scholarly journals Identification of TMEM206 proteins as pore of ASOR acid-sensitive chloride channels

2019 ◽  
Author(s):  
Florian Ullrich ◽  
Sandy Blin ◽  
Katina Lazarow ◽  
Tony Daubitz ◽  
Jens-Peter von Kries ◽  
...  
Keyword(s):  
Cell Death ◽  
Plasma Membrane ◽  
Ion Channels ◽  
Chloride Channel ◽  
Chloride Channels ◽  
Ion Permeation ◽  
Anion Channels ◽  
Acid Sensing Ion Channels ◽  
Genome Wide ◽  
A Genome

ABSTRACTAcid-sensing ion channels have important functions in physiology and pathology, but the molecular composition of acid-activated anion channels had remained unclear. We now used a genome-wide siRNA screen to molecularly identify the widely expressed acid-sensitive outwardly-rectifying ASOR chloride channel. ASOR is formed by TMEM206 proteins which display two transmembrane domains (TMs) and are expressed at the plasma membrane. Ion permeation-changing mutations along the length of TM2 and at the end of TM1 suggest that these segments line ASOR’s pore. While not belonging to a gene family, TMEM206 has orthologs in probably all vertebrates. Currents from evolutionarily distant orthologs share activation by protons, a feature essential for ASOR’s role in acid-induced cell death. TMEM206 defines a novel class of ion channels. Its identification will help to understand its physiological roles and the diverse ways by which anion-selective pores can be formed.

scholarly journals Identification of TMEM206 proteins as pore of PAORAC/ASOR acid-sensitive chloride channels

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Florian Ullrich ◽  
Sandy Blin ◽  
Katina Lazarow ◽  
Tony Daubitz ◽  
Jens Peter von Kries ◽  
...  
Keyword(s):  
Cell Death ◽  
Plasma Membrane ◽  
Ion Channels ◽  
Gene Family ◽  
Chloride Channels ◽  
Anion Channel ◽  
Ion Permeation ◽  
Acid Sensing Ion Channels ◽  
Genome Wide ◽  
A Genome

Acid-sensing ion channels have important functions in physiology and pathology, but the molecular composition of acid-activated chloride channels had remained unclear. We now used a genome-wide siRNA screen to molecularly identify the widely expressed acid-sensitive outwardly-rectifying anion channel PAORAC/ASOR. ASOR is formed by TMEM206 proteins which display two transmembrane domains (TMs) and are expressed at the plasma membrane. Ion permeation-changing mutations along the length of TM2 and at the end of TM1 suggest that these segments line ASOR’s pore. While not belonging to a gene family, TMEM206 has orthologs in probably all vertebrates. Currents from evolutionarily distant orthologs share activation by protons, a feature essential for ASOR’s role in acid-induced cell death. TMEM206 defines a novel class of ion channels. Its identification will help to understand its physiological roles and the diverse ways by which anion-selective pores can be formed.

scholarly journals Energetic Evolution of Cellular Transportomes

2017 ◽  
Author(s):  
Behrooz Darbani ◽  
Douglas B. Kell ◽  
Irina Borodina
Keyword(s):  
Ion Channels ◽  
Bacterial Species ◽  
Living Cells ◽  
Energetic Efficiency ◽  
Cellular Functions ◽  
Transporter Proteins ◽  
Genome Wide Analysis ◽  
Solute Carriers ◽  
Genome Wide ◽  
A Genome

ABSTRACTTransporter proteins mediate the translocation of substances across the membranes of living cells. We performed a genome-wide analysis of the compositional reshaping of cellular transporters (the transportome) across the kingdoms of bacteria, archaea, and eukarya. We show that the transportomes of eukaryotes evolved strongly towards a higher energetic efficiency, as ATP-dependent transporters diminished and secondary transporters and ion channels proliferated. This change has likely been important in the development of tissues performing energetically costly cellular functions. The transportome analysis also indicated seven bacterial species, includingNeorickettsia risticiiandNeorickettsia sennetsu, as likely origins of the mitochondrion in eukaryotes, due to the restricted presence therein of clear homologues of modern mitochondrial solute carriers.

scholarly journals SEC24A identified as an essential mediator of thapsigargin-induced cell death in a genome-wide CRISPR/Cas9 screen

