scholarly journals Live-cell assays for cell stress responses reveal new patterns of cell signaling caused by mutations in rhodopsin, α-synuclein and TDP-43

2019 ◽  
Author(s):  
Kevin M. Harlen ◽  
Elizabeth C. Roush ◽  
Joseph E. Clayton ◽  
Scott Martinka ◽  
Thomas E. Hughes
Keyword(s):  
Neurodegenerative Diseases ◽  
Neurodegenerative Disease ◽  
Second Messenger ◽  
Cell Stress ◽  
Live Cell ◽  
Phosphodiesterase Activity ◽  
Wild Type ◽  
Cell Assays ◽  
Second Messenger Signaling ◽  
Stress Dependent

ABSTRACTMany neurodegenerative diseases induce high levels of sustained cellular stress and alter a number of cellular processes. Genetically-encoded fluorescent biosensors are effective tools to examine neuronal activity and signaling in living cells. To examine how different mutations associated with neurodegenerative disease affect cell stress and signaling we created live-cell assays for ER-mediated cell stress and second messenger signaling. Analysis of the rhodopsin P23H mutation, the most common mutation in autosomal dominant Retinitis Pigmentosa, revealed increased cell stress levels compared to wild type rhodopsin. Moreover, this increase in cell stress correlated with blunted Ca2+ signaling in a stress dependent manner. Analysis of single cell Ca2+ signaling profiles revealed unique Ca2+ signaling responses exist in cells expressing wild type or P23H mutants, further supporting the notion that second messenger signaling is affected by cell stress. To explore the use of the ER-stress biosensor in other neurodegenerative diseases we examined how various mutants of α-synuclein and TDP-43 affected ER-mediated cell stress. Mutants of both α-synuclein and TDP-43 associated with Parkinson’s Disease and ALS demonstrated increases in ER-mediated cell stress. This increased cell stress was accompanied by changes in phosphodiesterase activity. Both HEK293T and SH-SY5Y cells expressing these proteins displayed a shift towards increased cAMP degradation rates, likely due to increased phosphodiesterase activity. Together these data illustrate how biosensors can provide nuanced, new views of neurodegenerative disease processes.

scholarly journals Live-Cell Assays for Cell Stress Responses Reveal New Patterns of Cell Signaling Caused by Mutations in Rhodopsin, α-Synuclein and TDP-43

2019 ◽  
Vol 13 ◽  
Author(s):  
Kevin M. Harlen ◽  
Elizabeth C. Roush ◽  
Joseph E. Clayton ◽  
Scott Martinka ◽  
Thomas E. Hughes
Keyword(s):  
Cell Signaling ◽  
Stress Responses ◽  
Cell Stress ◽  
Live Cell ◽  
Cell Assays

scholarly journals Familial Parkinson’s point mutation abolishes multiple system atrophy prion replication

2017 ◽  
Vol 115 (2) ◽  
pp. 409-414 ◽  
Author(s):  
Amanda L. Woerman ◽  
Sabeen A. Kazmi ◽  
Smita Patel ◽  
Atsushi Aoyagi ◽  
Abby Oehler ◽  
...  
Keyword(s):  
Biological Activity ◽  
Multiple System Atrophy ◽  
Neurodegenerative Diseases ◽  
Neurodegenerative Disease ◽  
Point Mutation ◽  
Cell Lines ◽  
Point Mutations ◽  
Wild Type ◽  
Prion Infection

In the neurodegenerative disease multiple system atrophy (MSA), α-synuclein misfolds into a self-templating conformation to become a prion. To compare the biological activity of α-synuclein prions in MSA and Parkinson’s disease (PD), we developed nine α-synuclein−YFP cell lines expressing point mutations responsible for inherited PD. MSA prions robustly infected wild-type, A30P, and A53T α-synuclein–YFP cells, but they were unable to replicate in cells expressing the E46K mutation. Coexpression of the A53T and E46K mutations was unable to rescue MSA prion infection in vitro, establishing that MSA α-synuclein prions are conformationally distinct from the misfolded α-synuclein in PD patients. This observation may have profound implications for developing treatments for neurodegenerative diseases.

scholarly journals Utilising Induced Pluripotent Stem Cells in Neurodegenerative Disease Research: Focus on Glia

