scholarly journals Quasi-synaptic calcium signal transmission between endoplasmic reticulum and mitochondria

1999 ◽  
Vol 18 (1) ◽  
pp. 96-108 ◽  
Author(s):  
G. Csordas
Keyword(s):  
Endoplasmic Reticulum ◽  
Signal Transmission ◽  
Calcium Signal

scholarly journals Quantification of calcium signal transmission from sarco‐endoplasmic reticulum to the mitochondria

2000 ◽  
Vol 529 (3) ◽  
pp. 553-564 ◽  
Author(s):  
Pál Pacher ◽  
György Csordás ◽  
Timothy G. Schneider ◽  
György Hajnóczky
Keyword(s):  
Endoplasmic Reticulum ◽  
Signal Transmission ◽  
Calcium Signal

scholarly journals Chemically-induced Neurite-like Outgrowth Reveals Multicellular Network Function in Patient-derived Glioblastoma Cells

2018 ◽  
Author(s):  
Barbara da Silva ◽  
Euan S. Polson ◽  
Alastair Droop ◽  
Ryan K. Mathew ◽  
Lucy F. Stead ◽  
...  
Keyword(s):  
De Novo ◽  
Ex Vivo ◽  
Signal Transmission ◽  
Calcium Signal ◽  
High Dose ◽  
Connected Vehicle ◽  
Network Function ◽  
Small Molecule Inhibition ◽  
Chemically Induced ◽  
Radiation Resistant

SummaryTumor stem cells and malignant multicellular networks have been separately implicated in the therapeutic resistance of Glioblastoma Multiforme (GBM), the most aggressive type of brain cancer in adults. We show that small molecule inhibition of RHO-associated serine/threonine kinase (ROCKi) significantly promoted the outgrowth of neurite-like cell projections in cultures of heterogeneous patient-derived GBM stem-like cells. These projections formedde novo-induced cellular network (iNet) ‘webs’, which regressed after withdrawal of ROCKi. Connected cells within the iNet web exhibited long range calcium signal transmission, and significant lysosomal and mitochondrial trafficking. In contrast to their less-connected vehicle control counterparts, iNet cells remained viable and proliferative after high-dose radiation. These findings demonstrate a link between ROCKi-regulated cell projection dynamics and the formation of radiation-resistant multicellular networks. Our study identifies means to reversibly induce iNet websex vivo, and may thereby accelerate future studies into the biology of GBM cellular networks.

Effect of antidepressants on ATP-dependent calcium uptake by neuronal endoplasmic reticulum

2001 ◽  
Vol 79 (11) ◽  
pp. 946-952 ◽  
Author(s):  
L Couture ◽  
R Élie ◽  
P -A Lavoie
Keyword(s):  
Endoplasmic Reticulum ◽  
Adenosine Triphosphate ◽  
Calcium Uptake ◽  
Tricyclic Antidepressants ◽  
Brain Cortex ◽  
Calcium Signal ◽  
Drug Concentrations ◽  
Brain Synaptosomes ◽  
Dependent Inhibition ◽  
Atypical Antidepressants

This study investigated the effect of tricyclic and atypical antidepressants on adenosine triphosphate (ATP) dependent calcium uptake by the endoplasmic reticulum of lysed synaptosomes from rat brain cortex. Tricyclic antidepressants (imipramine, desipramine, clomipramine, amitriptyline) exhibited no effect in the lower range (0.06 to 2 µM) of drug concentrations, and a concentration-dependent inhibition of calcium uptake in the upper range (6 to 200 µM). A concentration-dependent inhibition was observed for atypical antidepressants (mianserin, desmethylmianserin, venlafaxine, desmethylvenlafaxine, fluoxetine) in both the lower and the upper range of drug concentrations. Since no stimulation of calcium uptake was observed in either concentration range, it appears that the tricyclic and atypical antidepressants tested are not capable of normalizing, through their effect on the endoplasmic reticulum, an overactive calcium signal, which is possibly implicated in the etiology of affective disorders. Also, although only marginal inhibition of calcium uptake is expected at brain concentrations of tricyclics and mianserin–desmethylmianserin that are likely to be encountered during clinical use, a more substantial inhibition could occur with fluoxetine.Key words: adenosine triphosphate-dependent calcium uptake, neuronal endoplasmic reticulum, lysed brain synaptosomes, tricyclic antidepressants, atypical antidepressants.

scholarly journals Calcium Signal Transmission between Ryanodine Receptors and Mitochondria

2000 ◽  
Vol 275 (20) ◽  
pp. 15305-15313 ◽  
Author(s):  
Gábor Szalai ◽  
György Csordás ◽  
Basil M. Hantash ◽  
Andrew P. Thomas ◽  
György Hajnóczky
Keyword(s):  
Signal Transmission ◽  
Ryanodine Receptors ◽  
Calcium Signal

scholarly journals Endoplasmic reticulum stress activates human IRE1α through reversible assembly of inactive dimers into small oligomers

2021 ◽  
Author(s):  
Vladislav Belyy ◽  
Iratxe Zuazo-Gaztelu ◽  
Andrew Alamban ◽  
Avi Ashkenazi ◽  
Peter Walter
Keyword(s):  
Endoplasmic Reticulum ◽  
Single Molecule ◽  
Signal Transmission ◽  
Kinase Domain ◽  
Activation Mechanism ◽  
Live Cells ◽  
Unfolded Protein ◽  
The Unfolded Protein Response ◽  
Stress Dependent ◽  
Protein Response

