Stabilized Phosphatidylinositol-5-Phosphate Analogues as Ligands for the Nuclear Protein ING2: Chemistry, Biology, and Molecular Modeling

摘要

The interaction of Ptdlns(5)P with the tumor suppressor protein ING2 has been implicated in the regulation of chromatin modification. To enhance the stability of Ptdlns(5)P for studies of the biological role in vivo, two phosphatase-resistant moieties were used to replace the labile 5-phosphate. The total asymmetric synthesis of the 5-methylenephosphonate (MP) and 5-phosphothionate (PT) analogues of Ptdlns(5)P is described herein, and the resulting metabolically stabilized lipid analogues were evaluated in three ways. First, liposomes containing either the dioleoyl MP or PT analogues bound to recombinant ING2 similar to liposomes containing dipalmitoyl Ptdlns(5)P, indicating that the replacement of the hydrolyzable 5-phosphate group does not compromise the binding. Second, the dioleoyl MP and PT Ptdlns(5)P analogues were equivalent to dipalmitoyl Ptdlns(5)P in augmenting cell death induced by a DNA double-strand break in HT1080 cells. Finally, molecular modeling and docking of the MP or PT analogues to the C-terminus PtdlnsP-binding region of ING2 (consisting of a PHD finger and a polybasic region) revealed a number of complementary surface and electrostatic contacts between the lipids and ING2.