scholarly journals The Calcium-Dependent Protease Calpain-1 Links TRPC6 Activity to Podocyte Injury

2018 ◽  
Vol 29 (8) ◽  
pp. 2099-2109 ◽  
Author(s):  
Kim A.T. Verheijden ◽  
Ramon Sonneveld ◽  
Marinka Bakker-van Bebber ◽  
Jack F.M. Wetzels ◽  
Johan van der Vlag ◽  
...  
Keyword(s):  
Transient Receptor Potential ◽  
Calcium Influx ◽  
Receptor Potential ◽  
Transient Receptor Potential Channel ◽  
Slit Diaphragm ◽  
Calpain Inhibitor ◽  
Podocyte Injury ◽  
Calcium Dependent ◽  
Transient Receptor ◽  
Calcineurin Activity

BackgroundThe hallmark of podocytopathies, such as FSGS, is podocyte injury resulting in proteinuria. Transient receptor potential channel C6 (TRPC6) is a calcium-conducting ion channel expressed at the slit diaphragm. TRPC6 gain-of-function mutations and glomerular TRPC6 overexpression are associated with proteinuria. However, the pathways linking TRPC6 to podocyte injury, which is characterized by loss of the slit diaphragm protein nephrin, activation of several intracellular pathways (including calcineurin-NFAT signaling), and cytoskeletal rearrangement, remain elusive.MethodsWe tested whether the calcium-dependent protease calpain-1 mediates TRPC6-dependent podocyte injury in human and experimental FSGS and cultured podocytes.ResultsCompared with kidneys of healthy controls, kidneys of patients with FSGS had increased TRPC6 expression, increased calpain and calcineurin activity, and reduced expression of the calpain target Talin-1, which links the actin cytoskeleton to integrins and is critical for podocyte cytoskeletal stability. In a rat model of human FSGS, increased glomerular and urinary calpain activity associated with reduced Talin-1 abundance, enhanced calcineurin activity, and increased proteinuria. Treatment with the calpain inhibitor calpeptin prevented these effects. In cultured podocytes, pharmacologic stimulation of TRPC6-dependent calcium influx increased calpain-1 and calcineurin activity and reduced Talin-1 expression, and knockdown of TRPC6 or calpain-1 prevented these effects.ConclusionsWe elucidated a novel mechanism that links TRPC6 activity to calpain-1 activation and through Talin-1 loss and possibly, calcineurin activation, the podocyte injury characterizing FSGS. Therefore, calpain-1 and/or TRPC6 inhibition could be future therapeutic options to treat patients with FSGS or other podocytopathies.

ZEB2 transduces HIF1α dependent regulation of Transglutaminase 2 in glomerular podocytes

2021 ◽  
Author(s):  
Anil kumar Pasupulati
Keyword(s):  
Transient Receptor Potential ◽  
Calcium Influx ◽  
Hypoxia Inducible Factor ◽  
Receptor Potential ◽  
Transglutaminase 2 ◽  
Transient Receptor Potential Channel ◽  
Glomerular Injury ◽  
Podocyte Injury ◽  
Calcium Dependent ◽  
Downstream Target

Glomerular podocytes are instrumental in ensuring glomerular permselectivity and regulating the integrity of glomerular biology. However, podocytes are vulnerable to various noxious stimuli such as hypoxia, and podocyte injury presented with glomerulosclerosis and impaired kidney function. The mechanism of hypoxia-induced podocyte injury vis-a-vis glomerulosclerosis has remained enigmatic. Hypoxia inducible factor 1α (HIF1α) that transduces hypoxic adaptations, induces Transglutaminase 2 (TG2), a calcium dependent enzyme that catalyzes intramolecular ε-(γ-glutamyl) lysine cross-links of extracellular matrix (ECM) proteins. In this study, we investigated the mechanism of regulation of TG2 by HIF1α. Stabilization of HIF1⍺ by FG4592 (Roxadustat) and physiological hypoxia, resulted in elevated expression of ZEB2 (zinc-finger E-box-homeobox 2) and its downstream target TRPC6 (transient receptor potential channel 6). ZEB2 transcriptionally activates TG2 expression, whereas, via TRPC6, it induces calcium influx, inturn it increases the TG2 activity. Blocking the TRPC6 action or suppressing its expression only partially attenuated FG4592 induced TG2 activity, whereas suppression of ZEB2 expression significantly abolished TG2 activity. This study demonstrates that stabilization of HIF1α stimulates both TG2 expression and activity, whereas abrogation of HIF1⍺ by metformin prevented HIF1⍺ regulated TG2 and consequent glomerular injury.

