OBJECTIVE: We reported the overcoming effect of Ni2+ on the in vitro 2-cell block of mouse embryos. In this study, we aim to investigate whether Ni2+ should induce intracellular Ca2+ transient in the mouse embryos. MATERIALS AND METHODS: Embryos were collected at post hCG 32hr from the oviduct of the ICR mouse and cultured in M2 medium omitted phenol red. Intracellular Ca2+ was checked by using a confocal laser scanning microscope and fluo-3AM by using various intracellular Ca2+ antagonists. RESULTS: In 1mM Ni2+ treated medium which contained Ca2+(1.71mM), 75.7% of the embryos showed [Ca2+]i transient about 200 sec later. In the Ca2+-free medium, 69.8% of the embryos showed [Ca2+]i transient. In U73122, phospholipaseC(PLC) inhibitor (5uM, 10min) pretreated group, 33.3% of the embryos showed [Ca2+]i transient. Heparine, inositol 1,4,5-triphosphate receptor(IP3R) antagonist preinjected embryos showed no response with 1mM Ni2+. In danthrolene treatment, ryanodine receptor(RyR)-antagonist, 43% embryos showed [Ca2+]i transient but they showed delayed response about 340sec in the presence of Ca2+. CONCLUSIONS: Summing up the above results, Ni2+ seems to induce Ca2+-release from the Ca2+-store even in the Ca2+-free medium. IP3 receptors of the mouse 2-cell embryos might have an essential role for the intracellular Ca2+ increase by Ni2+.
Animals ; Embryonic Structures* ; Heparin ; Inositol 1,4,5-Trisphosphate ; Inositol 1,4,5-Trisphosphate Receptors ; Mice* ; Mice, Inbred ICR ; Oviducts ; Phenolsulfonphthalein ; Ryanodine

Inositol 1,4,5-trisphosphate receptor 1 (ITPR1) is an important intracellular channel for releasing Ca²⁺. In order to investigate the effects of the ITPR1 overexpression on Ca²⁺ concentration and lipid content in duck uterine epithelial cells and its effects on calcium transport-related genes, the structural domain of ITPR1 gene of duck was cloned into an eukaryotic expression vector and transfected into duck uterine epithelial cells. The overexpression of the ITPR1 gene, the concentration of Ca²⁺, the lipid content, and the expression of other 6 calcium transport-related genes was determined. The results showed that the concentration of Ca²⁺ in uterine epithelial cells was significantly reduced after transfection (P<0.05), the triglyceride content was significantly increased (P<0.01), and the high-density lipoprotein content was significantly decreased (P<0.01). The correlation analysis results showed that the overexpression of the C-terminal half of the ITPR1 gene was significantly positively correlated with the total cholesterol content (P<0.01), which was significantly positively correlated with the low-density lipoprotein content (P<0.05). The overexpression of the N-terminal half of the ITPR1 gene was significantly positively correlated with the triglyceride content (P<0.01), which was significantly negatively correlated with the concentration of Ca²⁺ (P<0.05). RT-qPCR results of 6 calcium transport-related genes showed that the overexpression of the C-terminal half of the ITPR1 gene significantly inhibited the expression of the IP3R2, VDAC2 and CAV1 genes, and the overexpression of the N-terminal half of the ITPR1 gene significantly promoted the expression of the IP3R3 and CACNA2D1 genes. In conclusion, the ITPR1 gene overexpression can promote Ca²⁺ release in duck uterus epithelial cells, promote the synthesis of triglyceride, low-density lipoprotein and cholesterol, and inhibit the production of high-density lipoprotein, and the ITPR1 gene overexpression affected the expression of all 6 calcium transport-related genes.
Animals ; Calcium/metabolism* ; Ducks/genetics* ; Epithelial Cells ; Female ; Inositol ; Inositol 1,4,5-Trisphosphate Receptors ; Lipids ; Uterus

