scholarly journals Mechanically Induced Integrin Ligation Mediates Intracellular Calcium Signaling with Single Pulsating Cavitation Bubbles

2020 ◽  
Author(s):  
Fenfang Li ◽  
Tae Hyun Park ◽  
George Sankin ◽  
Christopher Gilchrist ◽  
Defei Liao ◽  
...  
Keyword(s):  
Ion Channels ◽  
Cell Injury ◽  
Atp Release ◽  
Apical Surface ◽  
Cavitation Bubbles ◽  
Intracellular Calcium Signaling ◽  
Intracellular Ca ◽  
Spread Area ◽  
Membrane Poration ◽  
Blocking Antibodies

Ultrasound or shockwave-induced cavitation is used therapeutically to stimulate neural and muscle tissue, but the mechanisms underlying this mechanotransduction are unclear. Intracellular Ca2+ signaling is one of the earliest events in mechanotransduction. In this study, we investigate the mechanism of Ca2+ signaling in individual HEK293T cells stimulated by single cavitation bubbles. Ca2+ responses are rare at cell-bubble distance that avoids membrane poration, even with overexpression of the mechanosensitive ion channel Piezo1, but could be increased in frequency to 42% of cells by attaching RGD beads to the apical surface of the cells. By using Piezo1 knockout and Piezo1-expressing cells, integrin-blocking antibodies, and inhibitors of P2X ion channels, key molecular players are identified in the RGD bead-enhanced Ca2+ response: increased integrin ligation by substrate ECM triggers ATP release and activation of P2X—but not Piezo1—ion channels. These molecular players have not been examined previously in cavitation-induced Ca2+ signaling. The resultant Ca2+ influx causes dynamic changes in cell spread area. This approach to eliciting a Ca2+ response with cavitation microbubbles without cell injury, and the uncovered mechanotransduction mechanism by which increased integrin-ligation mediates ATP release and Ca2+ signaling will inform new strategies to stimulate tissues with ultrasound and shockwaves.

scholarly journals Acid-Sensing Ion Channels in Acidosis-Induced Injury of Human Brain Neurons

2010 ◽  
Vol 30 (6) ◽  
pp. 1247-1260 ◽  
Author(s):  
Minghua Li ◽  
Koichi Inoue ◽  
Deborah Branigan ◽  
Eric Kratzer ◽  
Jillian C Hansen ◽  
...  
Keyword(s):  
Ion Channels ◽  
Human Brain ◽  
Cortical Neurons ◽  
Cell Injury ◽  
Acidic Solution ◽  
Brain Neurons ◽  
Acid Sensing Ion Channels ◽  
Intracellular Ca ◽  
Inward Currents ◽  
High Level

Acidosis is a common feature of the human brain during ischemic stroke and is known to cause neuronal injury. However, the mechanism underlying acidosis-mediated injury of the human brain remains elusive. We show that a decrease in the extracellular pH evoked inward currents characteristic of acid-sensing ion channels (ASICs) and increased intracellular Ca2+ in cultured human cortical neurons. Acid-sensing ion channels in human cortical neurons show electrophysiological and pharmacological properties distinct from those in neurons of the rodent brain. Reverse transcriptase-PCR and western blot detected a high level of the ASIC1a subunit with little or no expression of other ASIC subunits. Treatment of human cortical neurons with acidic solution induced substantial cell injury, which was attenuated by the ASIC1a blockade. Thus, functional homomeric ASIC1a channels are predominantly expressed in neurons from the human brain. Activation of these channels has an important role in acidosis-mediated injury of human brain neurons.

