The dual-specificity phosphatase and tensin homolog deleted on chromosome 10 (PTEN) performs its tumor suppressor functions by dephosphorylating phosphatidylinositol 3,4,5-trisphosphate (PIP3) at the 3-position.  This activity depresses activation of the kinase AKT and cell survival signaling.  Loss of this PTEN activity by mutation leads to increased incidence of cancer. Phosphatidylinositol-3,4,5-trisphosphate-dependent Rac exchanger 2 (P-Rex2) interacts with PTEN and noncompetitively inhibits its phosphatase activity.  P-Rex2 is a guanine-nucleotide exchange factor (GEF) that activates Rac family small G proteins by exchanging GDP to GTP, resulting in cell proliferation signaling.  Overexpression of P-Rex2 has been shown to result in dysfunctional PTEN inhibition, which effectively mimics PTEN loss. Overexpression and mutation of P-Rex2 has been observed in many types of cancers, including melanoma, breast, and prostate cancer.  P-Rex2 and PTEN have been reported to interact through two sets of domains:  the phosphatase domain of P-Rex2 interacts with the PTEN tail and the diffuse B-cell lymphoma homology (DH) and pleckstrin homology (PH) domains of P-Rex2 interact with the phosphatase domain of PTEN.   The structural basis for these interactions between P-Rex2 and PTEN has not been defined.  The aim of our work is to explore this inhibitory interaction using X-ray crystallography.  To accomplish this, bacterial and insect cells were engineered to express the PH and the DH-PH domains of P-Rex2 and full length PTEN. Following protein purification using affinity and size-exclusion chromatography, crystallization trials were performed to obtain crystals of the PH and DH-PH domains of P-Rex2 alone and in complex with PTEN. Determination of the structures of P-Rex2 alone and in complex with PTEN will contribute to our understanding of P-Rex2 roles and will reveal the landscape of its interaction interface with PTEN, which will contribute to development of small molecules that restore PTEN function.

Investigation of the structure and function of P-Rex2: Implications for a molecular mechanism of PTEN inhibition

253rd National Meeting (2017)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.