TY - JOUR
T1 - Myo-inositol 1,3,4,5-tetrakisphosphate can independently mobilise intracellular calcium, via the inositol 1,4,5-trisphosphate receptor
T2 - studies with myo-inositol 1,4,5-trisphosphate-3-phosphorothioate and myo-inositol hexakisphosphate
AU - Wilcox, Robert A.
AU - Whitham, Emma M.
AU - Liu, Changsheng
AU - Potter, Barry V.L.
AU - Nahorski, Stefan R.
PY - 1993/12/27
Y1 - 1993/12/27
N2 - Myo-inositol 1,3,4,5-tetrakisphosphate [Ins(1,3,4,5)P4] acts as a full agonist for Ca2+ release in saponin-permeabilised SH-SY5Y neuroblastoma cells. Studies were conducted in the presence of myo-inositol hexakisphosphate (InsP6, 10 μM), to inhibit the Ins(1,3,4,5)P4-3-phosphatase catalysed back conversion of Ins(1,3,4,5)P4 to Ins(1,4,5)P3. HPLC analysis confirmed that Ins(1,3,4,5)P4 releases the entire content of Ins(1,4,5)P3-sensitive intracellular Ca2+ stores, independent of 3-phosphatase activity. Further we utilised racemic myo-inositol 1,4,5-trisphosphate-3-phosphorothioate [dl-Ins(1,3,4,5)P4-3S], a novel intrinsically Ins(1,3,4,5)P4-3-phosphatase resistant Ins(1,3,4,5)P4 analogue. DL-Ins(1,3,4,5)P4-3S specifically displaced [3H]Ins(1,4,5)P3 from bovine adrenal cortex Ins(1,4,5)P3 binding sites (IC50 = 889 nM, compared to Ins(1,4,5)P3,1C50 = 4.4 nM and Ins(1,3,4,5)P4, IC50 = 152 nM). dl-Ins(1,3,4,5)P4-3S was a full agonist for Ca2+ release (EC50 = 4.7 μM), being 90- and 2-fold less potent than Ins(1,4,5)P3 and Ins(1,3,4,5)P4 (with InsP6), respectively. dl-Ins(1,3,4,5)P4-3S will be an important tool for identification of potentially exclusive Ins(1,3,4,5)P4 second messenger functions, since its resistance to 3-phosphatase action precludes the inconvenient artefact of steady state Ins(1,4,5)P3 generation.
AB - Myo-inositol 1,3,4,5-tetrakisphosphate [Ins(1,3,4,5)P4] acts as a full agonist for Ca2+ release in saponin-permeabilised SH-SY5Y neuroblastoma cells. Studies were conducted in the presence of myo-inositol hexakisphosphate (InsP6, 10 μM), to inhibit the Ins(1,3,4,5)P4-3-phosphatase catalysed back conversion of Ins(1,3,4,5)P4 to Ins(1,4,5)P3. HPLC analysis confirmed that Ins(1,3,4,5)P4 releases the entire content of Ins(1,4,5)P3-sensitive intracellular Ca2+ stores, independent of 3-phosphatase activity. Further we utilised racemic myo-inositol 1,4,5-trisphosphate-3-phosphorothioate [dl-Ins(1,3,4,5)P4-3S], a novel intrinsically Ins(1,3,4,5)P4-3-phosphatase resistant Ins(1,3,4,5)P4 analogue. DL-Ins(1,3,4,5)P4-3S specifically displaced [3H]Ins(1,4,5)P3 from bovine adrenal cortex Ins(1,4,5)P3 binding sites (IC50 = 889 nM, compared to Ins(1,4,5)P3,1C50 = 4.4 nM and Ins(1,3,4,5)P4, IC50 = 152 nM). dl-Ins(1,3,4,5)P4-3S was a full agonist for Ca2+ release (EC50 = 4.7 μM), being 90- and 2-fold less potent than Ins(1,4,5)P3 and Ins(1,3,4,5)P4 (with InsP6), respectively. dl-Ins(1,3,4,5)P4-3S will be an important tool for identification of potentially exclusive Ins(1,3,4,5)P4 second messenger functions, since its resistance to 3-phosphatase action precludes the inconvenient artefact of steady state Ins(1,4,5)P3 generation.
KW - Calcium mobilization
KW - Inositol 1,3,4,5-tetrakisphosphate analogue
KW - Inositol 1,3,4,5-tetrakisphosphate-3-phosphatase
KW - Ins(1,4,5)P receptor
KW - SH-SY5Y cell
UR - http://www.scopus.com/inward/record.url?scp=0027140497&partnerID=8YFLogxK
U2 - 10.1016/0014-5793(93)80817-E
DO - 10.1016/0014-5793(93)80817-E
M3 - Article
C2 - 8262243
AN - SCOPUS:0027140497
SN - 0014-5793
VL - 336
SP - 267
EP - 271
JO - FEBS Letters
JF - FEBS Letters
IS - 2
ER -
