Calcium signalling

Sakaki, Y., et al. (1988). Structure and function of the calcium-binding photoprotein aequorin studies by recombinant DNA technology. In Yagi, Y., and Miyazaki, T. (eds.), Calcium Signal Cell Response, pp. 151-156. Jpn. Sci. Soc. Press Tokyo, Japan. 

In the skin, ENaC is expressed in keratinocytes of the epidermis and in hair follicles. It could play a role in terminal differentiation by modulating keratinocyte calcium signaling. The skin expresses MR, GR, and 11 3HSD2, but the role of aldosterone and glucocorticoids on ENaC activity and keratinocyte differentiation is not yet understood. 

Hille B, Billiard J, Babcock DF et al (1999) Stimulation of exocytosis without a calcium signal. J Physiol 520 23-31... 

Berridge MJ et al (2003) Calcium signalling dynamics, homeostasis and remodelling. Nat Rev Mol Cell Biol 4 517-529... 

Detection of Calcium Signals in Neutrophils Using Fluorescent Dyes... 

Previous studies indicate that osmotic gradients promote membrane fusion, while hyperosmotic conditions inhibit membrane fusion during exocytosis. Consistent with this idea is the observation that the release of lysosomal enzymes from rabbit neutrophils, induced by the chemotactic peptide J -formylmethionyl-leucyl-phenylalanine (FMLP), is inhibited almost 80% in a 700-mosmol/kg medium. Inhibition is immediate (within 10 s), increases with osmolality, and is independent of the osmoticant. Neutrophils loaded with the calcium indicator indo-1 exhibit an FMLP-induced calcium signal that is inhibited by hyperosmolality. Hyperosmolality (700 mosmol/kg) increases basal calcium levels and reduces the peak of the calcium signal elicited by FMLP at concentrations ranging from 10 ° to 10 M. 

Studies using chlorotetracycline, a dye that detects membrane-bound calcium within cells, show that part of the signal results from release of intracellularly sequestered calcium. Thus, in neutrophils, hyperosmolality inhibits not only exocytosis but also the calcium signal that initiates exocytosis. 

Figure 7. Sensitivity of the FMLP-induced calcium signal to removal of extracellular calcium. Indo-l-loaded neutrophils were stimulated with 10 M FMLP in a medium of normal osmolality (320 mosmol/kg) and indo-1 fluorescence was recorded as described in Figure 6. Trace 1 Cells in a medium with normal calcium (1.5 mN). Trace 2 EGTA added to chelate extracellular calcium before stimulation extracellular calcium (1.5 milf) readded 70 s after stimulation. Trace 3 Cells in a medium with normal calcium EGTA added 70 s after stimulation to chelate extracellular calcium.

Figure 10. Three phases of the FMLP-induced calcium signal in rabbit neutrophils. (Reproduced from ref. 22. Copyright 1987 Elsevier Science Publishers, BV.)...

Berridge M Inositol triphosphate and calcium signalling. Nature 1993 361 315. 

Carmignoto G, Pasti L, Pozzan T (1998) On the role of voltage-dependent calcium channels in calcium signaling of astrocytes in situ. J Neurosci 18 4637-4645 Cartier L, Hartley O, Dubois-Dauphin M, Krause KH (2005) Chemokine receptors in the central nervous system role in brain inflammation and neurodegenerative diseases. Brain Res Brain Res Rev 48 16 2... 

Perea G, Araque A (2005) Properties of synapticaUy evoked astrocyte calcium signal reveal synaptic information processing by astrocytes. J Neurosci 25 2192-2203 Perea G, Araque A (2007) Astrocytes potentiate transmitter release at single hippocampal synapses. Science 317 1083-1086... 

Winship IR, Plaa N, Murphy TH (2007) Rapid astrocyte calcium signals correlate with neuronal activity and onset of the hemodynamic response in vivo. J Neurosci 27 6268-6272 Wu MM, Buchanan J, Luik RM, Lewis RS (2006) Ca store depletion causes STIMl to accumulate in ER regions closely associated with the plasma membrane. J Cell Biol 174 803-813 Wyss-Coray T (2006) Inflammation in Alzheimer disease driving force, bystander or beneficial response Nat Med 12 1005-1015... 

Perea G, Araque A (2005) Glial calcium signaling and neuron-glia communication. CeU Calcium... 

In the epidermis, one observes an accumulation of calcium in the tricellular junction (arrow head) and in the tangential wall (open arrow). In young flax hypocotyl, the calcium-signal intensities were lower than in mature flax hypocotyl (conq)are A and C). 

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