At the Crossing of ER Stress and MAMs: A Key Role of Sigma-1 Receptor?

Author(s):  
Benjamin Delprat ◽  
Lucie Crouzier ◽  
Tsung-Ping Su ◽  
Tangui Maurice
Keyword(s):  
Metabolites ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 422
Author(s):  
Zhanat Koshenov ◽  
Furkan E. Oflaz ◽  
Martin Hirtl ◽  
Johannes Pilic ◽  
Olaf A. Bachkoenig ◽  
...  

The endoplasmic reticulum (ER) is a complex, multifunctional organelle of eukaryotic cells and responsible for the trafficking and processing of nearly 30% of all human proteins. Any disturbance to these processes can cause ER stress, which initiates an adaptive mechanism called unfolded protein response (UPR) to restore ER functions and homeostasis. Mitochondrial ATP production is necessary to meet the high energy demand of the UPR, while the molecular mechanisms of ER to mitochondria crosstalk under such stress conditions remain mainly enigmatic. Thus, better understanding the regulation of mitochondrial bioenergetics during ER stress is essential to combat many pathologies involving ER stress, the UPR, and mitochondria. This article investigates the role of Sigma-1 Receptor (S1R), an ER chaperone, has in enhancing mitochondrial bioenergetics during early ER stress using human neuroblastoma cell lines. Our results show that inducing ER stress with tunicamycin, a known ER stressor, greatly enhances mitochondrial bioenergetics in a time- and S1R-dependent manner. This is achieved by enhanced ER Ca2+ leak directed towards mitochondria by S1R during the early phase of ER stress. Our data point to the importance of S1R in promoting mitochondrial bioenergetics and maintaining balanced H2O2 metabolism during early ER stress.


2015 ◽  
Vol 112 (47) ◽  
pp. E6562-E6570 ◽  
Author(s):  
Shang-Yi A. Tsai ◽  
Jian-Ying Chuang ◽  
Meng-Shan Tsai ◽  
Xiao-fei Wang ◽  
Zheng-Xiong Xi ◽  
...  

The sigma-1 receptor (Sig-1R) chaperone at the endoplasmic reticulum (ER) plays important roles in cellular regulation. Here we found a new function of Sig-1R, in that it translocates from the ER to the nuclear envelope (NE) to recruit chromatin-remodeling molecules and regulate the gene transcription thereof. Sig-1Rs mainly reside at the ER–mitochondrion interface. However, on stimulation by agonists such as cocaine, Sig-1Rs translocate from ER to the NE, where Sig-1Rs bind NE protein emerin and recruit chromatin-remodeling molecules, including lamin A/C, barrier-to-autointegration factor (BAF), and histone deacetylase (HDAC), to form a complex with the gene repressor specific protein 3 (Sp3). Knockdown of Sig-1Rs attenuates the complex formation. Cocaine was found to suppress the gene expression of monoamine oxidase B (MAOB) in the brain of wild-type but not Sig-1R knockout mouse. A single dose of cocaine (20 mg/kg) in rats suppresses the level of MAOB at nuclear accumbens without affecting the level of dopamine transporter. Daily injections of cocaine in rats caused behavioral sensitization. Withdrawal from cocaine in cocaine-sensitized rats induced an apparent time-dependent rebound of the MAOB protein level to about 200% over control on day 14 after withdrawal. Treatment of cocaine-withdrawn rats with the MAOB inhibitor deprenyl completely alleviated the behavioral sensitization to cocaine. Our results demonstrate a role of Sig-1R in transcriptional regulation and suggest cocaine may work through this newly discovered genomic action to achieve its addictive action. Results also suggest the MAOB inhibitor deprenyl as a therapeutic agent to block certain actions of cocaine during withdrawal.


Genes ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 139
Author(s):  
Ilaria Pontisso ◽  
Laurent Combettes

Ca2+ signaling plays a pivotal role in the control of cellular homeostasis and aberrant regulation of Ca2+ fluxes have a strong impact on cellular functioning. As a consequence of this ubiquitous role, Ca2+ signaling dysregulation is involved in the pathophysiology of multiple diseases including cancer. Indeed, multiple studies have highlighted the role of Ca2+ fluxes in all the steps of cancer progression. In particular, the transfer of Ca2+ at the ER-mitochondrial contact sites, also known as mitochondrial associated membranes (MAMs), has been shown to be crucial for cancer cell survival. One of the proteins enriched at this site is the sigma-1 receptor (S1R), a protein that has been described as a Ca2+-sensitive chaperone that exerts a protective function in cells in various ways, including the modulation of Ca2+ signaling. Interestingly, S1R is overexpressed in many types of cancer even though the exact mechanisms by which it promotes cell survival are not fully elucidated. This review summarizes the findings describing the roles of S1R in the control of Ca2+ signaling and its involvement in cancer progression.


