Professor of Biochemistry
- College of Natural and Agricultural Sciences
Research Specialization - My laboratory studies the mechanisms by which upstream transcription factors regulates transcription initiation in mammalian cells, focusing particular attention on a transcription factor encoded by a tumor suppressor gene, p53. The decision to initiate transcription of a gene is the key control point and determines the properties of both normal and abnormal cells. The biochemical activity of p53 and its concentration in the cell regulate the amount and timing of the expression of many genes involved in cell cycle control and apoptosis. When activated by DNA damage, p53 stimulates transcription initiation through protein-protein interactions with RNA polymerase II (pol II) and its accessory factors (TFs, TAFs and coactivators). Our approach is to utilize in vitro reconstituted transcription reactions and biochemical methods to dissect the mechanisms. This combination of protein biochemistry and molecular biology will allow us to characterize aspects of transcriptional regulation by p53 which are fundamental in cell growth regulation.
- PhD Biochemistry 1990
- West Virginia University
Damon Runyon Postdoctoral Fellow, UCLA 1991-1995
Molecular Biology and
Song, X.D., H.M. Sheppard, A.W. Norman and X. Liu. 1998. MAP-kinase is involved in the degradation of p53 protein in the bryostatin-1 induced differentiation of the acute promyelocytic leukemia cell line NB4. J. Biol. Chem. 274:1677-1682.
Sheppard, H.M., S.I. Corneillie, C. Espiritu, A. Gatti and X. Liu. 1999. New insights into the mechanism of inhibition of p53 by SV40 large T antigen. Mol. Cell. Biol. 19:2746-2753.
Ross, J.F., X. Liu and B.D. Dynlacht. 1999. Transcription repression by the retinoblastoma tumor suppressor protein in the absence of chromatin. Molecular Cell 3:195-205.
Nie, Y., H.-H. Li, C.M. Bula and X. Liu. 2000. Stimulation of p53 DNA-binding by c-Abl requires the p53 C-terminus and tetramerization. Mol. Cell. Biol. 20:741-748.
Gatti, A., H.-H. Li, J.A. Traugh and X. Liu. 2000. Phosphorylation of human p53 on Thr-55. Biochemistry 39:9837-9842.
Xing, J., H.M. Sheppard, S.I. Corneillie and X. Liu. p53 stimulates TFIID-TFIIA-promoter complex formation and p53/T antigen complex represses TBP binding to TATA element. Submitted.
Li, H.-H., A.G. Li, H.M. Sheppard and X. Liu. Phosphorylation by TAFII250 leads to the degradation of p53. Submitted