Neuroscience
Abstract
Mucopolysaccharidosis type II (MPS II) is a lysosomal storage disorder caused by deficiency of the iduronate-2-sulfatase (IDS) enzyme, resulting in cellular accumulation of glycosaminoglycans (GAGs) throughout the body. Treatment of MPS II remains a considerable challenge as current enzyme replacement therapies do not adequately control many aspects of the disease, including skeletal and neurological manifestations. We developed an IDS transport vehicle (ETV:IDS) that is engineered to bind to the transferrin receptor; this design facilitates receptor-mediated transcytosis of IDS across the blood-brain barrier and improves its distribution into the brain while maintaining distribution to peripheral tissues. Here we show that chronic systemic administration of ETV:IDS in a mouse model of MPS II reduced levels of peripheral and central nervous system GAGs, microgliosis, and neurofilament light chain, a biomarker of neuronal injury. Additionally, ETV:IDS rescued auricular and skeletal abnormalities when introduced in adult MPS II mice. These effects were accompanied by improvements in several neurobehavioral domains, including motor skills, sensorimotor gating, and learning and memory. Together, these results highlight the therapeutic potential of ETV:IDS for treating peripheral and central abnormalities in MPS II. DNL310, an investigational ETV:IDS molecule, is currently in clinical trials as a potential treatment for patients with MPS II.
Authors
Annie Arguello, René Meisner, Elliot R. Thomsen, Hoang N. Nguyen, Ritesh Ravi, Jeffrey Simms, Iris Lo, Jessica Speckart, Julia Holtzman, Thomas M. Gill, Darren Chan, Yuhsiang Cheng, Chi-Lu Chiu, Jason C. Dugas, Meng Fang, Isabel A. Lopez, Hilda Solanoy, Buyankhishig Tsogtbaatar, Yuda Zhu, Akhil Bhalla, Kirk R. Henne, Anastasia G. Henry, Anthony Delucchi, Simona Costanzo, Jeffrey M. Harris, Dolores Diaz, Kimberly Scearce-Levie, Pascal E. Sanchez
Abstract
Current treatments for Parkinson’s disease (PD) provide only symptomatic relief, with no disease-modifying therapies identified to date. Repurposing FDA-approved drugs to treat PD could significantly shorten the time needed for and reduce the costs of drug development compared with conventional approaches. We developed an efficient strategy to screen for modulators of β-glucocerebrosidase (GCase), a lysosomal enzyme that exhibits decreased activity in patients with PD, leading to accumulation of the substrate glucosylceramide and oxidized dopamine and α-synuclein, which contribute to PD pathogenesis. Using a GCase fluorescent probe and affinity-based fluorescence polarization assay, we screened 1280 structurally diverse, bioactive, and cell-permeable FDA-approved drugs and found that the antipsychotic quetiapine bound GCase with high affinity. Moreover, quetiapine treatment of induced pluripotent stem cell–derived (iPSC-derived) dopaminergic neurons from patients carrying mutations in GBA1 or LRRK2 led to increased wild-type GCase protein levels and activity and partially lowered accumulation of oxidized dopamine, glucosylceramide, and α-synuclein. Similarly, quetiapine led to activation of wild-type GCase and reduction of α-synuclein in a GBA mutant mouse model (Gba1D409V/+ mice). Together, these results suggest that repurposing quetiapine as a modulator of GCase may be beneficial for patients with PD exhibiting decreased GCase activity.
