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Updated: Jun 21, 2026

Assessing Cellular Target Engagement by SHP2 (PTPN11) Phosphatase Inhibitors
Published on: July 17, 2020
PtdIns5P protects Akt from dephosphorylation through PP2A inhibition
Damien Ramel1, Frédéric Lagarrigue, Sophie Dupuis-Coronas
1INSERM U563, Toulouse, France. damien.ramel@inserm.fr
Abstract:
Phosphatidylinositol 5-phosphate (PtdIns5P), the most recently discovered phosphoinositide, has been proposed to play a role as a lipid mediator of intracellular signaling. We have previously shown that PtdIns5P generated by IpgD, an effector of the causative agent of dysentery Shigella flexneri, activates the PI 3-kinase/Akt pathway. Here, we demonstrate that PtdIns5P is able to protect Akt from dephosphorylation. This effect is not due to inhibition of the phosphoinositide phosphatase regulating PtdIns(3,4,5)P(3) levels PTEN but rather to PtdIns5P-induced phosphorylation and subsequent inhibition of the catalytic subunit of PP2A phosphatases. These data shed light on a new mechanism used by S. flexneri bacteria to sustain Akt activation to increase survival of the host cells during bacterial replication.
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