2018 ◽  
Vol 4 (1) ◽  
Author(s):  
Tamutenda Chidawanyika ◽  
Elizabeth Sergison ◽  
Michael Cole ◽  
Kenneth Mark ◽  
Surachai Supattapone
Keyword(s):  
Cell Death ◽  
Genome Wide ◽  
A Genome

scholarly journals Intracellular Staphylococcus aureus Perturbs the Host Cell Ca2+ Homeostasis To Promote Cell Death

mBio ◽  
2020 ◽  
Vol 11 (6) ◽  
pp. e02250-20
Author(s):  
Kathrin Stelzner ◽  
Ann-Cathrin Winkler ◽  
Chunguang Liang ◽  
Aziza Boyny ◽  
Carsten P. Ade ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Cell Death ◽  
Host Cell ◽  
Intracellular Bacterium ◽  
Tissue Destruction ◽  
Content Type ◽  
Host Cell Death ◽  
Genome Wide ◽  
A Genome ◽  
Spread Of Infection

ABSTRACTThe opportunistic human pathogen Staphylococcus aureus causes serious infectious diseases that range from superficial skin and soft tissue infections to necrotizing pneumonia and sepsis. While classically regarded as an extracellular pathogen, S. aureus is able to invade and survive within human cells. Host cell exit is associated with cell death, tissue destruction, and the spread of infection. The exact molecular mechanism employed by S. aureus to escape the host cell is still unclear. In this study, we performed a genome-wide small hairpin RNA (shRNA) screen and identified the calcium signaling pathway as being involved in intracellular infection. S. aureus induced a massive cytosolic Ca2+ increase in epithelial host cells after invasion and intracellular replication of the pathogen. This was paralleled by a decrease in endoplasmic reticulum Ca2+ concentration. Additionally, calcium ions from the extracellular space contributed to the cytosolic Ca2+ increase. As a consequence, we observed that the cytoplasmic Ca2+ rise led to an increase in mitochondrial Ca2+ concentration, the activation of calpains and caspases, and eventually to cell lysis of S. aureus-infected cells. Our study therefore suggests that intracellular S. aureus disturbs the host cell Ca2+ homeostasis and induces cytoplasmic Ca2+ overload, which results in both apoptotic and necrotic cell death in parallel or succession.IMPORTANCE Despite being regarded as an extracellular bacterium, the pathogen Staphylococcus aureus can invade and survive within human cells. The intracellular niche is considered a hideout from the host immune system and antibiotic treatment and allows bacterial proliferation. Subsequently, the intracellular bacterium induces host cell death, which may facilitate the spread of infection and tissue destruction. So far, host cell factors exploited by intracellular S. aureus to promote cell death are only poorly characterized. We performed a genome-wide screen and found the calcium signaling pathway to play a role in S. aureus invasion and cytotoxicity. The intracellular bacterium induces a cytoplasmic and mitochondrial Ca2+ overload, which results in host cell death. Thus, this study first showed how an intracellular bacterium perturbs the host cell Ca2+ homeostasis.

scholarly journals Applying genome-wide CRISPR-Cas9 screens for therapeutic discovery in facioscapulohumeral muscular dystrophy

2020 ◽  
Vol 12 (536) ◽  
pp. eaay0271 ◽  
Author(s):  
Angela Lek ◽  
Yuanfan Zhang ◽  
Keryn G. Woodman ◽  
Shushu Huang ◽  
Alec M. DeSimone ◽  
...  
Keyword(s):  
Cell Death ◽  
Muscular Dystrophy ◽  
Phenotypic Selection ◽  
Facioscapulohumeral Muscular Dystrophy ◽  
Loss Of Function ◽  
Hypoxia Response ◽  
Genome Wide ◽  
A Genome ◽  
Structural And Functional Properties ◽  
Cellular Hypoxia

The emergence of CRISPR-Cas9 gene-editing technologies and genome-wide CRISPR-Cas9 libraries enables efficient unbiased genetic screening that can accelerate the process of therapeutic discovery for genetic disorders. Here, we demonstrate the utility of a genome-wide CRISPR-Cas9 loss-of-function library to identify therapeutic targets for facioscapulohumeral muscular dystrophy (FSHD), a genetically complex type of muscular dystrophy for which there is currently no treatment. In FSHD, both genetic and epigenetic changes lead to misexpression of DUX4, the FSHD causal gene that encodes the highly cytotoxic DUX4 protein. We performed a genome-wide CRISPR-Cas9 screen to identify genes whose loss-of-function conferred survival when DUX4 was expressed in muscle cells. Genes emerging from our screen illuminated a pathogenic link to the cellular hypoxia response, which was revealed to be the main driver of DUX4-induced cell death. Application of hypoxia signaling inhibitors resulted in increased DUX4 protein turnover and subsequent reduction of the cellular hypoxia response and cell death. In addition, these compounds proved successful in reducing FSHD disease biomarkers in patient myogenic lines, as well as improving structural and functional properties in two zebrafish models of FSHD. Our genome-wide perturbation of pathways affecting DUX4 expression has provided insight into key drivers of DUX4-induced pathogenesis and has identified existing compounds with potential therapeutic benefit for FSHD. Our experimental approach presents an accelerated paradigm toward mechanistic understanding and therapeutic discovery of a complex genetic disease, which may be translatable to other diseases with well-established phenotypic selection assays.