Protein folding homeostasis in the endoplasmic reticulum (ER) is regulated by a signaling network, termed the unfolded protein response (UPR). Inositol-requiring enzyme 1 (IRE1) is an ER membrane-resident kinase/RNase that mediates signal transmission in the most evolutionarily conserved branch of the UPR. Dimerization and/or higher-order oligomerization of IRE1 are thought to be important for its activation mechanism, yet the actual oligomeric states of inactive, active, and attenuated mammalian IRE1 complexes remained unknown. We developed an automated two-color single-molecule tracking approach to dissect the oligomerization of tagged endogenous human IRE1 in live cells. In contrast to previous models, our data indicate that IRE1 exists as a constitutive homodimer at baseline and assembles into small oligomers upon ER stress. We demonstrate that the formation of inactive dimers and stress-dependent oligomers is fully governed by IRE1's lumenal domain. Phosphorylation of IRE1's kinase domain occurs more slowly than oligomerization and is retained after oligomers disassemble back into dimers. Our findings suggest that assembly of IRE1 dimers into larger oligomers specifically enables trans-autophosphorylation, which in turn drives IRE1's RNase activity.

Calcium signal transmission in chick sensory neurones is diffusion based

Cell Calcium ◽  
2008 ◽  
Vol 43 (3) ◽  
pp. 236-249 ◽  
Author(s):  
William Coatesworth ◽  
Stephen Bolsover
Keyword(s):  
Signal Transmission ◽  
Calcium Signal ◽  
Sensory Neurones

scholarly journals A localized elevation of cytosolic free calcium is associated with cytokinesis in the zebrafish embryo.

1995 ◽  
Vol 131 (6) ◽  
pp. 1539-1545 ◽  
Author(s):  
D C Chang ◽  
C Meng
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Division ◽  
Zebrafish Embryo ◽  
Regulatory Mechanism ◽  
Spatiotemporal Variation ◽  
Calcium Signal ◽  
Free Calcium ◽  
Cytosolic Free Calcium ◽  
Cell Cleavage ◽  
Insp3 Receptors

Cytokinesis, a key step in cell division, is known to be precisely regulated both in its timing and location. At present, the regulatory mechanism of cytokinesis is not well understood, although it has been suggested that calcium signaling may play an important role in this process. To test this notion, we introduced a sensitive fluorescent Ca2+ indicator into the zebrafish embryo and used confocal microscopy to measure the spatiotemporal variation of intracellular free Ca2+ concentration ([Ca2+]i) during cell cleavage. It was evident that a localized elevation of [Ca2+]i is closely associated with cytokinesis. First, we found that during cytokinesis, the level of free Ca2+ was elevated locally precisely at the cleavage site. Second, the rise of free Ca2+ was very rapid and occurred just preceding the initiation of furrow contraction. These observations strongly suggest that cytokinesis may be triggered by a calcium signal. In addition, we found that this cytokinesis-associated calcium signal arose mainly from internal stores of Ca2+ rather than from external free Ca2+; it could be blocked by the antagonist of inositol trisphosphate (InsP3) receptors. These findings suggest that the localized elevation of [Ca2+]i is caused by the release of free Ca2+ from the endoplasmic reticulum through the InsP3-regulated calcium channels.

Proinflammatory treatment of astrocytes with lipopolysaccharide results in augmented Ca2+ signaling through increased expression of VIA phospholipase A2 (iPLA2)

2011 ◽  
Vol 300 (3) ◽  
pp. C542-C549 ◽  
Author(s):  
Mikhail Strokin ◽  
Marina Sergeeva ◽  
Georg Reiser
Keyword(s):  
Endoplasmic Reticulum ◽  
Small Interfering Rna ◽  
Signal Transmission ◽  
Brain Inflammation ◽  
Inflammatory Conditions ◽  
Bromoenol Lactone ◽  
Interfering Rna ◽  
The Brain ◽  
Expression And Activity

Many Ca2+-regulated intracellular processes are involved in the development of neuroinflammation. However, the changes of Ca2+ signaling in the brain under inflammatory conditions were hardly studied. ATP-induced Ca2+ signaling is a central event of signal transmission in astrocytic networks. We investigated primary astrocytes after proinflammatory stimulation with lipopolysaccharide (LPS; 100 ng/ml) for 6–24 h. We reveal that Ca2+ responses to purinergic ATP stimulation are significantly increased in amplitude and duration after stimulation with LPS. We detected that increased amplitudes of Ca2+ responses to ATP in LPS-treated astrocytes can be explained by substantial increase of Ca2+ load in stores in endoplasmic reticulum. The mechanism implies enhanced Ca2+ store refilling due to the amplification of capacitative Ca2+ entry. The reason for the increased duration of Ca2+ responses in LPS-treated cells is also the amplified capacitative Ca2+ entry. Next, we established that the molecular mechanism for the LPS-induced amplification of Ca2+ responses in astrocytes is increased expression and activity of VIA phospholipase A2 (VIA iPLA2). Indeed, both gene silencing with specific small interfering RNA and pharmacological inhibition of VIA iPLA2 with S-bromoenol lactone reduced the load of the Ca2+ stores and caused a decrease in the amplitudes of Ca2+ responses in LPS-treated astrocytes to values, which were comparable with those in untreated cells. Our findings highlight a novel regulatory role of VIA iPLA2 in development of inflammation in brain. We suggest that this enzyme might be a possible target for treatment of pathologies related to brain inflammation.

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