Ca2+ oscillations in hepatocytes do not require the modulation of InsP3 3‐kinase activity by Ca2+

Receptor‐mediated production of inositol 1,4,5‐trisphosphate (InsP3) initiates Ca2+ release and is responsible for cytosolic Ca2+ oscillations. InsP3 oscillations have also been observed in some cells. One of the enzymes controlling InsP3 catabolism, the InsP3 3‐kinase, is stimulated by Ca2+; this regulation is presumably part of the reason for InsP3 oscillations that have been observed in some cells. Here, we investigate the possible role of Ca2+‐activated InsP3 catabolism on the characteristics of the InsP3‐induced Ca2+ oscillations. Numerical simulations show that if it is assumed that the Ca2+‐independent InsP3 catabolism is predominant, Ca2+ oscillations remain qualitatively unchanged although the relative amplitude of the oscillations in InsP3 concentrations becomes minimal. We tested this prediction in hepatocytes by masking the Ca2+‐dependent InsP3 catabolism by 3‐kinase through the injection of massive amounts of InsP3 5‐phosphatase, which is not stimulated by Ca2+. We find that in such injected hepatocytes, Ca2+ oscillations generated by modest agonist levels are suppressed, presumably because of the decreased dose in InsP3, but that at higher doses of agonist, oscillations reappear, with characteristics similar to those of untreated cells at low agonist doses. Altogether, these results suggest that oscillations in InsP3 concentration due to Ca2+‐stimulated InsP3 catabolism do not play a major role for the oscillations in Ca2+ concentration.

[1]  Nancy L. Allbritton,et al.  Metabolism of Inositol 1,4,5-Trisphosphate and Inositol 1,3,4,5-Tetrakisphosphate by the Oocytes of Xenopus laevis * , 1998, The Journal of Biological Chemistry.

[2]  Kenneth W. Young,et al.  Intracellular signalling: Receptor-specific messenger oscillations , 2001, Nature.

[3]  J. Vandekerckhove,et al.  Cloning and expression in Escherichia coli of a rat brain cDNA encoding a Ca2+/calmodulin-sensitive inositol 1,4,5-trisphosphate 3-kinase. , 1990, The Biochemical journal.

[4]  J. Poggioli,et al.  How far does phospholipase C activity depend on the cell calcium concentration? A study in intact cells. , 1987, The Biochemical journal.

[5]  R Y Tsien,et al.  Generation of calcium oscillations in fibroblasts by positive feedback between calcium and IP3. , 1991, Science.

[6]  M. Berridge,et al.  The versatility and universality of calcium signalling , 2000, Nature Reviews Molecular Cell Biology.

[7]  G. Dupont,et al.  Simulations of the effects of inositol 1,4,5-trisphosphate 3-kinase and 5-phosphatase activities on Ca2+ oscillations. , 1997, Cell calcium.

[8]  A. Conigrave,et al.  A purification strategy for inositol 1,4,5-trisphosphate 3-kinase from rat liver based upon heparin interaction chromatography. , 1992, Cellular signalling.

[9]  M. Iino,et al.  Ca2+‐sensor region of IP3 receptor controls intracellular Ca2+ signaling , 2001 .

[10]  M. Berridge,et al.  Inositol Trisphosphate as a Second Messenger in Signal Transduction , 1987, Annals of the New York Academy of Sciences.

[11]  J. Luzio,et al.  Isolation and sequence of a full length cDNA encoding a novel rat inositol 1,4,5-trisphosphate 3-kinase. , 1994, Biochimica et biophysica acta.

[12]  J. Putney,et al.  Effect of cytoplasmic Ca2+ on (1,4,5)IP3 formation in vasopressin-activated hepatocytes. , 1997, Cell calcium.

[13]  L. Stryer,et al.  Molecular model for receptor-stimulated calcium spiking. , 1988, Proceedings of the National Academy of Sciences of the United States of America.

[14]  M Claret,et al.  Coordinated intercellular calcium waves induced by noradrenaline in rat hepatocytes: dual control by gap junction permeability and agonist , 1997, The EMBO journal.