Inositol 1,4,5-trisphosphate receptors (InsP3Rs) modulate Ca2+ release from intracellular Ca2+ store and are extensively expressed in the membrane of endoplasmic/sarcoplasmic reticulum and Golgi. Although caffeine and 2-aminoethoxydiphenyl borate (2-APB) have been widely used to block InsP3Rs, the use of these is limited due to their multiple actions. In the present study, we examined and compared the ability of caffeine and 2-APB as a blocker of Ca2+ release from intracellular Ca2+ stores and Ca2+ entry through store-operated Ca2+ (SOC) channel in the mouse pancreatic acinar cell. Caffeine did not block the Ca2+ entry, but significantly inhibited carbamylcholine (CCh)-induced Ca2+ release. In contrast, 2-APB did not block CCh-induced Ca2+ release, but remarkably blocked SOC-mediated Ca2+ entry at lower concentrations. In permeabilized acinar cell, caffeine had an inhibitory effect on InsP3-induced Ca2+ release, but 2-APB at lower concentration, which effectively blocked Ca2+ entry, had no inhibitory action. At higher concentrations, 2-APB has multiple paradoxical effects including inhibition of InsP3-induced Ca2+ release and direct stimulation of Ca2+ release. Based on the results, we concluded that caffeine is useful as an inhibitor of InsP3R, and 2-APB at lower concentration is considered a blocker of Ca2+ entry through SOC channels in the pancreatic acinar cell.
Acinar Cells ; Animals ; Boron Compounds ; Caffeine ; Calcium ; Carbachol ; Inositol 1,4,5-Trisphosphate Receptors ; Membranes ; Mice ; Reticulum

OBJECTIVE: To explore the clinical and genetic characteristics of a child with spinocerebellar ataxia type 29 (SCA29) due to novel variant of the inositol 1,4,5-trisphosphate receptor type 1 (ITPR1) gene. METHODS: The child was subjected high-throughput sequencing, and candidate variant was verified by Sanger sequencing of his family members. RESULTS: The child was found to harbor a c.800C>T (p.T267M) variant of the ITPR1 gene, which was not found in his parents and their fetus. The variant has occurred in a hotspot of the ITPR1 gene variants and was unreported before in China. Based on his clinical and genetic characteristics, the child was diagnosed with SCA29. CONCLUSION The novel heterozygous c.800C>T (p.T267M) of the ITPR1 gene probably underlay the SCA29 in this child.
Child ; Humans ; Family ; Inositol 1,4,5-Trisphosphate Receptors/genetics* ; Mutation ; Spinocerebellar Ataxias/genetics* ; Spinocerebellar Degenerations

Pancreatic acinar cells exhibit a polarity that is characterized by the localization of secretory granules at the apical membrane. However, the factors that regulate cellular polarity in these cells are not well understood. In this study, we investigated the effect of Mist1, a basic helix-loop-helix transcription factor, on the cellular architecture of pancreatic acinar cells. Mist1-null mice displayed secretory granules that were diffuse throughout the pancreatic acinar cells, from the apical to basolateral membranes, whereas Mist1 heterozygote mice showed apical localization of secretory granules. Deletion of the Mist1 gene decreased the expression of type 3 inositol 1,4,5-triphosphate receptors (IP3R) but did not affect apical localization and expression of IP3R2. Mist1-null mice also displayed an increase in luminal areas and an increase in the expression of zymogen granules in pancreatic acinar cells. These results suggest that Mist1 plays a critical role in polar localization of cellular organelles and in maintaining cellular architecture in mouse pancreatic acinar cells.
Acinar Cells ; Animals ; Cell Polarity ; Heterozygote ; Inositol 1,4,5-Trisphosphate Receptors ; Membranes ; Mice ; Organelles ; Phenobarbital ; Secretory Vesicles ; Transcription Factors

Radiation therapy for variety of human solid tumors utilizes mechanism of cell death after DNA damage caused by radiation. In response to DNA damage, cytochrome c was released from mitochondria by activation of pro-apoptotic Bcl-2 family proteins, and then elicits massive Ca2+ release from the ER that lead to cell death. It was also suggested that irradiation may cause the deregulation of Ca2+ homeostasis and trigger programmed cell death and regulate death specific enzymes. Thus, in this study, we investigated how cellular Ca2+ metabolism in RKO cells, in comparison to radiation-resistant A549 cells, was altered by gamma (gamma)-irradiation. In irradiated RKO cells, Ca2+ influx via activation of NCX reverse mode was enhanced and a decline of [Ca2+]i via forward mode was accelerated. The amount of Ca2+ released from the ER in RKO cells by the activation of IP3 receptor was also enhanced by irradiation. An increase in [Ca2+]i via SOCI was enhanced in irradiated RKO cells, while that in A549 cells was depressed. These results suggest that gamma-irradiation elicits enhancement of cellular Ca2+ metabolism in radiation-sensitive RKO cells yielding programmed cell death.
Calcium* ; Cell Death ; Colorectal Neoplasms* ; Cytochromes c ; DNA Damage ; Homeostasis ; Humans ; Inositol 1,4,5-Trisphosphate Receptors ; Metabolism* ; Mitochondria