Protective effects of adenosine in the perfused rat heart: changes in metabolism and intracellular ion homeostasis

1993 ◽  
Vol 264 (4) ◽  
pp. C986-C994 ◽  
Author(s):  
T. A. Fralix ◽  
E. Murphy ◽  
R. E. London ◽  
C. Steenbergen
Keyword(s):  
Cell Injury ◽  
Recovery Of Function ◽  
Ion Homeostasis ◽  
High Energy ◽  
Left Ventricular ◽  
Protective Effects ◽  
Intracellular Ca ◽  
Developed Pressure ◽  
High Energy Phosphate Metabolism ◽  
Glycolytic Rate

Increased concentrations of intracellular H+, Na+, and Ca2+ have been observed during ischemia, and these ionic alterations have been correlated with several indexes of cell injury in a number of studies. Recently, adenosine was proposed to play a role in ischemic preconditioning, since adenosine antagonists block the protective effects of these brief intermittent periods of ischemia and reflow. In this study we evaluated the protective effects of adenosine (20 microM) on high-energy phosphate metabolism, H+ and Ca2+ accumulation, and glycolytic rate during 30 min of no-flow ischemia. Adenosine was observed to slow the onset of contracture (7.0 +/- 0.9 min) and to improve left ventricular developed pressure (62 +/- 7% of initial) during reperfusion compared with untreated hearts (5.0 +/- 0.6 min and 18 +/- 5%, respectively). Intracellular Ca accumulation at the end of 30 min of ischemia was higher in the untreated (2,835 +/- 465 nM) than in the adenosine-treated (2,064 +/- 533 nM) hearts, while intracellular pH fell more in the untreated (5.85 +/- 0.17) than in the adenosine-treated hearts (6.27 +/- 0.16). Glycolytic rate and the rate of ATP decline were significantly attenuated in the adenosine-treated hearts during ischemia. Thus adenosine treatment slowed the rate of metabolism and delayed the accumulation of H+ and Ca2+ during ischemia, resulting in better recovery of function upon reflow.

PGE2, Ca2+, and cAMP mediate ATP activation of Cl− channels in pigmented ciliary epithelial cells

2001 ◽  
Vol 281 (5) ◽  
pp. C1614-C1623 ◽  
Author(s):  
Johannes C. Fleischhauer ◽  
Claire H. Mitchell ◽  
Kim Peterson-Yantorno ◽  
Miguel Coca-Prados ◽  
Mortimer M. Civan
Keyword(s):  
Intraocular Pressure ◽  
Epithelial Cells ◽  
Aqueous Humor ◽  
Second Messengers ◽  
Atp Release ◽  
Channel Activity ◽  
Atp Assay ◽  
Intracellular Ca ◽  
Cl Channels ◽  
Nonpigmented Ciliary Epithelial

Purines regulate intraocular pressure. Adenosine activates Cl− channels of nonpigmented ciliary epithelial cells facing the aqueous humor, enhancing secretion. Tamoxifen and ATP synergistically activate Cl− channels of pigmented ciliary epithelial (PE) cells facing the stroma, potentially reducing net secretion. The actions of nucleotides alone on Cl− channel activity of bovine PE cells were studied by electronic cell sorting, patch clamping, and luciferin/luciferase ATP assay. Cl−channels were activated by ATP > UTP, ADP, and UDP, but not by 2-methylthio-ATP, all at 100 μM. UTP triggered ATP release. The second messengers Ca2+, prostaglandin (PG)E2, and cAMP activated Cl− channels without enhancing effects of 100 μM ATP. Buffering intracellular Ca2+activity with 1,2-bis(2-aminophenoxy)ethane- N,N,N′,N′- tetraacetic acid or blocking PGE2 formation with indomethacin inhibited ATP-triggered channel activation. The Rp stereoisomer of 8-bromoadenosine 3′,5′-cyclic monophosphothioate inhibited protein kinase A activity but mimicked 8-bromoadenosine 3′,5′-cyclic monophosphate. We conclude that nucleotides can act at >1 P2Y receptor to trigger a sequential cascade involving Ca2+, PGE2, and cAMP. cAMP acts directly on Cl−channels of PE cells, increasing stromal release and potentially reducing net aqueous humor formation and intraocular pressure.