Authors
Lena F. Burbulla, Jianbin Zheng, Pingping Song, Weilan Jiang, Michaela E. Johnson, Patrik Brundin, Dimitri Krainc
Abstract
Genetic variants in Granulin (GRN), which encodes the secreted glycoprotein Progranulin (PGRN), are associated with several neurodegenerative diseases including frontotemporal lobar degeneration, neuronal ceroid lipofuscinosis, and Alzheimer’s disease. These genetic alterations manifest in pathological changes due to a reduction of PGRN expression; therefore, identifying factors that can modulate PGRN levels in vivo would enhance our understanding of PGRN in neurodegeneration, and could reveal novel potential therapeutic targets. Here, we report that modulation of the endocytosis-lysosomal pathway via reduction of Nemo-like kinase (Nlk) in microglia, and not neurons, can alter total brain Pgrn levels in mice. We demonstrate that Nlk reduction promotes Pgrn degradation by enhancing its trafficking through endocytosis-lysosomal pathway, specifically in microglia. Furthermore, genetic interaction studies in mice showed that Nlk heterozygosity in Grn haploinsufficient mice further reduces Pgrn levels and induces neuropathological phenotypes associated with PGRN deficiency. Our results reveal a new mechanism for Pgrn level regulation in the brain through the active catabolism by microglia and provide insights into the pathophysiology of PGRN-associated diseases.
Authors
Tingting Dong, Leon Tejwani, Youngseob Jung, Hiroshi Kokubu, Kimberly Luttik, Terri M. Driessen, Janghoo Lim
Abstract
ER stress and activation of the unfolded protein response in the periphery as well as the central nervous system have been linked to various metabolic abnormalities. Chemically lowering protein kinase R–like ER kinase (PERK) activity within the hypothalamus leads to decreased food intake and body weight. However, the cell populations required in this response remain undefined. In the current study, we investigated the effects of proopiomelanocortin-specific (POMC-specific) PERK deficiency on energy balance and glucose metabolism. Male mice deficient for PERK in POMC neurons exhibited improvements in energy balance on a high-fat diet, showing decreased food intake and body weight, independent of changes in glucose and insulin tolerances. The plant-based inhibitor of PERK, celastrol, increases leptin sensitivity, resulting in decreased food intake and body weight in a murine model of diet-induced obesity (DIO). Our data extend these observations by demonstrating that celastrol-induced improvements in leptin sensitivity and energy balance were attenuated in mice with PERK deficiency in POMC neurons. Altogether, these data suggest that POMC-specific PERK deficiency in male mice confers protection against DIO, possibly providing a new therapeutic target for the treatment of diabetes and metabolic syndrome.
Authors
Zhenyan He, Linh Lieu, Yanbin Dong, Sadia Afrin, Dominic Chau, Anita Kabahizi, Briana Wallace, Jianhong Cao, Eun-Sang Hwang, Ting Yao, Yiru Huang, Jennifer Okolo, Bo Cheng, Yong Gao, Ling Hu, Kevin W. Williams
Abstract
Status epilepticus (SE) is a neurological emergency usually accompanied by acute cerebral edema and long-term cognitive impairment, and is characterized by neurodegeneration and aberrant hyperphosphorylated tau protein (p-tau) aggregation. The glia-lymphatic (glymphatic) system plays a central role in facilitating the clearance of metabolic waste from the brain, but its relationship with cerebral edema and cognitive dysfunction after SE is unclear. We hypothesized that cerebral edema after SE might impair glymphatic system function through compression, thus leading to impaired removal of metabolic waste, and ultimately affecting long-term cognitive function. Our results showed that glymphatic system function was temporarily impaired, as evidenced by 2-photon imaging, MRI enhancement, imaging of brain sections, and astrocytic water channel aquaporin 4 (AQP4) protein polarization. The severity of cerebral edema on MRI correlated well with glymphatic system dysfunction within 8 days following SE. Moreover, when cerebral edema was alleviated by glibenclamide treatment or genetic deletion of Trpm4, post-SE glymphatic system function recovered earlier, along with fewer p-tau–deposited neurons and neuronal degeneration and better cognitive function. These findings suggest that SE-induced cerebral edema may cause glymphatic system dysfunction and render the post-SE brain vulnerable to p-tau aggregation and neurocognitive impairment.