BACKGROUND AND OBJECTIVES: Elevated intracellular calcium level is known to play important roles in the apoptotic pathway. IP3 receptor (ligand-gated channels that release Ca2+ from intracellular stores) is emerging as a key site for regulation of apoptosis. 2-Aminoethoxydiphenyl borate (2-APB) is one of the reliable IP3 receptor antagonists. We examined the effect of 2-APB on gentamicin ototoxicity in vitro, using the HEI-OC1 cell line. MATERIALS AND METHOD: HEI-OC1 cells were trWWeated with 100micrometer gentamicin. Using a CaspACE assay, we measured the caspases-3 activity in the gentamicin treated hair cells with and without 2-APB pre-incubation. We also observed intra-cellular calcium concentrations in HEI-OC1 cells using a confocal microscopy (calcium green-1 stain). Live cell imaging was performed by using fluorescence video-time lapse system. RESULTS: Cytosolic calcium elevation by gentamicin was remarkably inhibited by 2-APB. Caspases-3 activities of gentamicin treated cells were higher than those of the control. After incubation with 2-APB, caspases-3 activities and cell death of gentamicin treated cells were shown to decrease. CONCLUSION: 2-APB reduces Caspases-3 activity in the gentamicin treated HEI-OC1 cells by inhibition of cytosolic calcium increase.
Apoptosis ; Calcium ; Caspase 3 ; Cell Death ; Cell Line ; Cytosol ; Fluorescence ; Gentamicins* ; Hair ; Inositol 1,4,5-Trisphosphate Receptors* ; Microscopy, Confocal

Calcium has versatile roles in diverse physiological functions. Among these functions, intracellular Ca²⁺ plays a key role during the secretion of salivary glands. In this review, we introduce the diverse cellular components involved in the saliva secretion and related dynamic intracellular Ca²⁺ signals. Calcium acts as a critical second messenger for channel activation, protein translocation, and volume regulation, which are essential events for achieving the salivary secretion. In the secretory process, Ca²⁺ activates K⁺ and Cl⁻ channels to transport water and electrolyte constituting whole saliva. We also focus on the Ca²⁺ signals from intracellular stores with discussion about detailed molecular mechanism underlying the generation of characteristic Ca²⁺ patterns. In particular, inositol triphosphate signal is a main trigger for inducing Ca²⁺ signals required for the salivary gland functions. The biphasic response of inositol triphosphate receptor and Ca²⁺ pumps generate a self-limiting pattern of Ca²⁺ efflux, resulting in Ca²⁺ oscillations. The regenerative Ca²⁺ oscillations have been detected in salivary gland cells, but the exact mechanism and function of the signals need to be elucidated. In future, we expect that further investigations will be performed toward better understanding of the spatiotemporal role of Ca²⁺ signals in regulating salivary secretion.
Calcium Signaling ; Calcium ; Chloride Channels ; Inositol ; Inositol 1,4,5-Trisphosphate Receptors ; Protein Transport ; Saliva ; Salivary Glands ; Salivation ; Second Messenger Systems ; Secretory Pathway ; Water

