The FPR2-induced rise in cytosolic calcium in human neutrophils relies on an emptying of intracellular calcium stores and is inhibited by a gelsolin-derived PIP2-binding peptide

<p>Abstract</p> <p>Background</p> <p>The molecular basis for neutrophil recognition of chemotactic peptides is their binding to specific G-protein-coupled cell surface receptors (GPCRs). Human neutrophils express two pattern recognition GPCRs, FPR1 and FPR2, which belong to the family of formyl peptide receptors. The high degree of homology between these two receptors suggests that they share many functional and signal transduction properties, although they exhibit some differences with respect to signaling. The aims of this study were to determine whether FPR2 triggers a unique signal that allows direct influx of extracellular calcium without the emptying of intracellular calcium stores, and whether the gelsolin-derived PIP₂-binding peptide, PBP10, selectively inhibits FPR2-mediated transient rise in intracellular Ca²⁺.</p> <p>Results</p> <p>The transient rise in intracellular Ca²⁺induced by agonists for FPR1 or FPR2 in human neutrophils occurred also in the presence of a chelator of Ca²⁺(EGTA). PBP10 inhibited not only FPR2-induced oxidase activity, but also the transient rise in intracellular Ca²⁺.</p> <p>Conclusions</p> <p>Ca²⁺signaling mediated <it>via </it>FPR2 follows the same route as FPR1, which involves initial emptying of the intracellular stores. PBP10 inhibits selectively the signals generated by FPR2, both with respect to NADPH-oxidase activity and the transient rise in intracellular Ca²⁺induced by agonist exposure.</p

The role of the cytoskeleton in capacitaftive calcium entry in myenteric glia

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73680/1/j.1365-2982.2003.00406.x.pd

P2Y1 and P2Y12 receptor cross-talk in calcium signalling: Evidence from nonstarved and long-term serum-deprived glioma C6 cells

The current work presents results of experiments on the calcium response evoked by the stimulation by extracellular nucleotides occurring in control, nonstarved glioma C6 cells and in cells after long-term (96 h) serum starvation. Three nucleotide receptors were studied: P2Y1, P2Y2 and P2Y12. Two of them, P2Y1 and P2Y2, directly stimulate calcium response. The protein level of the P2Y2 receptor did not change during the serum starvation, while P2Y1 protein level fell dramatically. Observed changes in the calcium response generated by P2Y1 are directly correlated with the receptor protein level as well as with the amount of calcium present in the intracellular calcium stores, partially depleted during starvation process. The third receptor, P2Y12, did not directly evoke calcium response, however it is activated by the same ligand as P2Y1. The experiments with AR-C69941MX, the P2Y12-specific antagonist, indicated that in control and serum-starved cells, calcium response evoked by P2Y1 receptor is potentiated by the activity of P2Y12-dependent signaling pathways. This potentiation may be mediated by P2Y12 inhibitory effect on the plasma membrane calcium pump. The calcium influx enhanced by the cooperation of P2Y1 and P2Y12 receptor activity directly depends on the capacitative calcium entrance mechanism

Corticolimbic Expression of TRPC4 and TRPC5 Channels in the Rodent Brain

The canonical transient receptor potential (TRPC) channels are a family of non-selective cation channels that are activated by increases in intracellular Ca2+ and Gq/phospholipase C-coupled receptors. We used quantitative real-time PCR, in situ hybridization, immunoblots and patch-clamp recording from several brain regions to examine the expression of the predominant TRPC channels in the rodent brain. Quantitative real-time PCR of the seven TRPC channels in the rodent brain revealed that TRPC4 and TRPC5 channels were the predominant TRPC subtypes in the adult rat brain. In situ hybridization histochemistry and immunoblotting further resolved a dense corticolimbic expression of the TRPC4 and TRPC5 channels. Total protein expression of HIP TRPC4 and 5 proteins increased throughout development and peaked late in adulthood (6–9 weeks). In adults, TRPC4 expression was high throughout the frontal cortex, lateral septum (LS), pyramidal cell layer of the hippocampus (HIP), dentate gyrus (DG), and ventral subiculum (vSUB). TRPC5 was highly expressed in the frontal cortex, pyramidal cell layer of the HIP, DG, and hypothalamus. Detailed examination of frontal cortical layer mRNA expression indicated TRPC4 mRNA is distributed throughout layers 2–6 of the prefrontal cortex (PFC), motor cortex (MCx), and somatosensory cortex (SCx). TRPC5 mRNA expression was concentrated specifically in the deep layers 5/6 and superficial layers 2/3 of the PFC and anterior cingulate. Patch-clamp recording indicated a strong metabotropic glutamate-activated cation current-mediated depolarization that was dependent on intracellular Ca2+and inhibited by protein kinase C in brain regions associated with dense TRPC4 or 5 expression and absent in regions lacking TRPC4 and 5 expression. Overall, the dense corticolimbic expression pattern suggests that these Gq/PLC coupled nonselective cation channels may be involved in learning, memory, and goal-directed behaviors

