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Jun-yuan Ji

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Jun-yuan Ji, Ph.D.

Assistant Professor
Department of Molecular and Cellular Medicine

Room 248 Reynolds Medical Building
College Station, Texas 77843
Phone: 979-845-6389
Fax: 979-847-9481
Email: ji@medicine.tamhsc.edu

Education and Post-Graduate Training

Jun-yuan Ji is an Assistant Professor of Molecular and Cellular Medicine. He received his B.S. in Cell Biology from Lanzhou University in 1994, and a M.S. in Developmental Biology from the Institute of Genetics and Developmental Biology at the Chinese Academy of Sciences in 1997, where he worked in the laboratory of Professor Fang-zhen Sun. He obtained his Ph.D. in Zoology from the University of Washington at Seattle in 2003 working with Professor Gerold Schubiger. He then did postdoctoral research in Professor Nicholas Dyson’s laboratory at Massachusetts General Hospital Cancer Center and Harvard Medical School. Dr. Ji joined the faculty at the college in 2009.

Research Interests

Our laboratory is interested in cell cycle and transcriptional regulation during development and tumorigenesis. UsingDrosophila and cultured human cancer cell lines as model systems, we combine genetic, cell biological, and biochemical approaches to elucidate the molecular and genetic regulatory circuits that control cell proliferation. Specifically, our major focus is to study the functions and regulation of Cyclin-dependent kinase 8 (CDK8). By performing genetic screens using Drosophila, we identified CDK8 as a potent inhibitor of E2F1, which is a key transcription factor that regulates the G1 to S-phase transition. In both Drosophila and human cancer cells, we observed that CDK8 inhibits E2F1-dependent transcription by directly binding to and phosphorylating E2F1, which may turn off the re-initiation of E2F1-mediated transcription. Interestingly, CDK8 is recently identified as an oncoprotein. The genes encoding CDK8 and its regulatory partner Cyclin C (CCNC) are frequently amplified or mutated in various types of human cancers. Importantly, inhibiting CDK8 potently blocks the growth of colorectal cancer cells that harbor CDK8 amplification, suggesting that CDK8 kinase is a promising drug target. Therefore, it is important to understand the regulatory network, including both upstream regulators and downstream effectors, of CDK8-Cyclin C in both normal development and tumorigenesis.

Selected Publications

Xu, W., and Ji, J.Y. (2011) Dysregulation of CDK8 and Cyclin C in tumorigenesis. Journal of Genetics and Genomics 38, 439-452.

Mulligan, P., Yang, F., Di Stefano, L.*, Ji, J.Y.*, Ouyang, J.*, Nishikawa, J.L., Toiber, D., Kulkarni, M., Wang, Q., Najafi-Shoushtari, S.H., Mostoslavsky, R., Gygi, S.P., Gill, G., Dyson, N.J., and Näär, A.M. (2011) A SIRT1-LSD1 corepressor complex regulates Notch target gene expression and development. Molecular Cell 42, 689-699. (* Equal contributors)

Walker, A.K., Yang, F., Jiang, K., Ji, J.Y., Watts, J.L., Purushotham, A., Boss, O., Hirsch, M.L., Ribich, S., Smith, J.J., Israelian, K., Westphal, C.H., Rodgers, J.T., Shioda, T., Elson, S. L., Mulligan, P., Najafi-Shoushtari, H., Black, J. C., Thakur, J.K., Kadyk, L.C., Whetstine, J.R., Mostoslavsky, R., Puigserver, P., Li, X., Dyson, N.J., Hart, A.C., and Naar, A. M. (2010) Conserved role of SIRT1 orthologs in fasting-dependent inhibition of the lipid/cholesterol regulator SREBP. Genes & Development 24, 1403-1417.

Ji, J.Y. and Dyson, N.J. (2010) Interplay between Cyclin-dependent Kinases and E2F-dependent Transcription. In Cell Cycle Deregulation in Cancer (ed. G. Enders), Springer Science , pp 23-41.

Zhang, J., Ji, J.Y., Yu, M., Overholtzer, M., Smolen, G.A., Wang, R., Brugge, J.S., Dyson, N.J., and Haber, D.A. (2009) YAP-dependent induction of amphiregulin identifies a non-cell-autonomous component of the Hippo pathway. Nature Cell Biology 11, 1444-1450.

Morris, E.J. *, Ji, J.Y.*, Yang, F., Di Stefano, L., Herr, A., Moon, N.S., Kwon, E.J., Haigis, K.M., Näär, A.M., and Dyson, N.J. (2008) E2F1 represses β-catenin transcription and is antagonized by both pRB and CDK8. Nature 455, 552-556. (*Equal contributors)

Di Stefano, L., Ji, J.Y., Moon, N.S., Herr, A., and Dyson, N. (2007) Mutation of Drosophila Lsd1 disrupts H3-K4 methylation, resulting in tissue-specific defects during development. Current Biology 17, 808-812.

Morris, E.J., Michaud,W.A., Ji, J.Y., Moon, N.S., Rocco, J.W., and Dyson, N.J. (2006) Functional identification of Api5 as a suppressor of E2F-dependent apoptosis in vivo. PLoS Genetics 2, 1834-1848.

Ji, J.Y., Crest, J., and Schubiger, G. (2005). Genetic interactions between Cdk1-CyclinB and the Separase complex inDrosophila. Development 132, 1875-1884.

Ji, J.Y., Squrriell, J.M., and Schubiger, G. (2004). Both Cyclin B levels and DNA-replication checkpoint regulate the early embryonic mitoses in Drosophila. Development 131, 401-411. (Cover image)

Ji, J.Y., Haghnia, M., Trusty, C., Goldstein, L.S.B., and Schubiger, G. (2002). A genetic screen for suppressors and enhancers of the Drosophila Cdk1-Cyclin B identifies maternal factors that regulate microtubule and microfilament stability. Genetics 162, 1179-1195.