A Small Molecule Mimicking a Phosphatidylinositol (4,5)-Bisphosphate Binding Pleckstrin Homology Domain

Abstract

Inositol phospholipids have emerged as important key players in a wide variety of cellular functions. Among the seven existing inositol phospholipids, phosphatidylinositol (4,5)-bisphosphate (PI(4,5)P 2 ) has attracted much attention in recent years due to its important role in numerous cellular signaling events and regulations, which in turn impact several human diseases. This particular lipid is recognized in the cell by specific lipid binding domains, such as the Pleckstrin-homology (PH) domain, which is also employed as a tool to monitor this important lipid. Here, we describe the synthesis and biological characterization of a small molecule that mimics the PH domain as judged by its ability to bind specifically to only PI(4,5)P 2 and effectively compete with the PH domain in vitro and in a cellular environment.The binding constant of this small molecule PH domain mimetic (PHDM) was determined to be 17.6 ± 10.1 µM, similar in potency to the PH domain. Using NIH 3T3 mouse fibroblast cells we demonstrated that this compound is cell permeable and able to modulate PI(4,5)P 2 -dependent effects in a cellular environment such as the endocytosis of the transferrin receptor, loss of mitochondria as well as stress fiber formation. This highly PI(4,5)P 2 -specific chemical mimetic of a PH domain, is not only a powerful research tool, but might also be a lead compound in future drug developments targeting PI(4,5)P 2 -dependent diseases such as Lowe syndrome.

Targeting PTEN using small molecule inhibitors

“…PTP1B for example, described in the literature as valuable type 2 diabetes target, is a classical PTP acting on proteinaceous substrates [17]. SopB on the other hand, is a bacterial virulence factor with phosphoinositide phosphatase activity which has the capability to hydrolyse all seven natural occurring phosphoinositides [18,19] . We performed a kinetic study of these three enzymes in the presence of bpVpic and VO-OHpic to obtain IC50 values using OMFP as substrate.…”

Molecular recognition with boronic acids—applications in chemical biology

“…Recently, Vilar and Woscholski developed a novel small molecule that was capable of binding specifically to the lipid phosphatidylinositol-(4,5)-bisphosphate (PIP 2 ) [47]. Receptor 13 (the chemical pleckstrin homology domain mimetic; see Fig.…”

Inositol 5-phosphatases: insights from the Lowe syndrome protein OCRL

“…Therapeutic approaches that target PI(4,5)P2 effectors may also be of benefit as inhibitors of actin polymerization partially counteracted the in-vitro defects in cytokinesis observed in OCRL deficient cells[34]. Along a related avenue, the recent report of a PI(4,5)P2 sensor, which titrates intracellular PI(4,5)P2 levels, may be used as a therapeutic tool for those affected with OCRL dysfunction[80]. Overall, it is clear that the further development of therapeutics geared towards modulating the 5-phosphorylated PIs will provide a multitude of benefits not restricted to basic research.…”