Neuroscience
Abstract
Neuronal hyperexcitability and cytoplasmic mislocalization of the nuclear RNA binding proteinTDP43 are universal features in amyotrophic lateral sclerosis (ALS), but the relationship between these phenomena remains poorly defined. Here, we show that neuronal hyperexcitability drives TDP43 pathology by upregulating shortened (s)TDP43 splice variants missing the canonical C-terminus. sTDP43 isoforms preferentially accumulate in the cytoplasm,forming insoluble inclusions that sequester full-length TDP43 via preserved N-terminal interactions. Consistent with these findings, sTDP43 overexpression is highly toxic to mammalian neurons, suggesting that neurodegeneration results from complementary gain- and loss-of-function mechanisms. In humans and mice, sTDP43 transcripts are significantly enriched in vulnerable motor neurons, and we observed a striking accumulation of sTDP43 protein within neurons and glia of ALS patients. These studies uncover a hitherto unknown role of alternative TDP43 splice isoforms in ALS, and indicate that sTDP43 production may be a key contributor to the susceptibility of motor neurons in ALS.
Authors
Kaitlin Weskamp, Elizabeth M. Tank, Roberto Miguez, Jonathon P. McBride, Nicolás B. Gómez, Matthew White, Ziqiang Lin, Carmen Moreno Gonzalez, Andrea Serio, Jemeen Sreedharan, Sami J. Barmada
Abstract
Parkinson's disease (PD) is a neurodegenerative disorder associated with loss of striatal dopamine, secondary to degeneration of midbrain dopamine (mDA) neurons in the substantia nigra, rendering cell transplantation a promising therapeutic strategy. To establish human induced pluripotent stem cell (hiPSC)-based autologous cell therapy, we report a platform of core techniques for the production of mDA progenitors as a safe and effective therapeutic product. First, by combining metabolism-regulating microRNAs with reprogramming factors, we developed a method to more efficiently generate clinical grade iPSCs, as evidenced by genomic integrity and unbiased pluripotent potential. Second, we established a “spotting”-based in vitro differentiation methodology to generate functional and healthy mDA cells in a scalable manner. Third, we developed a chemical method that safely eliminates undifferentiated cells from the final product. Dopaminergic cells thus produced express high levels of characteristic mDA markers, produce and secrete dopamine, and exhibit electrophysiological features typical of mDA cells. Transplantation of these cells into rodent models of PD robustly restores motor dysfunction and reinnervates host brain, while showing no evidence of tumor formation or redistribution of the implanted cells. We propose that this platform is suitable for the successful implementation of human personalized autologous cell therapy for PD.
Authors
Bin Song, Young Cha, Sanghyeok Ko, Jeha Jeon, Nayeon Lee, Hyemyung Seo, Kyung-joon Park, In-Hee Lee, Claudia Lopes, Melissa Feitosa, María José Luna, Jin Hyuk Jung, Jisun Kim, Dabin Hwang, Bruce Cohen, Martin Teicher, Pierre Leblanc, Bob Carter, Jeffrey H. Kordower, Vadim Y. Bolshakov, Sek Won Kong, Jeffrey S. Schweitzer, Kwang-Soo Kim
Abstract
Leptomeningeal anastomoses or pial collateral vessels play a critical role in cerebral blood flow (CBF) restoration following ischemic stroke. The magnitude of this adaptive response is postulated to be controlled by the endothelium, although the underlying molecular mechanisms remain under investigation. Here we demonstrated that endothelial genetic deletion, using EphA4f/f/Tie2-Cre and EphA4f/f/VeCahderin-CreERT2 mice and vessel painting strategies, implicated EphA4 receptor tyrosine kinase as a major suppressor of pial collateral remodeling, CBF and functional recovery following permanent middle cerebral artery occlusion. Pial collateral remodeling is limited by the cross talk between EphA4-Tie2 signaling in vascular endothelial cells, which is mediated through p-Akt regulation. Furthermore, peptide inhibition of EphA4 resulted in acceleration of the pial arteriogenic response. Our findings demonstrate EphA4 is a negative regulator of Tie2 receptor signaling which limits pial collateral arteriogenesis following cerebrovascular occlusion. Therapeutic targeting of EphA4 and/or Tie2 represents an attractive new strategy for improving collateral function, neural tissue health and functional recovery following ischemic stroke.
