title: Profiling TRA-1-81 antigen distribution on a human embryonic stem cell.
abstract: Human embryonic stem (hES) cells hold great promise in regenerative medicine. Although hES cells have unlimited self-renewal potential, they tend to differentiate spontaneously in culture. TRA-1-81 is a biomarker of undifferentiated hES cells. Quantitative characterization of TRA-1-81 expression level in a single cell helps capture the "turn-on" signal and understand the mechanism of early differentiation. Here, we report on our examination of TRA-1-81 distribution and association on a hES cell membrane using an atomic force microscope (AFM). Our results suggest that aggregated distribution of TRA-1-81 antigen is characteristic for undifferentiated hES cells. We also evaluated the TRA-1-81 expression level at approximately 17,800 epitopes and approximately 700 epitopes per cell on an undifferentiated cell and a spontaneously differentiated cell, respectively. The method in this study can be adapted in examining other surface proteins on various cell types, thus providing a general tool for investigating protein distribution and association at the single cell level.
authors.affiliation: Department of Biological, Chemical and Physical Sciences, Illinois Institute of Technology, 3101 S. Dearborn Street, Life Sciences Building, Chicago, IL 60616, USA.
authors.forename: Dengli
authors.initials: D
authors.lastname: Qiu
authors.forename: Jialing
authors.initials: J
authors.lastname: Xiang
authors.forename: Zhaoxia
authors.initials: Z
authors.lastname: Li
authors.forename: Aparna
authors.initials: A
authors.lastname: Krishnamoorthy
authors.forename: Liaohai
authors.initials: L
authors.lastname: Chen
authors.forename: Rong
authors.initials: R
authors.lastname: Wang
mesh_terms: D000954:Antigens, Surface / Q000276:immunology*; D002460:Cell Line; D002462:Cell Membrane / Q000276:immunology*; D053595:Embryonic Stem Cells / Q000276:immunology*; D018604:Epitope Mapping / Q000379:methods*; D006801:Humans
chemical_list: D000954:Antigens, Surface; C519803:TRA-1-81 antigen, human