Embryonic stem (ES) cells are known to have an infinite proliferation and pluripotency that are associated with complex processes. The objective of this study was to examine expression of genes differentially regulated during differentiation of human ES cells by suppression subtractive hybridization (SSH). Human ES cells were induced to differentiate into neural precursor cells via embryoid body. Neural precursor cells were isolated physically based on morphological criteria. Immunocytochemical analysis showed expression of pax6 in neural precursor cells, confirming that the isolated cells were neural precursor cells. Undifferentiated human ES cells and neural precursor cells were subject to the SSH. TPX2 (Targeting Protein for Xklp2 (Xenopus centrosomal kinesin-like protein 2)) was identified, cloned and analyzed during differentiation of human ES cells into neural lineages. Expression of TPX2 was gradually down-regulated in embryoid bodies and neural precursor cells relative to undifferentiated ES cells. Targeting Protein for Xklp2 has been shown to be involved in cell division by interaction with microtubule development in cancer cells. Taken together, result of this study suggests that TPX2 may be involved in proliferation and differentiation of human ES cells.

ABSTRACT   INTRODUCTION   MATERIALS AND METHODS    Culture of Human ES Cells    Differentiation of Human ES Cells into Neural Precursor Cells    Immunocytochemical Analysis    Extraction of RNA    Synthesis of cDNA by Reverse Transcription    Suppression Subtractive Hybridization    Analysis of Gene Expression by Semi-Quantitative RT-PCR   RESULTS    Identification of Differentially Expressed Genes by SSH    Un-subtracted    Down-Regulation of TPX2 Expression during Neural Differentiation   DISCUSSION   REFFRENCES

• Hye Min Noh(Graduate School of Life Science and Biotechnology, College of Medicine, Pochon CHA University)
• Seong-Jun Choi(Graduate School of Life Science and Biotechnology, College of Medicine, Pochon CHA University)
• Sehee Kim(Graduate School of Life Science and Biotechnology, College of Medicine, Pochon CHA University)
• Kye-Seong Kim(College of Medicine, Hanyang University)
• Jin Kyeoung Kim(Graduate School of Life Science and Biotechnology, College of Medicine, Pochon CHA University) Corresponding author