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Pathologic α-syn destabilizes the TSC 1 and 2 complex leading to mTORC1 activation, enhanced protein translation and neurodegeneration in PD.Abstract:Pathological α-synuclein (α-syn) plays an important role in the pathogenesis of α-synucleinopathies such as Parkinson’s disease (PD). Disruption of protein homeostasis is thought be central to PD pathogenesis, however the molecular mechanism of this deregulation is poorly understood. Here we report that pathologic α-syn binds to tuberous sclerosis protein (TSC) 2 and destabilizes the TSC1-TSC2 complex leading to activation of the mechanistic target of rapamycin (mTOR) complex 1 (mTORC1) and enhanced mRNA translation. Dopamine neuron loss, behavioral deficits and aberrant biochemical signaling in the α-syn preformed fibril (PFF) and Drosophila α-syn transgenic models of pathologic α-syn induced degeneration were attenuated by genetic and pharmacologic inhibition of mTOR and protein translation. Our findings establish a potential molecular mechanism by which pathologic α-syn activates mTORC1 leading to enhanced protein translation and concomitant neurodegeneration in PD.

Alzheimer’s disease (AD) is the most common cause of age-related dementia. Increasing evidence suggests that neuroinflammation mediated by microglia and astrocytes contributes to disease progression and severity in AD and other neurodegenerative disorders. During AD progression, resident microglia undergo proinflammatory activation, resulting in an increased capacity to convert resting astrocytes to reactive astrocytes. Therefore, microglia are a major therapeutic target for AD and blocking microglia-astrocyte activation could limit neurodegeneration in AD. Here we report that NLY01, an engineered exedin-4, glucagon-like peptide-1 receptor (GLP-1R) agonist, selectively blocks β-amyloid (Aβ)-induced activation of microglia through GLP-1R activation and inhibits the formation of reactive astrocytes as well as preserves neurons in AD models. In two transgenic AD mouse models (5xFAD and 3xTg-AD), repeated subcutaneous administration of NLY01 blocked microglia-mediated reactive astrocyte conversion and preserved neuronal viability, resulting in improved spatial learning and memory. Our study indicates that the GLP-1 pathway plays a critical role in microglia-reactive astrocyte associated neuroinflammation in AD and the effects of NLY01 are primarily mediated through a direct action on Aβ-induced GLP-1R+ microglia, contributing to the inhibition of astrocyte reactivity. These results show that targeting upregulated GLP-1R in microglia is a viable therapy for AD and other neurodegenerative disorders. Supplementary Information The online version contains supplementary material available at 10.1186/s40478-021-01180-z.

Parkinson's disease (PD) is mediated, in part, by intraneuronal accumulation of α-synuclein aggregates andsubsequent death of dopamine (DA) neurons in the substantia nigra pars compacta (SNpc). Microglial hyperactivation of the NOD-like receptor protein 3 (NLRP3) inflammasome has been well-documented in various neurodegenerative diseases, including PD. We show here that loss of parkin activity in mouse and human DA neurons results in spontaneous neuronal NLRP3 inflammasome assembly, leading to DA neuron death. Parkin normally inhibits inflammasome priming by ubiquitinating and targeting NLRP3 for proteasomal degradation. Loss of parkin activity also contributes to the assembly of an active NLRP3 inflammasome complex via mitochondrial-derived reactive oxygen species (mitoROS) generation through the accumulation of another parkin ubiquitination substrate, ZNF746/PARIS. Inhibition of neuronal NLRP3 inflammasome assembly prevents degeneration of DA neurons in familial and sporadic PD models. Strategies aimed at limiting neuronal NLRP3 inflammasome activation hold promise as a disease-modifying therapy for PD.

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The G2019S mutation in leucine-rich repeat kinase 2 (LRRK2) is a common cause of familial Parkinson’s disease (PD). This mutation results in dopaminergic neurodegeneration via dysregulated protein translation, although how alterations in protein synthesis contributes to neurodegeneration in human neurons is not known. Here we define the translational landscape in LRRK2-mutant dopaminergic neurons derived from human induced pluripotent stem cells (hiPSCs) via ribosome profiling. We found that mRNAs that have complex secondary structure in the 5’ untranslated region (UTR) are translated more efficiently in G2019S LRRK2 neurons. This leads to the enhanced translation of multiple genes involved in Ca2+ regulation and to increased Ca2+ influx and elevated intracellular Ca2+ levels, a major contributor to PD pathogenesis. This study reveals a link between dysregulated translation control and Ca2+ homeostasis in G2019S LRRK2 human dopamine neurons, which potentially contributes to the progressive and selective dopaminergic neurotoxicity in PD.

Summary Mutations and loss of activity in PARKIN, an E3 ubiquitin ligase, play a role in the pathogenesis of Parkinson's disease (PD). PARKIN regulates many aspects of mitochondrial quality control including mitochondrial autophagy (mitophagy) and mitochondrial biogenesis. Defects in mitophagy have been hypothesized to play a predominant role in the loss of dopamine (DA) neurons in PD. Here, we show that although there are defects in mitophagy in human DA neurons lacking PARKIN, the mitochondrial deficits are primarily due to defects in mitochondrial biogenesis that are driven by the upregulation of PARIS and the subsequent downregulation of PGC-1α. CRISPR/Cas9 knockdown of PARIS completely restores the mitochondrial biogenesis defects and mitochondrial function without affecting the deficits in mitophagy. These results highlight the importance mitochondrial biogenesis versus mitophagy in the pathogenesis of PD due to inactivation or loss of PARKIN in human DA neurons., Graphical Abstract, Highlights • Human DA neuron loss of PARKIN leads to increased PARIS and decreased PGC-1α • Human DA neuron PARKIN loss leads to reduced mitochondrial autophagy and biogenesis • Decreased mitochondrial biogenesis drives the mitochondrial defects in DA neurons • PARIS is a key mediator of the mitochondrial defects in DA neurons lacking PARKIN, In this article, Dawson and colleagues show that human DA neurons lacking PARKIN exhibit mitochondrial defects that are driven by the upregulation of PARIS, downregulation of PGC-1α, and decreased mitochondrial biogenesis. While mitophagy is impaired in human DA neurons lacking PARKIN, it does not appear to contribute to the mitochondrial deficits.

Cet article est consacre au site indien de Isampur. Les AA se proposent d'etudier la geomorphologie du site acheuleen et le materiel lithique mis au jour. D'apres les artefacts et outils retrouves, Isampur devait servir d'atelier.

The allelopathic potential of the agroforestry trees Ficus subincisa Buch.-Ham. ex J. E. Smith, Bauhinia purpurea L., and Toona hexandra Wallich ex Roxb. was investigated on Triticum aestivum L., Brassica campestris L., and Hordeum vulgare L. test crops. The leaf and bark leachates of trees were both toxic to the germination of the test crops. The inhibition of the germination of test crops was significant. The effects of leachates on test crops were concentration dependent. So, higher concentrations of leaf and bark leachates showed stimulatory effects on the radicle and plumule growth of all test crops. The acceptance of these multipurpose tree species as agroforestry trees in association with field crops decreased in the order Ficus subincisa, Bauhinia purpurea, and Toona hexandra.