TY - JOUR
T1 - Antagonists of myo-inositol 3,4,5,6-tetrakisphosphate allow repeated epithelial chloride secretion
AU - Rudolf, Marco T.
AU - Dinkel, Carlo
AU - Traynor-Kaplan, Alexis E.
AU - Schultz, Carsten
N1 - Funding Information:
We thank Dr. Peter Schulze for MS spectra and Ms. Nicole Heath for revising the manuscript. This work was supported by the Deutsche Forschungsgemeinschaft and the Fonds der Chemischen Industrie.
PY - 2003/7/31
Y1 - 2003/7/31
N2 - Cystic fibrosis (CF) patients suffer from a defect in hydration of mucosal membranes due to mutations in the cystic fibrosis transmembrane regulator (CFTR), an apical chloride channel in mucosal epithelia. Disease expression in CF knockout mice is organ specific, varying with the level of expression of calcium activated Cl- channels (CLCA). Therefore, restoring transepithelial Cl- secretion by augmenting alternate Cl- channels, such as CLCA, could be beneficial. However, CLCA-mediated Cl- secretion is transient, due in part to the inhibitory effects of myo-inositol 3,4,5,6-tetrakisphosphate [Ins(3,4,5,6)P4]. This suggests that antagonists of Ins(3,4,5,6)P4 could be useful in treatment of CF. We have, therefore, synthesized a series of membrane-permeant Ins(3,4,5,6)P4 derivatives, carrying alkyl substituents on the hydroxyl groups and screened them for effects on Cl- secretion in a human colonic epithelial cell line, T84. While membrane-permeant Ins(3,4,5,6)P4 derivatives had no direct effects on carbachol-stimulated Cl- secretion, Ins(3,4,5,6)P4 derivatives, but not enantiomeric Ins(1,4,5,6)P4 derivatives, reversed the inhibitory effect of Ins(3,4,5,6)P4 on subsequent thapsigargin activation of Cl- secretion. The extent of the antagonistic effect of the Ins(3,4,5,6)P4 derivatives varied with the position of the alkyl substituents. Derivatives with a cyclohexylidene ketal or a butyl-chain at the 1-position reversed the Ins(3,4,5,6)P4-mediated inhibition of Cl- secretion by up to 96 and 85%, respectively, whereas butylation of the 1- and 2-position generated a reversal effect of only 65%. Derivatives carrying the butyl chain only at the 2-position showed no antagonistic effect. These data: (1) Support the hypothesis that Ins(3,4,5,6)P4 stereospecifically inhibits Ca2+ activated Cl- secretion and that Ins(3,4,5,6)P4 mediates most, if not all of the cholinergic-mediated inhibition of chloride secretion in T84 cells; (2) Demonstrate Ins(3,4,5,6)P4-mediated inhibition can be completely reversed with rationally designed membrane-permeant Ins(3,4,5,6)P4 antagonists; (3) Demonstrate that a SAR for membrane-permeant Ins(3,4,5,6) P4 antagonists can be generated and screened in a physiologically relevant cell-based assay; (4) Indicate that Ins(3,4,5,6)P4 derivatives could serve as a starting point for the development of therapeutics to treat cystic fibrosis.
AB - Cystic fibrosis (CF) patients suffer from a defect in hydration of mucosal membranes due to mutations in the cystic fibrosis transmembrane regulator (CFTR), an apical chloride channel in mucosal epithelia. Disease expression in CF knockout mice is organ specific, varying with the level of expression of calcium activated Cl- channels (CLCA). Therefore, restoring transepithelial Cl- secretion by augmenting alternate Cl- channels, such as CLCA, could be beneficial. However, CLCA-mediated Cl- secretion is transient, due in part to the inhibitory effects of myo-inositol 3,4,5,6-tetrakisphosphate [Ins(3,4,5,6)P4]. This suggests that antagonists of Ins(3,4,5,6)P4 could be useful in treatment of CF. We have, therefore, synthesized a series of membrane-permeant Ins(3,4,5,6)P4 derivatives, carrying alkyl substituents on the hydroxyl groups and screened them for effects on Cl- secretion in a human colonic epithelial cell line, T84. While membrane-permeant Ins(3,4,5,6)P4 derivatives had no direct effects on carbachol-stimulated Cl- secretion, Ins(3,4,5,6)P4 derivatives, but not enantiomeric Ins(1,4,5,6)P4 derivatives, reversed the inhibitory effect of Ins(3,4,5,6)P4 on subsequent thapsigargin activation of Cl- secretion. The extent of the antagonistic effect of the Ins(3,4,5,6)P4 derivatives varied with the position of the alkyl substituents. Derivatives with a cyclohexylidene ketal or a butyl-chain at the 1-position reversed the Ins(3,4,5,6)P4-mediated inhibition of Cl- secretion by up to 96 and 85%, respectively, whereas butylation of the 1- and 2-position generated a reversal effect of only 65%. Derivatives carrying the butyl chain only at the 2-position showed no antagonistic effect. These data: (1) Support the hypothesis that Ins(3,4,5,6)P4 stereospecifically inhibits Ca2+ activated Cl- secretion and that Ins(3,4,5,6)P4 mediates most, if not all of the cholinergic-mediated inhibition of chloride secretion in T84 cells; (2) Demonstrate Ins(3,4,5,6)P4-mediated inhibition can be completely reversed with rationally designed membrane-permeant Ins(3,4,5,6)P4 antagonists; (3) Demonstrate that a SAR for membrane-permeant Ins(3,4,5,6) P4 antagonists can be generated and screened in a physiologically relevant cell-based assay; (4) Indicate that Ins(3,4,5,6)P4 derivatives could serve as a starting point for the development of therapeutics to treat cystic fibrosis.
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U2 - 10.1016/S0968-0896(03)00188-3
DO - 10.1016/S0968-0896(03)00188-3
M3 - Article
C2 - 12837542
AN - SCOPUS:0038016550
SN - 0968-0896
VL - 11
SP - 3315
EP - 3329
JO - Bioorganic and Medicinal Chemistry
JF - Bioorganic and Medicinal Chemistry
IS - 15
ER -