Chronic cellular stress associated with neurodegenerative disease can result in the persistence of stress granule (SG) structures, membraneless organelles that form in response to cellular stress. In Huntington’s disease (HD), chronic expression of mutant huntingtin generates various forms of cellular stress, including activation of the unfolded protein response and oxidative stress. However, it has yet to be determined whether SGs are a feature of HD neuropathology. We examined the miRNA composition of extracellular vesicles (EVs) present in the cerebrospinal fluid (CSF) of HD patients and show that a subset of their target mRNAs were differentially expressed in the prefrontal cortex of HD patients. Of these targets, SG components were enriched, including the SG nucleating Ras GTPase-activating protein-binding protein 1 (G3BP1). We investigated localization and levels of G3BP1 and found a significant increase in the density of G3BP1-positive granules in the cortex and hippocampus of R6/2 transgenic mice and in the superior frontal cortex of HD patient brains. Intriguingly, we also observed that the SG-associated TAR DNA-Binding Protein-43 (TDP43), a nuclear RNA/DNA binding protein, was mislocalized to the cytoplasm of G3BP1-granule positive HD cortical neurons. These findings suggest that G3BP1 SG dynamics may play a role in the pathophysiology of HD.
Isabella I. Sanchez, Thai B. Nguyen, Whitney E. England, Ryan G. Lim, Anthony Q. Vu, Ricardo Miramontes, Lauren M. Byrne, Sebastian Markmiller, Alice L. Lau, Iliana Orellana, Maurice A. Curtis, Richard Lewis Maxwell Faull, Gene W. Yeo, Christie D. Fowler, Jack C. Reidling, Edward J. Wild, Robert C. Spitale, Leslie M. Thompson
Down syndrome (DS), caused by trisomy of chromosome 21, occurs in 1 of every 800 live births. Early defects in cortical development likely account for the cognitive impairments in DS, although the underlying molecular mechanism remains elusive. Here, we performed histological assays and unbiased single-cell RNA sequencing (scRNA-seq) analysis on cerebral organoids derived from four euploid cell lines and from induced pluripotent stem cells (iPSCs) from three individuals with trisomy 21 to explore cell type-specific abnormalities associated with DS during early brain development. We found that neurogenesis was significantly affected based on diminished proliferation and decreased expression of layer II and IV markers in cortical neurons in the subcortical regions; this may be responsible for the reduced size of the organoids. Furthermore, suppression of the DSCAM-PAK1 pathway which showed enhanced activities in DS) via CRISPR/Cas9, CRISPRi or small-molecule inhibitor treatment reverses abnormal neurogenesis, thereby increasing the size of organoids derived from DS iPSCs. Our study demonstrated that 3D cortical organoids developed in vitro are a valuable model of DS and provided a direct link between dysregulation of the DSCAM-PAK1 pathway and developmental brain defects in DS.
Xiao-Yan Tang, Lei Xu, Jingshen Wang, Yuan Hong, Yuanyuan Wang, Qian Zhu, Da Wang, Xin-Yue Zhang, Chun-Yue Liu, Kai-Heng Fang, Xiao Han, Shihua Wang, Xin Wang, Min Xu, Anita Bhattacharyya, Xing Guo, Mingyan Lin, Yan Liu
Charcot-Marie-Tooth disease type 4J (CMT4J) is caused by recessive, loss-of-function mutations in FIG4, encoding a phosphoinositol(3,5)P2-phosphatase. CMT4J patients have both neuron loss and demyelination in the peripheral nervous system, with vacuolization indicative of endosome/lysosome trafficking defects. Although the disease is highly variable, the onset is often in childhood and FIG4 mutations can dramatically shorten lifespan. There is currently no treatment for CMT4J. Here we present the results of preclinical studies testing a gene therapy approach to restore FIG4 expression. A mouse model of CMT4J, the Fig4-pale tremor (plt) allele, was dosed with a single-stranded AAV9 to deliver a codon-optimized human FIG4 sequence. Untreated, Fig4plt/plt mice have a median survival of approximately 5 weeks. When treated with the AAV9-FIG4 vector at postnatal day 1 or 4, mice survived at least one year, with largely normal gross motor performance and little sign of neuropathy by neurophysiological or histopathological evaluation. When treated at postnatal day 7 or 11, life span was still significantly prolonged and peripheral nerve function was improved, but rescue was less complete. No unanticipated adverse effects were observed. Therefore, AAV9-mediated delivery of FIG4 is a well-tolerated and efficacious strategy in a mouse model of CMT4J.