Authors
Benjamin Okyere, William A. Mills III, Xia Wang, Michael Chen, Jiang Chen, Amanda Hazy, Yun Qian, John B. Matson, Michelle H. Theus
Abstract
While the impact of T helper 17 (Th17) cells in autoimmunity is undisputable, their pathogenic effector mechanism is still enigmatic. We have discovered SNARE complex proteins in Th17 cells enabling a vesicular glutamate release pathway inducing local intracytoplasmic calcium release and subsequent damage in neurons. This pathway is glutamine dependent and triggered by binding of β1-integrin to VCAM-1 on neurons in inflammatory context. Glutamate secretion could be blocked by inhibiting either glutaminase or KV1.3 channels, known to be linked to integrin expression and highly expressed on stimulated T cells. While KV1.3 is not expressed in the CNS tissue, intrathecal administration of a KV1.3 channel blocker or a glutaminase inhibitor ameliorated disability in experimental neuroinflammation. In humans, T cells from multiple sclerosis patients secreted higher levels of glutamate, and cerebrospinal fluid glutamine levels were increased. Altogether, our findings demonstrate that β1-integrin- and KV1.3 channel-dependent signaling stimulates glutamate release from Th17 cells upon direct cell-cell contact between Th17 cells and neurons.
Authors
Katharina Birkner, Beatrice Wasser, Tobias Ruck, Carine Thalman, Dirk Luchtman, Katrin Pape, Samantha Schmaul, Lynn Bitar, Eva-Maria Krämer-Albers, Albrecht Stroh, Sven G. Meuth, Frauke Zipp, Stefan Bittner
Abstract
BACKGROUND Spinal muscular atrophy (SMA) is caused by deficient expression of survival motor neuron (SMN) protein. New SMN-enhancing therapeutics are associated with variable clinical benefits. Limited knowledge of baseline and drug-induced SMN levels in disease-relevant tissues hinders efforts to optimize these treatments.METHODS SMN mRNA and protein levels were quantified in human tissues isolated during expedited autopsies.RESULTS SMN protein expression varied broadly among prenatal control spinal cord samples, but was restricted at relatively low levels in controls and SMA patients after 3 months of life. A 2.3-fold perinatal decrease in median SMN protein levels was not paralleled by comparable changes in SMN mRNA. In tissues isolated from nusinersen-treated SMA patients, antisense oligonucleotide (ASO) concentration and full-length (exon 7 including) SMN2 (SMN2-FL) mRNA level increases were highest in lumbar and thoracic spinal cord. An increased number of cells showed SMN immunolabeling in spinal cord of treated patients, but was not associated with an increase in whole-tissue SMN protein levels.CONCLUSIONS A normally occurring perinatal decrease in whole-tissue SMN protein levels supports efforts to initiate SMN-inducing therapies as soon after birth as possible. Limited ASO distribution to rostral spinal and brain regions in some patients likely limits clinical response of motor units in these regions for those patients. These results have important implications for optimizing treatment of SMA patients and warrant further investigations to enhance bioavailability of intrathecally administered ASOs.FUNDING SMA Foundation, SMART, NIH (R01-NS09677, R01-NS062269), Ionis Pharmaceuticals, and PTC Therapeutics. Biogen provided support for absolute real-time RT-PCR.
