Visualize PIM‐1 Protein Function and Its Interaction With PI3K/Akt/mTOR Pathway Regulated by Its Active Sites Through FRET Biosensors

Pro-viral Insertion site for the Moloney Murine Leukemia virus 1 (PIM-1) is widely involved in various biological processes and diseases, which is based on its structure and functional sites. However, the relationship between active sites and function of PIM-1 kinase remains unclear due to the lack of effective study approaches in live cells. Herein, to visualize the effect of different active sites in PIM-1 protein on its function activity and relation with PI3K/Akt/mTOR pathway, three mutant probes of EPHY which was developed previously based on fluorescence resonance energy transfer (FRET) technology to detect PIM-1 kinase activity in living cells were further constructed and transfected into cells followed by treating with PIM-1 inhibitors, ATP and PI3K inhibitor, respectively. The results showed that Lys67 is related to substrate binding and catalytic activity of PIM-1 kinase, thereby directly regulating PI3K/Akt/mTOR signaling pathway. Pro81/Asn82 are primarily participated in PIM-1 binding to ATP, thus also involving in the modulation on PI3K/Akt/mTOR signaling pathway, but play less role in the interaction between PIM-1 protein and its substrate. Asp167 has few effects on both the catalytic function activity of PIM-1 and PI3K/AKT/mTOR pathway, even though the binding ability of PIM-1 protein to its substrate is dramatically inhibited by D167A mutation. Altogether, the mutant probes works well as visualization tools to unearth the function of active sites in PIM-1 kinase, not only facilitating the further clarification of molecular mechanism underlying PIM-1 related signaling pathways, but also shedding light on drug development and disease therapy targeting PIM-1 protein.