Concerted actions of IL-1β inhibit Na+ absorption and stimulate anion secretion by IMCD cells

1998 ◽  
Vol 275 (6) ◽  
pp. F946-F954 ◽  
Author(s):  
Russell F. Husted ◽  
Chong Zhang ◽  
John B. Stokes
Keyword(s):  
Collecting Duct ◽  
Primary Cultures ◽  
Acute Effect ◽  
Inhibitory Effect ◽  
Apical Surface ◽  
Onset Of Action ◽  
Anion Secretion ◽  
Intracellular Ca ◽  
Transport Inhibitors ◽  
Interleukin 1Α

Increasing evidence indicates that factors other than adrenocorticoid hormones can influence long-term regulation of Na+ transport by inner medullary collecting duct (IMCD) cells. We now report that, of 14 interleukins tested, only interleukin-1α (IL-1α) and IL-1β inhibited Na+ transport by primary cultures of rat IMCD. IL-1β reduced both basal and mineralocorticoid (MC)-stimulated Na+ transport by 50–70%; its effect on glucocorticoid (GC)-stimulated Na+ transport was significantly less. IL-1β continued to blunt MC stimulation of Na+ transport even after it had been removed from the medium for 24 h. The onset of action to inhibit Na+ transport was within 20 min. The acute effect from the basolateral surface was greater than that from the apical surface, but the effect from each surface was additive. In addition to its inhibitory effect on Na+ transport, chronic IL-1β exposure increased both basal and cAMP-stimulated anion secretion rates. IL-1β had no acute effect on anion secretion. Monolayers chronically treated with IL-1β had an increased capacity to secrete fluid, as predicted from its effects on ion transport. Inhibitors of cyclooxygenase did not blunt the actions of IL-1β. Furthermore, IL-1β did not produce a rise in intracellular Ca2+. These results suggest novel signaling pathways induced by IL-1β regulating Na+ and Cl− transport by the IMCD.

scholarly journals Hyperforin/HP-β-Cyclodextrin Enhances Mechanosensitive Ca2+ Signaling in HaCaT Keratinocytes and in Atopic Skin Ex Vivo Which Accelerates Wound Healing

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Hiroya Takada ◽  
Jun Yonekawa ◽  
Masami Matsumoto ◽  
Kishio Furuya ◽  
Masahiro Sokabe
Keyword(s):  
Wound Healing ◽  
Ex Vivo ◽  
Atp Release ◽  
Aqueous Solubility ◽  
P2y Receptors ◽  
Hacat Keratinocytes ◽  
Wound Edge ◽  
Atopic Skin ◽  
Intracellular Ca ◽  
Mechanical Stretching

Cutaneous wound healing is accelerated by mechanical stretching, and treatment with hyperforin, a major component of a traditional herbal medicine and a known TRPC6 activator, further enhances the acceleration. We recently revealed that this was due to the enhancement of ATP-Ca2+ signaling in keratinocytes by hyperforin treatment. However, the low aqueous solubility and easy photodegradation impede the topical application of hyperforin for therapeutic purposes. We designed a compound hydroxypropyl-β-cyclodextrin- (HP-β-CD-) tetracapped hyperforin, which had increased aqueous solubility and improved photoprotection. We assessed the physiological effects of hyperforin/HP-β-CD on wound healing in HaCaT keratinocytes using live imaging to observe the ATP release and the intracellular Ca2+ increase. In response to stretching (20%), ATP was released only from the foremost cells at the wound edge; it then diffused to the cells behind the wound edge and activated the P2Y receptors, which caused propagating Ca2+ waves via TRPC6. This process might facilitate wound closure, because the Ca2+ response and wound healing were inhibited in parallel by various inhibitors of ATP-Ca2+ signaling. We also applied hyperforin/HP-β-CD on an ex vivo skin model of atopic dermatitis and found that hyperforin/HP-β-CD treatment for 24 h improved the stretch-induced Ca2+ responses and oscillations which failed in atopic skin.