Authors
Kewei Liu, Juan Zhu, Yuan Chang, Zhenzhou Lin, Zhu Shi, Xing Li, Xing Chen, Chuman Lin, Suyue Pan, Kaibin Huang
Abstract
Mitochondrial dysfunction is a major pathophysiological contributor to the progression of Parkinson’s disease (PD); however, whether it contributes to epigenetic dysregulation remains unknown. Here, we show that both chemically and genetically driven mitochondrial dysfunctions share a common mechanism of epigenetic dysregulation. Under both scenarios, lysine 27 acetylation of likely variant H3.3 (H3.3K27ac) increased in dopaminergic neuronal models of PD, thereby opening that region to active enhancer activity via H3K27ac. These vulnerable epigenomic loci represent potential transcription factor motifs for PD pathogenesis. We further confirmed that mitochondrial dysfunction induces H3K27ac in ex vivo and in vivo (MitoPark) neurodegenerative models of PD. Notably, the significantly increased H3K27ac in postmortem PD brains highlights the clinical relevance to the human PD population. Our results reveal an exciting mitochondrial dysfunction-metabolism-H3K27ac-transcriptome axis for PD pathogenesis. Collectively, the mechanistic insights link mitochondrial dysfunction to epigenetic dysregulation in dopaminergic degeneration and offer potential new epigenetic intervention strategies for PD.
Authors
Minhong Huang, Dan Lou, Adhithiya Charli, Dehui Kong, Huajun Jin, Gary Zenitsky, Vellareddy Anantharam, Arthi Kanthasamy, Zhibin Wang, Anumantha G. Kanthasamy
Abstract
Repetitive mild traumatic brain injuries (mTBI) disrupt central nervous system (CNS) barriers, the erosion of which has been linked to long-term neurodegenerative and psychiatric conditions. Although much attention has been devoted to CNS vasculature following mTBI, little is known about the glia limitans superficialis - a barrier of surface-associated astrocytes that helps protect the CNS parenchyma and maintain homeostasis. Here, we identify the glia limitans superficialis as a crucial barrier surface whose breakdown after acute repeat mTBI facilitates increased cell death and recruitment of peripheral myelomonocytic cells. Using intravital microscopy, we show that brain resident microglia fortify this structure after a single mTBI yet fail to do so following secondary injury, which triggers massive recruitment of myelomonocytic cells from the periphery that contribute to further destruction of the glia limitans superficialis but not cortical cell death. We demonstrate instead that reactive oxygen species (ROS) generated in response to repeat head injury are largely responsible for enhanced cortical cell death, and therapeutic administration of the antioxidant, glutathione, markedly reduces this cell death, preserves the glia limitans, and prevents myelomonocytic cells from entering the brain parenchyma. Collectively, our findings underscore the importance of preserving the glia limitans superficialis after brain injury and offer a therapeutic means to protect this structure and the underlying cortex.
Authors
Hannah D. Mason, Alexis M. Johnson, Nicole A. Mihelson, Panagiotis Mastorakos, Dorian B. McGavern
Abstract
Dysfunctional dopaminergic neurotransmission is central to movement disorders and mental diseases. The dopamine transporter (DAT) regulates extracellular dopamine levels but the genetic and mechanistic link between DAT function and dopamine-related pathologies is not clear. Particularly, the pathophysiological significance of monoallelic missense mutations in DAT is unknown. Here we use clinical information, neuroimaging, and large-scale exome sequencing data to uncover the occurrence and phenotypic spectrum of a novel DAT coding variant, DAT-K619N, which localizes to the critical C-terminal PDZ-binding motif of human (h)DAT. We identified the rare, but recurrent hDAT-K619N variant in exome-sequenced samples of patients with neuropsychiatric diseases and a patient with early-onset, neurodegenerative parkinsonism and comorbid neuropsychiatric disease. We show that hDAT-K619N displays reduced uptake capacity, decreased surface expression, and accelerated turnover in cell cultures. Unilateral expression in mouse nigrostriatal neurons revealed differential effects of hDAT-K619N and hDAT-WT on dopamine-directed behaviors, and hDAT-K619N expression in Drosophila leads to impairments in dopamine transmission with accompanying hyperlocomotion and age-dependent disturbances of the negative geotactic response. Moreover, cellular studies and viral expression of hDAT-K619N in mice demonstrated a dominant-negative effect of the hDAT-K619N mutant. Summarized, our results suggest that hDAT-K619N can effectuate dopamine dysfunction of pathological relevance in a dominant-negative manner.
