Sixty years elapsed since Chang (Hsiang-Tung Chang, Xiang-Tong Zhang) presented his seminal report "Cortical neurons with particular reference to the apical dendrite" at the Cold Spring Harbor Symposium. Thanks to the development of elaborated techniques through the 6 decades, our understanding of the dendrite has been pushed forward greatly: the backward and forward conductions during excitation, sodium and calcium conductances, chemical excitation by uncaging glutamate at a dimension of micrometer, and the quantitative study of chemical organization of postsynaptic density (PSD), etc. Though the progression is great, there are still tough problems in dendritic research, especially the integration through dendritic spine.
Calcium Signaling ; Dendrites ; physiology ; Glutamic Acid ; metabolism

No abstract available.
Animal ; Calcium Signaling/physiology* ; Exocytosis/physiology ; Pancreas/physiology* ; Pancreas/cytology

Lysophosphatidylethanolamine (LPE), a lyso-type metabolite of phosphatidylethanolamine, has been reported to be an intercellular signaling molecule. LPE mobilizes intracellular Ca²⁺ through G-protein-coupled receptor (GPCR) in some cells types. However, GPCRs for lysophosphatidic acid (LPA) were not implicated in the LPE-mediated activities in LPA GPCR overexpression systems or in SK-OV3 ovarian cancer cells. In the present study, in human SH-SY5Y neuroblastoma cells, experiments with LPA₁ antagonists showed LPE induced intracellular Ca²⁺ increases in an LPA₁ GPCR-dependent manner. Furthermore, LPE increased intracellular Ca²⁺ through pertussis-sensitive G proteins, edelfosine-sensitive-phospholipase C, 2-APB-sensitive IP₃ receptors, Ca²⁺ release from intracellular Ca²⁺ stores, and subsequent Ca²⁺ influx across plasma membranes, and LPA acted on LPA₁ and LPA₂ receptors to induce Ca²⁺ response in a 2-APB-sensitive and insensitive manner. These findings suggest novel involvements for LPE and LPA in calcium signaling in human SH-SY5Y neuroblastoma cells.
Calcium Signaling* ; Calcium* ; Cell Membrane ; GTP-Binding Proteins ; Humans* ; Neuroblastoma* ; Ovarian Neoplasms

Store-operated calcium entry (SOCE), a major mode of extracellular calcium entry, plays roles in a variety of cell activities. Accumulating evidence indicates that the intracellular calcium ion concentration and calcium signaling are critical for the responses induced by oxidative stress. The present study was designed to investigate the potential effect of SOCE inhibition on H₂O₂-induced apoptosis in endothelial progenitor cells (EPCs), which are the predominant cells involved in endothelial repair. The results showed that H₂O₂-induced EPC apoptosis was reversed by SOCE inhibition induced either using the SOCE antagonist ML-9 or via silencing of stromal interaction molecule 1 (STIM1), a component of SOCE. Furthermore, SOCE inhibition repressed the increases in intracellular reactive oxygen species (ROS) levels and endoplasmic reticulum (ER) stress and ameliorated the mitochondrial dysfunction caused by H₂O₂. Our findings provide evidence that SOCE inhibition exerts a protective effect on EPCs in response to oxidative stress induced by H₂O₂ and may serve as a potential therapeutic strategy against vascular endothelial injury.
Apoptosis* ; Calcium Signaling ; Calcium* ; Endoplasmic Reticulum ; Endothelial Progenitor Cells* ; Oxidative Stress ; Reactive Oxygen Species

OBJECTIVETo investigate the effects of power frequency magnetic field on the Ca2+ transport dynamics of isolated sarcoplasmic reticulum vesicles.

METHODSThe assays of Ca2+ uptake time course and the Ca2+-ATPase activity of sarcoplasmic reticulum vesicles were investigated by using dynamic mode of spectrometry with a Ca2+ dye; Ca2+ release channel activation was examined by 3H-ryanodine binding and Ca2+ release assays; membrane fluidity of sarcoplasmic reticulum vesicles was examined by fluorescence polarization, without or with exposure to the vesicles at a 0.4 mT, 50 Hz sinusoidal magnetic field.

