Design of potent and selective inhibitors of myo-inositol 1,4,5-trisphosphate 5-phosphatase.
The interactions of synthetic analogues of D-myo-inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] with the Ins(1,4,5)P3 receptor in permeabilized SH-SY5Y cells and with two key metabolic enzymes, Ins(1,4,5)P(3)3-kinase from a supernatant preparation of rat brain homogenates and Ins(1,4,5)P(3)5-phosphatase from human erythrocyte ghosts, have been examined. L-chiro-Inositol 2,3,5-trisphosphorothioate [L-chiro-Ins(2,3,5)PS3], which we have previously identified as a partial agonist at the Ins(1,4,5)P3 receptor [Safrany, S. T., Wilcox, R. A., Liu, C., Dubreuil, D., Potter, B. V. L., & Nahorski S. R. (1993) Mol. Pharmacol. 43, 499-503], is identified as the most potent 5-phosphatase inhibitor yet described (inhibiting dephosphorylation of [3H]Ins(1,4,5)P3 with Ki = 230nM). L-chiro-Ins(2,3,5)PS3 was also found to be the most potent small-molecule inhibitor of 3-kinase (Ki = 820 nM). The properties of three novel, potent, and selective inhibitors of 5-phosphatase are described. L-myo-Inositol 1,4,5-trisphosphorothioate inhibited 5-phosphatase with Ki = 430 nM, showing 250-fold selectivity over 3-kinase (Ki = 108 microM); myo-inositol 1,3,5-trisphosphorothioate inhibited 5-phosphatase with 475-fold selectivity over 3-kinase (Ki = 520 nM and 247 microM, respectively). The most potent, selective inhibitor of 5-phosphatase was L-chiro-inositol 1,4,6-trisphosphorothioate [L-chiro-Ins(1,4,6)PS3]. L-chiro-Ins(1,4,6)PS3 inhibited 5-phosphatase with Ki = 300 nM and did not interact with the Ins(1,4,5)P3 receptor or 3-kinase at doses tested. These studies, therefore, identify a highly potent and selective inhibitor of 5-phosphatase, which should be considered the tool of choice when inhibiting this enzyme in a broken cell or cell-free system.
Safrany
S T
ST
Department of Cell Physiology and Pharmacology, University of Leicester, U.K.
Mills
S J
SJ
Liu
C
C
Lampe
D
D
Noble
N J
NJ
Nahorski
S R
SR
Potter
B V
BV
D000818:Animals; D015220:Calcium Channels / Q000737:chemistry*; D015195:Drug Design; D004791:Enzyme Inhibitors; D004910:Erythrocyte Membrane / Q000201:enzymology; D006801:Humans; D066298:In Vitro Techniques; D015544:Inositol 1,4,5-Trisphosphate / Q000737:chemistry* / Q000378:metabolism; D053496:Inositol 1,4,5-Trisphosphate Receptors; D000072181:Inositol Polyphosphate 5-Phosphatases; D010744:Phosphoric Monoester Hydrolases / Q000037:antagonists & inhibitors*; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism; D051381:Rats; D018160:Receptors, Cytoplasmic and Nuclear / Q000737:chemistry*; D015290:Second Messenger Systems; D015398:Signal Transduction / Q000187:drug effects; D013329:Structure-Activity Relationship
D015220:Calcium Channels; D004791:Enzyme Inhibitors; C506926:ITPR1 protein, human; D053496:Inositol 1,4,5-Trisphosphate Receptors; D018160:Receptors, Cytoplasmic and Nuclear; D015544:Inositol 1,4,5-Trisphosphate; D017853:Phosphotransferases (Alcohol Group Acceptor); C051038:Inositol 1,4,5-trisphosphate 3-kinase; D010744:Phosphoric Monoester Hydrolases; D000072181:Inositol Polyphosphate 5-Phosphatases