scholarly journals TRPC6 channel as an emerging determinant of the podocyte injury susceptibility in kidney diseases

2015 ◽  
Vol 309 (5) ◽  
pp. F393-F397 ◽  
Author(s):  
Daria V. Ilatovskaya ◽  
Alexander Staruschenko
Keyword(s):  
Transient Receptor Potential ◽  
Calcium Influx ◽  
Kidney Diseases ◽  
Critical Role ◽  
Receptor Potential ◽  
Calcium Flux ◽  
Calcium Handling ◽  
Podocyte Injury ◽  
Trpc6 Channel ◽  
Transient Receptor

Podocytes (terminally differentiated epithelial cells of the glomeruli) play a key role in the maintenance of glomerular structure and permeability and in the incipiency of various renal abnormalities. Injury to podocytes is considered a major contributor to the development of kidney disease as their loss causes proteinuria and progressive glomerulosclerosis. The physiological function of podocytes is critically dependent on proper intracellular calcium handling; excessive calcium influx in these cells may result in the effacement of foot processes, apoptosis, and subsequent glomeruli damage. One of the key proteins responsible for calcium flux in the podocytes is transient receptor potential cation channel, subfamily C, member 6 (TRPC6); a gain-of-function mutation in TRPC6 has been associated with the onset of the familial forms of focal segmental glomerulosclerosis (FSGS). Recent data also revealed a critical role of this channel in the onset of diabetic nephropathy. Therefore, major efforts of the research community have been recently dedicated to unraveling the TRPC6-dependent effects in the initiation of podocyte injury. This mini-review focuses on the TRPC6 channel in podocytes and colligates recent data in an attempt to shed some light on the mechanisms underlying the pathogenesis of TRPC6-mediated glomeruli damage and its potential role as a therapeutic target for the treatment of chronic kidney diseases.

scholarly journals Design, Synthesis and In Vitro Experimental Validation of Novel TRPV4 Antagonists Inspired by Labdane Diterpenes

Marine Drugs ◽  
2020 ◽  
Vol 18 (10) ◽  
pp. 519
Author(s):  
Sarah Mazzotta ◽  
Gabriele Carullo ◽  
Aniello Schiano Moriello ◽  
Pietro Amodeo ◽  
Vincenzo Di Marzo ◽  
...  
Keyword(s):  
Transient Receptor Potential ◽  
Calcium Influx ◽  
Biological Activities ◽  
Receptor Potential ◽  
Transient Receptor Potential Channel ◽  
Design Synthesis ◽  
Cellular Assays ◽  
Transient Receptor ◽  
Trpv4 Channel

Labdane diterpenes are widespread classes of natural compounds present in variety of marine and terrestrial organisms and plants. Many of them represents “natural libraries” of compounds with interesting biological activities due to differently functionalized drimane nucleus exploitable for potential pharmacological applications. The transient receptor potential channel subfamily V member 4 (TRPV4) channel has recently emerged as a pharmacological target for several respiratory diseases, including the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Inspired by the labdane-like bicyclic core, a series of homodrimane-derived esters and amides was designed and synthesized by modifying the flexible tail in position 1 of (+)-sclareolide, an oxidized derivative of the bioactive labdane-type diterpene sclareol. The potency and selectivity towards rTRPV4 and hTRPV1 receptors were assessed by calcium influx cellular assays. Molecular determinants critical for eliciting TRPV4 antagonism were identified by structure-activity relationships. Among the selective TRPV4 antagonists identified, compound 6 was the most active with an IC50 of 5.3 μM. This study represents the first report of semisynthetic homodrimane TRPV4 antagonists, selective over TRPV1, and potentially useful as pharmacological tools for the development of novel TRPV4 channel modulators.

