TRPV1 promotes opioid analgesia during inflammation

International audienc

Glutathione-S-transferase P promotes glycolysis in asthma in association with oxidation of pyruvate kinase M2

Background: Interleukin-1-dependent increases in glycolysis promote allergic airways disease in mice and disruption of pyruvate kinase M2 (PKM2) activity is critical herein. Glutathione-S-transferase P (GSTP) has been implicated in asthma pathogenesis and regulates the oxidation state of proteins via S-glutathionylation. We addressed whether GSTP-dependent S-glutathionylation promotes allergic airways disease by promoting glycolytic reprogramming and whether it involves the disruption of PKM2. Methods: We used house dust mite (HDM) or interleukin-1β in C57BL6/NJ WT or mice that lack GSTP. Airway basal cells were stimulated with interleukin-1β and the selective GSTP inhibitor, TLK199. GSTP and PKM2 were evaluated in sputum samples of asthmatics and healthy controls and incorporated analysis of the U-BIOPRED severe asthma cohort database. Results: Ablation of Gstp decreased total S-glutathionylation and attenuated HDM-induced allergic airways disease and interleukin-1β-mediated inflammation. Gstp deletion or inhibition by TLK199 decreased the interleukin-1β-stimulated secretion of pro-inflammatory mediators and lactate by epithelial cells. 13C-glucose metabolomics showed decreased glycolysis flux at the pyruvate kinase step in response to TLK199. GSTP and PKM2 levels were increased in BAL of HDM-exposed mice as well as in sputum of asthmatics compared to controls. Sputum proteomics and transcriptomics revealed strong correlations between GSTP, PKM2, and the glycolysis pathway in asthma. Conclusions: GSTP contributes to the pathogenesis of allergic airways disease in association with enhanced glycolysis and oxidative disruption of PKM2. Our findings also suggest a PKM2-GSTP-glycolysis signature in asthma that is associated with severe disease

Activation of the Transient Receptor Potential Vanilloid-1 (TRPV1) channel mediates Extracellular Signal Regulated Kinase (ERK) phosphorylation via Beta-arrestin-2 signaling

The Transient Receptor Potential Vanilloid 1 (TRPV1) channel plays a pivotal role in pain sensation and transduction under physiological and pathophysiological conditions. Recent work highlighted a possible role for β-arrestin-2, a scaffolding protein that mediates G-protein coupled receptor desensitization, in channel regulation. Interestingly, β-arrestin-2 also acts as a signaling scaffold for the MAPK (ERK1/2) pathway which was described as an important nociceptive marker. In this thesis, several experimental approaches were employed to investigate TRPV1 signaling and to characterize whether β-arrestin-2 as well as ERK play a role downstream of channel activation. The work presented here describes for the first time a unique β-arrestin-2 signaling pathway following TRPV1 channel activation. In particular, we found that calcium influx through TRPV1 channels induced translocation of β-arrestin-2 from the cytosol to the nucleus. In addition, we showed that TRPV1 activation elicited ERK phosphorylation in a β-arrestin-2-dependent manner. Our data suggest that the signaling cascade starts with calcium influx through TRPV1 channels that activates protein kinase C (PKC) and induces its translocation to the plasma membrane. The activation of PKC was necessary for ERK activation as well as β-arrestin-2 nuclear translocation. While this work is the first to describe β-arrestin-2 nuclear translocation downstream of TRPV1 stimulation, the functional relevance of this translocation is yet-to-be unveiled. Given the crucial role of TRPV1 in nociception, understanding its signaling as well as the mechanisms by which the channel is modulated may pave the way to develop a novel class of analgesics

<i>S</i>-Glutathionylation-Controlled Apoptosis of Lung Epithelial Cells; Potential Implications for Lung Fibrosis

Glutathione (GSH), a major antioxidant in mammalian cells, regulates several vital cellular processes, such as nutrient metabolism, protein synthesis, and immune responses. In addition to its role in antioxidant defense, GSH controls biological processes through its conjugation to reactive protein cysteines in a post-translational modification known as protein S-glutathionylation (PSSG). PSSG has recently been implicated in the pathogenesis of multiple diseases including idiopathic pulmonary fibrosis (IPF). Hallmarks of IPF include repeated injury to the alveolar epithelium with aberrant tissue repair, epithelial cell apoptosis and fibroblast resistance to apoptosis, and the accumulation of extracellular matrix and distortion of normal lung architecture. Several studies have linked oxidative stress and PSSG to the development and progression of IPF. Additionally, it has been suggested that the loss of epithelial cell homeostasis and increased apoptosis, accompanied by the release of various metabolites, creates a vicious cycle that aggravates disease progression. In this short review, we highlight some recent studies that link PSSG to epithelial cell apoptosis and highlight the potential implication of metabolites secreted by apoptotic cells

Targeting the Transient Receptor Potential Vanilloid Type 1 (TRPV1) Assembly Domain Attenuates Inflammation-induced Hypersensitivity

Artículo de publicación ISIThe transient receptor potential channel vanilloid type 1 (TRPV1) is a non-selective cation channel expressed in sensory neurons of the dorsal root and trigeminal ganglia. TRPV1 is a polymodal channel activated by noxious heat, capsaicin, and protons. As a sensor for noxious stimuli, TRPV1 channel has been described as a key contributor to pain signaling. To form a functional channel, TRPV1 subunits must assemble into tetramers, and several studies have identified the TRPV1 C terminus as an essential element in subunit association. Here we combined biochemical assays with electrophysiology and imaging-based bimolecular fluorescence complementation (BiFC) and bioluminescence resonance energy transfer (BRET) in live cells to identify a short motif in the C-terminal tail of the TRPV1 subunit that governs channel assembly. Removing this region through early truncation or targeted deletion results in loss of subunit association and channel function. Importantly, we found that interfering with TRPV1 subunit association using a plasma membrane-tethered peptide attenuated mechanical and thermal hypersensitivity in two mouse models of inflammatory hyperalgesia. This represents a novel mechanism to disrupt TRPV1 subunit assembly and hence may offer a new analgesic tool for pain relief.This work was supported by the Heart and Stroke Foundation of Canada and the Canadian Institute of Health Research

TRPV1 promotes opioid analgesia during inflammation

International audienc

Glutaredoxin attenuates glutathione levels via deglutathionylation of Otub1 and subsequent destabilization of system xC

Glutathione (GSH) is a critical component of the cellular redox system that combats oxidative stress. The glutamate-cystine antiporter, system x , is a key player in GSH synthesis that allows for the uptake of cystine, the rate-limiting building block of GSH. It is unclear whether GSH or GSH-dependent protein oxidation [protein -glutathionylation (PSSG)] regulates the activity of system x . We demonstrate that an environment of enhanced PSSG promotes GSH increases via a system x -dependent mechanism. Absence of the deglutathionylase, glutaredoxin (GLRX), augmented SLC7A11 protein and led to significant increases of GSH content. -glutathionylation of C23 or C204 of the deubiquitinase OTUB1 promoted interaction with the E2-conjugating enzyme UBCH5A, leading to diminished ubiquitination and proteasomal degradation of SLC7A11 and augmentation of GSH, effects that were reversed by GLRX. These findings demonstrate an intricate link between GLRX and GSH via -glutathionylation of OTUB1 and system x and illuminate a previously unknown feed-forward regulatory mechanism whereby enhanced GSH protein oxidation augments cellular GSH