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Ten new articles from Professor Ted M. Dawson, our Honorary Editors-in-Chief

Published on: 9 Jun 2021 Viewed: 708

In this issue, we will share ten articles from Professor Ted M. Dawson, our Honorary Editors-in-Chief.

Title: Blocking microglial activation of reactive astrocytes is neuroprotective in models of Alzheimer's disease
Authors: Jong-Sung Park, Tae-In Kam, Saebom Lee, Hyejin Park, Yumin Oh, Seung-Hwan Kwon, Jae-Jin Song, Donghoon Kim, Hyunhee Kim, Aanishaa Jhaldiyal, Dong Hee Na, Kang Choon Lee, Eun Ji Park, Martin G. Pomper, Olga Pletnikova, Juan C. Troncoso, Han Seok Ko, Valina L. Dawson, Ted M. Dawson, Seulki Lee
Type: Research Articles from Acta Neuropathologica Communications
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.
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Title: AIF3 splicing switch triggers neurodegeneration
Authors: Shuiqiao Liu, Mi Zhou, Zhi Ruan, Yanan Wang, Calvin Chang, Masayuki Sasaki, Veena Rajaram, Andrew Lemoff, Kalyani Nambiar, Jennifer E. Wang, Kimmo J. Hatanpaa, Weibo Luo, Ted M. Dawson, Valina L. Dawson, Yingfei Wang
Type: Research article from Molecular Neurodegeneration
Apoptosis-inducing factor (AIF), as a mitochondrial flavoprotein, plays a fundamental role in mitochondrial bioenergetics that is critical for cell survival and also mediates caspase-independent cell death once it is released from mitochondria and translocated to the nucleus under ischemic stroke or neurodegenerative diseases. Although alternative splicing regulation of AIF has been implicated, it remains unknown which AIF splicing isoform will be induced under pathological conditions and how it impacts mitochondrial functions and neurodegeneration in adult brain.
AIF splicing induction in brain was determined by multiple approaches including 5′ RACE, Sanger sequencing, splicing-specific PCR assay and bottom-up proteomic analysis. The role of AIF splicing in mitochondria and neurodegeneration was determined by its biochemical properties, cell death analysis, morphological and functional alterations and animal behavior. Three animal models, including loss-of-function harlequin model, gain-of-function AIF3 knockin model and conditional inducible AIF splicing model established using either Cre-loxp recombination or CRISPR/Cas9 techniques, were applied to explore underlying mechanisms of AIF splicing-induced neurodegeneration.
We identified a nature splicing AIF isoform lacking exons 2 and 3 named as AIF3. AIF3 was undetectable under physiological conditions but its expression was increased in mouse and human postmortem brain after stroke. AIF3 splicing in mouse brain caused enlarged ventricles and severe neurodegeneration in the forebrain regions. These AIF3 splicing mice died 2–4 months after birth. AIF3 splicing-triggered neurodegeneration involves both mitochondrial dysfunction and AIF3 nuclear translocation. We showed that AIF3 inhibited NADH oxidase activity, ATP production, oxygen consumption, and mitochondrial biogenesis. In addition, expression of AIF3 significantly increased chromatin condensation and nuclear shrinkage leading to neuronal cell death. However, loss-of-AIF alone in harlequin or gain-of-AIF3 alone in AIF3 knockin mice did not cause robust neurodegeneration as that observed in AIF3 splicing mice.
We identified AIF3 as a disease-inducible isoform and established AIF3 splicing mouse model. The molecular mechanism underlying AIF3 splicing-induced neurodegeneration involves mitochondrial dysfunction and AIF3 nuclear translocation resulting from the synergistic effect of loss-of-AIF and gain-of-AIF3. Our study provides a valuable tool to understand the role of AIF3 splicing in brain and a potential therapeutic target to prevent/delay the progress of neurodegenerative diseases.