Transient Receptor Potential Channel TRPM8 Agonists Stimulate Calcium Influx and Neurotensin Secretion in Neuroendocrine Tumor Cells

2007 ◽  
Vol 85 (2) ◽  
pp. 81-92 ◽  
Author(s):  
Stefan Mergler ◽  
Mathias Z. Strowski ◽  
Simone Kaiser ◽  
Thomas Plath ◽  
Yvonne Giesecke ◽  
...  
Keyword(s):  
Neuroendocrine Tumor ◽  
Tumor Cells ◽  
Transient Receptor Potential ◽  
Calcium Influx ◽  
Receptor Potential ◽  
Transient Receptor Potential Channel ◽  
Transient Receptor

scholarly journals TRPC5 Does Not Cause or Aggravate Glomerular Disease

2017 ◽  
Vol 29 (2) ◽  
pp. 409-415 ◽  
Author(s):  
Xuexiang Wang ◽  
Ranadheer R. Dande ◽  
Hao Yu ◽  
Beata Samelko ◽  
Rachel E. Miller ◽  
...  
Keyword(s):  
Transient Receptor Potential ◽  
Calcium Influx ◽  
Receptor Potential ◽  
Transient Receptor Potential Channel ◽  
Transgenic Mouse Models ◽  
Cytoskeletal Remodeling ◽  
Englerin A ◽  
Transient Receptor ◽  
Ion Pore

Transient receptor potential channel 5 (TRPC5) is highly expressed in brain and kidney and mediates calcium influx and promotes cell migration. In the kidney, loss of TRPC5 function has been reported to benefit kidney filter dynamics by balancing podocyte cytoskeletal remodeling. However, in vivo gain-in-function studies of TRPC5 with respect to kidney function have not been reported. To address this gap, we developed two transgenic mouse models on the C57BL/6 background by overexpressing either wild-type TRPC5 or a TRPC5 ion-pore mutant. Compared with nontransgenic controls, neither transgenic model exhibited an increase in proteinuria at 8 months of age or a difference in LPS-induced albuminuria. Moreover, activation of TRPC5 by Englerin A did not stimulate proteinuria, and inhibition of TRPC5 by ML204 did not significantly lower the level of LPS-induced proteinuria in any group. Collectively, these data suggest that the overexpression or activation of the TRPC5 ion channel does not cause kidney barrier injury or aggravate such injury under pathologic conditions.

scholarly journals Glutathione depletion activates the yeast vacuolar transient receptor potential channel, Yvc1p, by reversible glutathionylation of specific cysteines

2016 ◽  
Vol 27 (24) ◽  
pp. 3913-3925 ◽  
Author(s):  
Avinash Chandel ◽  
Krishna K. Das ◽  
Anand K. Bachhawat
Keyword(s):  
Calcium Channel ◽  
Transient Receptor Potential ◽  
Transmembrane Domain ◽  
Trp Channels ◽  
Calcium Influx ◽  
Receptor Potential ◽  
Transient Receptor Potential Channel ◽  
Glutathione Depletion ◽  
Glutathione S Transferase ◽  
Transient Receptor

Glutathione depletion and calcium influx into the cytoplasm are two hallmarks of apoptosis. We have been investigating how glutathione depletion leads to apoptosis in yeast. We show here that glutathione depletion in yeast leads to the activation of two cytoplasmically inward-facing channels: the plasma membrane, Cch1p, and the vacuolar calcium channel, Yvc1p. Deletion of these channels partially rescues cells from glutathione depletion–induced cell death. Subsequent investigations on the Yvc1p channel, a homologue of the mammalian TRP channels, revealed that the channel is activated by glutathionylation. Yvc1p has nine cysteine residues, of which eight are located in the cytoplasmic regions and one on the transmembrane domain. We show that three of these cysteines, Cys-17, Cys-79, and Cys-191, are specifically glutathionylated. Mutation of these cysteines to alanine leads to a loss in glutathionylation and a concomitant loss in calcium channel activity. We further investigated the mechanism of glutathionylation and demonstrate a role for the yeast glutathione S-transferase Gtt1p in glutathionylation. Yvc1p is also deglutathionylated, and this was found to be mediated by the yeast thioredoxin, Trx2p. A model for redox activation and deactivation of the yeast Yvc1p channel is presented.

Flickering calcium microdomains signal turning of migrating cellsThis article is one of a selection of papers published in this special issue on Calcium Signaling.