Calcium Signals in Nerve Cells

Physiology ◽  
1991 ◽  
Vol 6 (1) ◽  
pp. 6-10 ◽  
Author(s):  
PG Kostyuk ◽  
AV Tepikin
Keyword(s):  
Endoplasmic Reticulum ◽  
Ion Channels ◽  
Nerve Cell ◽  
Second Messengers ◽  
Cell Activity ◽  
Nerve Cells ◽  
Calcium Signals ◽  
Intracellular Ca ◽  
Ca Ions

Increases in intracellular Ca ions follow each cycle of nerve cell activity. Sources of Ca are voltage- and receptor-operated membrane ion channels and endoplasmic reticulum (ER). Ca release from ER can be triggered by different second messengers, and uptake into the ER can terminate the Ca signal.

Mechanical strain-induced Ca2+waves are propagated via ATP release and purinergic receptor activation

2000 ◽  
Vol 279 (2) ◽  
pp. C295-C307 ◽  
Author(s):  
H. Sauer ◽  
J. Hescheler ◽  
M. Wartenberg
Keyword(s):  
Gap Junctions ◽  
Purinergic Receptor ◽  
Mechanical Strain ◽  
Atp Release ◽  
Anion Channel ◽  
Receptor Activation ◽  
Disulfonic Acid ◽  
Channel Blockers ◽  
Junctional Coupling ◽  
Intracellular Ca

Mechanical strain applied to prostate cancer cells induced an intracellular Ca2+ (Cai 2+) wave spreading with a velocity of 15 μm/s. Cai 2+ waves were not dependent on extracellular Ca2+ and membrane potential because propagation was unaffected in high-K+ and Ca2+-free solution. Waves did not depend on the cytoskeleton or gap junctions because cytochalasin B and nocodazole, which disrupt microfilaments and microtubules, respectively, and 1-heptanol, which uncouples gap junctions, were without effects. Fluorescence recovery after photobleaching experiments revealed an absence of gap junctional coupling. Cai 2+ waves were inhibited by the purinergic receptor antagonists basilen blue and suramin; by pretreatment with ATP, UTP, ADP, UDP, 2-methylthio-ATP, and benzoylbenzoyl-ATP; after depletion of ATP by 2-deoxyglucose; and after ATP scavenging by apyrase. Waves were abolished by the anion channel inhibitors 5-nitro-2-(3-phenylpropylamino)benzoic acid, tamoxifen, 4,4′-diisothiocyanatostilbene-2,2′-disulfonic acid, niflumic acid, and gadolinium. ATP release following strain was significantly inhibited by anion channel blockers. Hence, ATP is secreted via mechanosensitive anion channels and activates purinergic receptors on the same cell or neighboring cells in an autocrine and paracrine manner, thus leading to Cai 2+ wave propagation.

Mitochondrial Ca2+ Activates a Cation Current in Aplysia Bag Cell Neurons

2010 ◽  
Vol 103 (3) ◽  
pp. 1543-1556 ◽  
Author(s):  
Charlene M. Hickey ◽  
Julia E. Geiger ◽  
Chris J. Groten ◽  
Neil S. Magoski
Keyword(s):  
Endoplasmic Reticulum ◽  
Ion Channels ◽  
Time Course ◽  
Reversal Potential ◽  
Neuroendocrine Cells ◽  
Dependent Manner ◽  
Inward Current ◽  
Cation Current ◽  
Intracellular Ca ◽  
Bag Cell Neurons

