Naringenin Ameliorates Drosophila ReepA Hereditary Spastic Paraplegia-Linked Phenotypes (original) (raw)
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ER Proteostasis Control of Neuronal Physiology and Synaptic Function
Trends in neurosciences, 2018
Neuronal proteostasis is maintained by the dynamic integration of different processes that regulate the synthesis, folding, quality control, and localization of proteins. The endoplasmic reticulum (ER) serves as a fundamental pillar of the proteostasis network, and is emerging as a key compartment to sustain normal brain function. The unfolded protein response (UPR), the main mechanism that copes with ER stress, plays a central role in the quality control of many ion channels and receptors, in addition to crosstalk with signaling pathways that regulate connectivity, synapse formation, and neuronal plasticity. We provide here an overview of recent advances in the involvement of the UPR in maintaining neuronal proteostasis, and discuss its emerging role in brain development, neuronal physiology, and behavior, as well as the implications for neurodegenerative diseases involving cognitive decline.
Modulation of Endoplasmic Reticulum Stress: An Opportunity to Prevent Neurodegeneration?
CNS & Neurological Disorders - Drug Targets, 2015
Neurodegenerative diseases (e.g. Alzheimer's disease, Parkinson's disease, Huntington's disease, amyotrophic lateral sclerosis and prion-related diseases) have in common the presence of protein aggregates in specific brain areas where significant neuronal loss is detected. In these pathologies, accumulating evidence supports a close correlation between neurodegeneration and endoplasmic reticulum (ER) stress, a condition that arises from ER lumen overload with misfolded proteins. Under these conditions, ER stress sensors initiate the unfolded protein response to restore normal ER function. If stress is too prolonged, or adaptive responses fail, apoptotic cell death ensues. Therefore, it was recently suggested that the manipulation of the ER unfolded protein response could be an effective strategy to avoid neuronal loss in neurodegenerative disorders. We will review the mechanisms underlying ER stress-associated neurodegeneration and discuss the possibility of ER as a therapeutic target.
A molecular chaperone inducer protects neurons from ER stress
Cell Death and Differentiation, 2008
The endoplasmic reticulum (ER) stress response is a defense system for dealing with the accumulation of unfolded proteins in the ER lumen. Recent reports have shown that ER stress is involved in the pathology of some neurodegenerative diseases and cerebral ischemia. In a screen for compounds that induce the ER-mediated chaperone BiP (immunoglobulin heavy-chain binding protein)/GRP78 (78 kDa glucose-regulated protein), we identified BiP inducer X (BIX). BIX preferentially induced BiP with slight inductions of GRP94 (94 kDa glucose-regulated protein), calreticulin, and C/EBP homologous protein. The induction of BiP mRNA by BIX was mediated by activation of ER stress response elements upstream of the BiP gene, through the ATF6 (activating transcription factor 6) pathway. Pretreatment of neuroblastoma cells with BIX reduced cell death induced by ER stress. Intracerebroventricular pretreatment with BIX reduced the area of infarction due to focal cerebral ischemia in mice. In the penumbra of BIX-treated mice, ER stress-induced apoptosis was suppressed, leading to a reduction in the number of apoptotic cells. Considering these results together, it appears that BIX induces BiP to prevent neuronal death by ER stress, suggesting that it may be a potential therapeutic agent for cerebral diseases caused by ER stress.
Endoplasmic Reticulum Stress and Unfolded Protein Response in Neurodegenerative Diseases
International Journal of Molecular Sciences
The endoplasmic reticulum (ER) is an important organelle involved in protein quality control and cellular homeostasis. The accumulation of unfolded proteins leads to an ER stress, followed by an adaptive response via the activation of the unfolded protein response (UPR), PKR-like ER kinase (PERK), inositol-requiring transmembrane kinase/endoribonuclease 1α (IRE1α) and activating transcription factor 6 (ATF6) pathways. However, prolonged cell stress activates apoptosis signaling leading to cell death. Neuronal cells are particularly sensitive to protein misfolding, consequently ER and UPR dysfunctions were found to be involved in many neurodegenerative diseases including Alzheimer’s disease, Parkinson’s disease, amyotrophic lateral sclerosis and prions diseases, among others characterized by the accumulation and aggregation of misfolded proteins. Pharmacological UPR modulation in affected tissues may contribute to the treatment and prevention of neurodegeneration. The association bet...
annabolteus.com
and several other neurodegenerative disorders share a common neuropathology, primarily featuring the presence of abnormal protein inclusions containing specific misfolded proteins. Recent evidence indicates that alteration in organelle function is a common pathological feature of protein misfolding disorders. The endoplasmic reticulum (ER) is an essential compartment for protein folding, maturation, and secretion. Signs of ER stress have been extensively described in most experimental models of neurological disorders and more recently in the brains of human patients affected with neurodegenerative conditions. ER stress is caused by functional disturbances, which result in the accumulation of unfolded/misfolded proteins at the ER lumen. To cope with ER stress, cells activate an integrated signaling response termed the Unfolded Protein Response (UPR), which aims to reestablish homeostasis through transcriptional upregulation of genes involved in protein folding, quality control and degradation pathways. Small molecules with chaperone-like activity have been shown to alleviate ER stress and decrease protein misfolding in experimental disease settings. In this chapter we overview the role of ER stress in pathological conditions such as protein misfolding disorders and spinal cord injury, and discuss possible pharmacological strategies to target the UPR with therapeutic benefits.
