scholarly journals The Unfolded Protein Response in Immune Cells as an Emerging Regulator of Neuroinflammation

2021 ◽  
Vol 13 ◽  
Author(s):  
Dominique Fernández ◽  
Antonia Geisse ◽  
Jose Ignacio Bernales ◽  
Alonso Lira ◽  
Fabiola Osorio

Immune surveillance is an essential process that safeguards the homeostasis of a healthy brain. Among the increasing diversity of immune cells present in the central nervous system (CNS), microglia have emerged as a prominent leukocyte subset with key roles in the support of brain function and in the control of neuroinflammation. In fact, impaired microglial function is associated with the development of neurodegenerative diseases, including Alzheimer’s disease (AD) and Parkinson’s disease (PD). Interestingly, these pathologies are also typified by protein aggregation and proteostasis dysfunction at the level of the endoplasmic reticulum (ER). These processes trigger activation of the unfolded protein response (UPR), which is a conserved signaling network that maintains the fidelity of the cellular proteome. Remarkably, beyond its role in protein folding, the UPR has also emerged as a key regulator of the development and function of immune cells. However, despite this evidence, the contribution of the UPR to immune cell homeostasis, immune surveillance, and neuro-inflammatory processes remains largely unexplored. In this review, we discuss the potential contribution of the UPR in brain-associated immune cells in the context of neurodegenerative diseases.

2019 ◽  
Vol 20 (7) ◽  
pp. 1792 ◽  
Author(s):  
Kyeorda Kemp ◽  
Cody Poe

The unfolded protein response (UPR) is a highly conserved pathway that allows cells to respond to stress in the endoplasmic reticulum caused by an accumulation of misfolded and unfolded protein. This is of great importance to secretory cells because, in order for proteins to traffic from the endoplasmic reticulum (ER), they need to be folded appropriately. While a wealth of literature has implicated UPR in immune responses, less attention has been given to the role of UPR in T cell development and function. This review discusses the importance of UPR in T cell development, homeostasis, activation, and effector functions. We also speculate about how UPR may be manipulated in T cells to ameliorate pathologies.


Viruses ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 17 ◽  
Author(s):  
Benjamin P. Johnston ◽  
Craig McCormick

Herpesviruses usurp cellular stress responses to promote viral replication and avoid immune surveillance. The unfolded protein response (UPR) is a conserved stress response that is activated when the protein load in the ER exceeds folding capacity and misfolded proteins accumulate. The UPR aims to restore protein homeostasis through translational and transcriptional reprogramming; if homeostasis cannot be restored, the UPR switches from “helper” to “executioner”, triggering apoptosis. It is thought that the burst of herpesvirus glycoprotein synthesis during lytic replication causes ER stress, and that these viruses may have evolved mechanisms to manage UPR signaling to create an optimal niche for replication. The past decade has seen considerable progress in understanding how herpesviruses reprogram the UPR. Here we provide an overview of the molecular events of UPR activation, signaling and transcriptional outputs, and highlight key evidence that herpesviruses hijack the UPR to aid infection.


Cancers ◽  
2021 ◽  
Vol 13 (17) ◽  
pp. 4443
Author(s):  
Ankit Patel ◽  
Masanori Oshi ◽  
Li Yan ◽  
Ryusei Matsuyama ◽  
Itaru Endo ◽  
...  

Hepatocellular carcinoma is a leading cause of cancer death worldwide. The unfolded protein response (UPR) has been revealed to confer tumorigenic capacity in cancer cells. We hypothesized that a quantifiable score representative of the UPR could be used as a biomarker for cancer progression in HCC. In this study, a total of 655 HCC patients from 4 independent HCC cohorts were studied to examine the relationships between enhancement of the UPR and cancer biology and patient survival in HCC utilizing an UPR score. The UPR correlated with carcinogenic sequence and progression of HCC consistently in two cohorts. Enhanced UPR was associated with the clinical parameters of HCC progression, such as cancer stage and multiple parameters of cell proliferation, including histological grade, mKI67 gene expression, and enrichment of cell proliferation-related gene sets. The UPR was significantly associated with increased mutational load, but not with immune cell infiltration or angiogeneis across independent cohorts. The UPR was consistently associated with worse survival across independent cohorts of HCC. In conclusion, the UPR score may be useful as a biomarker to predict prognosis and to better understand HCC.


