Interactions between inositol tris- and tetrakis-phosphates. Effects on intracellular Ca2+ mobilization in SH-SY5Y cells.

Abstract

The potential Ca2(+)-releasing activity of the inositol tetrakisphosphates Ins(1,3,4,6)P4 and DL-Ins(1,4,5,6)P4 and the inositol pentakisphosphate Ins(1,3,4,5,6)P5 and their effect on Ins(1,4,5)P3- and DL-Ins (1,3,4,5)P4-mediated Ca2+ release were examined in permeabilized SH-SY5Y human neuroblastoma cells. Neither DL-Ins(1,4,5,6)P4 nor Ins(1,3,4,5,6)P5 exhibit Ca2(+)-releasing activity at concentrations up to 10 microM, but Ins(1,3,4,6)P4 releases Ca2+ dose-dependently, with an EC50 value (conen, giving half-maximal effect) of 5.92 +/- 0.47 microM. Maximal response by this tetrakisphosphate (49 +/- 2.5%) is significantly less than that seen with Ins(1,4,5)P3 (60 +/- 3%) and is achieved at a concentration of 30 microM. In the presence of this concentration of Ins(1,3,4,6)P4 the EC50 value for Ins(1,4,5)P3-mediated Ca2+ release increases from 0.12 +/- 0.02 microM to 2.11 +/- 0.51 microM, providing evidence that this naturally occurring inositol tetrakisphosphate may recognize and exhibit its Ca2(+)-releasing activity via the Ins(1,4,5)P3 receptor. DL-Ins(1,3,4,5)P4, however, at its maximally effective concentration (10 microM) does not significantly affect Ins(1,4,5)P3-mediated Ca2+ release, and therefore appears to mediate its Ca2(+)-mobilizing action through a receptor distinct from that for Ins(1,4,5)P3.

• Authors: D J Gawler, B V Potter, R Gigg, S R Nahorski
• Journal: The Biochemical journal (Biochem J) Vol. 276 ( Pt 1) Pg. 163-7 (May 15 1991) ISSN: 0264-6021 [Print] England
• PMID: 1645528 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Calcium Channels
• ITPR1 protein, human
• Inositol 1,4,5-Trisphosphate Receptors
• Inositol Phosphates
• Receptors, Cell Surface
• Receptors, Cytoplasmic and Nuclear
• inositol-1,3,4,5-tetrakisphosphate
• inositol-1,3,4,6-tetrakisphosphate
• inositol-1,4,5,6-tetrakisphosphate
• inositol pentaphosphate
• Inositol 1,4,5-Trisphosphate
• Calcium

Topics

• Binding, Competitive
• Calcium (metabolism)
• Calcium Channels
• Cell Line
• Humans
• Inositol 1,4,5-Trisphosphate (metabolism, pharmacology)
• Inositol 1,4,5-Trisphosphate Receptors
• Inositol Phosphates (pharmacology)
• Kinetics
• Neuroblastoma
• Receptors, Cell Surface (drug effects, metabolism)
• Receptors, Cytoplasmic and Nuclear