Maximiliano Presa, Rachel M. Bailey, Crystal Davis, Tara Murphy, Jenn Cook, Randy Walls, Hannah Wilpan, Laurent Bogdanik, Guy M. Lenk, Robert W. Burgess, Steven J. Gray, Cathleen Lutz
Synaptic plasticity is identified as innate to hypothalamic feeding circuits in their adaptation to the changing metabolic milieu in control of feeding and obesity. However, less is known about the regulatory principles of the dynamic changes of AgRP perikarya, a crucial region of the neuron gating excitation, and hence, feeding. Here we show that AgRP neurons activated either by food deprivation, ghrelin or chemogenetics decreased their own inhibitory tone while triggering mitochondrial adaptations in neighboring astrocytes. We found that it was the inhibitory neurotransmitter, GABA, released by AgRP neurons that evoked this astrocytic response, which in turn, resulted in increased glial ensheetment of AgRP perikaryal by glial processes and increased excitability of AgRP neurons. We also identified that astrocyte-derived prostaglandin E2 directly activated, via EP2 receptors, AgRP neurons. Taken together, these observations unmasked a feedforward, self-exciting loop in AgRP neuronal control mediated by astrocytes, a mechanism directly relevant for hunger, feeding and overfeeding.
Luis Varela, Bernardo Stutz, Jae Eun Song, Jae Geun Kim, Zhong-Wu Liu, Xiao-Bing Gao, Tamas L. Horvath
Opioid use disorder (OUD) has become a leading cause of death in the US, yet current therapeutic strategies remain highly inadequate. To identify novel potential treatments for OUD, we screened a targeted selection of over 100 drugs using a recently developed opioid self-administration assay in zebrafish. This paradigm showed that finasteride, a steroidogenesis inhibitor approved for the treatment of benign prostatic hyperplasia and androgenetic alopecia, reduced self-administration of multiple opioids without affecting locomotion or feeding behavior. These findings were confirmed in rats; furthermore, finasteride reduced the physical signs associated with opioid withdrawal. In rat models of neuropathic pain, finasteride did not alter the antinociceptive effect of opioids and reduced withdrawal-induced hyperalgesia. Steroidomic analyses of the brains of fish treated with finasteride revealed a significant increase in dehydroepiandrosterone sulfate (DHEAS). Treatment with precursors of DHEAS reduced opioid self-administration in zebrafish in a fashion akin to the effects of finasteride. These results highlight the importance of steroidogenic pathways as a rich source of therapeutic targets for OUD and point to the potential of finasteride as a new treatment option for this disorder.
