genetic perturbations.

Aberrant protein aggregation is a pathological cellular hallmark of many neurodegenerative diseases, such as Alzheimer's disease (AD) and frontotemporal dementia (FTD), where the tau protein is aggregating, forming neurofibrillary tangles (NFTs), and propagating from neuron to neuron. These processes have been linked to disease progression and a decline in cognitive function. Various therapeutic approaches aim at the prevention or reduction of tau aggregates in neurons.

Pharmacological mTOR-inhibition facilitates clearance of AD-related tau aggregates in the mouse brain.

In this study we aimed to reduce tau pathology, a hallmark of Alzheimer's Disease (AD), by activating mTOR-dependent autophagy in a transgenic mouse model of tauopathy by long-term dosing of animals with mTOR-inhibitors. Rapamycin treatment reduced the burden of hyperphosphorylated and aggregated pathological tau in the cerebral cortex only when applied to young mice, prior to the emergence of pathology. Conversely, PQR530 which exhibits better brain exposure and superior pharmacokinetic properties, reduced tau pathology even when the treatment started after the onset of pathology.

Arrayed CRISPR reveals genetic regulators of tau aggregation, autophagy and mitochondria in Alzheimer's disease model.

Alzheimer's disease (AD) is a common neurodegenerative disease with poor prognosis. New options for drug discovery targets are needed. We developed an imaging based arrayed CRISPR method to interrogate the human genome for modulation of in vitro correlates of AD features, and used this to assess 1525 human genes related to tau aggregation, autophagy and mitochondria.

Differential efficacy of the TSPO ligands etifoxine and XBD-173 in two rodent models of Multiple Sclerosis.

Neurosteroids such as progesterone and allopregnanolone have been shown to exert neuroprotective effects under a variety of pathological or insult conditions, and there is evidence that the neurosteroid system is perturbed in Multiple Sclerosis (MS) patients. Neurosteroids are synthesized in the central nervous system (CNS) through a series of metabolic transformations, beginning with a rate-limiting step of cholesterol transport through the outer mitochondrial membrane via the transporter translocator protein (TSPO). We examined the effects of etifoxine and XBD-173, two different brain penetrant TSPO agonists, for their ability to ameliorate clinical signs in two different experimental autoimmune encephalitis (EAE) models.

Transcriptional regulation of Annexin A2 promotes starvation-induced autophagy.

Autophagy is an important degradation pathway, which is induced after starvation, where it buffers nutrient deprivation by recycling macromolecules in organisms from yeast to man. While the classical pathway mediating this response is via mTOR inhibition, there are likely to be additional pathways that support the process. Here, we identify Annexin A2 as an autophagy modulator that regulates autophagosome formation by enabling appropriate ATG9A trafficking from endosomes to autophagosomes via actin.

IGF-1 receptor antagonism inhibits autophagy.

Inhibition of the insulin/insulin-like growth factor signalling pathway increases lifespan and protects against neurodegeneration in model organisms, and has been considered as a potential therapeutic target. This pathway is upstream of mTORC1, a negative regulator of autophagy. Thus, we expected autophagy to be activated by insulin-like growth factor-1 (IGF-1) inhibition, which could account for many of its beneficial effects.

Guidelines for the use and interpretation of assays for monitoring autophagy.

In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding.

Arf6 promotes autophagosome formation via effects on phosphatidylinositol 4,5-bisphosphate and phospholipase D.

Macroautophagy (in this paper referred to as autophagy) and the ubiquitin-proteasome system are the two major catabolic systems in cells. Autophagy involves sequestration of cytosolic contents in double membrane-bounded vesicles called autophagosomes. The membrane source for autophagosomes has received much attention, and diverse sources, such as the plasma membrane, Golgi, endoplasmic reticulum, and mitochondria, have been implicated.

Autophagosome precursor maturation requires homotypic fusion.

Autophagy is a catabolic process in which lysosomes degrade intracytoplasmic contents transported in double-membraned autophagosomes. Autophagosomes are formed by the elongation and fusion of phagophores, which can be derived from preautophagosomal structures coming from the plasma membrane and other sites like the endoplasmic reticulum and mitochondria. The mechanisms by which preautophagosomal structures elongate their membranes and mature toward fully formed autophagosomes still remain unknown.

Regulation of mammalian autophagy in physiology and pathophysiology.

(Macro)autophagy is a bulk degradation process that mediates the clearance of long-lived proteins and organelles. Autophagy is initiated by double-membraned structures, which engulf portions of cytoplasm. The resulting autophagosomes ultimately fuse with lysosomes, where their contents are degraded.

Plasma membrane helps autophagosomes grow.

The membrane origin of autophagosomes has long been a mystery and it may involve multiple sources. In this punctum, we discuss our recent finding that the plasma membrane contributes to the formation of pre-autophagic structures via clathrin-mediated endocytosis. Our study suggests that Atg16L1 interacts with clathrin heavy-chain/AP2 and is also localized on vesicles (positive for clathrin or cholera toxin B) close to the plasma membrane.

α-Synuclein impairs macroautophagy: implications for Parkinson's disease.

Parkinson's disease (PD) is characterized pathologically by intraneuronal inclusions called Lewy bodies, largely comprised of α-synuclein. Multiplication of the α-synuclein gene locus increases α-synuclein expression and causes PD. Thus, overexpression of wild-type α-synuclein is toxic.

