scholarly journals A novel form of macropinocytosis mediates ultra-rapid transfer of pathological alpha- synuclein to lysosomes

2022 ◽  
Author(s):  
Armin Bayati ◽  
Emily Banks ◽  
Chanshuai Han ◽  
Wen Luo ◽  
Cornelia Zorca ◽  
...  
Keyword(s):  
Subcellular Fractionation ◽  
Alpha Synuclein ◽  
Protein Species ◽  
Superresolution Microscopy ◽  
Internalization Mechanism ◽  
Lysosomal Targeting ◽  
Cell Propagation ◽  
External Face ◽  
Cell To Cell Transfer ◽  
Rapid Transfer

The nervous system spread of alpha-synuclein fibrils leads to Parkinson′s disease (PD) and other synucleinopathies, yet the mechanisms underlying internalization and cell-to-cell transfer are enigmatic. Here we use confocal and superresolution microscopy, subcellular fractionation and electron microscopy of immunogold labelled alpha-synuclein pre-formed fibrils (PFF) to demonstrate that this toxic protein species enters cells using a novel form of ultra-rapid macropinocytosis with transfer to lysosomes in as little as 2 minutes, an unprecedented cell biological kinetic for lysosomal targeting. PFF uptake circumvents classical endosomal pathways and is independent of clathrin. Immunogold-labelled PFF are seen at the highly curved inward edge of membrane ruffles, in newly formed macropinosomes, and in lysosomes. While many of the fibrils remain in lysosomes that continue to take up PFF for hours, a portion are transferred to neighboring naive cells on the external face of vesicles, likely exosomes. These data indicate that PFF uses a novel internalization mechanism as a component of cell-to-cell propagation.

scholarly journals Differential compartmental processing and phosphorylation of pathogenic human tau and native mouse tau in the line 66 model of frontotemporal dementia

2020 ◽  
Vol 295 (52) ◽  
pp. 18508-18523
Author(s):  
Nora Lemke ◽  
Valeria Melis ◽  
Dilyara Lauer ◽  
Mandy Magbagbeolu ◽  
Boris Neumann ◽  
...  
Keyword(s):  
Frontotemporal Dementia ◽  
Tau Protein ◽  
Neurodegenerative Disorders ◽  
Genetic Variants ◽  
Subcellular Fractionation ◽  
Brain Regions ◽  
Transgenic Mouse Model ◽  
Protein Species ◽  
Synapse Loss ◽  
Triton X

Synapse loss is associated with motor and cognitive decline in multiple neurodegenerative disorders, and the cellular redistribution of tau is related to synaptic impairment in tauopathies, such as Alzheimer's disease and frontotemporal dementia. Here, we examined the cellular distribution of tau protein species in human tau overexpressing line 66 mice, a transgenic mouse model akin to genetic variants of frontotemporal dementia. Line 66 mice express intracellular tau aggregates in multiple brain regions and exhibit sensorimotor and motor learning deficiencies. Using a series of anti-tau antibodies, we observed, histologically, that nonphosphorylated transgenic human tau is enriched in synapses, whereas phosphorylated tau accumulates predominantly in cell bodies and axons. Subcellular fractionation confirmed that human tau is highly enriched in insoluble cytosolic and synaptosomal fractions, whereas endogenous mouse tau is virtually absent from synapses. Cytosolic tau was resistant to solubilization with urea and Triton X-100, indicating the formation of larger tau aggregates. By contrast, synaptic tau was partially soluble after Triton X-100 treatment and most likely represents aggregates of smaller size. MS corroborated that synaptosomal tau is nonphosphorylated. Tau enriched in the synapse of line 66 mice, therefore, appears to be in an oligomeric and nonphosphorylated state, and one that could have a direct impact on cognitive function.

scholarly journals Cryo-EM structure of alpha-synuclein fibrils

2018 ◽  
Author(s):  
Ricardo Guerrero-Ferreira ◽  
Nicholas M. I. Taylor ◽  
Daniel Mona ◽  
Philippe Ringler ◽  
Matthias E. Lauer ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Rational Design ◽  
Alpha Synuclein ◽  
Diagnosis And Treatment ◽  
Cryo Electron Microscopy ◽  
Cell Propagation ◽  
Hydrophobic Cleft

AbstractIntracellular inclusions of alpha-synuclein are the neuropathological hallmark of progressive disorders called synucleinopathies. Alpha-synuclein fibrils are associated with transmissive cell-to-cell propagation of pathology. We report the structure of an alpha-synuclein fibril (residues 1-121) determined by cryo-electron microscopy at 3.4Å resolution. Two protofilaments form a polar fibril composed of staggered β-strands. The backbone of residues 38 to 95, including the fibril core and the non-amyloid component region, are well resolved in the EM map. Residues 50-57, containing three mutation sites associated with familial synucleinopathies, form the interface between the two protofilaments and contribute to fibril stability. A hydrophobic cleft may have implications for fibril elongation, and inform the rational design of molecules for diagnosis and treatment of synucleinopathies.

scholarly journals Targeting of P-selectin to two regulated secretory organelles in PC12 cells.