Authors
Freja Herborg, Kathrine L. Jensen, Sasha Tolstoy, Natascha V. Arends, Leonie P. Posselt, Aparna Shekar, Jenny I Aguilar, Viktor K. Lund, Kevin Erreger, Mattias Rickhag, Matthew D. Lycas, Markus N. Lonsdale, Troels Rahbek-Clemmensen, Andreas T. Sørensen, Amy H. Newman, Annemette Løkkegaard, Ole Kjaerulff, Thomas Werge, Lisbeth B. Møller, Heinrich J.G. Matthies, Aurelio Galli, Lena E. Hjermind, Ulrik Gether
Abstract
Degenerative cervical myelopathy (DCM) is the most common cause of nontraumatic spinal cord injury in adults worldwide. Surgical decompression is generally effective in improving neurological outcomes and halting progression of myelopathic deterioration. However, a subset of patients experience suboptimal neurological outcomes. Given the emerging evidence that apolipoprotein E4 (ApoE4) allelic status influences neurodegenerative conditions, we examined whether the presence of the ApoE4 allele may account for the clinical heterogeneity of treatment outcomes in patients with DCM. Our results demonstrate that human ApoE4+ DCM patients have a significantly lower extent of improvement after decompression surgery. Functional analysis of our DCM mouse model in targeted-replacement mice expressing human ApoE4 revealed delayed gait recovery, forelimb grip strength, and hind limb mechanical sensitivity after decompression surgery, compared with their ApoE3 counterparts. This was accompanied by an exacerbated proinflammatory response resulting in higher concentrations of TNF-α, IL-6, CCL3, and CXCL9. At the site of injury, there was a significant decrease in gray matter area, an increase in the activation of microglia/macrophages, and increased astrogliosis after decompression surgery in the ApoE4 mice. Our study is the first to our knowledge to investigate the pathophysiological underpinnings of ApoE4 in DCM, which suggests a possible personalized medicine approach for the treatment of DCM in ApoE4 carriers.
Authors
Alexa Desimone, James Hong, Sydney T. Brockie, Wenru Yu, Alex M. Laliberte, Michael G. Fehlings
Abstract
Angelman syndrome (AS) is a severe neurodevelopmental disorder for which only symptomatic treatment with limited benefits is available. AS is caused by mutations affecting the maternally inherited ubiquitin protein ligase E3A (UBE3A) gene. Previous studies showed that the silenced paternal Ube3a gene can be activated by targeting the antisense Ube3a-ATS transcript. We investigated antisense oligonucleotide–induced (ASO-induced) Ube3a-ATS degradation and its ability to induce UBE3A reinstatement and rescue of AS phenotypes in an established Ube3a mouse model. We found that a single intracerebroventricular injection of ASOs at postnatal day 1 (P1) or P21 in AS mice resulted in potent and specific UBE3A reinstatement in the brain, with levels up to 74% of WT levels in the cortex and a full rescue of sensitivity to audiogenic seizures. AS mice treated with ASO at P1 also showed rescue of established AS phenotypes, such as open field and forced swim test behaviors, and significant improvement on the reversed rotarod. Hippocampal plasticity of treated AS mice was comparable to WT but not significantly different from PBS-treated AS mice. No rescue was observed for the marble burying and nest building phenotypes. Our findings highlight the promise of ASO-mediated reactivation of UBE3A as a disease-modifying treatment for AS.
Authors
Claudia Milazzo, Edwin J. Mientjes, Ilse Wallaard, Søren Vestergaard Rasmussen, Kamille Dumong Erichsen, Tejaswini Kakunuri, A.S. Elise van der Sman, Thomas Kremer, Meghan T. Miller, Marius C. Hoener, Ype Elgersma
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