scholarly journals Loss of Depalmitoylation Exaggerates Synaptic Upscaling and Leads to Neuroinflammation in a Lysosomal Storage Disease

2021 ◽  
Author(s):  
Kevin P Koster ◽  
Eden Flores-Barrera ◽  
Emilce Artur de la Villarmois ◽  
Thu T.A. Nguyen ◽  
Amanda Niqula ◽  
...  
Keyword(s):  
Ampa Receptors ◽  
Protein Trafficking ◽  
Cortical Neurons ◽  
Microglial Activation ◽  
Storage Disease ◽  
Homeostatic Plasticity ◽  
Synaptic Proteins ◽  
Lysosomal Storage ◽  
Palmitoyl Protein Thioesterase

Palmitoylation and depalmitoylation are the dichotomic processes of lipid modification regulating protein trafficking, recycling, and degradation, thereby controlling proteostasis. Despite our understanding of palmitoylation, depalmitoylation is far less studied. Here, we study a lysosomal depalmitoylating enzyme, palmitoyl-protein thioesterase 1 (PPT1), associated with the devastating neurodegenerative condition CLN1 disease and show that dark-rearing Ppt1-/- mice, which induces synaptic upscaling in vivo, worsen the symptoms. In Ppt1-/- cortical neurons, upscaling induction triggers exaggerated responses of synaptic calcium-permeable AMPA receptors composed of palmitoylated GluA1 subunits. Consequently, Ppt1-/- visual cortex exhibits hypersynchrony in vivo. Remarkably, we also find an overload of palmitoylated A-kinase anchor protein 5 (Akap5) in Ppt1-/- mouse brains, leading to microglial activation through NFAT. These findings indicate Ppt1 acts as a gatekeeper of homeostatic plasticity by regulating the proteostasis of palmitoylated synaptic proteins. Moreover, our results suggest that perturbed depalmitoylation results in neuroinflammation, which is common to neurodegenerative diseases.

scholarly journals Loss of EPAC2 results in altered synaptic composition of dendritic spines and excitatory and inhibitory balance

2019 ◽  
Author(s):  
Kelly A Jones ◽  
Michiko Sumiya ◽  
Kevin M Woolfrey ◽  
Deepak P Srivastava ◽  
Peter Penzes
Keyword(s):  
Ampa Receptors ◽  
Cortical Neurons ◽  
Glutamate Transporter ◽  
Autism Spectrum ◽  
Small Gtpase ◽  
Anterior Cingulate ◽  
Synaptic Proteins ◽  
Inhibitory Synapses ◽  
Nucleotide Exchange

EPAC2 is a guanine nucleotide exchange factor that regulates GTPase activity of the small GTPase Rap and Ras) and is highly enriched at synapses. Activation of EPAC2 has been shown to induce dendritic spine shrinkage and increase spine motility, effects that are necessary for synaptic plasticity. These morphological effects are dysregulated by rare mutations of EPAC2 associated with autism spectrum disorders. In addition, EPAC2 destabilizes synapses through the removal of synaptic GluA2/3-containing AMPA receptors. Previous work has shown that Epac2 knockout mice (Epac2-/-) display abnormal social interactions, as well as gross disorganization of the frontal cortex and abnormal spine motility in vivo. In this study we sought to further understand the cellular consequences of knocking out Epac2 on the development of neuronal and synaptic structure and organization of cortical neurons. Using primary cortical neurons generated from Epac2+/+ or Epac2-/- mice, we confirm that EPAC2 is required for cAMP-dependent spine shrinkage. Neurons from Epac2-/- mice also displayed increased synaptic expression of GluA2/3-containing AMPA receptors, as well as of the adhesion protein N-cadherin. Intriguingly, analysis of excitatory and inhibitory synaptic proteins revealed that loss of EPAC2 resulted in altered of expression of vesicular glutamate transporter 1 (VGluT1) and vesicular GABA transporter (VGAT), indicating a potential imbalance in excitatory/inhibitory inputs onto neurons. Finally, examination of cortical neurons located within the anterior cingulate cortex further revealed subtle deficits in the establishment of dendritic arborization in vivo. These data provide evidence that EPAC2 is required for the correct composition of synapses and that loss of this protein could result in an imbalance of excitatory and inhibitory synapses.

