Optimal Suppression of Protein Phosphatase 2A Activity Is Critical for Maintenance of Human Embryonic Stem Cell Self‐Renewal

• Published in: Stem cells (Dayton, Ohio) Vol. 28; no. 5; pp. 874 - 884
• Main Authors: Yoon, Byung Sun, Jun, Eun Kyoung, Park, Gyuman, Jun Yoo, Seung, Moon, Jai‐Hee, Soon Baik, Cheong, Kim, Aeree, Kim, Hyunggee, Kim, Jong‐Hoon, Young Koh, Gou, Taek Lee, Hoon, You, Seungkwon
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 01.05.2010
• Subjects: Biomarkers - analysis; Biomarkers - metabolism; Cell Differentiation - drug effects; Cell Differentiation - physiology; Cell Division - physiology; Cell Line; Culture Media, Conditioned; Down-Regulation - drug effects; Down-Regulation - physiology; Embryonic Stem Cells - cytology; Embryonic Stem Cells - enzymology; Enzyme Activation - drug effects; Enzyme Activation - physiology; Enzyme Inhibitors - pharmacology; Human embryonic stem cells; Humans; Okadaic acid; Okadaic Acid - pharmacology; Pluripotent Stem Cells - cytology; Pluripotent Stem Cells - metabolism; Protein Phosphatase 2 - antagonists & inhibitors; Protein Phosphatase 2 - genetics; Protein Phosphatase 2 - metabolism; Protein phosphatase 2A; Self‐renewal; Signal Transduction - drug effects; Signal Transduction - physiology; Sphingosine - analogs & derivatives; Sphingosine - pharmacology; Xeno‐free
• ISSN: 1066-5099; 1549-4918
• DOI: 10.1002/stem.412

The self‐renewal of embryonic stem cells involves a balance between processes governed by crosstalk between intrinsic and extrinsic factors. We hypothesized that protein serine/threonine phosphatase 2A (PP2A) may play a central role in the signaling pathways that regulate human embryonic stem cell (hESC) self‐renewal. Biochemical analyses revealed that PP2A activity gradually increases over the course of hESC differentiation; PP2A/C and PP2A/A levels also increased. The overexpression of PP2A/C or the addition of PP2A activator C2‐ceramide promoted hESC differentiation. Accordingly, the addition of PP2A inactivator okadaic acid (OA) maintained hESC self‐renewal in the absence of basic fibroblast growth factor (bFGF). The hESCs maintained with OA expressed pluripotency markers and exhibited substantial telomerase activity with normal karyotypes. The hESCs were able to differentiate into derivatives of the three germ layers, both in vitro and in vivo. Furthermore, the addition of OA and bFGF enabled the maintenance of hESC self‐renewal without feeder cells, even in chemically defined xeno‐free media. These findings shed a light on the role of PP2A in hESC differentiation and provide a novel strategy for maintaining the self‐renewal capability of hESC in bFGF‐free, feeder cell‐free, and xeno‐free media through the optimal suppression of PP2A activity using OA. STEM CELLS 2010;28:874–884