Gabriel D. Bosse, Roberto Cadeddu, Gabriele Floris, Ryan D. Farero, Eva Vigato, Suhjung J. Lee, Tejia Zhang, Nilesh W. Gaikwad, Kristen A. Keefe, Paul E.M. Phillips, Marco Bortolato, Randall T. Peterson
BACKGROUND. Recently the α1 adrenergic receptor antagonist terazosin was shown to activate PGK1, a possible target for the mitochondrial deficits in Parkinson disease related to its function as the initial enzyme in ATP synthesis during glycolysis. An epidemiologic study of terazosin users showed a lower incidence of Parkinson disease when compared to users of tamsulosin, an α1 adrenergic receptor antagonist of a different class that does not activate PGK1. However, prior research on tamsulosin has suggested that it may in fact potentiate neurodegeneration, raising the question of whether it is an appropriate control group. METHODS. To address this question, we undertook an epidemiological study on Parkinson disease occurrence rate in 113,450 individuals from the U.S.A. with > 5 years of follow-up. Patients were classified as tamsulosin users (n = 45,380), terazosin/alfuzosin/doxazosin users (n = 22,690) or controls matched on age, gender and Charlson Comorbidity Index score (n = 45,380). RESULTS. Incidence of Parkinson disease in tamsulosin users was 1.53%, which was significantly higher than that in both terazosin/alfuzosin/doxazosin users (1.10%; p<0.0001) and matched controls (1.01%; p < 0.0001). Terazosin/alfuzosin/doxazosin users did not differ in Parkinson disease risk from matched controls (p = 0.29). CONCLUSION. These results suggest that zosins may not confer a protective effect against Parkinson disease, but rather that tamsulosin may in some way potentiate Parkinson disease progression. FUNDING. This work was supported by Cerevel Therapeutics.
Rahul Sasane, Amy Bartels, Michelle Field, Maria I. Sierra, Sridhar Duvvuri, David L. Gray, Sokhom S. Pin, John J. Renger, David J. Stone
X-linked adrenoleukodystrophy (ALD) is a progressive neurodegenerative disease caused by mutations in ABCD1, the peroxisomal very long-chain fatty acid (VLCFA) transporter. ABCD1 deficiency results in accumulation of saturated VLCFAs. A drug screen using a phenotypic motor assay in a zebrafish ALD model identified chloroquine as the top hit. Chloroquine increased expression of stearoyl-CoA desaturase-1 (scd1), the enzyme mediating fatty acid saturation status, suggesting that a shift towards mono-unsaturated fatty acids relieved toxicity. In human ALD fibroblasts chloroquine also increased SCD1 levels and reduced saturated VLCFAs. Conversely, pharmacological inhibition of SCD1 expression led to an increase in saturated VLCFAs, and CRISPR knockout of scd1 in zebrafish mimicked the motor phenotype of ALD zebrafish. Importantly, saturated VLCFAs caused ER stress in ALD fibroblasts whereas mono-unsaturated VLCFA did not. In parallel, we used liver X receptor (LXR) agonists to increase SCD1 expression, causing a shift from saturated towards mono-unsaturated VLCFA, and normalizing phospholipid profiles. Finally, Abcd1-/y mice receiving LXR agonist in their diet had VLCFA reductions in ALD-relevant tissues. These results suggest that metabolic rerouting of saturated to mono-unsaturated VLCFAs may alleviate lipid toxicity, a strategy that may be beneficial in ALD and other peroxisomal diseases in which VLCFAs play a key role.
Quentin Raas, Malu-Clair van de Beek, Sonja Forss-Petter, Inge M.E. Dijkstra, Abigail DeSchiffart, Briana C. Freshner, Tamara J. Stevenson, Yorrick R.J. Jaspers, Liselotte M. Nagtzaam, Ronald J.A. Wanders, Michel van Weeghel, Joo-Yeon Engelen-Lee, Marc Engelen, Florian Eichler, Johannes Berger, Joshua L. Bonkowsky, Stephan Kemp
The excitability of interneurons requires Nav1.1, the α subunit of voltage-gated sodium channel. Nav1.1 deficiency and mutations reduce interneuron excitability, a major pathological mechanism for epilepsy syndromes. However, the regulatory mechanisms of Nav1.1 expression remain unclear. Here we provide evidence that neddylation is critical to Nav1.1 stability. Mutant mice lacking Nae1, an obligatory component of the E1 ligase for neddylation, in parvalbumin-positive interneurons (PVINs) exhibited spontaneous epileptic seizures and premature death. Electrophysiological studies indicate that Nae1 deletion reduced in PVIN excitability and GABA release, and consequently increased the network excitability of pyramidal neurons (PyNs). Further analysis revealed a reduction in sodium current density, not a change in channel property, in mutant PVINs and decreased Nav1.1 protein level. These results suggest that insufficient neddylation in PVINs reduces Nav1.1 stability and thus the excitability of PVINs; ensuing increased PyN activity causes seizures in mice. In agreement, Nav1.1 was found reduced by proteomic analysis that revealed abnormality in synapses and metabolic pathways. Our findings, for the first time, described a role of neddylation in maintaining Nav1.1 stability for PVIN excitability and reveal a new mechanism in pathogenesis of epilepsy.
