scholarly journals Rab7 Reduces α-Synuclein Toxicity in Rats and Primary Neurons

2021 ◽  
Author(s):  
Éva M. Szegõ ◽  
Eva M. Szegö ◽  
Chris Van den Haute ◽  
Lennart Höfs ◽  
Veerle Baekelandt ◽  
...  
Keyword(s):  
Dna Damage ◽  
Rat Brain ◽  
Neuronal Degeneration ◽  
Degradation Pathway ◽  
Alpha Synuclein ◽  
Dominant Negative ◽  
Primary Neurons ◽  
Vicious Cycle ◽  
Axon Terminals

Abstract BackgroundDuring the pathogenesis of Parkinson’s disease (PD), aggregation of alpha-synuclein (αSyn) induces a vicious cycle of cellular impairments that lead to neurodegeneration. Consequently, removing toxic αSyn aggregates constitutes a plausible strategy against PD. In this work, we tested whether stimulating the autolysosomal degradation of αSyn aggregates through the Ras-related in brain 7 (Rab7) pathway can reverse αSyn-induced cellular impairment and prevent neurodegeneration in vivo.MethodsThe disease-related A53T mutant of αSyn was expressed in primary neurons and in dopaminergic neurons of the rat brain simultaneously with wild type (WT) Rab7 or its dominant-negative T22N mutant as a control. The cellular integrity was quantified by morphological and biochemical analyses.ResultsIn primary neurons, WT Rab7 rescued the αSyn -induced loss of neurons and neurites. Furthermore, Rab7 decreased the amount of reactive oxygen species and the amount of Triton X-100 insoluble αSyn. In rat brain, WT Rab7 reduced αSyn -induced loss of dopaminergic axon terminals in the striatum and the loss of dopaminergic dendrites in the substantia nigra pars reticulata. Further, WT Rab7 lowered αSyn pathology as quantified by phosphorylated αSyn staining. Finally, WT Rab7 attenuated αSyn-induced DNA damage in primary neurons and rat brain.ConclusionRab7 reduced αSyn-induced pathology, ameliorated αSyn-induced neuronal degeneration, oxidative stress and DNA damage. These findings indicate that Rab7 is able to disrupt the vicious cycle of cellular impairment, αSyn pathology and neurodegeneration present in PD. Stimulation of Rab7 and the autolysosomal degradation pathway could therefore constitute a beneficial strategy for PD.

scholarly journals Cleavage and Inactivation of ATM during Apoptosis

1999 ◽  
Vol 19 (9) ◽  
pp. 6076-6084 ◽  
Author(s):  
Graeme C. M. Smith ◽  
Fabrizio d’adda di Fagagna ◽  
Nicholas D. Lakin ◽  
Stephen P. Jackson
Keyword(s):  
Dna Damage ◽  
Dna Binding ◽  
Caspase 3 ◽  
Cysteine Proteases ◽  
Dominant Negative ◽  
Protein Kinase Activity ◽  
Dna Damage Signalling ◽  
In Cells

ABSTRACT The activation of the cysteine proteases with aspartate specificity, termed caspases, is of fundamental importance for the execution of programmed cell death. These proteases are highly specific in their action and activate or inhibit a variety of key protein molecules in the cell. Here, we study the effect of apoptosis on the integrity of two proteins that have critical roles in DNA damage signalling, cell cycle checkpoint controls, and genome maintenance—the product of the gene defective in ataxia telangiectasia, ATM, and the related protein ATR. We find that ATM but not ATR is specifically cleaved in cells induced to undergo apoptosis by a variety of stimuli. We establish that ATM cleavage in vivo is dependent on caspases, reveal that ATM is an efficient substrate for caspase 3 but not caspase 6 in vitro, and show that the in vitro caspase 3 cleavage pattern mirrors that in cells undergoing apoptosis. Strikingly, apoptotic cleavage of ATM in vivo abrogates its protein kinase activity against p53 but has no apparent effect on the DNA binding properties of ATM. These data suggest that the cleavage of ATM during apoptosis generates a kinase-inactive protein that acts, through its DNA binding ability, in a trans-dominant-negative fashion to prevent DNA repair and DNA damage signalling.

