Morehouse School of Medicine
Department of Physiology
720 Westview Drive, SW
Atlanta, GA 30310
Phone: 404-752-1894
Fax: 404-752-1968
E-mail: xyao@msm.edu

Education

B.S.      Jiangxi College of Medicine , China , 1985
Ph.D.    University of California-Berkeley, 1995
Postdoc University of California-San Diego, 1997

Affiliations
Interim Director, Image Analysis Facility

Member, Cancer Research Program

Research interest  

Mitotic chromosome segregation and genomic stability

During cell division, each daughter cell inherits one copy of every chromosome. Accurate transmission of genetic materials (chromosomes) requires that the sister chromatids are disentangled and then segregated toward opposite poles of the cell before division.  Defects in chromosome segregation produce cells that are aneuploid (containing an abnormal number of chromosomes).  Aneuploidy is a leading cause of spontaneous miscarriages in humans and is also a hallmark of many human cancer cells. 
    Kinetochore, a multi-protein super-structure, mediates attachment of chromosomes to the mitotic spindle and governs complex chromosome movements during cell division.  In addition to mediating the mechanical process of chromosome segregation, kinetochores integrate the interaction of the mitotic spindle with chromosome in cell cycle progression.  Kinetochore serves as surveillance machinery for a 'checkpoint' in this process, termed spindle assembly checkpoint, a signaling pathway that ensures the fidelity of chromosome segregation.  Currently, we are trying to understand how protein-protein interactions at the kinetochore is orchestrated during cell division and what happens when specific protein-protein interaction is perturbed in real-time live cells using optical reporters.

Cellular polarity in health and diseases

Rho-family GTPases, including Cdc42, Rac1 and RhoA, regulate actin cytoskeleton and cell adhesion and are implicated in cell polarisation in several cell types, including T cells, fibroblasts, macrophages, astrocytes, epithelial cells and neuronal cells. Our research objectives are directed to understand cellular mechanisms involved in establishment and maintenance of cell polarity using gastric epithelial cells as a model system.

Many protein complexes required to establish and maintain epithelial function and structural integrity are polarized epithelial cells. Recent studies in gastric cell culture and in animal demonstrate the functional importance of ezrin in establishment and maintenance of gastric parietal cell polarity. One avenue of our current efforts is directed to evaluate the organization, assembly and function of the ezrin protein complex.

Helicobacter pylori translocates cytotoxins such as CagA into gastric epithelial cells and has been implicated to peptic ulceration and gastric carcinoma. Currently, we are examining how Helicobacter pylori perturb protein-protein interactions at the apical-junctional complex of gastric epithelium and what can be done to prevent the dysplastic alterations in epithelial cell physiology.

Go to page 2