2021 ◽  
Vol 22 (9) ◽  
pp. 4334
Author(s):  
Katrina Albert ◽  
Jonna Niskanen ◽  
Sara Kälvälä ◽  
Šárka Lehtonen
Keyword(s):  
Stem Cells ◽  
Neurodegenerative Diseases ◽  
Neurodegenerative Disease ◽  
Induced Pluripotent Stem Cells ◽  
Glial Cells ◽  
Pluripotent Stem Cells ◽  
Cell Types ◽  
Human Ipscs ◽  
Induced Pluripotent

Induced pluripotent stem cells (iPSCs) are a self-renewable pool of cells derived from an organism’s somatic cells. These can then be programmed to other cell types, including neurons. Use of iPSCs in research has been two-fold as they have been used for human disease modelling as well as for the possibility to generate new therapies. Particularly in complex human diseases, such as neurodegenerative diseases, iPSCs can give advantages over traditional animal models in that they more accurately represent the human genome. Additionally, patient-derived cells can be modified using gene editing technology and further transplanted to the brain. Glial cells have recently become important avenues of research in the field of neurodegenerative diseases, for example, in Alzheimer’s disease and Parkinson’s disease. This review focuses on using glial cells (astrocytes, microglia, and oligodendrocytes) derived from human iPSCs in order to give a better understanding of how these cells contribute to neurodegenerative disease pathology. Using glia iPSCs in in vitro cell culture, cerebral organoids, and intracranial transplantation may give us future insight into both more accurate models and disease-modifying therapies.

Spatial organization enhances versatility and specificity in cyclic di-GMP signaling

2020 ◽  
Vol 401 (12) ◽  
pp. 1323-1334
Author(s):  
Sandra Kunz ◽  
Peter L. Graumann
Keyword(s):  
Protein Interactions ◽  
Cell Cycle Progression ◽  
Spatial Organization ◽  
Caulobacter Crescentus ◽  
Second Messenger ◽  
Protein Protein Interactions ◽  
Spatial Cues ◽  
Signaling Specificity ◽  
Regulatory Circuits ◽  
Second Messenger Signaling

AbstractThe second messenger cyclic di-GMP regulates a variety of processes in bacteria, many of which are centered around the decision whether to adopt a sessile or a motile life style. Regulatory circuits include pathogenicity, biofilm formation, and motility in a wide variety of bacteria, and play a key role in cell cycle progression in Caulobacter crescentus. Interestingly, multiple, seemingly independent c-di-GMP pathways have been found in several species, where deletions of individual c-di-GMP synthetases (DGCs) or hydrolases (PDEs) have resulted in distinct phenotypes that would not be expected based on a freely diffusible second messenger. Several recent studies have shown that individual signaling nodes exist, and additionally, that protein/protein interactions between DGCs, PDEs and c-di-GMP receptors play an important role in signaling specificity. Additionally, subcellular clustering has been shown to be employed by bacteria to likely generate local signaling of second messenger, and/or to increase signaling specificity. This review highlights recent findings that reveal how bacteria employ spatial cues to increase the versatility of second messenger signaling.

The Cryo-EM Effect: Structural Biology of Neurodegenerative Disease Proteostasis Factors

2021 ◽  
Author(s):  
Benjamin C Creekmore ◽  
Yi-Wei Chang ◽  
Edward B Lee
Keyword(s):  
Neurodegenerative Diseases ◽  
Protein Aggregation ◽  
Neurodegenerative Disease ◽  
Electron Tomography ◽  
Ubiquitin Proteasome System ◽  
26S Proteasome ◽  
X Ray Crystallography ◽  
New Information ◽  
A Cell ◽  
Regulate Protein