scholarly journals Genome-wide survey and expression analysis of the SLAC/SLAH gene family in pear (Pyrus bretschneideri) and other members of the Rosaceae

2018 ◽  
Author(s):  
Guodong Chen ◽  
Xiaolong Li ◽  
Xin qiao ◽  
Jiaming Li ◽  
Li Wang ◽  
...  
Keyword(s):  
Gene Family ◽  
Stress Responses ◽  
Prunus Persica ◽  
Higher Plants ◽  
Chloride Transport ◽  
Structural Characteristics ◽  
Evolutionary Analysis ◽  
Anion Channels ◽  
Genome Wide ◽  
A Genome

AbstractS-type anion channels (SLAC/SLAHs), which play important roles in plant anion (such as nitrate and chloride) transport, growth and development, abiotic stress responses and hormone signaling. However, there is far less information about this family in Rosaceae species. We performed a genome-wide analysis and identified SLAC/SLAH gene family members in pear (Pyrus bretschneideri) and four other species of Rosaceae (Malus domestica, Prunus persica, Fragaria vesca and Prunus mume). A total of 21 SLAC/SLAH genes were identified from the five Rosaceae species. Based on the structural characteristics and a phylogenetic analysis of these genes, the SLAC/SLAH gene family could be classified into three main groups (I, II and III). The evolutionary analysis showed that the SLAC/SLAH gene family was comparatively conserved during the evolution of Rosaceae species. Transcriptome data demonstrated that PbrSLAC/SLAH genes were detected in all parts of the pear. However, PbrSLAC1 showed a higher expression level in leaf, while PbrSLAH2/3 was mainly expressed in roots. In addition, PbrSLAC/SLAH genes were only located on the plasma membrane in transient expression experiments in Arabidopsis protoplasts cells. These results provide valuable information that increases our understanding of the evolution, expression and functions of the SLAC/SLAH gene family in higher plants.

scholarly journals Conserved His-Gly motif of acid-sensing ion channels resides in a reentrant ‘loop’ implicated in gating and ion selectivity

2020 ◽  
Author(s):  
Nate Yoder ◽  
Eric Gouaux
Keyword(s):  
Ion Channels ◽  
Ion Selectivity ◽  
Fear Memory ◽  
Amino Terminus ◽  
Ion Permeation ◽  
Structural Explanation ◽  
Cryo Electron Microscopy ◽  
Acid Sensing Ion Channels ◽  
And Function

ABSTRACTAcid-sensing ion channels (ASICs) are proton-gated members of the epithelial sodium channel/degenerin (ENaC/DEG) superfamily of ion channels and are expressed throughout central and peripheral nervous systems. The homotrimeric splice variant ASIC1a has been implicated in nociception, fear memory, mood disorders and ischemia. Here we extract full-length chicken ASIC1a (cASIC1a) from cell membranes using styrene maleic acid (SMA) copolymer, yielding structures of ASIC1a channels in both high pH resting and low pH desensitized conformations by single-particle cryo-electron microscopy (cryo-EM). The structures of resting and desensitized channels reveal a reentrant loop at the amino terminus of ASIC1a that includes the highly conserved ‘His-Gly’ (HG) motif. The reentrant loop lines the lower ion permeation pathway and buttresses the ‘Gly-Ala-Ser’ (GAS) constriction, thus providing a structural explanation for the role of the His-Gly dipeptide in the structure and function of ASICs.

scholarly journals Identification of Genes Regulating Cell Death inStaphylococcus aureus

2019 ◽  
Author(s):  
Rebecca Yee ◽  
Jie Feng ◽  
Jiou Wang ◽  
Jiazhen Chen ◽  
Ying Zhang
Keyword(s):  
Cell Death ◽  
Acetic Acid ◽  
Drug Targets ◽  
Opportunistic Pathogen ◽  
Infection Model ◽  
Chronic Infections ◽  
Bacterial Cell Death ◽  
Genome Wide ◽  
A Genome ◽  
Genetic Mechanisms