Gain-of-function of poly(ADP-ribose) polymerase-1 upon cleavage by apoptotic proteases: implications for apoptosis

2001 ◽  
Vol 114 (20) ◽  
pp. 3771-3778 ◽  
Author(s):  
Damien D’Amours ◽  
Frédéric R. Sallmann ◽  
Vishva M. Dixit ◽  
Guy G. Poirier
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Catalytic Activity ◽  
Dna Binding ◽  
Energy Levels ◽  
Mouse Fibroblast ◽  
Dominant Negative ◽  
Energy Depletion ◽  
Parp 1

Poly(ADP-ribosyl)ation is an important mechanism for the maintenance of genomic integrity in response to DNA damage. The enzyme responsible for poly(ADP-ribose) synthesis, poly(ADP-ribose) polymerase 1 (PARP-1), has been implicated in two distinct modes of cell death induced by DNA damage, namely apoptosis and necrosis. During the execution phase of apoptosis, PARP-1 is specifically proteolyzed by caspases to produce an N-terminal DNA-binding domain (DBD) and a C-terminal catalytic fragment. The functional consequence of this proteolytic event is not known. However, it has recently been shown that overactivation of full-length PARP-1 can result in energy depletion and necrosis in dying cells. Here, we investigate the molecular basis for the differential involvement of PARP-1 in these two types of cellular demise. We show that the C-terminal apoptotic fragment of PARP-1 loses its DNA-dependent catalytic activity upon cleavage with caspase 3. However, the N-terminal apoptotic fragment, retains a strong DNA-binding activity and totally inhibits the catalytic activity of uncleaved PARP-1. This dominant-negative behavior was confirmed and extended in cellular extracts where DNA repair was completely inhibited by nanomolar concentrations of the N-terminal fragment. Furthermore, overexpression of the apoptotic DBD in mouse fibroblast inhibits endogenous PARP-1 activity very efficiently in vivo, thereby confirming our biochemical observations. Taken together, these experiments indicate that the apoptotic DBD of PARP-1 acts cooperatively with the proteolytic inactivation of the enzyme to trans-inhibit NAD hydrolysis and to maintain the energy levels of the cell. These results are consistent with a model in which cleavage of PARP-1 promotes apoptosis by preventing DNA repair-induced survival and by blocking energy depletion-induced necrosis.

scholarly journals COP9 signalosome is an essential and druggable parasite target that regulates protein degradation

2020 ◽  
Author(s):  
Swagata Ghosh ◽  
Laura Farr ◽  
Aditya Singh ◽  
Laura-Ann Leaton ◽  
Jay Padalia ◽  
...  
Keyword(s):  
Protein Degradation ◽  
Therapeutic Potential ◽  
Degradation Pathway ◽  
Dominant Negative ◽  
Cop9 Signalosome ◽  
Dependent Manner ◽  
Parasite Protein ◽  
Upstream Regulator ◽  
Dominant Negative Mutation

ABSTRACTUnderstanding how the protozoan protein degradation pathway is regulated could uncover new parasite biology for drug discovery. We found the COP9 signalosome (CSN) conserved in multiple pathogens such as Leishmania, Trypanosoma, Toxoplasma, and used the severe diarrhea-causing Entamoeba histolytica to study its function in medically significant protozoa. We show that CSN is an essential upstream regulator of parasite protein degradation. Genetic disruption of E. histolytica CSN by two distinct approaches inhibited cell proliferation and viability. Both CSN5 knockdown and dominant negative mutation trapped cullin in a neddylated state, disrupting UPS activity and protein degradation. In addition, zinc ditiocarb (ZnDTC), a main metabolite of the inexpensive FDA-approved alcohol-abuse drug disulfiram, was active against parasites acting in a COP9-dependent manner. ZnDTC, given as disulfiram-zinc, had oral efficacy in clearing parasites in vivo. Our findings provide insights into the regulation of parasite protein degradation, and supports the significant therapeutic potential of COP9 inhibition.Summary sentenceParasite-encoded COP9 signalosome is an essential upstream regulator of ubiquitin-proteasome mediated protein degradation, and shows significant potential as a therapeutic target.

scholarly journals Alpha-Synuclein and the Endolysosomal System in Parkinson’s Disease: Guilty by Association

Biomolecules ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1333
Author(s):  
Maxime Teixeira ◽  
Razan Sheta ◽  
Walid Idi ◽  
Abid Oueslati
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Neuronal Degeneration ◽  
Lewy Bodies ◽  
Cellular Membrane ◽  
Degradation Pathway ◽  
Alpha Synuclein ◽  
Potential Interaction ◽  
Abnormal Accumulation ◽  
Cellular Components