Author(s):  
Chao Li

Endoplasmic reticulum (ER) stress triggers a series of signaling and transcriptional events termed the unfolded protein response (UPR). Severe ER stress is associated with the development of fibrosis in different organs including lung, liver, kidney, heart, and intestine. ER stress is an essential response of epithelial and immune cells in the pathogenesis of inflammatory bowel disease (IBD) including Crohn’s disease. Intestinal epithelial cells are susceptible to ER stress-mediated damage due to secretion of a large amount of proteins that are involved in mucosal defense. In other cells, ER stress is linked to myofibroblast activation, extracellular matrix production, macrophage polarization, and immune cell differentiation. This review focuses on the role of UPR in the pathogenesis in IBD from an immunologic perspective. The roles of macrophage and mesenchymal cells in the UPR from in vitro and in vivo animal models are discussed. The links between ER stress and other signaling pathways such as senescence and autophagy are introduced. Recent advances in the understanding of the epigenetic regulation of UPR signaling are also updated here. The future directions of development of the UPR research and therapeutic strategies to manipulate ER stress levels are also reviewed.


2020 ◽  
Vol 39 (12) ◽  
pp. 1690-1699
Author(s):  
H Yu ◽  
K Wen ◽  
X Zhou ◽  
Y Zhang ◽  
Z Yan ◽  
...  

The unfolded protein response (UPR) is one of a switch of autophagy and apoptosis, and the endoplasmic reticulum stress (ERS) which inducing UPR plays a role in the malformations caused by some genetic and environmental factors. Exposure to flutamide during pregnancy will also cause abnormalities in some male offspring reproductive organs such as cryptorchidism. In this study, after administered the pregnant mouse orally at a dose of 300 mg/kg body weight every day during gestational day (GD)12 to GD18, flutamide can not only caused hypospadias in the male mouse offspring but also damaged the morphology and function of their testis. And the expression of UPR-related genes and proteins, autophagy, apoptosis, and angiogenesis-related genes of the damaged/teratogenic testis and penis in the mice were investigated to determine the role of UPR in this model. It was found that flutamide activated maybe the Atg7-Atg3-Lc3 pathway through the UPR pathway, caused cells excessive autophagy and apoptosis, and inhibited the formation of penile and testicular blood vessels by activating UPR and affecting the messenger RNA level of vascular endothelial growth factor and hypoxia-inducible factor 1.


Author(s):  
Emma Louise Wilson ◽  
Emmanouil Metzakopian

AbstractMitochondria-ER contact sites (MERCS) are known to underpin many important cellular homoeostatic functions, including mitochondrial quality control, lipid metabolism, calcium homoeostasis, the unfolded protein response and ER stress. These functions are known to be dysregulated in neurodegenerative diseases, including Parkinson’s disease (PD), Alzheimer’s disease (AD) and amyloid lateral sclerosis (ALS), and the number of disease-related proteins and genes being associated with MERCS is increasing. However, many details regarding MERCS and their role in neurodegenerative diseases remain unknown. In this review, we aim to summarise the current knowledge regarding the structure and function of MERCS, and to update the field on current research in PD, AD and ALS. Furthermore, we will evaluate high-throughput screening techniques, including RNAi vs CRISPR/Cas9, pooled vs arrayed formats and how these could be combined with current techniques to visualise MERCS. We will consider the advantages and disadvantages of each technique and how it can be utilised to uncover novel protein pathways involved in MERCS dysfunction in neurodegenerative diseases.


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