Plasma membrane contributes to the formation of pre-autophagosomal structures.

Autophagy is a catabolic process in which lysosomes degrade intracytoplasmic contents transported in double-membraned autophagosomes. Autophagosomes are formed by the elongation and fusion of phagophores, which derive from pre-autophagosomal structures. The membrane origins of autophagosomes are unclear and may involve multiple sources, including the endoplasmic reticulum and mitochondria.

In search of an "autophagomometer".

Recent years have seen the realization that macroautophagy (which we will call autophagy) is not only important in yeast but is necessary for diverse functions in plants and animals. Importantly, autophagy can have an impact on human pathologies including infectious diseases, cancers, and neurodegenerative conditions. Thus, we need to be able to measure autophagy accurately in order to understand how it can be regulated physiologically and with exogenous agents.

Autophagic clearance of aggregate-prone proteins associated with neurodegeneration.

Autophagy has emerged as a field of rapidly growing interest with implications in several disease conditions, such as cancer, infectious diseases, and neurodegenerative diseases. Autophagy is a major degradation pathway for aggregate-prone, intracytosolic proteins causing neurodegenerative disorders, such as Huntington's disease and forms of Parkinson's disease. Up-regulating autophagy may be a tractable therapeutic intervention for clearing these disease-causing proteins.

Rab5 modulates aggregation and toxicity of mutant huntingtin through macroautophagy in cell and fly models of Huntington disease.

Huntington disease (HD) is caused by a polyglutamine-expansion mutation in huntingtin (HTT) that makes the protein toxic and aggregate-prone. The subcellular localisation of huntingtin and many of its interactors suggest a role in endocytosis, and recently it has been shown that huntingtin interacts indirectly with the early endosomal protein Rab5 through HAP40. Here we show that Rab5 inhibition enhanced polyglutamine toxicity, whereas Rab5 overexpression attenuated toxicity in our cell and fly models of HD.

Clearance of mutant aggregate-prone proteins by autophagy.

The accumulation of mutant aggregate-prone proteins is a feature of several human disorders, collectively referred to as protein conformation disorders or proteinopathies. We have shown that autophagy, a cytosolic, non-specific bulk degradation system, is an important clearance route for many cytosolic toxic, aggregate-prone proteins, like mutant huntingtin and mutant alpha-synucleins. Induction of autophagy enhances the clearance of both soluble and aggregated forms of the mutant protein, and protects against toxicity caused by these mutations in cell, fly, and mouse models.

Aggregate-prone proteins are cleared from the cytosol by autophagy: therapeutic implications.

Intracellular protein misfolding/aggregation are features of many late-onset neurodegenerative diseases, called proteinopathies. These include Alzheimer's disease, Parkinson's disease, tauopathies, and polyglutamine expansion diseases [e.g.

Role of autophagy in the clearance of mutant huntingtin: a step towards therapy?

Macroautophagy (henceforth referred to simply as autophagy) is a bulk degradation process involved in the clearance of long-lived proteins, protein complexes and organelles. A portion of the cytosol, with its contents to be degraded, is enclosed by double-membrane structures called autophagosomes/autophagic vacuoles, which ultimately fuse with lysosomes where their contents are degraded. In this review, we will describe how induction of autophagy is protective against toxic intracytosolic aggregate-prone proteins that cause a range of neurodegenerative diseases.

Protective roles for induction of autophagy in multiple proteinopathies.

Many late-onset neurodegenerative diseases, including Parkinson's disease, tauopathies, Huntington's disease and forms of spinocerebellar ataxia, are caused by aggregate-prone proteins. Previously we showed that mutant huntingtin is an autophagy substrate and that autophagy induction reduced soluble and aggregated huntingtin levels and attenuated its toxicity in cell, fly and mouse models of disease. We have recently shown in cell and fly models that autophagy induction may have general protective effects across a range of diseases caused by aggregate-prone intracellular proteins.

Dyneins, autophagy, aggregation and neurodegeneration.

We recently showed that the dynein motor machinery plays a role in the delivery of autophagosome contents to lysosomes, in the process of autophagosome-lysosome fusion. This may explain a number of important previous observations, including why intracellular aggregates form in mice with dynein mutations that have motor neuron-like disease. These studies highlight the importance of dyneins and autophagy in the clearance of aggregate-prone proteins in general, and also in the specific case of Huntington's disease.

Autophagy and its possible roles in nervous system diseases, damage and repair.

Increased numbers of autophagosomes/autophagic vacuoles are seen in a variety of physiological and pathological states in the nervous system. In many cases, it is unclear if this phenomenon is the result of increased autophagic activity or decreased autophagosome-lysosome fusion. The functional significance of autophagy and its relationship to cell death in the nervous system is also poorly understood.

Palmitoylation of huntingtin by HIP14 is essential for its trafficking and function.

Post-translational modification by the lipid palmitate is crucial for the correct targeting and function of many proteins. Here we show that huntingtin (htt) is normally palmitoylated at cysteine 214, which is essential for its trafficking and function. The palmitoylation and distribution of htt are regulated by the palmitoyl transferase huntingtin interacting protein 14 (HIP14).