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Title: Targeting Parthanatos in Ischemic Stroke
Authors: Raymond C. Koehler, Valina L. Dawson, Ted M. Dawson
Type: Review from Frontiers in Neurology
Parthanatos is a cell death signaling pathway in which excessive oxidative damage to DNA leads to over-activation of poly(ADP-ribose) polymerase (PARP). PARP then generates the formation of large poly(ADP-ribose) polymers that induce the release of apoptosis-inducing factor from the outer mitochondrial membrane. In the cytosol, apoptosis-inducing factor forms a complex with macrophage migration inhibitory factor that translocates into the nucleus where it degrades DNA and produces cell death. In a review of the literature, we identified 24 publications from 13 laboratories that support a role for parthanatos in young male mice and rats subjected to transient and permanent middle cerebral artery occlusion (MCAO). Investigators base their conclusions on the use of nine different PARP inhibitors (19 studies) or PARP1-null mice (7 studies). Several studies indicate a therapeutic window of 4–6 h after MCAO. In young female rats, two studies using two different PARP inhibitors from two labs support a role for parthanatos, whereas two studies from one lab do not support a role in young female PARP1-null mice. In addition to parthanatos, a body of literature indicates that PARP inhibitors can reduce neuroinflammation by interfering with NF-κB transcription, suppressing matrix metaloproteinase-9 release, and limiting blood-brain barrier damage and hemorrhagic transformation. Overall, most of the literature strongly supports the scientific premise that a PARP inhibitor is neuroprotective, even when most did not report behavior outcomes or address the issue of randomization and treatment concealment. Several third-generation PARP inhibitors entered clinical oncology trials without major adverse effects and could be repurposed for stroke. Evaluation in aged animals or animals with comorbidities will be important before moving into clinical stroke trials.
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Title: Protocol for measurement of calcium dysregulation in human induced pluripotent stem cell-derived dopaminergic neurons
Authors: XilingYin, Jungwoo WrenKim, ShiyuLiu, Ted M.Dawson, Valina L.Dawson
Type: Protocol from STAR Protocols
• Calcium imaging of human iPSC-derived DA neurons loaded with Fluo-4-AM
• Whole-cell voltage clamping for dye loading and calcium current recording
• Detailed guidelines for analyzing calcium dysregulation in human DA neurons
Calcium regulation is a critical process in neurons, and Ca2+ signaling is a major contributor to neurological disorders including Parkinson’s disease (PD). Here, combining calcium imaging with whole-cell Ca2+ current recording, we provide a detailed protocol for measuring Ca2+ homeostasis in dopaminergic (DA) neurons derived from human induced pluripotent stem cells (hiPSCs). This approach can be applied to investigate the role of Ca2+ homeostasis in neuronal functionality as well as in disease processes.
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Title: Lymphocyte Activation Gene 3 (Lag3) Contributes to α-Synucleinopathy in α-Synuclein Transgenic Mice
Authors: Hao Gu, Xiuli Yang, Xiaobo Mao, Enquan Xu, Chen Qi, Haibo Wang, Saurav Brahmachari, Bethany York, Manjari Sriparna, Amanda Li, Michael Chang Pavan Patel, Valina L. Dawson, Ted M. Dawson
Type: Original Research Article from Frontiers in Cellular Neuroscience
Aggregation of misfolded α-synuclein (α-syn) is the major component of Lewy bodies and neurites in Parkinson’s disease (PD) and related α-synucleinopathies. Some α-syn mutations (e.g., A53T) in familial PD recapitulate the α-syn pathology in transgenic mice, which supports the importance of pathologic α-syn in driving the pathogenesis of α-synucleinopathies. Lymphocyte activation gene 3 (Lag3) is a receptor of α-syn fibrils facilitating pathologic α-syn spread; however, the role of Lag3 in mediating the pathogenesis in α-syn transgenic mice is not clear. Here, we report that depletion of Lag3 in human α-syn A53T transgenic (hA53T) mice significantly reduces the level of detergent-insoluble α-syn aggregates and phosphorylated ser129 α-syn, and inhibits activation of microglia and astrocytes. The absence of Lag3 significantly delays disease progression and reduces the behavioral deficits in hA53T transgenic mice leading to prolonged survival. Taken together, these results show that Lag3 contributes to the pathogenesis in the α-syn A53T transgenic mouse model.
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Title: LRRK2 Modulates the Exocyst Complex Assembly by Interacting with Sec8
Authors: Milena Fais, Giovanna Sanna, Manuela Galioto, Thi Thanh Duyen Nguyen, Mai Uyên Thi Trần, Paola Sini, Franco Carta, Franco Turrini, Yulan Xiong, Ted M. Dawson, Valina L. Dawson, Claudia Crosio, Ciro Iaccarino
Type: Article from Cells
Mutations in LRRK2 play a critical role in both familial and sporadic Parkinson’s disease (PD). Up to date, the role of LRRK2 in PD onset and progression remains largely unknown. However, experimental evidence highlights a critical role of LRRK2 in the control of vesicle trafficking, likely by Rab phosphorylation, that in turn may regulate different aspects of neuronal physiology. Here we show that LRRK2 interacts with Sec8, one of eight subunits of the exocyst complex. The exocyst complex is an evolutionarily conserved multisubunit protein complex mainly involved in tethering secretory vesicles to the plasma membrane and implicated in the regulation of multiple biological processes modulated by vesicle trafficking. Interestingly, Rabs and exocyst complex belong to the same protein network. Our experimental evidence indicates that LRRK2 kinase activity or the presence of the LRRK2 kinase domain regulate the assembly of exocyst subunits and that the over-expression of Sec8 significantly rescues the LRRK2 G2019S mutant pathological effect. Our findings strongly suggest an interesting molecular mechanism by which LRRK2 could modulate vesicle trafficking and may have important implications to decode the complex role that LRRK2 plays in neuronal physiology.
