The Research Of New Substrates Of The E3 Ubiqutin Ligase FBW7

The SCF type E3 ubiquitin ligase FBW7 has been demonstrated as a key tumor suppressor, which plays an important role in cell proliferation and differentiation. Skpl, Cullinl, Rbx1 and FBW7 consist of the SCFFBW7 complex. FBW7 interacts with its targets directly and then recognize the CPDs in their targets promoting their degradation via ubiquitination dependent pathway. It can degradate many kinds of proteins, such as c-Myc, c-Jun, CyclinE, Mcl-1, mTOR, c-Myb, Aurora A, p100 and so on. Despite of that, we still knew little about the function of FBW7. Thus, it is very important to find new substrates of FBW7 which would give rise a novel insight into the tumor treatment.In our research, Bioinformatics and Mass Spectrometry have been used to predict substrate proteins of FBW7, among of which we find and further study the protein of a transcription factor FoxM1 and histone methyltransferase G9a. By constructing eukaryotic expression clones, we performed the exogenous and endogenous related experiments to prove that FBW7 can regulate the stability of FoxMl in M phase of cell cycle. Our results give a new insight to uncover a new signal pathway of FBW7 regulating cell cycle and supply some new ideas into the therapy of malignancies. Simily we used the same idea to determine the stability regulation of G9a by FBW7. Considering its methylase character, we studied its epigenetic regulation-related physiological function through the methylation level detection experiments of H3K9mel and H3K9me2, which were two substrates of G9a.Finally, we take a large scale screening as for the substrates of FBW7 by Bioinformatics and Mass Spectrometry methods.In this way, we found some more interesting proteins in a high efficiency and scientific way. Most importantly, the study supplied some new insights into the function of FBW7 via which we can uncover the new roles of FBW7 in cancer and other severe human diseases.