RESULTS0.4 mT, 50 Hz sinusoidal magnetic field exposure caused about a 16% decline of the initial Ca2+ uptake rate from a (29.18 +/- 3.90) pmol.mg(-1).s(-1) to a (24.60 +/- 3.81) pmol.mg(-1).s(-1) and a 26% decline of the Ca2+-ATPase activity from (0.93 +/- 0.05) micromol.mg(-1).min(-1) to (0.69 +/- 0.07) micromol.mg(-1).min(-1) of sarcoplasmic reticulum vesicles, whereas caused a 15% increase of the initial Ca2+ release rate from (4.83 +/- 0.82) pmol.mg(-1).s(-1) to (5.65 +/- 0.43) pmol.mg(-1).s(-1) and a 5% increase in 3H-ryanodine binding to the receptor from (1.10 +/- 0.12) pmol/mg to (1.16 +/- 0.13) pmol/mg, respectively.

CONCLUSIONThe decline of Ca2+-ATPase activity and the increase of Ca2+ release channel activity should result in a down-regulation of Ca2+ dynamic uptake and an up-regulation of Ca2+ release induced by exposing the sarcoplasmic reticulum to a 0.4 mT, 50 Hz power frequency magnetic field.

Animals ; Calcium ; metabolism ; Calcium Signaling ; Electromagnetic Fields ; Muscle, Skeletal ; metabolism ; Rabbits ; Sarcoplasmic Reticulum ; metabolism ; radiation effects

OBJECTIVETo establish a simple but effective method of laser scanning confocal microscopic imaging for Ca2+ oscillations of pancreatic acinar cells in adult mice.

METHODSPancreatic acinar cells from adult Kunming mice were isolated acutely with collagenase, and then loaded with fluo-4-AM, a Ca2+ indicator. A laser scanning confocal microscope armed with 488 nm laser was employed to record the dynamic fluorescent signals in-time and synchronously while acetylcholine (ACh) was added in the pancreatic acinar cells.

RESULTS(1) The classic pancreatic acinar cell Ca2+ oscillations were induced by a certain concentration of ACh (100 nmol/L) successfully and steadily, which could be blocked by atropine completely. (2) Plasmic Ca2+ oscillations from different parts of one acinar cell were usually with different amplitudes and almost the same frequencies. But both of amplitudes and frequencies were different among different cells. (3) The acinar cell Ca2+ oscillations were induced by ACh in a concentration-dependent manner.

CONCLUSIONThe laser scanning confocal microscopic imaging for adult mouse pancreatic acinar cell Ca2+ oscillations was established successfully. The features of being easy to use, direct to see lively, high efficiency and good flexibility make it a popular tool for researchers to choose.

Acinar Cells ; chemistry ; Animals ; Calcium ; analysis ; Calcium Signaling ; Cells, Cultured ; Mice ; Microscopy, Confocal ; methods ; Pancreas ; cytology

The transient receptor potential melastatin type 7 (TRPM7) channel is a widely expressed non-selective cation channel with fusion to the C-terminal alpha kinase domain and regarded as a key regulator of whole body Mg2+ homeostasis in mammals. However, the roles of TRPM7 during osteoclastogenesis in RAW264.7 cells and bone marrow-derived monocyte/macrophage precursor cells (BMMs) are not clear. In the present study, we investigate the roles of TRPM7 in osteoclastogenesis using methods of small interfering RNA (siRNA), RT-PCR, patch-clamp, and calcium imaging. RANKL (receptor activator of NF-kappaB ligand) stimulation did not affect the TRPM7 expression and TRPM7-mediated current was activated in HEK293, RAW264.7, and BMM cells by the regulation of Mg2+. Knock-down of TRPM7 by siTRPM7 reduced intracellular Ca2+ concentration ([Ca2+]i) increases by 0 mM [Mg2+]e in HEK293 cells and inhibited the generation of RANKL-induced Ca2+ oscillations in RAW264.7 cells. Finally, knock-down of TRPM7 suppressed RANKL-mediated osteoclastogenesis such as activation and translocation of NFATc1, formation of multinucleated cells, and the bone resorptive activity, sequentially. These results suggest that TRPM7 plays an essential role in the RANKL-induced [Ca2+]i oscillations that triggers the late stages of osteoclastogenesis.
Calcium ; Calcium Signaling ; HEK293 Cells ; Homeostasis ; Mammals ; NF-kappa B ; Phosphotransferases ; RNA, Small Interfering