Previously, we reviewed biological evidence that mercury could induce autoimmunity and coronary arterial wall relaxation as observed in Kawasaki syndrome (KS) through its effects on calcium signaling, and that inositol 1,4,5-triphosphate 3-kinase C (ITPKC) susceptibility in KS would predispose patients to mercury by increasing Ca2+ release. Hg2+ sensitizes inositol 1,4,5-triphosphate (IP3) receptors at low doses, which release Ca2+ from intracellular stores in the sarcoplasmic reticulum, resulting in delayed, repetitive calcium influx. ITPKC prevents IP3 from triggering IP3 receptors to release calcium by converting IP3 to inositol 1,3,4,5-tetrakisphosphate. Defective IP3 phosphorylation resulting from reduced genetic expressions of ITPKC in KS would promote IP3, which increases Ca2+ release. Hg2+ increases catecholamine levels through the inhibition of S-adenosylmethionine and subsequently catechol-O-methyltransferase (COMT), while a single nucleotide polymorphism of the COMT gene (rs769224) was recently found to be significantly associated with the development of coronary artery lesions in KS. Accumulation of norepinephrine or epinephrine would potentiate Hg2+-induced calcium influx by increasing IP3 production and increasing the permeability of cardiac sarcolemma to Ca2+. Norepinephrine and epinephrine also promote the secretion of atrial natriuretic peptide, a potent vasodilator that suppresses the release of vasoconstrictors. Elevated catecholamine levels can induce hypertension and tachycardia, while increased arterial pressure and a rapid heart rate would promote arterial vasodilation and subsequent fatal thromboses, particularly in tandem. Genetic risk factors may explain why only a susceptible subset of children develops KS although mercury exposure from methylmercury in fish or thimerosal in pediatric vaccines is nearly ubiquitous. During the infantile acrodynia epidemic, only 1 in 500 children developed acrodynia whereas mercury exposure was very common due to the use of teething powders. This hypothesis mirrors the leading theory for KS in which a widespread infection only induces KS in susceptible children. Acrodynia can mimic the clinical picture of KS, leading to its inclusion in the differential diagnosis for KS. Catecholamine levels are often elevated in acrodynia and may also play a role in KS. We conclude that KS may be the acute febrile form of acrodynia.
Acrodynia ; Arterial Pressure ; Autoimmunity ; Calcium ; Calcium Signaling ; Catechol O-Methyltransferase ; Catecholamines ; Child ; Coronary Vessels ; Diagnosis, Differential ; Epinephrine ; Heart Rate ; Humans ; Hydrazines ; Hypertension ; Inositol ; Inositol 1,4,5-Trisphosphate ; Inositol 1,4,5-Trisphosphate Receptors ; Inositol Phosphates ; Mucocutaneous Lymph Node Syndrome ; Norepinephrine ; Permeability ; Phosphorylation ; Polymorphism, Single Nucleotide ; Powders ; Relaxation ; Risk Factors ; S-Adenosylmethionine ; Sarcolemma ; Sarcoplasmic Reticulum ; Tachycardia ; Thimerosal ; Thrombosis ; Tooth ; Tooth Eruption ; Vaccines ; Vasoconstrictor Agents ; Vasodilation

BACKGORUND: The physiological activity of osteoblsts is known to be closely related to increased intracellular Ca2+ activity ([Ca2+ ]i) in osteoblasts. The cellular regulation of ([Ca2+ ]i) in osteoblasts is mediated by Ca2+ movements associated with Ca2+ release from intracellular Ca2+ stores, and transmembrane Ca2+ influx via Na Ca2+ exchanger, and Ca2+ ATPase. Reactive oxygen species, such as H2O2, play an important role in the regulation of cellular functions, and act as signaling molecules or as toxins in cells. METHODS: Osteoblasts were isolated from the femurs and tibias of neonatal Sprague-Dawley rats, and cultured for 7 days. The cultured osteoblasts were loaded with a Ca2+ -sensitive fluorescent dye, Fura-2 AM ester, and fluorescence images were monitored using a cooled CCD camera. Ca-spike changes upon ATP application were checked for (1) osteoblasts in Ca2+ -free and 2.5 mM CaCl2 normal Tyrode solution, (2) osteoblasts in which the Ca2+ of the endoplastic reticulumin had been depleted with ryanodine, thapsigargin ord caffein, and (3) osteoblasts pretreated with H2O2, in which the expression of iP3 receptor was checked by Western blotting. RESULTS: ATP increased intracellular free Ca2+ regardless of extracellular Ca2+ concentration. When the intracellular Ca2+ store was depleted, the level of increased Ca2+ activity by ATP was suppressed. H2O2 sustained the Ca2+ increase induced by ATP. The expression of iP3 receptor was enhanced by H2O2. CONCLUSiONS:H2O2 modulates intracellular Ca2+ activity in osteoblasts by increasing Ca2+ release from the intracellular Ca2+ stores.
Adenosine Triphosphate ; Blotting, Western ; Calcium-Transporting ATPases ; Femur ; Fluorescence ; Fura-2 ; Inositol 1,4,5-Trisphosphate Receptors ; Osteoblasts* ; Rats, Sprague-Dawley ; Reactive Oxygen Species* ; Ryanodine ; Thapsigargin ; Tibia