Discipline: Biological Sciences
Subcategory: Biochemistry (not Cell and Molecular Biology and Genetics)
Shabree Anthony - University of the Virgin Islands
Co-Author(s): Dr. Arne Gericke, Worcester Polytechnic Institute, Worcester, Massachusetts; Dr. Alonzo H. Ross, Worcester Polytechnic Institute, Worcester, Massachusetts
The peripheral interactions between lipids and proteins have been shown to be vital in a number of biochemical pathways. Phosphoinositides (PIPs) are very minor components of the plasma membrane (2 mol%), but they are essential molecules in a large array of biological processes such as cell signaling, protein transport, and cell migration.
It is well established that phosphatase and tensin homolog located on chromosome ten (PTEN) is a tumor suppressing protein deleted on chromosome 10 in human cancers. PTEN plays a critical role in the Phosphatidyl-3-Inositol kinase (P13K) pathway by converting phosphatidylinositol (3,4,5) trisphosphate (PIP3) to phosphatidylinositol (4,5) bisphosphate (PIP2), inhibiting PIP3-dependent kinases, such as Akt.
Therefore, we hypothesized that in large unilamellar vesicles, the hydrolysis of PIP3 by PTEN should be observed. To mimic the inner leaflet of the plasma membrane, the model was composed of POPC (phosphatidylcholine), POPS (1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-L-serine), PIP2, and PIP3 (54/30/8/8). In this project, we successfully demonstrated the phosphatase activities of PTEN in these model membranes. Following the fabrication of the model membrane through extrusion, we used a rapid colorimetric phosphatase assay to demonstrate that both POPS and PIP2 are essential for PTEN to bind to the vesicle and/or to find its substrate (PIP3), which allows it to be converted into PIP2.
Funder Acknowledgement(s): This research was funded by the NSF REU.
Faculty Advisor: Dr. Arne Gericke, firstname.lastname@example.org
Role: I assisted in the extraction and purification of the protein (PTEN), and the fabrication of the large unilamellar vesicles used as the model membranes. Additionally, I assisted in performing the colorimetric phosphatase assays and analyzing the data.