Authors
Daniel M. Ramos, Constantin d’Ydewalle, Vijayalakshmi Gabbeta, Amal Dakka, Stephanie K. Klein, Daniel A. Norris, John Matson, Shannon J. Taylor, Phillip G. Zaworski, Thomas W. Prior, Pamela J. Snyder, David Valdivia, Christine L. Hatem, Ian Waters, Nikhil Gupte, Kathryn J. Swoboda, Frank Rigo, C. Frank Bennett, Nikolai Naryshkin, Sergey Paushkin, Thomas O. Crawford, Charlotte J. Sumner
Abstract
Multiple sclerosis (MS) is a disabling disease of the CNS. Inflammatory features of MS include lymphocyte accumulations in the CNS and cerebrospinal fluid (CSF). The preclinical events leading to established MS are still enigmatic. Here we compared gene expression patterns of CSF cells from MS-discordant monozygotic twin pairs. Six “healthy” co-twins, who carry a maximal familial risk for developing MS, showed subclinical neuroinflammation (SCNI) with small MRI lesions. Four of these subjects had oligoclonal bands (OCBs). By single-cell RNA sequencing of 2752 CSF cells, we identified clonally expanded CD8+ T cells, plasmablasts, and, to a lesser extent, CD4+ T cells not only from MS patients but also from subjects with SCNI. In contrast to nonexpanded T cells, clonally expanded T cells showed characteristics of activated tissue-resident memory T (TRM) cells. The TRM-like phenotype was detectable already in cells from SCNI subjects but more pronounced in cells from patients with definite MS. Expanded plasmablast clones were detected only in MS and SCNI subjects with OCBs. Our data provide evidence for very early concomitant activation of 3 components of the adaptive immune system in MS, with a notable contribution of clonally expanded TRM-like CD8+ cells.
Authors
Eduardo Beltrán, Lisa Ann Gerdes, Julia Hansen, Andrea Flierl-Hecht, Stefan Krebs, Helmut Blum, Birgit Ertl-Wagner, Frederik Barkhof, Tania Kümpfel, Reinhard Hohlfeld, Klaus Dornmair
Abstract
Gene therapy approaches are being deployed to treat recessive genetic disorders by restoring the expression of mutated genes. However, the feasibility of these approaches for dominantly-inherited diseases—where treatment may require reduction in the expression of a toxic mutant protein resulting from a gain-of-function (GoF) allele—is unclear. Here we show the efficacy of allele-specific RNAi as a potential therapeutic for Charcot-Marie-Tooth type 2D (CMT2D), caused by dominant mutations in glycyl tRNA-synthetase (GARS). A de novo mutation in GARS was identified in a patient with a severe peripheral neuropathy, and a mouse model precisely recreating the mutation was produced. These mice developed a neuropathy by 3-4 weeks-of-age, validating the pathogenicity of the mutation. RNAi sequences targeting mutant GARS mRNA, but not wild-type, were optimized and then packaged into AAV9 for in vivo delivery. This almost completely prevented the neuropathy in mice treated at birth. Delaying treatment until after disease onset showed modest benefit, though this effect decreased the longer treatment was delayed. These outcomes were reproduced in a second mouse model of CMT2D using a vector specifically targeting that allele. The effects were dose dependent, and persisted for at least one year. Our findings demonstrate the feasibility of AAV9-mediated allele-specific knockdown and provide proof-of-concept for gene therapy approaches for dominant neuromuscular diseases.
Authors
Kathryn H. Morelli, Laurie B. Griffin, Nettie K. Pyne, Lindsay M. Wallace, Allison M. Fowler, Stephanie N. Oprescu, Ryuichi Takase, Na Wei, Rebecca Meyer-Schuman, Dattatreya Mellacheruvu, Jacob O. Kitzman, Samuel G. Kocen, Timothy J. Hines, Emily L. Spaulding, James R. Lupski, Alexey Nesvizhskii, Pedro Mancias, Ian J. Butler, Xiang-Lei Yang, Ya-Ming Hou, Anthony Antonellis, Scott Q. Harper, Robert W. Burgess
Abstract
Arcuate nucleus agouti-related peptide (AgRP) neurons play a central role in feeding and are under complex regulation by both homeostatic hormonal and nutrient signals and hypothalamic neuronal pathways. Feeding may also be influenced by environmental cues, sensory inputs and other behaviors implying the involvement of higher brain regions. However, whether such pathways modulate feeding through direct synaptic control of AgRP neuron activity is unknown. Here we show that nociceptin-expressing neurons in the anterior bed nuclei of the stria terminalis (aBNST) make direct GABAergic inputs onto AgRP neurons. We found that activation of these neurons inhibited AgRP neurons and feeding. Activity of these neurons increased upon food availability and their ablation resulted in obesity. Furthermore, these neurons received afferent inputs from a range of upstream brain regions as well as hypothalamic nuclei. Therefore, aBNST nociceptin/GABAergic neurons may act as a gateway to feeding behavior by connecting AgRP neurons to both homeostatic and non-homeostatic neuronal inputs.