Ion channels may be gated by Ca2+ entering from the extracellular space or released from intracellular stores—typically the endoplasmic reticulum. The present study examines how Ca2+ impacts ion channels in the bag cell neurons of Aplysia californica. These neuroendocrine cells trigger ovulation through an afterdischarge involving Ca2+ influx from Ca2+ channels and Ca2+ release from both the mitochondria and endoplasmic reticulum. Liberating mitochondrial Ca2+ with the protonophore, carbonyl cyanide-4-trifluoromethoxyphenyl-hydrazone (FCCP), depolarized bag cell neurons, whereas depleting endoplasmic reticulum Ca2+ with the Ca2+-ATPase inhibitor, cyclopiazonic acid, did not. In a concentration-dependent manner, FCCP elicited an inward current associated with an increase in conductance and a linear current/voltage relationship that reversed near −40 mV. The reversal potential was unaffected by changing intracellular Cl−, but left-shifted when extracellular Ca2+ was removed and right-shifted when intracellular K+ was decreased. Strong buffering of intracellular Ca2+ decreased the current, although the response was not altered by blocking Ca2+-dependent proteases. Furthermore, fura imaging demonstrated that FCCP elevated intracellular Ca2+ with a time course similar to the current itself. Inhibiting either the V-type H+-ATPase or the ATP synthetase failed to produce a current, ruling out acidic Ca2+ stores or disruption of ATP production as mechanisms for the FCCP response. Similarly, any involvement of reactive oxygen species potentially produced by mitochondrial depolarization was mitigated by the fact that dialysis with xanthine/xanthine oxidase did not evoke an inward current. However, both the FCCP-induced current and Ca2+ elevation were diminished by disabling the mitochondrial permeability transition pore with the alkylating agent, N-ethylmaleimide. The data suggest that mitochondrial Ca2+ gates a voltage-independent, nonselective cation current with the potential to drive the afterdischarge and contribute to reproduction. Employing Ca2+ from mitochondria, rather than the more common endoplasmic reticulum, represents a diversification of the mechanisms that influence neuronal activity.

scholarly journals Neuroglial ATP release through innexin channels controls microglial cell movement to a nerve injury

2010 ◽  
Vol 136 (4) ◽  
pp. 425-442 ◽  
Author(s):  
Stuart E. Samuels ◽  
Jeffrey B. Lipitz ◽  
Gerhard Dahl ◽  
Kenneth J. Muller
Keyword(s):  
Glial Cell ◽  
Nerve Injury ◽  
Glial Cells ◽  
Cell Injury ◽  
Atp Release ◽  
Cell Movement ◽  
Calcium Wave ◽  
Directed Movement ◽  
The Central Nervous System ◽  
Microglial Migration

Microglia, the immune cells of the central nervous system, are attracted to sites of injury. The injury releases adenosine triphosphate (ATP) into the extracellular space, activating the microglia, but the full mechanism of release is not known. In glial cells, a family of physiologically regulated unpaired gap junction channels called innexons (invertebrates) or pannexons (vertebrates) located in the cell membrane is permeable to ATP. Innexons, but not pannexons, also pair to make gap junctions. Glial calcium waves, triggered by injury or mechanical stimulation, open pannexon/innexon channels and cause the release of ATP. It has been hypothesized that a glial calcium wave that triggers the release of ATP causes rapid microglial migration to distant lesions. In the present study in the leech, in which a single giant glial cell ensheathes each connective, hydrolysis of ATP with 10 U/ml apyrase or block of innexons with 10 µM carbenoxolone (CBX), which decreased injury-induced ATP release, reduced both movement of microglia and their accumulation at lesions. Directed movement and accumulation were restored in CBX by adding ATP, consistent with separate actions of ATP and nitric oxide, which is required for directed movement but does not activate glia. Injection of glia with innexin2 (Hminx2) RNAi inhibited release of carboxyfluorescein dye and microglial migration, whereas injection of innexin1 (Hminx1) RNAi did not when measured 2 days after injection, indicating that glial cells’ ATP release through innexons was required for microglial migration after nerve injury. Focal stimulation either mechanically or with ATP generated a calcium wave in the glial cell; injury caused a large, persistent intracellular calcium response. Neither the calcium wave nor the persistent response required ATP or its release. Thus, in the leech, innexin membrane channels releasing ATP from glia are required for migration and accumulation of microglia after nerve injury.

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