title: Inositol tetrakisphosphate as a frequency regulator in calcium oscillations in HeLa cells.
abstract: Cellular signaling mediated by inositol (1,4,5)trisphosphate (Ins(1, 4,5)P(3)) results in oscillatory intracellular calcium (Ca(2+)) release. Because the amplitude of the Ca(2+) spikes is relatively invariant, the extent of the agonist-mediated effects must reside in their ability to regulate the oscillating frequency. Using electroporation techniques, we show that Ins(1,4,5)P(3), Ins(1,3,4, 5)P(4), and Ins(1,3,4,6)P(4) cause a rapid intracellular Ca(2+) release in resting HeLa cells and a transient increase in the frequency of ongoing Ca(2+) oscillations stimulated by histamine. Two poorly metabolizable analogs of Ins(1,4,5)P(3), Ins(2,4,5)P(3), and 2,3-dideoxy-Ins(1,4,5)P(3), gave a single Ca(2+) spike and failed to alter the frequency of ongoing oscillations. Complete inhibition of Ins(1,4,5)P(3) 3-kinase (IP3K) by either adriamycin or its specific antibody blocked Ca(2+) oscillations. Partial inhibition of IP3K causes a significant reduction in frequency. Taken together, our results indicate that Ins(1,3,4,5)P(4) is the frequency regulator in vivo, and IP3K, which phosphorylates Ins(1,4, 5)P(3) to Ins(1,3,4,5)P(4), plays a major regulatory role in intracellular Ca(2+) oscillations.
authors.affiliation: Laboratory of Biochemistry, NHLBI, National Institutes of Health, Bethesda, Maryland 20892, USA.
authors.forename: D M
authors.initials: DM
authors.lastname: Zhu
authors.forename: E
authors.initials: E
authors.lastname: Tekle
authors.forename: C Y
authors.initials: CY
authors.lastname: Huang
authors.forename: P B
authors.initials: PB
authors.lastname: Chock
mesh_terms: D000906:Antibodies / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D004317:Doxorubicin / Q000494:pharmacology; D018274:Electroporation; D006367:HeLa Cells; D006632:Histamine / Q000494:pharmacology; D006801:Humans; D015544:Inositol 1,4,5-Trisphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D007295:Inositol Phosphates / Q000494:pharmacology*; D019869:Phosphatidylinositol 3-Kinases; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000037:antagonists & inhibitors / Q000276:immunology
chemical_list: D000906:Antibodies; D007295:Inositol Phosphates; C081655:inositol-1,3,4,5-tetrakisphosphate; C081653:inositol-1,3,4,6-tetrakisphosphate; D004317:Doxorubicin; D006632:Histamine; D015544:Inositol 1,4,5-Trisphosphate; D019869:Phosphatidylinositol 3-Kinases; D017853:Phosphotransferases (Alcohol Group Acceptor); C051038:Inositol 1,4,5-trisphosphate 3-kinase; D002118:Calcium