Authors
Mark A. Smith, Agharul I. Choudhury, Justyna A. Glegola, Paulius Viskaitis, Elaine E. Irvine, Pedro Caldas Custodio de Campos Silva, Sanjay Khadayate, Hanns Ulrich Zeilhofer, Dominic J. Withers
Abstract
Parkinson’s disease (PD) is a common neurodegenerative disease that lacks therapies to prevent progressive neurodegeneration. Impaired energy metabolism and reduced ATP levels are common features of PD. Previous studies revealed that terazosin (TZ) enhances the activity of phosphoglycerate kinase 1 (PGK1), thereby stimulating glycolysis and increasing cellular ATP levels. Therefore, we asked whether enhancement of PGK1 activity would change the course of PD. In toxin-induced and genetic PD models in mice, rats, flies, and induced pluripotent stem cells, TZ increased brain ATP levels and slowed or prevented neuron loss. The drug increased dopamine levels and partially restored motor function. Because TZ is prescribed clinically, we also interrogated 2 distinct human databases. We found slower disease progression, decreased PD-related complications, and a reduced frequency of PD diagnoses in individuals taking TZ and related drugs. These findings suggest that enhancing PGK1 activity and increasing glycolysis may slow neurodegeneration in PD.
Authors
Rong Cai, Yu Zhang, Jacob E. Simmering, Jordan L. Schultz, Yuhong Li, Irene Fernandez-Carasa, Antonella Consiglio, Angel Raya, Philip M. Polgreen, Nandakumar S. Narayanan, Yanpeng Yuan, Zhiguo Chen, Wenting Su, Yanping Han, Chunyue Zhao, Lifang Gao, Xunming Ji, Michael J. Welsh, Lei Liu
Abstract
Angelman syndrome (AS) is a neurodevelopmental disorder characterized by intellectual disability, lack of speech, ataxia, EEG abnormalities, and epilepsy. Seizures in AS individuals are common, debilitating, and often drug-resistant. Therefore, there is an unmet need for better treatment options. Cannabidiol (CBD), a major phytocannabinoid constituent of cannabis, has antiseizure activity and behavioral benefits in preclinical and clinical studies for some disorders associated with epilepsy, suggesting that the same could be true for AS. Here we show that acute CBD (100 mg/kg) attenuated hyperthermia- and acoustically-induced seizures in a mouse model of AS. However, neither acute CBD nor a two-weeklong course of CBD administered immediately after a kindling protocol could halt the pro-epileptogenic plasticity observed in AS model mice. CBD had a dose-dependent sedative effect, but did not have an impact on motor performance. CBD abrogated the enhanced intracortical local field potential power, including delta and theta rhythms observed in AS model mice, indicating that CBD administration could also help normalize the EEG deficits observed in individuals with AS. Our results provide critical preclinical evidence supporting CBD treatment of seizures and alleviation of EEG abnormalities in AS, and will thus help guide the rational development of CBD as an AS treatment.
Authors
Bin Gu, Manhua Zhu, Madison R. Glass, Marie Rougié, Viktoriya D. Nikolova, Sheryl S. Moy, Paul R. Carney, Benjamin D. Philpot
Copyright © 2019 American Society for Clinical Investigation
ISSN: 0021-9738 (print), 1558-8238 (online)