Abstract Neurodegenerative diseases are characterized by the accumulation of misfolded proteins. This protein aggregation suggests that abnormal proteostasis contributes to aging-related neurodegeneration. A better fundamental understanding of proteins that regulate proteostasis may provide insight into the pathophysiology of neurodegenerative disease and may perhaps reveal novel therapeutic opportunities. The 26S proteasome is the key effector of the ubiquitin-proteasome system responsible for degrading polyubiquitinated proteins. However, additional factors, such as valosin-containing protein (VCP/p97/Cdc48) and C9orf72, play a role in regulation and trafficking of substrates through the normal proteostasis systems of a cell. Nonhuman AAA+ ATPases, such as the disaggregase Hsp104, also provide insights into the biochemical processes that regulate protein aggregation. X-ray crystallography and cryo-electron microscopy (cryo-EM) structures not bound to substrate have provided meaningful information about the 26S proteasome, VCP, and Hsp104. However, recent cryo-EM structures bound to substrate have provided new information about the function and mechanism of these proteostasis factors. Cryo-EM and cryo-electron tomography data combined with biochemical data have also increased the understanding of C9orf72 and its role in maintaining proteostasis. These structural insights provide a foundation for understanding proteostasis mechanisms with near-atomic resolution upon which insights can be gleaned regarding the pathophysiology of neurodegenerative diseases.

scholarly journals Visualizing Association of the Retroviral Gag Protein with Unspliced Viral RNA in the Nucleus

mBio ◽  
2020 ◽  
Vol 11 (2) ◽  
Author(s):  
Rebecca J. Kaddis Maldonado ◽  
Breanna Rice ◽  
Eunice C. Chen ◽  
Kevin M. Tuffy ◽  
Estelle F. Chiari ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Nuclear Envelope ◽  
Rous Sarcoma Virus ◽  
Nuclear Export ◽  
Live Cell ◽  
Viral Rna ◽  
Wild Type ◽  
Gag Protein ◽  
Rous Sarcoma ◽  
Sarcoma Virus

ABSTRACT Packaging of genomic RNA (gRNA) by retroviruses is essential for infectivity, yet the subcellular site of the initial interaction between the Gag polyprotein and gRNA remains poorly defined. Because retroviral particles are released from the plasma membrane, it was previously thought that Gag proteins initially bound to gRNA in the cytoplasm or at the plasma membrane. However, the Gag protein of the avian retrovirus Rous sarcoma virus (RSV) undergoes active nuclear trafficking, which is required for efficient gRNA encapsidation (L. Z. Scheifele, R. A. Garbitt, J. D. Rhoads, and L. J. Parent, Proc Natl Acad Sci U S A 99:3944–3949, 2002, https://doi.org/10.1073/pnas.062652199; R. Garbitt-Hirst, S. P. Kenney, and L. J. Parent, J Virol 83:6790–6797, 2009, https://doi.org/10.1128/JVI.00101-09). These results raise the intriguing possibility that the primary contact between Gag and gRNA might occur in the nucleus. To examine this possibility, we created a RSV proviral construct that includes 24 tandem repeats of MS2 RNA stem-loops, making it possible to track RSV viral RNA (vRNA) in live cells in which a fluorophore-conjugated MS2 coat protein is coexpressed. Using confocal microscopy, we observed that both wild-type Gag and a nuclear export mutant (Gag.L219A) colocalized with vRNA in the nucleus. In live-cell time-lapse images, the wild-type Gag protein trafficked together with vRNA as a single ribonucleoprotein (RNP) complex in the nucleoplasm near the nuclear periphery, appearing to traverse the nuclear envelope into the cytoplasm. Furthermore, biophysical imaging methods suggest that Gag and the unspliced vRNA physically interact in the nucleus. Taken together, these data suggest that RSV Gag binds unspliced vRNA to export it from the nucleus, possibly for packaging into virions as the viral genome. IMPORTANCE Retroviruses cause severe diseases in animals and humans, including cancer and acquired immunodeficiency syndromes. To propagate infection, retroviruses assemble new virus particles that contain viral proteins and unspliced vRNA to use as gRNA. Despite the critical requirement for gRNA packaging, the molecular mechanisms governing the identification and selection of gRNA by the Gag protein remain poorly understood. In this report, we demonstrate that the Rous sarcoma virus (RSV) Gag protein colocalizes with unspliced vRNA in the nucleus in the interchromatin space. Using live-cell confocal imaging, RSV Gag and unspliced vRNA were observed to move together from inside the nucleus across the nuclear envelope, suggesting that the Gag-gRNA complex initially forms in the nucleus and undergoes nuclear export into the cytoplasm as a viral ribonucleoprotein (vRNP) complex.

