Abstract
Human embryonic stem cells (hESCs) are characterized by their immortality and pluripotency. Human mesenchymal stem cells (hMSC), on the other hand, have limited self-renewal and differentiation capabilities. The underlying molecular differences that account for this characteristic self-renewal and plasticity are, however, poorly understood. This study reports a nuclear proteomic analysis of human embryonic and bone marrow–derived mesenchymal stem cells. Our proteomic screen highlighted a 5-fold difference in the expression of Reptin52. We show, using two-dimensional difference gel electrophoresis (2-DIGE), western analysis, and quantitative reverse transcriptase polymerase chain reaction, that Reptin52 is more abundantly expressed in hESC than hMSC. Moreover, we observed differential expression of Pontin52 and β-catenin—proteins known to interact with Reptin52. This difference in the expression of Reptin52 and Pontin52 (known regulators of β-catenin) further supports a role for Wnt signaling in stem cell self-renewal and proliferation.
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