AbstractStaphylococcus aureusis an opportunistic pathogen that causes acute and chronic infections. Due toS. aureus’ s highly resistant and persistent nature, it is paramount to identify better drug targets in order to eradicateS. aureusinfections. Despite the efforts in understanding bacterial cell death, the genes and pathways ofS. aureuscell death remain elusive. Here, we performed a genome-wide screen using a transposon mutant library to study the genetic mechanisms involved inS. aureuscell death. Using a precisely controlled heat-ramp and acetic acid exposure assays, mutations in 27 core genes (hsdR1, hslO, nsaS, sspA, folD, mfd, vraF, kdpB, USA300HOU_2684, 0868, 0369, 0420, 1154, 0142, 0930, 2590, 0997, 2559, 0044, 2004, 1209, 0152, 2455, 0154, 2386, 0232, 0350 involved in transporters, transcription, metabolism, peptidases, kinases, transferases, SOS response, nucleic acid and protein synthesis) caused the bacteria to be more death-resistant. In addition, we identified mutations in core 10 genes (capA, gltT, mnhG1,USA300HOU_1780, 2496, 0200, 2029, 0336, 0329, 2386, involved in transporters, metabolism, transcription, cell wall synthesis) from heat-ramp and acetic acid that caused the bacteria to be more death-sensitive or with defect in persistence. Interestingly, death-resistant mutants were more virulent than the parental strain USA300 and caused increased mortality in aCaenorhabditis elegansinfection model. Conversely, death-sensitive mutants were less persistent and formed less persister cells upon exposure to different classes of antibiotics. These findings provide new insights into the mechanisms ofS. aureuscell death and offer new therapeutic targets for developing more effective treatments caused byS. aureus.

scholarly journals The Golgi as a “Proton Sink” in Cancer

2021 ◽  
Vol 9 ◽  
Author(s):  
Koen M. O. Galenkamp ◽  
Cosimo Commisso
Keyword(s):  
Cell Death ◽  
Plasma Membrane ◽  
Ion Channels ◽  
Cancer Cells ◽  
Atp Hydrolysis ◽  
Membrane Transporters ◽  
Glycolytic Flux ◽  
Proton Channels ◽  
Optimal Functioning ◽  
Dependent Processes

Cancer cells exhibit increased glycolytic flux and adenosine triphosphate (ATP) hydrolysis. These processes increase the acidic burden on the cells through the production of lactate and protons. Nonetheless, cancer cells can maintain an alkaline intracellular pH (pHi) relative to untransformed cells, which sets the stage for optimal functioning of glycolytic enzymes, evasion of cell death, and increased proliferation and motility. Upregulation of plasma membrane transporters allows for H+ and lactate efflux; however, recent evidence suggests that the acidification of organelles can contribute to maintenance of an alkaline cytosol in cancer cells by siphoning off protons, thereby supporting tumor growth. The Golgi is such an acidic organelle, with resting pH ranging from 6.0 to 6.7. Here, we posit that the Golgi represents a “proton sink” in cancer and delineate the proton channels involved in Golgi acidification and the ion channels that influence this process. Furthermore, we discuss ion channel regulators that can affect Golgi pH and Golgi-dependent processes that may contribute to pHi homeostasis in cancer.

scholarly journals SEC24A facilitates colocalization and Ca2+ flux between the endoplasmic reticulum and mitochondria

2021 ◽  
Vol 134 (6) ◽  
Author(s):  
Tamutenda Chidawanyika ◽  
Rajarshi Chakrabarti ◽  
Kathryn S. Beauchemin ◽  
Henry N. Higgs ◽  
Surachai Supattapone
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Death ◽  
Fold Increase ◽  
Cellular Mechanism ◽  
Autophagic Flux ◽  
Wild Type ◽  
Genome Wide ◽  
Fold Reduction ◽  
A Genome ◽  
Indicator Dyes

ABSTRACT A genome-wide screen recently identified SEC24A as a novel mediator of thapsigargin-induced cell death in HAP1 cells. Here, we determined the cellular mechanism and specificity of SEC24A-mediated cytotoxicity. Measurement of Ca2+ levels using organelle-specific fluorescent indicator dyes showed that Ca2+ efflux from endoplasmic reticulum (ER) and influx into mitochondria were significantly impaired in SEC24A-knockout cells. Furthermore, SEC24A-knockout cells also showed ∼44% less colocalization of mitochondria and peripheral tubular ER. Knockout of SEC24A, but not its paralogs SEC24B, SEC24C or SEC24D, rescued HAP1 cells from cell death induced by three different inhibitors of sarcoplasmic/endoplasmic reticulum Ca2+ ATPases (SERCA) but not from cell death induced by a topoisomerase inhibitor. Thapsigargin-treated SEC24A-knockout cells showed a ∼2.5-fold increase in autophagic flux and ∼10-fold reduction in apoptosis compared to wild-type cells. Taken together, our findings indicate that SEC24A plays a previously unrecognized role in regulating association and Ca2+ flux between the ER and mitochondria, thereby impacting processes dependent on mitochondrial Ca2+ levels, including autophagy and apoptosis.

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