It has been reported that activation of metabotropic glutamate receptor 1 (mGluR1) can mediate endocannabinoid-induced short-term depression of synaptic transmission in cerebellar parallel fiber (PF)-Purkinje cell (PC) synapse. mGluR1 has signaling pathways involved in intracellular calcium increase which may contribute to endocannabinoid release. Two major mGluR1-evoked calcium signaling pathways are known: (1) slow-kinetic inward current carried by transient receptor potential canonical (TRPC) channel which is permeable to Ca2+; (2) IP3-induced calcium release from intracellular calcium store. However, it is unclear how much each calcium source contributes to endocannabinoid signaling. Here, we investigated whether calcium influx through mGluR1-evoked TRPC channel contributes to endocannabinoid signaling in cerebellar Purkinje cells. At first, we applied SKF96365 to inhibit TRPC, which blocked endocannabinoid-induced short-term depression completely. However, an alternative TRP channel inhibitor, BTP2 did not affect endocannabinoid-induced short-term depression although it blocked mGluR1-evoked TRPC currents. Endocannabinoid signaling occurred normally even though the TRPC current was mostly blocked by BTP2. Our data imply that TRPC current does not play an important role in endocannabinoid signaling. We also suggest precaution in applying SKF96365 to inhibit TRP channels and propose BTP2 as an alternative TRPC inhibitor.
Calcium ; Calcium Signaling ; Cerebellum ; Depression ; Endocannabinoids ; Imidazoles ; Purkinje Cells ; Receptors, Metabotropic Glutamate ; Synapses ; Synaptic Transmission

Recent human genetic studies have shown that Gβ5 is related to various clinical symptoms, such as sinus bradycardia, cognitive disability, and attention deficit hyperactivity disorder. Although the calcium signaling cascade is closely associated with a heterotrimeric G-protein, the function of Gβ5 in calcium signaling and its relevance to clinical symptoms remain unknown. In this study, we investigated the in vitro changes of store-operated calcium entry (SOCE) with exogenous expression of Gβ5. The cells expressing Gβ5 had enhanced SOCE after depletion of calcium ion inside the endoplasmic reticulum. Gβ5 also augmented Stim1- and Orai1-dependent SOCE. An ORAI1 loss-of-function mutant did not show inhibition of Gβ5-induced SOCE, and a STIM1-ERM truncation mutant showed no enhancement of SOCE. These results suggested a novel role of GNB5 and Stim1, and provided insight into the regulatory mechanism of SOCE.
Attention Deficit Disorder with Hyperactivity ; Bradycardia ; Calcium ; Calcium Signaling ; Endoplasmic Reticulum ; GTP-Binding Proteins ; Humans ; In Vitro Techniques

A stochastic model of intracellular calcium oscillations is put forward by taking into account the random opening-closing of Ca2+ channels in endoplasmic reticulum (ER) membrane. The numerical results of the stochastic model show simple and complex calcium oscillations, which accord with the experiment results.
Calcium Channels/*metabolism ; *Calcium Signaling ; Endoplasmic Reticulum/*metabolism ; Intracellular Space ; Kinetics ; Mathematics ; Models, Biological ; Stochastic Processes