Epithelial Cell Adhesion Molecule (EpCAM) Complex Proteins Promote Transcription Factor-mediated Pluripotency Reprogramming

• Published in: The Journal of biological chemistry 2011-09, Vol.286 (38), p.33520-33532
• Main Authors: Huang, Hsiang-Po, Chen, Pin-Hsun, Yu, Chun-Ying, Chuang, Ching-Yu, Stone, Lee, Hsiao, Wen-Chu, Li, Chung-Leung, Tsai, Shih-Chih, Chen, Kai-Yun, Chen, Hsin-Fu, Ho, Hong-Nerng, Kuo, Hung-Chih
• Format: Article
• Language: English
• Subjects: Animals; Antigens, Neoplasm - chemistry; Antigens, Neoplasm - metabolism; Cell Adhesion; Cell Adhesion Molecules - chemistry; Cell Adhesion Molecules - metabolism; Cellular Reprogramming; Claudins - metabolism; Developmental Biology; Embryo, Mammalian - cytology; Embryonic Stem Cell; Embryonic Stem Cells - cytology; Embryonic Stem Cells - metabolism; EpCAM; Epithelial Cell Adhesion Molecule; Fibroblasts - metabolism; Humans; Induced Pluripotent Stem (iPS) Cell; Induced Pluripotent Stem Cells - cytology; Induced Pluripotent Stem Cells - metabolism; Mice; Models, Biological; Oct4; p53; Pluripotent Stem Cells - cytology; Pluripotent Stem Cells - metabolism; Protein Structure, Tertiary; Signal Transduction; Transcription Factors; Transcription Factors - metabolism; Tumor Suppressor Protein p53 - metabolism
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M111.256164

Epithelial cell adhesion molecule (EpCAM) is a transmembrane glycoprotein that is highly expressed in embryonic stem cells (ESCs) and its role in maintenance of pluripotency has been suggested previously. In epithelial cancer cells, activation of the EpCAM surface-to-nucleus signaling transduction pathway involves a number of membrane proteins. However, their role in somatic cell reprogramming is still unknown. Here we demonstrate that EpCAM and its associated protein, Cldn7, play a critical role in reprogramming. Quantitative RT-PCR analysis of Oct4, Sox2, Klf4, and c-Myc (OSKM) infected mouse embryonic fibroblasts (MEFs) indicated that EpCAM and Cldn7 were up-regulated during reprogramming. Analysis of numbers of alkaline phosphatase- and Nanog-positive clones, and the expression level of pluripotency-related genes demonstrated that inhibition of either EpCAM or Cldn7 expression resulted in impairment in reprogramming efficiency, whereas overexpression of EpCAM, EpCAM plus Cldn7, or EpCAM intercellular domain (EpICD) significantly enhanced reprogramming efficiency in MEFs. Furthermore, overexpression of EpCAM or EpICD significantly repressed the expression of p53 and p21 in the reprogramming MEFs, and both EpCAM and EpICD activated the promoter activity of Oct4. These observations suggest that EpCAM signaling may enhance reprogramming through up-regulation of Oct4 and possible suppression of the p53-p21 pathway. In vitro and in vivo characterization indicated that the EpCAM-reprogrammed iPSCs exhibited similar molecular and functional features to the mouse ESCs. In summary, our studies provide additional insight into the molecular mechanisms of reprogramming and suggest a more effective means of induced pluripotent stem cell generation. EpCAM is highly expressed in ESCs. However, the role of EpCAM complex proteins in pluripotency reprogramming is still unknown. Overexpression of EpCAM complex proteins significantly repressed the expression of p53 and enhanced reprogramming efficiency in MEFs. EpCAM signaling enhance reprogramming through suppression of the p53-p21 pathway. EpCAM signaling enhance reprogramming through suppression of the p53-p21 pathway.