Abnormal accumulation of the protein α- synuclein (α-syn) into proteinaceous inclusions called Lewy bodies (LB) is the neuropathological hallmark of Parkinson’s disease (PD) and related disorders. Interestingly, a growing body of evidence suggests that LB are also composed of other cellular components such as cellular membrane fragments and vesicular structures, suggesting that dysfunction of the endolysosomal system might also play a role in LB formation and neuronal degeneration. Yet the link between α-syn aggregation and the endolysosomal system disruption is not fully elucidated. In this review, we discuss the potential interaction between α-syn and the endolysosomal system and its impact on PD pathogenesis. We propose that the accumulation of monomeric and aggregated α-syn disrupt vesicles trafficking, docking, and recycling, leading to the impairment of the endolysosomal system, notably the autophagy-lysosomal degradation pathway. Reciprocally, PD-linked mutations in key endosomal/lysosomal machinery genes (LRRK2, GBA, ATP13A2) also contribute to increasing α-syn aggregation and LB formation. Altogether, these observations suggest a potential synergistic role of α-syn and the endolysosomal system in PD pathogenesis and represent a viable target for the development of disease-modifying treatment for PD and related disorders.

scholarly journals The Drosophila hep pathway mediates Lrrk2-induced neurodegeneration

2018 ◽  
Vol 96 (4) ◽  
pp. 441-449 ◽  
Author(s):  
Dejun Yang ◽  
Joseph M. Thomas ◽  
Tianxia Li ◽  
Youngseok Lee ◽  
Zhaohui Liu ◽  
...  
Keyword(s):  
Dopaminergic Neurons ◽  
Molecular Mechanisms ◽  
Neuronal Degeneration ◽  
Genetic Modifier ◽  
Dominant Negative ◽  
Signal Pathways ◽  
Mapk Cascades ◽  
Dominant Negative Allele ◽  
Transgenic Flies

Although the pathogenesis of Parkinson’s disease (PD) remains unclear, mutations in leucine-rich repeat kinase 2 (Lrrk2) are among the major causes of familial PD. Most of these mutations disrupt Lrrk2 kinase and (or) GTPase domain function, resulting in neuronal degeneration. However, the signal pathways underlying Lrrk2-induced neuronal degeneration are not fully understood. There is an expanding body of evidence that suggests a link between Lrrk2 function and MAP kinase (MAPK) cascades. To further investigate this link in vivo, genetic RNAi screens of the MAPK pathways were performed in a Drosophila model to identify genetic modifier(s) that can suppress G2019S-Lrrk2-induced PD-like phenotypes. The results revealed that the knockdown of hemipterous (hep, or JNKK) increased fly survival time, improved locomotor function, and reduced loss of dopaminergic neurons in G2019S-Lrrk2 transgenic flies. Expression of the dominant-negative allele of JNK (JNK-DN), a kinase that is downstream of hep in G2019S-Lrrk2 transgenic flies, elicited a similar effect. Moreover, treatment with the JNK inhibitor SP600125 partially reversed the G2019S-Lrrk2-induced loss of dopaminergic neurons. These results indicate that the hep pathway plays an important role in Lrrk2-linked Parkinsonism in flies. These studies provide new insights into the molecular mechanisms underlying Lrrk2-linked PD pathogenesis and aid in identifying potential therapeutic targets.

DNA Damage in Rat Brain Cells after In Vivo Exposure to 2450 MHz Electromagnetic Radiation and Various Methods of Euthanasia

1998 ◽  
Vol 149 (6) ◽  
pp. 637 ◽  
Author(s):  
Robert S. Malyapa ◽  
Eric W. Ahern ◽  
Chen Bi ◽  
William L. Straube ◽  
Marie LaRegina ◽  
...  
Keyword(s):  
Dna Damage ◽  
Electromagnetic Radiation ◽  
Rat Brain ◽  
Brain Cells

scholarly journals VCP Protects Neurons from Proteopathic Seeding

2021 ◽  
Author(s):  
Jiang Zhu ◽  
Sara Pittman ◽  
Dhruva Dhavale ◽  
Rachel French ◽  
Jessica N. Patterson ◽  
...  
Keyword(s):  
Alpha Synuclein ◽  
Neuronal Uptake ◽  
Primary Neurons ◽  
Guide Rna ◽  
Late Endosomes ◽  
A Genome ◽  
Cellular Machinery ◽  
Or Gene ◽  
Intrastriatal Injection