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Title: Efficacy of Nilotinib in Patients With Moderately Advanced Parkinson Disease - A Randomized Clinical Trial
Authors: Tanya Simuni, Brian Fiske, Kalpana Merchant, Christopher S. Coffey, Elizabeth Klingner, Chelsea Caspell-Garcia, David-Erick Lafontant, Helen Matthews, Richard K. Wyse, Patrik Brundin, David K. Simon, Michael Schwarzschild, David Weiner, Jamie Adams, Charles Venuto, Ted M. Dawson, Liana Baker, Melissa Kostrzebski, Tina Ward, Gary Rafaloff, for the Parkinson Study Group NILO-PD Investigators and Collaborators
Type: Original Investigation from JAMA Neurology
Key Points
Do the safety, tolerability, exploratory clinical outcomes, brain penetration, and biomarker profile of nilotinib in aggregate support its development for treatment of Parkinson disease (PD)?
In this 6-month, multicenter, randomized placebo-controlled clinical trial of 76 participants with moderately advanced PD, nilotinib at 150-mg and 300-mg daily doses met prespecified safety and tolerability criteria. There was no evidence of symptomatic benefit of nilotinib on any measures of PD disability and there was trend toward worsening in the motor function in active treatment arms; in the cerebrospinal fluid, nilotinib level was less than 0.3% of that in the serum and failed to change dopamine metabolites levels.
While nilotinib demonstrated acceptable safety and tolerability in this cohort, the low cerebrospinal fluid exposure, lack of biomarkers effects, and efficacy data trending in the negative direction indicate that further testing of nilotinib in treatment of Parkinson disease is not warranted.

There is a critical need for careful and independent validation of reported symptomatic efficacy and dopaminergic biomarker changes induced by nilotinib in Parkinson disease (PD).
To assess safety and tolerability of nilotinib in participants with moderately advanced PD. Secondary and exploratory objectives were to assess its affect on PD disability, pharmacokinetics, cerebrospinal fluid (CSF) penetration, and biomarkers.
Design, Setting, and Participants
This was a 6-month, multicenter, randomized parallel-group, double-blind, placebo-controlled trial. Recruitment was from November 20, 2017, to December 28, 2018, and follow-up ended on September 9, 2019. The study was conducted at 25 US sites. The study approached 173 patients, of whom 48 declined, 125 were screened, and 76 who received a stable regimen of PD medications were enrolled (39% screen failure).
Participants were randomized 1:1:1 to placebo, 150-mg nilotinib, or 300-mg nilotinib once daily orally for 6 months, followed by 2-month off-drug evaluation.
Main Outcomes and Measures
The primary outcomes were safety and tolerability. The tolerability end point was defined as the ability to complete the study while receiving the assigned dose. An active arm was considered tolerable if the percentage of participants meeting the tolerability end point for that group was not significantly lower than the percentage observed in the placebo group. Secondary outcomes included change in PD disability (Movement Disorder Society Unified Parkinson’s Disease Rating Scale [MDS-UPDRS], Part II OFF/ON). Exploratory outcomes included serum and CSF pharmacokinetic profile, and CSF dopaminergic biomarkers.
At baseline, mean (SD) participants’ age was 64.6 (7.5) years, 52 were male (68%), mean (SD) disease duration was 9.9 years (4.7), MDS-UPDRS Part 1-3 OFF score was 66.4 (19.3), ON score was 48.4 (16.2), and Montreal Cognitive Assessment score was 27.1 (2.2). The number of participants who completed the study receiving the assigned dose were 21 (84%), 19 (76%), and 20 (77%) in the placebo, 150-mg, and 300-mg arms, respectively. Both active doses had acceptable safety profile. The most common reasons for drug suspension were asymptomatic, dose-dependent elevations of amylase, and/or lipase. Nilotinib, 150 mg and 300 mg, exhibited worse MDS-UPDRS-3 ON scores compared with placebo, achieving significance for nilotinib, 300 mg, at month 1 (P < .01). There was no difference in the change of MDS-UPDRS-3 OFF from baseline to 6 months between groups (P = .17). Cerebrospinal fluid/serum ratio of nilotinib concentration was 0.2% to 0.3%. There was no evidence of treatment-related alteration of dopamine metabolites in the CSF.