Author(s):  
Mani Iyer Prasanth ◽  
Dicson Sheeja Malar ◽  
Tewin Tencomnao ◽  
James Michael Brimson
Keyword(s):  

2020 ◽  
Vol 11 ◽  
Author(s):  
José Miguel Vela

Outbreaks of emerging infections, such as COVID-19 pandemic especially, confront health professionals with the unique challenge of treating patients. With no time to discover new drugs, repurposing of approved drugs or in clinical development is likely the only solution. Replication of coronaviruses (CoVs) occurs in a modified membranous compartment derived from the endoplasmic reticulum (ER), causes host cell ER stress and activates pathways to facilitate adaptation of the host cell machinery to viral needs. Accordingly, modulation of ER remodeling and ER stress response might be pivotal in elucidating CoV-host interactions and provide a rationale for new therapeutic, host-based antiviral approaches. The sigma-1 receptor (Sig-1R) is a ligand-operated, ER membrane-bound chaperone that acts as an upstream modulator of ER stress and thus a candidate host protein for host-based repurposing approaches to treat COVID-19 patients. Sig-1R ligands are frequently identified in in vitro drug repurposing screens aiming to identify antiviral compounds against CoVs, including severe acute respiratory syndrome CoV-2 (SARS-CoV-2). Sig-1R regulates key mechanisms of the adaptive host cell stress response and takes part in early steps of viral replication. It is enriched in lipid rafts and detergent-resistant ER membranes, where it colocalizes with viral replicase proteins. Indeed, the non-structural SARS-CoV-2 protein Nsp6 interacts with Sig-1R. The activity of Sig-1R ligands against COVID-19 remains to be specifically assessed in clinical trials. This review provides a rationale for targeting Sig-1R as a host-based drug repurposing approach to treat COVID-19 patients. Evidence gained using Sig-1R ligands in unbiased in vitro antiviral drug screens and the potential mechanisms underlying the modulatory effect of Sig-1R on the host cell response are discussed. Targeting Sig-1R is not expected to reduce dramatically established viral replication, but it might interfere with early steps of virus-induced host cell reprogramming, aid to slow down the course of infection, prevent the aggravation of the disease and/or allow a time window to mature a protective immune response. Sig-1R-based medicines could provide benefit not only as early intervention, preventive but also as adjuvant therapy.


2017 ◽  
Vol 398 (10) ◽  
pp. 1141-1149 ◽  
Author(s):  
Tieying Song ◽  
Jianhui Zhao ◽  
Xiaojing Ma ◽  
Zaiwang Zhang ◽  
Bo Jiang ◽  
...  

Abstract The neurobiological mechanisms of obesity-induced peripheral neuropathy are poorly understood. We evaluated the role of Sigma-1 receptor (Sig-1R) and NMDA receptor (NMDARs) in the spinal cord in peripheral neuropathy using an animal model of high fat diet-induced diabetes. We examined the expression of Sig-1R and NMDAR subunits GluN2A and GluN2B along with postsynaptic density protein 95 (PSD-95) in the spinal cord after 24-week HFD treatment in both wild-type and Sig-1R−/− mice. Finally, we examined the effects of repeated intrathecal administrations of selective Sig-1R antagonists BD1047 in HFD-fed wild-type mice on peripheral neuropathy. Wild-type mice developed tactile allodynia and thermal hypoalgesia after 24-week HFD treatment. HFD-induced peripheral neuropathy correlated with increased expression of GluN2A and GluN2B subunits of NMDARs, PDS-95, and Sig-1R, as well as increased Sig-1R-NMDAR interaction in the spinal cord. In contrast, Sig-1R−/− mice did not develop thermal hypoalgesia or tactile allodynia after 24-week HFD treatment, and the levels of GluN2A, GluN2B, and PSD-95 were not altered in the spinal cord of HFD-fed Sig-1R−/− mice. Finally, repeated intrathecal administrations of selective Sig-1R antagonists BD1047 in HFD-fed wild-type mice attenuated peripheral neuropathy. Our results suggest that obesity-associated peripheral neuropathy may involve Sig-1R-mediated enhancement of NMDAR expression in the spinal cord.


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