New Approaches to Profile the Microbiome for Treatment of Neurodegenerative Disease

2021 ◽  
pp. 1-29
Author(s):  
David R. Elmaleh ◽  
Matthew A. Downey ◽  
Ljiljana Kundakovic ◽  
Jeremy E. Wilkinson ◽  
Ziv Neeman ◽  
...  
Keyword(s):  
Neurodegenerative Diseases ◽  
Neurodegenerative Disease ◽  
Gut Microbiome ◽  
Treatment Options ◽  
Treatment Strategies ◽  
Modern Society ◽  
Aging Brain ◽  
New Approaches ◽  
Microbiome Profile ◽  
Carry Over

Progressive neurodegenerative diseases represent some of the largest growing treatment challenges for public health in modern society. These diseases mainly progress due to aging and are driven by microglial surveillance and activation in response to changes occurring in the aging brain. The lack of efficacious treatment options for Alzheimer’s disease (AD), as the focus of this review, and other neurodegenerative disorders has encouraged new approaches to address neuroinflammation for potential treatments. Here we will focus on the increasing evidence that dysbiosis of the gut microbiome is characterized by inflammation that may carry over to the central nervous system and into the brain. Neuroinflammation is the common thread associated with neurodegenerative diseases, but it is yet unknown at what point and how innate immune function turns pathogenic for an individual. This review will address extensive efforts to identify constituents of the gut microbiome and their neuroactive metabolites as a peripheral path to treatment. This approach is still in its infancy in substantive clinical trials and requires thorough human studies to elucidate the metabolic microbiome profile to design appropriate treatment strategies for early stages of neurodegenerative disease. We view that in order to address neurodegenerative mechanisms of the gut, microbiome and metabolite profiles must be determined to pre-screen AD subjects prior to the design of specific, chronic titrations of gut microbiota with low-dose antibiotics. This represents an exciting treatment strategy designed to balance inflammatory microglial involvement in disease progression with an individual’s manifestation of AD as influenced by a coercive inflammatory gut.

scholarly journals Single nucleotide polymorphisms alter kinase anchoring and the subcellular targeting of A-kinase anchoring proteins

2018 ◽  
Vol 115 (49) ◽  
pp. E11465-E11474 ◽  
Author(s):  
F. Donelson Smith ◽  
Mitchell H. Omar ◽  
Patrick J. Nygren ◽  
Joseph Soughayer ◽  
Naoto Hoshi ◽  
...  
Keyword(s):  
Solid Phase ◽  
Second Messenger ◽  
Nuclear Accumulation ◽  
Nucleotide Polymorphisms ◽  
Binding Assays ◽  
Subcellular Targeting ◽  
Regulatory Subunits ◽  
Anchoring Proteins ◽  
Anchoring Protein ◽  
Second Messenger Signaling

A-kinase anchoring proteins (AKAPs) shape second-messenger signaling responses by constraining protein kinase A (PKA) at precise intracellular locations. A defining feature of AKAPs is a helical region that binds to regulatory subunits (RII) of PKA. Mining patient-derived databases has identified 42 nonsynonymous SNPs in the PKA-anchoring helices of five AKAPs. Solid-phase RII binding assays confirmed that 21 of these amino acid substitutions disrupt PKA anchoring. The most deleterious side-chain modifications are situated toward C-termini of AKAP helices. More extensive analysis was conducted on a valine-to-methionine variant in the PKA-anchoring helix of AKAP18. Molecular modeling indicates that additional density provided by methionine at position 282 in the AKAP18γ isoform deflects the pitch of the helical anchoring surface outward by 6.6°. Fluorescence polarization measurements show that this subtle topological change reduces RII-binding affinity 8.8-fold and impairs cAMP responsive potentiation of L-type Ca2+ currents in situ. Live-cell imaging of AKAP18γ V282M-GFP adducts led to the unexpected discovery that loss of PKA anchoring promotes nuclear accumulation of this polymorphic variant. Targeting proceeds via a mechanism whereby association with the PKA holoenzyme masks a polybasic nuclear localization signal on the anchoring protein. This led to the discovery of AKAP18ε: an exclusively nuclear isoform that lacks a PKA-anchoring helix. Enzyme-mediated proximity-proteomics reveal that compartment-selective variants of AKAP18 associate with distinct binding partners. Thus, naturally occurring PKA-anchoring-defective AKAP variants not only perturb dissemination of local second-messenger responses, but also may influence the intracellular distribution of certain AKAP18 isoforms.

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