Conclusions and Relevance
While we demonstrated acceptable safety and tolerability of nilotinib in our cohort, the low CSF exposure and lack of biomarkers effect combined with the efficacy data trending in the negative direction indicate that nilotinib should not be further tested in PD.
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Title: AMPA Receptor Surface Expression Is Regulated by S-Nitrosylation of Thorase and Transnitrosylation of NSF
Authors: George K.E. Umanah, Mehdi Ghasemi, Xiling Yin, Melissa Chang, Jin Wan Kim, Jianmin Zhang, Erica Ma, Leslie A. Scarffe, Yun-Il Lee, Rong Chen, Kavya Tangella, Amy McNamara, Leire Abalde-Atristain, Mohamad A. Dar, Samuel Bennett, Marisol Cortes, Shaida A. Andrabi, Paschalis-Thomas Doulias, Harry Ischiropoulos, Ted M. Dawson, Valina L. Dawson
Type: Article from Cell Reports
• The activation of NMDARs leads to increased S-nitrosylation of Thorase and NSF
• S-nitrosylation of Thorase inhibits ATPase activity and enhances AMPAR internalization
• S-nitrosylated Thorase transnitrosylates NSF, thereby modulating AMPAR trafficking
• S-nitrosylation of Thorase is required for long-term potentiation and depression
The regulation of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) trafficking affects multiple brain functions, such as learning and memory. We have previously shown that Thorase plays an important role in the internalization of AMPARs from the synaptic membrane. Here, we show that N-methyl-d-aspartate receptor (NMDAR) activation leads to increased S-nitrosylation of Thorase and N-ethylmaleimide-sensitive factor (NSF). S-nitrosylation of Thorase stabilizes Thorase-AMPAR complexes and enhances the internalization of AMPAR and interaction with protein-interacting C kinase 1 (PICK1). S-nitrosylated NSF is dependent on the S-nitrosylation of Thorase via trans-nitrosylation, which modulates the surface insertion of AMPARs. In the presence of the S-nitrosylation-deficient C137L Thorase mutant, AMPAR trafficking, long-term potentiation, and long-term depression are impaired. Overall, our data suggest that both S-nitrosylation and interactions of Thorase and NSF/PICK1 are required to modulate AMPAR-mediated synaptic plasticity. This study provides critical information that elucidates the mechanism underlying Thorase and NSF-mediated trafficking of AMPAR complexes.
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Title: Determinants of seeding and spreading of α-synuclein pathology in the brain
Authors: Martin T. Henrich, Fanni F. Geibl, Harini Lakshminarasimhan, Anna Stegmann, Benoit I. Giasson, Xiaobo Mao, Valina L. Dawson, Ted M. Dawson, Wolfgang H. Oertel, D. James Surmeier
Type: Research Article from Science Advances
In Parkinson's disease (PD), fibrillar forms of α-synuclein are hypothesized to propagate through synaptically coupled networks, causing Lewy pathology (LP) and neurodegeneration. To more rigorously characterize the determinants of spreading, preformed α-synuclein fibrils were injected into the mouse pedunculopontine nucleus (PPN), a brain region that manifests LP in PD patients and the distribution of developing α-synuclein pathology compared to that ascertained by anterograde and retrograde connectomic mapping. Within the PPN, α-synuclein pathology was cell-specific, being robust in PD-vulnerable cholinergic neurons but not in neighboring noncholinergic neurons. While nearly all neurons projecting to PPN cholinergics manifested α-synuclein pathology, the kinetics, magnitude, and persistence of the propagated pathology were unrelated to the strength of those connections. Thus, neuronal phenotype governs the somatodendritic uptake of pathological α-synuclein, and while the afferent connectome restricts the subsequent spreading of pathology, its magnitude and persistence is not a strict function of the strength of coupling.
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Title: Defects in Mitochondrial Biogenesis Drive Mitochondrial Alterations in PARKIN-Deficient Human Dopamine Neurons
Authors: Manoj Kumar, Jesús Acevedo-Cintrón, Aanishaa Jhaldiyal, Hu Wang, Shaida A. Andrabi, Stephen Eacker, Senthilkumar S. Karuppagounder, Saurav Brahmachari, Rong Chen, Hyesoo Kim, Han Seok Ko, Valina L. Dawson, Ted M.Dawson
Type: Article from Cells
• 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
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.
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