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Selective regulation of protein activity by complex Ca[sup]2+ oscillations : a theoretical study
Beate Knoke, Marko Marhl, Stefan Schuster, 2007, independent scientific component part or a chapter in a monograph

Abstract: Calcium oscillations play an important role in intracellular signal transduction. As a second messenger, ▫$Ca^{2+}$▫ represents a link between several input signals and several target processes in the cell. Whereas the frequency of simple ▫$Ca^{2+}$▫ oscillations enables a selective activation of a specific protein and herewith a particular process, the question arises of how at the same time two or more classes of proteins can be specifically regulated. The question is general and concerns the problem of how one second messenger can transmit more than one signal simultaneously (bow-tie structure of signalling). To investigate whether a complex ▫$Ca^{2+}$▫ signal like bursting, a succession of low-peak and high-peak oscillatory phases, could selectively activate different proteins, several bursting patterns with simplified square pulses were applied in a theoretical model. The results indicate that bursting ▫$Ca^{2+}$▫ oscillations allow a differential regulation of two different calcium-binding proteins, and hence, perform the desired function.
Keywords: biophysics, calcium oscillations, cellular dynamics, mathematical models, signalling, bow-tie structures, bursting, decoding
Published in DKUM: 07.06.2012; Views: 1593; Downloads: 28
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Spatio-temporal modelling explains the effect of reduced plasma membrane Ca[sup]2+[/sup] efflux on intracellular Ca[sup]2+[/sup] oscillations in hepatocytes
Marko Marhl, Marko Gosak, Matjaž Perc, C. Jane Dixon, Anne K. Green, 2008, original scientific article

Abstract: In many non-excitable eukaryotic cells, including hepatocytes, ▫$Ca^{2+}$▫ oscillations play a key role in intra- and intercellular signalling, thus regulating many cellular processes from fertilisation to death. Therefore, understanding the mechanisms underlying these oscillations, and consequently understanding how they may be regulated, is of great interest. In this paper, we study the influence of reduced ▫$Ca^{2+}$▫ plasma membrane efflux on ▫$Ca^{2+}$▫ oscillations in hepatocytes. Our previous experiments with carboxyeosin show that a reduced plasma membrane ▫$Ca^{2+}$▫ efflux increases the frequency of ▫$Ca^{2+}$▫ oscillations, but does not affect the duration of individual transients. This phenomenon can be best explained by taking into account not only the temporal,but also the spatial dynamics underlying the generation of ▫$Ca^{2+}$▫ oscillations in the cell. Here we divide the cell into a grid of elements and treat the ▫$Ca^{2+}$▫ dynamics as a spatio-temporal phenomenon. By converting an existing temporal model into a spatio-temporal one, we obtain theoretical predictions that are in much better agreement with the experimental observations.
Keywords: cellular signalling, calcium oscillations, intracellular oscilations, spatio-temporal dynamics, hepatocytes, stochastic simulations
Published in DKUM: 07.06.2012; Views: 1272; Downloads: 49
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