A spastic paraplegia mouse model reveals REEP1-dependent ER shaping
Journal of Clinical Investigation, 2013
Axonopathies are a group of clinically diverse disorders characterized by the progressive degeneration of axons of specific neurons. In hereditary spastic paraplegia (HSP) axons of cortical motor neurons degenerate and cause a spastic movement disorder. We identified a heterozygous REEP1 exon 2 deletion in a patient suffering from the autosomal-dominantly inherited HSP variant SPG31 and modelled this finding in mice to study the underlying cellular pathology. Heterozygous exon 2 deletion in mice resulted in a gait disorder closely resembling SPG31 in humans. Homozygous exon 2 deletion caused a complete loss of Reep1 and a more severe phenotype with earlier onset. At the molecular level, we demonstrate that REEP1 is a neuron-specific, membrane binding, and membrane curvature-inducing protein that resides in the ER. We further show that Reep1 expression is particularly prominent in cortical motor neurons. In Reep1-deficient mice, these neurons showed reduced complexity of the peripheral ER upon quantitative ultrastructural analysis. As the unfolded protein response upon induced ER-stress was significantly decreased in cultures of cortical neurons from Reep1-deficient mice, the observed impairments of ER morphology also correlate with impairments in ER function. Thus our study connects proper neuronal ER architecture and function to long term axon survival.
Endoplasmic Reticulum Stress Signaling and Neuronal Cell Death
International Journal of Molecular Sciences
Besides protein processing, the endoplasmic reticulum (ER) has several other functions such as lipid synthesis, the transfer of molecules to other cellular compartments, and the regulation of Ca2+ homeostasis. Before leaving the organelle, proteins must be folded and post-translationally modified. Protein folding and revision require molecular chaperones and a favorable ER environment. When in stressful situations, ER luminal conditions or chaperone capacity are altered, and the cell activates signaling cascades to restore a favorable folding environment triggering the so-called unfolded protein response (UPR) that can lead to autophagy to preserve cell integrity. However, when the UPR is disrupted or insufficient, cell death occurs. This review examines the links between UPR signaling, cell-protective responses, and death following ER stress with a particular focus on those mechanisms that operate in neurons.
Endoplasmic reticulum dysfunction in neurological disease
The Lancet Neurology, 2013
Endoplasmic reticulum (ER) dysfunction might have an important part to play in a range of neurological disorders, including cerebral ischaemia, sleep apnoea, Alzheimer's disease, multiple sclerosis, amyotrophic lateral sclerosis, the prion diseases, and familial encephalopathy with neuroserpin inclusion bodies. Protein misfolding in the ER initiates the well studied unfolded protein response in energy-starved neurons during stroke, which is relevant to the toxic eff ects of reperfusion. The toxic peptide amyloid β induces ER stress in Alzheimer's disease, which leads to activation of similar pathways, whereas the accumulation of polymeric neuroserpin in the neuronal ER triggers a poorly understood ER-overload response. In other neurological disorders, such as Parkinson's and Huntington's diseases, ER dysfunction is well recognised but the mechanisms by which it contributes to pathogenesis remain unclear. By targeting components of these signalling responses, amelioration of their toxic eff ects and so the treatment of a range of neurodegenerative disorders might become possible.
Frontiers in cellular neuroscience, 2014
Endoplasmic reticulum (ER) stress and protein misfolding are associated with various neurodegenerative diseases. ER stress activates unfolded protein response (UPR), an adaptative response. However, severe ER stress can induce cell death. Here we show that the E3 ubiquitin ligase and co-chaperone Carboxyl Terminus HSP70/90 Interacting Protein (CHIP) prevents neuron death in the hippocampus induced by severe ER stress. Organotypic hippocampal slice cultures (OHSCs) were exposed to Tunicamycin, a pharmacological ER stress inducer, to trigger cell death. Overexpression of CHIP was achieved with a recombinant adeno-associated viral vector (rAAV) and significantly diminished ER stress-induced cell death, as shown by analysis of propidium iodide (PI) uptake, condensed chromatin, TUNEL and cleaved caspase 3 in the CA1 region of OHSCs. In addition, overexpression of CHIP prevented upregulation of both CHOP and p53 both pro-apoptotic pathways induced by ER stress. We also detected an attenua...