[15]  J. Altin,et al.  Stimulation of hepatic inositol 1,4,5-trisphosphate kinase activity by Ca2+-dependent and -independent mechanisms. , 1988, The Biochemical journal.

[16]  Upinder S Bhalla,et al.  Simulations of inositol phosphate metabolism and its interaction with InsP(3)-mediated calcium release. , 2002, Biophysical journal.

[17]  P. Cobbold,et al.  Phorbol-ester-induced alterations of free calcium ion transients in single rat hepatocytes. , 1987, The Biochemical journal.

[18]  L M Loew,et al.  Determination of time-dependent inositol-1,4,5-trisphosphate concentrations during calcium release in a smooth muscle cell. , 1999, Biophysical journal.

[19]  E Bornberg-Bauer,et al.  Switching from simple to complex oscillations in calcium signaling. , 2000, Biophysical journal.

[20]  J. Putney,et al.  Spatial and temporal aspects of cellular calcium signaling , 1996, FASEB journal : official publication of the Federation of American Societies for Experimental Biology.

[21]  S. Swillens,et al.  Quantal release, incremental detection, and long-period Ca2+ oscillations in a model based on regulatory Ca2+-binding sites along the permeation pathway. , 1996, Biophysical journal.

[22]  M Claret,et al.  Mechanism of receptor‐oriented intercellular calcium wave propagation in hepatocytes , 2000, FASEB journal : official publication of the Federation of American Societies for Experimental Biology.

[23]  C. Heizmann,et al.  Calcium: The Molecular Basis of Calcium Action in Biology and Medicine , 2000, Springer Netherlands.

[24]  J. Stucki,et al.  Perturbation of myo-inositol-1,4,5-trisphosphate levels during agonist-induced Ca2+ oscillations. , 1998, Biophysical journal.

[25]  C. Erneux,et al.  The control of intracellular signal molecules at the level of their hydrolysis: the example of inositol 1,4,5-trisphosphate 5-phosphatase , 1994, Molecular and Cellular Endocrinology.

[26]  Ca(2+)-mobilizing hormones induce sequentially ordered Ca2+ signals in multicellular systems of rat hepatocytes. , 1994, The Biochemical journal.

[27]  L. Missiaen,et al.  Isoprenylated Human Brain Type I Inositol 1,4,5-Trisphosphate 5-Phosphatase Controls Ca2+ Oscillations Induced by ATP in Chinese Hamster Ovary Cells* , 1997, The Journal of Biological Chemistry.

[28]  Kenzo Hirose,et al.  Encoding of Ca2+ signals by differential expression of IP3 receptor subtypes , 1999, The EMBO journal.

[29]  A Goldbeter,et al.  Minimal model for signal-induced Ca2+ oscillations and for their frequency encoding through protein phosphorylation. , 1990, Proceedings of the National Academy of Sciences of the United States of America.

[30]  G. Hajnóczky,et al.  Minimal requirements for calcium oscillations driven by the IP3 receptor , 1997, The EMBO journal.

[31]  T Höfer,et al.  Model of intercellular calcium oscillations in hepatocytes: synchronization of heterogeneous cells. , 1999, Biophysical journal.

[32]  M. Sanderson,et al.  Mechanisms of calcium oscillations and waves: a quantitative analysis , 1995, FASEB journal : official publication of the Federation of American Societies for Experimental Biology.

[33]  G B Willars,et al.  Single-cell imaging of graded Ins(1,4,5)P3 production following G-protein-coupled-receptor activation. , 2001, The Biochemical journal.

[34]  M. Tanabe,et al.  Spatiotemporal dynamics of inositol 1,4,5-trisphosphate that underlies complex Ca2+ mobilization patterns. , 1999, Science.

[35]  R. Wojcikiewicz,et al.  Type I, II, and III inositol 1,4,5-trisphosphate receptors are unequally susceptible to down-regulation and are expressed in markedly different proportions in different cell types , 1995, The Journal of Biological Chemistry.