1996 ◽  
Vol 134 (5) ◽  
pp. 1229-1240 ◽  
Author(s):  
J P Norcott ◽  
R Solari ◽  
D F Cutler
Keyword(s):  
Amino Acids ◽  
Pc12 Cells ◽  
Transient Expression ◽  
Subcellular Fractionation ◽  
Cytoplasmic Domain ◽  
Dense Core ◽  
The Other ◽  
Lysosomal Targeting ◽  
Dense Core Granules ◽  
Carboxy Terminal

Targeting of P-selectin to the regulated secretory organelles (RSOs) of phaeochromocytoma PC12 cells has been investigated. By expressing from cDNA a chimera composed of HRP and P-selectin, and then following HRP activity through subcellular fractionation, we have discovered that P-selectin contains signals that target HRP to the synaptic-like microvesicles (SLMV) as well as the dense-core granules (DCGs) of these cells. Mutagenesis of the chimera followed by transient expression in PC12 cells shows that at least two different sequences within the carboxy-terminal cytoplasmic tail of P-selectin are necessary, but that neither is sufficient for trafficking to the SLMV. One of these sequences is centred on the 10 amino acids of the membrane-proximal C1 exon that is also implicated in lysosomal targeting. The other sequence needed for trafficking to the SLMV includes the last four amino acids of the protein. The same series of mutations have a different effect on DCG targeting, showing that traffic to the two different RSOs depends on different features within the cytoplasmic domain of P-selectin.

scholarly journals Endosomal-Lysosomal Processing of Neurodegeneration-Associated Proteins in Astrocytes

2020 ◽  
Vol 21 (14) ◽  
pp. 5149
Author(s):  
Ching-On Wong
Keyword(s):  
Alpha Synuclein ◽  
Amyloid Precursor Proteins ◽  
Protein Species ◽  
Metabolic Fate ◽  
Cellular Toxicity ◽  
Precursor Proteins ◽  
Associated Proteins ◽  
Lysosomal System ◽  
The Brain

Most common neurodegenerative diseases (NDs) are characterized by deposition of protein aggregates that are resulted from misfolding, dysregulated trafficking, and compromised proteolytic degradation. These proteins exert cellular toxicity to a broad range of brain cells and are found in both neurons and glia. Extracellular monomeric and oligomeric ND-associated proteins are taken up by astrocytes, the most abundant glial cell in the brain. Internalization, intracellular trafficking, processing, and disposal of these proteins are executed by the endosomal-lysosomal system of astrocytes. Endosomal-lysosomal organelles thus mediate the cellular impact and metabolic fate of these toxic protein species. Given the indispensable role of astrocytes in brain metabolic homeostasis, the endosomal-lysosomal processing of these proteins plays a fundamental role in altering the trajectory of neurodegeneration. This review aims at summarizing the mounting evidence that has established the essential role of astrocytic endosomal-lysosomal organelles in the processing of amyloid precursor proteins, Apolipoprotein E (ApoE), tau, alpha synuclein, and huntingtin, which are associated with NDs such as Alzheimer’s, Parkinson’s, and Huntington diseases.

scholarly journals Alpha-Synuclein Cell-to-Cell Transfer and Seeding in Grafted Dopaminergic Neurons In Vivo

PLoS ONE ◽  
2012 ◽  
Vol 7 (6) ◽  
pp. e39465 ◽  
Author(s):  
Elodie Angot ◽  
Jennifer A. Steiner ◽  
Carla M. Lema Tomé ◽  
Peter Ekström ◽  
Bengt Mattsson ◽  
...  
Keyword(s):  
Dopaminergic Neurons ◽  
Alpha Synuclein ◽  
Cell Transfer ◽  
Cell To Cell Transfer

Reactive microglia enhance the transmission of exosomal alpha-synuclein via toll-like receptor 2

Brain ◽  
2021 ◽  
Author(s):  
Yun Xia ◽  
Guoxin Zhang ◽  
Liang Kou ◽  
Sijia Yin ◽  
Chao Han ◽  
...  
Keyword(s):  
Microglial Activation ◽  
Inflammatory Responses ◽  
Alpha Synuclein ◽  
Toll Like Receptor ◽  
Direct Role ◽  
Reactive Microglia ◽  
Toll Like Receptor 2 ◽  
Cell Propagation