scholarly journals Rem2 regulates distinct homeostatic mechanisms in visual circuit plasticity

2017 ◽  
Author(s):  
Anna R. Moore ◽  
Sarah E. Richards ◽  
Katelyn Kenny ◽  
Leandro de Oliveira Royer ◽  
Urann Chan ◽  
...  
Keyword(s):  
Cortical Neurons ◽  
Neural Circuit ◽  
Ocular Dominance ◽  
Scaling Up ◽  
Homeostatic Plasticity ◽  
Intrinsic Excitability ◽  
Neuronal Membrane ◽  
List Type ◽  
Ocular Dominance Plasticity

SUMMARYActivity-regulated genes sculpt neural circuits in response to sensory experience. These calcium-sensitive genes generally fall into two categories: transcription factors and proteins that function at synapses. Yet little is known about activity-regulated, cytosolic proteins that transduce signals between the neuronal membrane and the nucleus. Using the visual system as a model, we investigated the role of the activity-regulated, non-canonical Ras-like GTPase Rem2 in vivo. We demonstrate that Rem2-/- mice fail to exhibit normal ocular dominance plasticity during the critical period. At the circuit level, cortical layer 2/3 neurons in Rem2-/- mice show deficits in both postsynaptic scaling up of excitatory synapses and misregulation of intrinsic excitability. Further, we reveal that Rem2 plays a novel, cell-autonomous role in regulating neuronal intrinsic excitability. Thus, Rem2 is a critical regulator of neural circuit function and distinct homeostatic plasticity mechanisms in vivo.HIGHLIGHTSRem2 is required in excitatory cortical neurons for normal ocular dominance plasticityRem2 regulates postsynaptic homoeostatic synaptic scaling upRem2 alters the intrinsic excitability of neurons in a cell-autonomous manner

scholarly journals Comparative proteomic profiling reveals mechanisms for early spinal cord vulnerability in CLN1 disease

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Hemanth R. Nelvagal ◽  
Maica Llavero Hurtado ◽  
Samantha L. Eaton ◽  
Rachel A. Kline ◽  
Douglas J. Lamont ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Storage Disease ◽  
Cell Signalling ◽  
Proteomic Profiling ◽  
Lysosomal Storage ◽  
Spinal Interneurons ◽  
Therapeutic Trials ◽  
And Control ◽  
Palmitoyl Protein Thioesterase ◽  
Function Cell

Abstract CLN1 disease is a fatal inherited neurodegenerative lysosomal storage disease of early childhood, caused by mutations in the CLN1 gene, which encodes the enzyme Palmitoyl protein thioesterase-1 (PPT-1). We recently found significant spinal pathology in Ppt1-deficient (Ppt1−/−) mice and human CLN1 disease that contributes to clinical outcome and precedes the onset of brain pathology. Here, we quantified this spinal pathology at 3 and 7 months of age revealing significant and progressive glial activation and vulnerability of spinal interneurons. Tandem mass tagged proteomic analysis of the spinal cord of Ppt1−/−and control mice at these timepoints revealed a significant neuroimmune response and changes in mitochondrial function, cell-signalling pathways and developmental processes. Comparing proteomic changes in the spinal cord and cortex at 3 months revealed many similarly affected processes, except the inflammatory response. These proteomic and pathological data from this largely unexplored region of the CNS may help explain the limited success of previous brain-directed therapies. These data also fundamentally change our understanding of the progressive, site-specific nature of CLN1 disease pathogenesis, and highlight the importance of the neuroimmune response. This should greatly impact our approach to the timing and targeting of future therapeutic trials for this and similar disorders.

