Sara Ramirez - PhD Student, Vanderbilt Interdisciplinary Graduate Program
2018 Winter Rotation Student
Chemical biology of the nuclear lipid signaling kinase IPMK.
Hometown - Fort Collins, CO
B.S. Biochem, Cell & Mol Biology University of Tennessee (Knoxville, TN)
Minor Chemistry University of Tennessee (Knoxville, TN)
Ph.D. IGP Program Vanderbilt University School of Medicine
The Blind lab has discovered new, unique enzyme activities for the classic lipid signaling enzymes IPMK and PTEN on PIP2 and PIP3, when these signaling lipids are bound to the only known nuclear PIP receptor called SF-1 (NR5A1). I wish to determine if these new enzyme activities of IPMK and PTEN are relevant in different models of cancer, and determine if IPMK is a viable target for structure-based drug design efforts. Preliminary data from our lab have linked IPMK to cancer cell proliferation and anchorage-independent growth. However, these genetic IPMK ablation experiments are complicated by the enzyme-independent functions of IPMK, making interpretation of genetic experiments very difficult. Chemically inhibiting IPMK would solve that problem, however no good small molecule inhibitors of IPMK currently exist.
The current IPMK small molecule inhibitors are poor compounds that have very broad off-target effects. To solve these problems, we are attempting to use chemical genetics to generate an ATP-analog sensitive IPMK, creating a “hole” in the active site that makes IPMK uniquely sensitive to “bumped” inhibitors. I am first bacterially expressing the chemical-genetic IPMK mutant and characterizing the enzyme activity. We will then use CRISPR/Cas9 to ablate IPMK in cancer cells, and then compare IPMK kinase-inhibited to IPMK null and IPMK kinase-dead mutants in proliferation assays. Pilot data from other members of our lab demonstrate we have used CRISPR to ablate all IPMK alleles from cancer cells, and can retrovirally complement back wild-type or kinase-dead IPMK. The larger project seeded here will use these cells in xenograft models and develop a chemical-genetic IPMK mouse, providing the proof-of-principle needed for big pharma to focus their resources into IPMK inhibitor development programs.