ITPKC Single Nucleotide Polymorphism Associated with the Kawasaki Disease in a Taiwanese Population

Kawasaki disease (KD) is characterized by systemic vasculitis with unknown etiology. Previous studies from Japan indicated that a gene polymorphism of ITPKC (rs28493229) is responsible for susceptibility to KD. We collected DNA samples from 1,531 Taiwanese subjects (341 KD patients and 1,190 controls) for genotyping ITPKC. In this study, no significant association was noted for the ITPKC polymorphism (rs28493229) between the controls and KD patients, although the CC genotype was overrepresented. We further combined our data with previously published case/control KD studies in the Taiwanese population and performed a meta-analysis. A significant association between rs28493229 and KD was found (Odds Ratio:1.36, 95% Confidence Interval 1.12–1.66). Importantly, a significant association was obtained between rs28493229 and KD patients with aneurysm formation (P = 0.001, under the recessive model). Taken together, our results indicated that C-allele of ITPKC SNP rs28493229 is associated with the susceptibility and aneurysm formation in KD patients in a Taiwanese population

The Mitochondrial Ca(2+) Uniporter: Structure, Function, and Pharmacology.

Mitochondrial Ca(2+) uptake is crucial for an array of cellular functions while an imbalance can elicit cell death. In this chapter, we briefly reviewed the various modes of mitochondrial Ca(2+) uptake and our current understanding of mitochondrial Ca(2+) homeostasis in regards to cell physiology and pathophysiology. Further, this chapter focuses on the molecular identities, intracellular regulators as well as the pharmacology of mitochondrial Ca(2+) uniporter complex

Release of PLGA–encapsulated dexamethasone from microsphere loaded porous surfaces

The aim of the present study was to investigate the morphology and function of a drug eluting metallic porous surface produced by the immobilization of poly lactide-co-glycolide microspheres bearing dexamethasone onto plasma electrolytically oxidized Ti–6Al–7Nb medical alloy. Spheres of 20 μm diameter were produced by an oil-in-water emulsion/solvent evaporation method and thermally immobilized onto titanium discs. The scanning electron microscopy investigations revealed that the size distribution and morphology of the attached spheres had not changed significantly. The drug release profiles following degradation in phosphate buffered saline for 1000 h showed that, upon immobilisation, the spheres maintained a sustained release, with a triphasic profile similar to the non-attached system. The only significant change was an increased release rate during the first 100 h. This difference was attributed to the effect of thermal attachment of the spheres to the surface

P2 nucleotide receptors on C2C12 satellite cells

In developing muscle cells environmental stimuli transmitted by purines binding to the specific receptors are crucial proliferation regulators. C2C12 myoblasts express numerous purinergic receptors representing both main classes: P2X and P2Y. Among P2Y receptors we have found the expression of P2Y1, P2Y2, P2Y4, P2Y6 and P2Y12 family members while among P2X receptors P2X4, P2X5 and P2X7 were discovered. We have been able to show that activation of those receptors is responsible for ERK class kinase activity, responsible for regulation of cell proliferation pathway. We have also demonstrated that this activity is calcium dependent suggesting Ca2+ ions as secondary messenger between receptor and kinase regulatory system. More specifically, we do suspect that in C2C12 myoblasts calcium channels of P2X receptors, particularly P2X5 play the main role in proliferation regulation. In further development of myoblasts into myotubes, when proliferation is gradually inhibited, the pattern of P2 receptors is changed. This phenomenon is followed by diminishing of the P2Y2-dependent Ca2+ signaling, while the mRNA expression of P2Y2 receptor reminds still on the high level. Moreover, P2X2 receptor mRNA, absent in myoblasts appears in myotubes. These data show that differentiation of C2C12 cell line satellite myoblasts is accompanied by changes in P2 receptors expression pattern