Abstract Increasing evidence suggests that microglial activation is strongly linked to the initiation and progression of Parkinson’s disease (PD). Cell-to-cell propagation of α-synuclein (α-syn) pathology is a highlighted feature of PD, and the focus of such research has been primarily on neurons. However, recent studies as well as the data contained herein suggest that microglia, the primary phagocytes in the brain, play a direct role in the spread of α-syn pathology. Recent data revealed that plasma exosomes derived from PD patients (PD-EXO) carry pathological α-syn and target microglia preferentially. Hence, PD-EXO is likely a key tool for investigating the role of microglia in α-syn transmission. We showed that intrastriatal injection of PD-EXO resulted in the propagation of exosomal α-syn from microglia to neurons following microglia activation. Toll-like receptor 2 (TLR2) in microglia was activated by exosomal α-syn and acted as a crucial mediator of PD-EXO-induced microglial activation. Additionally, partial microglia depletion resulted in a significant decrease of exogenous α-syn in the substantia nigra (SN). Furthermore, exosomal α-syn internalization was initiated by binding to TLR2 of microglia. Excessive α-syn phagocytosis may induce the inflammatory responses of microglia and provide the seed for microglia-to-neuron transmission. Consistently, TLR2 silencing in microglia mitigated α-syn pathology in vivo. Overall, the present data support the idea that the interaction of exosomal α-syn and microglial TLR2 contribute to excessive α-syn phagocytosis and microglial activation, which lead to the further propagation and spread of α-syn pathology, thereby highlighting the pivotal roles of reactive microglia in α-syn transmission.

Expression of laminin and beta-1 integrin in embryonic, neonatal, and adult rat heart

1991 ◽  
Vol 49 ◽  
pp. 182-183
Author(s):  
R.L. Price ◽  
T.K. Borg ◽  
L. Terracio ◽  
M. Nakagawa
Keyword(s):  
Temporal Expression ◽  
Qualitative And Quantitative ◽  
Adult Rat ◽  
Cytoplasmic Face ◽  
Extracellular Matrix Components ◽  
Basement Membrane Component ◽  
Beta 1 Integrin ◽  
Quantitative Changes ◽  
Cytoskeletal Elements ◽  
External Face

Little is known about the temporal expression of extracellular matrix components (ECM) and its receptors during development of the heart. Recent reports have shown that ECM components undergo both qualitative and quantitative changes during development, and it is believed that ECM components are important in the regulation of cell migration and cell:cell and cell:ECM recognition and adhesion.Integrins are transmembrane glycoproteins which bind several ECM components on their external face and cytoskeletal elements on the cytoplasmic face. Laminin is a basement membrane component which has been recognized as an important site for cell adhesion. Both the integrins and laminin are expressed early in development and continue to be expressed in the adult heart. With their documented roles in cell recognition, and cell:cell and cell:ECM migration and adhesion these proteins appear to be important components in development of the heart, and their temporal expression may play a pivotal role in morphogenesis and myofibrillogenesis of the heart.

The three-dimensional structure of frozen-hydrated left- and right-handed forms of bacterial flagellar filaments from an identical serotype

1986 ◽  
Vol 44 ◽  
pp. 298-299
Author(s):  
S. Trachtenberg ◽  
D. J. DeRosier
Keyword(s):  
Ionic Strength ◽  
Basal Body ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Protein Species ◽  
Liquid Environment ◽  
Bacterial Flagellum ◽  
Left And Right ◽  
Rotary Motor ◽  
Helical Parameters

The bacterial cell is propelled through the liquid environment by means of one or more rotating flagella. The bacterial flagellum is composed of a basal body (rotary motor), hook (universal coupler), and filament (propellor). The filament is a rigid helical assembly of only one protein species — flagellin. The filament can adopt different morphologies and change, reversibly, its helical parameters (pitch and hand) as a function of mechanical stress and chemical changes (pH, ionic strength) in the environment.

On the Role of Transferrin in 67Ga Uptake by Tumor Cells

1988 ◽  
Vol 27 (04) ◽  
pp. 151-153
Author(s):  
P. Thouvenot ◽  
F. Brunotte ◽  
J. Robert ◽  
L. J. Anghileri
Keyword(s):  
Specific Binding ◽  
Subcellular Fractionation ◽  
Animal Blood ◽  
Tumor Bearing ◽  
Cell Structures ◽  
The Difference ◽  
Sarcoma Cells ◽  
In Vitro Uptake

In vitro uptake of 67Ga-citrate and 59Fe-citrate by DS sarcoma cells in the presence of tumor-bearing animal blood plasma showed a dramatic inhibition of both 67Ga and 59Fe uptakes: about ii/io of 67Ga and 1/5o of the 59Fe are taken up by the cells. Subcellular fractionation appears to indicate no specific binding to cell structures, and the difference of binding seems to be related to the transferrin chelation and transmembrane transport differences

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