Assay of β-glucosidase 2 (GBA2) activity using lithocholic acid β-3-O-glucoside substrate for cultured fibroblasts and glucosylceramide for brain tissue

2019 ◽  
Vol 400 (6) ◽  
pp. 745-752
Author(s):  
Klaus Harzer ◽  
Yildiz Yildiz ◽  
Stefanie Beck-Wödl
Keyword(s):  
Lysosomal Storage Disease ◽  
Gaucher Disease ◽  
Storage Disease ◽  
Lithocholic Acid ◽  
Artificial Substrates ◽  
Lysosomal Storage ◽  
Spastic Paraplegia ◽  
Cultured Fibroblasts ◽  
Normal Controls

Abstract Beta (β)-glucosidase 2 (GBA2) is deficient in a form of human spastic paraplegia due to defects in GBA2 (SPG46). GBA2 was proposed as a modifier of Gaucher disease, a lysosomal storage disease resulting from deficient β-glucosidase 1; GBA1. Current GBA2 activity assays using artificial substrates incompletely model the activity encountered in vivo. We studied GBA2 activity, using lithocholic acid β-glucoside or glucosylceramide as natural β-glucosidase substrates in murine tissues or cultured patient fibroblasts with the pathologic genotypes: Gba1−/−; Gba2−/−; GBA1−/−; GBA2+/− and found expected and unexpected deviations from normal controls.

scholarly journals Class I HDAC Inhibitor Rescues Synaptic Damage and Neuron Loss in APP-Transfected Cells and APP/Ps1 Mice through the GRIP1/AMPA Pathway

2021 ◽  
Author(s):  
Ying Han ◽  
Le Chen ◽  
Jingyun Liu ◽  
Chunyang Wang ◽  
Yu Guo ◽  
...  
Keyword(s):  
Ampa Receptor ◽  
Ampa Receptors ◽  
Hippocampal Neurons ◽  
Cell Model ◽  
Cytoskeletal Proteins ◽  
Synaptic Proteins ◽  
Human Neuroblastoma ◽  
Transfected Cells ◽  
Related Proteins

Abstract As a neurodegenerative disease, Alzheimer's disease (AD) seriously affects the health of older people. It is now known that changes in synapses occur first in the course of disease, perhaps even before the formation of Aβ plaques. Histone deacetylase (HDAC) can mediate the damage of Aβ oligomers to dendritic spines. Therefore, we examined the relationship between HDAC activity and synaptic defects by using an HDACI, BG45 in Human neuroblastoma SH-SY5Y cell line with stable overexpression of Swedish mutant APP (APPsw) and in APP/Ps1 transgenic mice during this study. The cells were treated with 15µM BG45 and the APP/Ps1 mice 30mg/kg BG45. We detected the level of synapse-related proteins, HDACs, tau phosphorylation and AMPA receptors by western bloting and immunohistochemistry. We also measured the expression of cytoskeletal proteins in the cell model. The mRNA level of GRIK2, SCN3B, SYNPR, Grm2, Grid2IP, GRIP1,GRIP2 were. to explore the effects of HDACi on regulating the synaptic proteins and AMPA receptors. Our studies demonstrated that the expression of HDAC1、HDAC2 and HDAC3 was increased, which was accompanied by the downregulation of the synapse-related proteins synaptophysin (SYP), postsynaptic dendritic protein (PSD-95) and spinophilin as early as 24 h after transfection with APPsw gene. BG45 upregulated the expression of synapse-related proteins and repaired cytoskeletal damage. In vivo, BG45 alleviated the apoptotic loss of hippocampal neurons, upregulated synapse-related proteins, reduced Aβ deposition and phosphorylation of tau and increased the level of the synapse-related genes GRIK2, SCN3B, SYNPR, Grm2, and Grid2IP. BG45 increased the expression of the AMPA receptor subunits GluA1, GluA2 and GluA3 on APPsw-transfected cells and increased GRIP1 and GRIP2 expression and AMPA receptor phosphorylation in vivo. These results suggest that HDACs are involved in the early process of synaptic defects of AD and that BG45 may rescue synaptic damage and loss of hippocampal neurons by specifically inhibiting HDAC1、HDAC2 and HDAC3, thereby modulating AMPA receptor transduction, increasing synapse-related gene expression and finally improving excitatory synapses. BG45 may be considered as a potential drug for the treatment of early AD for further study.