Wenbing Chen, Bin Luo, Nannan Gao, Haiwen Li, Hongsheng Wang, Lei Li, Wanpeng Cui, Lei Zhang, Dong Sun, Fang Liu, Zhaoqi Dong, Xiao Ren, Hongsheng Zhang, Huabo Su, Wen-Cheng Xiong, Lin Mei
Approximately 80% of neuromyelitis optica spectrum disorder (NMOSD) patients harbor serum anti–aquaporin-4 autoantibodies targeting astrocytes in the CNS. Crucial for NMOSD lesion initiation is disruption of the blood-brain barrier (BBB), which allows the entrance of Abs and serum complement into the CNS and which is a target for new NMOSD therapies. Astrocytes have important functions in BBB maintenance; however, the influence of their loss and the role of immune cell infiltration on BBB permeability in NMOSD have not yet been investigated. Using an experimental model of targeted NMOSD lesions in rats, we demonstrate that astrocyte destruction coincides with a transient disruption of the BBB and a selective loss of occludin from tight junctions. It is noteworthy that BBB integrity is reestablished before astrocytes repopulate. Rather than persistent astrocyte loss, polymorphonuclear leukocytes (PMNs) are the main mediators of BBB disruption, and their depletion preserves BBB integrity and prevents astrocyte loss. Inhibition of PMN chemoattraction, activation, and proteolytic function reduces lesion size. In summary, our data support a crucial role for PMNs in BBB disruption and NMOSD lesion development, rendering their recruitment and activation promising therapeutic targets.
Anne Winkler, Claudia Wrzos, Michael Haberl, Marie-Theres Weil, Ming Gao, Wiebke Möbius, Francesca Odoardi, Dietmar R. Thal, Mayland Chang, Ghislain Opdenakker, Jeffrey L. Bennett, Stefan Nessler, Christine Stadelmann
The coronavirus disease 2019 (COVID-19) rapidly progressed to a global pandemic. Although patients totally recover from COVID-19 pneumonia, long-term effects on the brain still need to be explored. Here, two subtypes (mild type-MG and severe type-SG) with no specific neurological manifestations at the acute stage and no obvious lesions on the conventional MRI three months after discharge were recruited. Changes in gray matter morphometry, cerebral blood flow (CBF) and white matter (WM) microstructure were investigated using MRI. The relationship between brain imaging measurements and inflammation markers were further analyzed. Compared with healthy controls, the decrease in cortical thickness/CBF, and the changes in WM microstructure were observed to be more severe in the SG than MG, especially in the frontal and limbic systems. Furthermore, changes in brain microstructure, CBF and tracts parameters were significantly correlated with inflammatory markers. The indirect injury related to inflammatory storm may damage the brain, that led to these interesting observations. There are also other likely potential causes, such as hypoxemia and dysfunction of vascular endothelium, et al. The abnormalities in these brain areas need to be monitored in the process of complete recovery, which could help clinicians to understand the potential neurological sequelae of COVID-19.
Yuanyuan Qin, Jinfeng Wu, Tao Chen, Jia Li, Guiling Zhang, Di Wu, Yiran Zhou, Ning Zheng, Aoling Cai, Qin Ning, Anne Manyande, Fuqiang Xu, Jie Wang, Wenzhen Zhu