Abstract Background: Neuronal uptake and subsequent spread of proteopathic seeds, such as αS (alpha-synuclein), tau, and TDP-43, contribute to neurodegeneration and disease progression. The cellular machinery necessary for this process is poorly understood. Methods: Cas9 expressing αS FRET biosensors were transduced with a whole-genome guide RNA (gRNA) library, seeded with αS fibrils, and flow-sorted. Candidate genes protective against αS seeding were identified following gRNA sequencing of FRET+ and FRET- cell populations. Secondary validation of the high probability candidate suppressor VCP, utilized VCP inhibitors or gene knockdown in αS biosensors and primary neurons. In vivo validation was performed in VCP disease mutation mice following intrastriatal injection of αS seeds. TDP-43 seeding was performed in primary neurons from control or VCP mutant mice.Results: We devised a genome-wide CRISPR-Cas9 screen to identify suppressors of αS seeding. This approach identified Valosin Containing Protein (VCP) as a suppressor of αS seeding. Dominant mutations in VCP cause multisystem proteinopathy (MSP) a phenotypically and pathologically variable neurodegeneraive disease characterized by myopathy, motor neuron disease and dementia with TDP-43, αS and tau inclusions. VCP inhibition or MSP disease mutations increased αS seeding in cells and primary cultured neurons. This was similar to treatment with the lysosomal damaging agent, LLoMe or knockdown of the endolysosomal damage response associated VCP cofactor, UBXD1. Intrastriatal injection of αS seeds into VCP disease mice demonstrated enhanced seeding efficiency as compared with controls. Finally, this phenomenon was not specific to αS since VCP disease mutant expression increased TDP-43 seeding in neurons.Conclusion: VCP surveillance of permeabilized late endosomes protects neurons against the proteopathic spread of pathogenic protein aggregates. The spread of distinct aggregate species may dictate the pleiotropic phenotypes and pathologies in VCP associated MSP.

scholarly journals Acute radiofrequency electromagnetic radiation exposures cause neuronal DNA damage and impair neurogenesis in the young adolescent rat brain

2020 ◽  
Author(s):  
Kumari Vandana Singh ◽  
Chandra Prakash ◽  
Jay Prakash Nirala ◽  
Ranjan Kumar Nanda ◽  
Paulraj Rajamani
Keyword(s):  
Dna Damage ◽  
Electromagnetic Radiation ◽  
Mobile Phone ◽  
Rat Brain ◽  
Neuronal Degeneration ◽  
Young Adolescent ◽  
Acute Exposure ◽  
And Function ◽  
Lipid Radicals ◽  
Radiofrequency Electromagnetic Radiation

AbstractMobile phone is now a commonly used communication device in all age groups. Young adolescents use it for longer duration and effect of its radiofrequency electromagnetic radiation (RF-EMR) on their brain structure and function need detailed investigation. In the present study, we investigated the effect of RF-EMR emitted from mobile phones, on young adolescent rat brain. Wistar rats (5 weeks, male) were exposed to RF-EMR signal (2,115 MHz) from a mobile phone at a whole body averaged specific absorption rate (SAR) of 1.15 W/kg continuously for 8 h. Higher level of lipid peroxidation, carbon centered lipid radicals and DNA damage were observed in the brain of rat exposed to RF-EMR. Number of neural progenitor cells (NPCs) in dentate gyrus (DG) were found to be relatively low in RF-EMR exposed rats that may be due to reduced neurogenesis. Acute exposure to RF-EMR induced neuronal degeneration in DG region with insignificant variation in CA3, CA1 and cerebral cortex sub regions of hippocampus. Findings of this study, indicate that acute exposure of high frequency RF-EMR at relatively higher SAR may adversely impact the neurogenesis and function of adolescent rat brain. Generation of carbon centered lipid radicals, and nuclear DNA damage might be playing critical role in reduced neurogenesis and higher neuronal degeneration in the cortex and hippocampus of brain. Detailed understanding of RF-EMR induced alteration in brain function will be useful to develop appropriate interventions for reducing the impact caused by RF-EMR damage.

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