2010 ◽  
Vol 88 (2) ◽  
pp. 105-110 ◽  
Author(s):  
Chaoliang Wei ◽  
Xianhua Wang ◽  
Min Chen ◽  
Kunfu Ouyang ◽  
Ming Zheng ◽  
...  
Keyword(s):  
Transient Receptor Potential ◽  
Receptor Potential ◽  
Transient Receptor Potential Channel ◽  
High Threshold ◽  
Calcium Dependent ◽  
A Cell ◽  
Transient Receptor ◽  
Trisphosphate Receptor ◽  
Selection Of

It has been well-established that polarized migrating cells exhibit a stable and transient gradient of intracellular calcium concentration ([Ca2+]i), increasing from front-to-rear, that is thought to be responsible for rear retraction. The paradox that arises is how calcium at the front of a cell catalyzes critical high-threshold calcium-dependent processes during cell migration and particularly in decision-making for a cell to turn. In this brief review, we discuss the recent discovery of flickering high-[Ca2+]i microdomains (“calcium flickers”) at the front of migrating fibroblasts and their common role in transducing local membrane mechanical stress (via TRPM7, a stretch-activated calcium-permeating transient receptor potential channel) and chemoattractant-elicited signals (via type 2 inositol 1,4,5-trisphosphate receptor in the endoplasmic reticulum). Furthermore, we present a new model for patterned calcium flicker activity as the mechanism for steering the turning of a migrating cell.

scholarly journals Utility of Large-Scale Transiently Transfected Cells for Cell-Based High-Throughput Screens to Identify Transient Receptor Potential Channel A1 (TRPA1) Antagonists

2006 ◽  
Vol 12 (1) ◽  
pp. 61-69 ◽  
Author(s):  
Jun Chen ◽  
Marc R. Lake ◽  
Reza S. Sabet ◽  
Wende Niforatos ◽  
Steve D. Pratt ◽  
...  
Keyword(s):  
High Throughput ◽  
High Throughput Screening ◽  
Large Scale ◽  
Transient Receptor Potential ◽  
Calcium Influx ◽  
Receptor Potential ◽  
Transient Receptor Potential Channel ◽  
Chemical Library ◽  
Transient Receptor ◽  
High Throughput Screens

Despite increasing use of cell-based assays in high-throughput screening (HTS) and lead optimization, one challenge is the adequate supply of high-quality cells expressing the target of interest. To this end, cell lines stably expressing targets are often established, maintained, and scaled up by cell culture. These steps require large investments of time and resources. Moreover, significant variability invariably occurs in cell yield, viability, expression levels, and target activities. In particular, stable expression of targets such as transient receptor potential A1 (TRPA1) causes toxicity, cell line degeneration, and loss of functional activity. Therefore, in an effort to identify TRPA1 antagonists, the authors used large-scale transiently transfected (LSTT) cells, enabling rapid establishment of assays suitable for HTS. LSTT cells, which could- be stored frozen for a long period of time (e.g., at least 42 weeks), retained TRPA1 protein expression and could be easily revived to produce robust and consistent signals in calcium influx and electrophysiological assays. Using cells from a single transfection, a chemical library of 700,000 compounds was screened, and TRPA1 antagonists were identified. The use of LSTT circumvented issues associated with stable TRPA1 expression, increased flexibility and consistency, and greatly reduced labor and cost. This approach will also be applicable to other pharmaceutical targets.

scholarly journals TRPV1 is a physiological regulator of μ-opioid receptors

2017 ◽  
Vol 114 (51) ◽  
pp. 13561-13566 ◽  
Author(s):  
Paul C. Scherer ◽  
Nicholas W. Zaccor ◽  
Neil M. Neumann ◽  
Chirag Vasavda ◽  
Roxanne Barrow ◽  
...  
Keyword(s):  
G Protein ◽  
Transient Receptor Potential ◽  
Calcium Influx ◽  
Receptor Potential ◽  
Transient Receptor Potential Channel ◽  
G Protein Signaling ◽  
Protein Signaling ◽  
Calcium Calmodulin Dependent ◽  
Potential Strategy ◽  
Transient Receptor

Opioids are powerful analgesics, but also carry significant side effects and abuse potential. Here we describe a modulator of the μ-opioid receptor (MOR1), the transient receptor potential channel subfamily vanilloid member 1 (TRPV1). We show that TRPV1 binds MOR1 and blocks opioid-dependent phosphorylation of MOR1 while leaving G protein signaling intact. Phosphorylation of MOR1 initiates recruitment and activation of the β-arrestin pathway, which is responsible for numerous opioid-induced adverse effects, including the development of tolerance and respiratory depression. Phosphorylation stands in contrast to G protein signaling, which is responsible for the analgesic effect of opioids. Calcium influx through TRPV1 causes a calcium/calmodulin-dependent translocation of G protein-coupled receptor kinase 5 (GRK5) away from the plasma membrane, thereby blocking its ability to phosphorylate MOR1. Using TRPV1 to block phosphorylation of MOR1 without affecting G protein signaling is a potential strategy to improve the therapeutic profile of opioids.

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