Title: Multivalent Benzene Polyphosphate Derivatives are Non-Ca2+-Mobilizing Ins(1,4,5)P3 Receptor Antagonists
Authors: Mills, Stephen J.
Luyten, Tomas
Erneux, Christophe
Parys, Jan
Potter, Barry V.L. # ×
Issue Date: Dec-2012
Publisher: American Scientific Publishers
Series Title: Messenger vol:1 issue:2 pages:167-181
Abstract: Inositol 1,4,5-trisphosphate [Ins(1,4,5)P3 1] mobilizes intracellular Ca2+ through the Ins(1,4,5)P3 receptor [InsP3R]. Although some progress has been made in the design of synthetic InsP3R partial agonists and antagonists,
there are still few examples of useful small molecule competitive antagonists. A “multivalent” approach is
explored and new dimeric polyphosphorylated aromatic derivatives were designed, synthesized and biologically
evaluated. The established weak InsP3R ligand benzene 1,2,4-trisphosphate [Bz(1,2,4)P3 2] is dimerized through its 5-position in two different ways, first directly as the biphenyl derivative biphenyl 2,2',4,4',5,5'- hexakisphosphate, [BiPh(2,2',4,4',5,5')P6 8] and with its regioisomeric biphenyl 3,3',4,4',5,5'-hexakisphosphate
[BiPh(3,3',4,4',5,5')P6 11]. Secondly, a linker motif is introduced in a flexible ethylene-bridged dimer (9) with
its corresponding 1,2-bisphosphate dimer (10), both loosely analogous to the very weak antagonist 1,2-bis(2-
aminophenoxy)ethane-N,N,N,N-tetraacetic acid (BAPTA 7). In permeabilized L15 fibroblasts overexpressing type 1
InsP3R, BiPh(2,2',4,4',5,5')P6 (8) inhibits Ins(1,4,5)P3-induced Ca2+ release in a apparently competitive fashion [IC50 187 nM] and the Bz(1,2,4)P3 dimer (9) is only slightly weaker [IC50 380 nM]. Compounds were also evaluated against type I Ins(1,4,5)P3 5-phosphatase. All compounds are resistant to dephosphorylation, with BiPh(2,2',4,4',5,5')P6 (8), being the most effective inhibitor of any biphenyl derivative synthesized to date [IC50 480 nM] and the Bz(1,2,4)P3 ethylene dimer (9) weaker [IC50 3.55 microM]. BiPh(3,3',4,4',5,5')P6 (11) also inhibits 5-phosphatase [IC50 730 nM] and exhibits unexpected Ca2+ releasing activity [EC50 800 nM]. Thus, relocation of only a single mirrored phenyl phosphate group in (11) from that of antagonist (8) does not markedly change enzyme inhibitory activity, but elicits a dramatic switch in Ca2+-releasing activity. Such new agents demonstrate the power of the multivalent approach and may be useful to investigate the chemical biology of signaling through InsP3R and as templates for further design.
ISSN: 2167-955X
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Laboratory of Molecular and Cellular Signaling
× corresponding author
# (joint) last author

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