Engraftment of human CD34+ cells leads to widespread distribution of donor-derived cells and correction of tissue pathology in a novel murine xenotransplantation model of lysosomal storage disease

Blood ◽  
2003 ◽  
Vol 101 (5) ◽  
pp. 2054-2063 ◽  
Author(s):  
A. Alex Hofling ◽  
Carole Vogler ◽  
Michael H. Creer ◽  
Mark S. Sands
Keyword(s):  
Bone Marrow ◽  
Lysosomal Storage Disease ◽  
Storage Disease ◽  
Human Cells ◽  
Therapeutic Effects ◽  
Lysosomal Storage ◽  
Human Cd34 ◽  
Quantitative Measurements ◽  
Characteristic Features

A novel murine system was developed to study the in vivo localization of xenotransplanted human cells and assess their therapeutic effect in an authentic model of disease. The β-glucuronidase (GUSB) mutation of the mucopolysaccharidosis type VII (MPSVII) mouse was backcrossed onto the nonobese diabetic/severe combined immunodeficient (NOD/SCID) xenotransplantation strain. The resulting NOD/SCID/MPSVII mice displayed the characteristic features of lysosomal storage disease because of GUSB deficiency and were also capable of engrafting human cells. Human CD34+hematopoietic progenitor cells from healthy, GUSB+donors engrafted NOD/SCID/MPSVII mice in a manner similar to that of standard NOD/SCID mice. Six to 12 weeks following transplantation, 1% to 86% of the host bone marrow was positive for human CD45. By using a GUSB-specific histochemical assay, human engraftment was detected with single-cell sensitivity not only in well-characterized hematopoietic tissues like bone marrow, spleen, lymph node, and thymus, but also in other nonhematopoietic organs like liver, kidney, lung, heart, brain, and eye. Quantitative measurements of GUSB activity confirmed this expansive tissue distribution. The GUSB-specific assays were validated for their accuracy in identifying human cells through colocalization of human CD45 expression with GUSB activity in tissues of mice receiving transplants. An analysis of the therapeutic effects of engrafted human cells revealed a reduction of pathologic storage material in host organs, including the bone, spleen, and liver. Such xenotransplantation experiments in the NOD/SCID/MPSVII mouse represent a powerful approach to both study the in vivo biology of human cells and gather preclinical data regarding treatment approaches for a human disease.

scholarly journals Homeostatic Plasticity Requires Remodeling of the Homer-Shank Interactome

2020 ◽  
Author(s):  
Whitney E. Heavner ◽  
Haley Speed ◽  
Jonathan D. Lautz ◽  
Edward P. Gniffke ◽  
Karen B. Immendorf ◽  
...  
Keyword(s):  
Protein Interactions ◽  
Cortical Neurons ◽  
Barrel Cortex ◽  
Protein Complexes ◽  
Sensory Deprivation ◽  
Interaction Network ◽  
Autism Spectrum ◽  
Homeostatic Plasticity

AbstractNeurons maintain constant levels of excitability using homeostatic scaling, which adjusts relative synaptic strength in response to large changes in overall activity. It is still unknown how homeostatic scaling affects network-level protein interactions in the synapse despite extensive reporting of individual scaling-associated transcriptomic and proteomic changes. Here, we assessed a glutamatergic synapse protein interaction network (PIN) composed of 380 binary interactions among 21 protein members to identify protein complexes altered by synaptic scaling in vitro and in vivo. In cultured cortical neurons, we observed widespread bidirectional PIN alterations during up- and downscaling that reflected rapid glutamate receptor shuttling via synaptic scaffold remodeling. Sensory deprivation of the barrel cortex caused a PIN response that reflected changes in mGluR tone and NMDAR-dependent metaplasticity, consistent with emerging models of homeostatic plasticity in the barrel cortex that restore excitatory/inhibitory balance. Mice lacking Homer1 or Shank3B did not undergo normal PIN rearrangements, suggesting that these Autism Spectrum Disorder (ASD)-linked proteins serve as structural hubs for synaptic homeostasis. Our approach demonstrates how changes in the protein content of synapses during homeostatic plasticity translate into functional PIN alterations that mediate changes in neuron excitability.

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