Focusing of Gene Expression as the Basis of Stem Cell Differentiation

Roman M. Salasznyk, Robert F. Klees, Aaron M. Westcott,
Scott L. Vandenberg, Kristin P. Bennett, and George E. Plopper


Stem Cells and Development, 14(6):608-620, December 2005

GO Charts and Interactive Gene Ontologies: GO charts for biological process and molecular function categories, plus individual gene ontology reports for each relevant DAVID category. The reports also contain, for each protein, up-to-date links to related information in PubMed and MedLine.

Sorted Protein Lists: Master gene ontology reports, with PubMed and MedLine links where appropriate, for four kinds of proteins (classified, unclassified, unclassifiable, and unknown).

Raw Protein Lists: Raw data in three text files (hMSC, hOST, OSM).

Full Text: More complete text of paper, including Supplementary Table 1.


We applied 2D gel electrophoresis and 2D liquid chromatography tandem mass spectrometry (2D LC-MS/MS) to identify proteins that are expressed in human mesenchymal stem cells (hMSC) undergoing in vitro osteogenic differentiation induced by the osteogenic stimulants (OS) ascorbic acid-2-phosphate, β-glycerophosphate, and dexamethazone. To assess the effectiveness of OS in inducing osteogenic differentiation, and identify specific changes in protein expression which accompanied OS treatment, Progenesis workstation software and the Database for Annotation, Visualization and Integrated Discovery (DAVID) were used classify these proteins and compare them with those found in undifferentiated hMSC and fully differentiated human osteoblasts (hOST). Of the 534 spots identified in OS-treated hMSC 2D gels, 272 (64%) and 443 (78%) spots matched those found in hMSC and hOST gels, respectively. Of the 909 different proteins identified by 2D LC-MS/MS in all these cell populations, 144 (16%) were found only in hMSC; 154 (17%) were found only in OS-treated hMSC; and 121 (13%) were unique to hOST. Differential expression of some of the identified proteins was further confirmed by Western blot analyses. Significant differences in calcium-mediated signaling molecules and extracellular matrix components were found during osteogenic commitment and differentiation in OS-treated cells. Gene ontology analysis with DAVID revealed that these functionally related proteins may serve as novel biomarkers for identifying hMSC commitment along osteogenic fates and demonstrate that protein expression profiling is a valuable tool in elucidating the osteogenic differentiation of hMSC.

Corresponding author:

George E. Plopper, Ph.D.
Assistant Professor Department of Biology
Rensselaer Polytechnic Institute
110 8 Street
Troy NY 12180-3596
(518) 276-8288 phone
(518) 276-2162 fax

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This work was supported by Grant #1R01EB002197-01 from the National Institutes of Health (to G.E.P.). We would also like to acknowledge David Moore of Siena College, who assisted with the web site.