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PPAR Research
Volume 2007 (2007), Article ID 81219, 13 pages
http://dx.doi.org/10.1155/2007/81219
Research Article

PPARγ2 Regulates a Molecular Signature of Marrow Mesenchymal Stem Cells

1The Jackson Laboratory, 600 Main Street, Bar Harbor 04609, ME, USA
2Department of Orthopaedic Surgery, Center for Diabetes and Endocrine Research, University of Toledo Medical Center, 3035 Arlington Avenue, Mail Stop 1008, Toledo 43614, OH, USA

Received 23 March 2007; Accepted 25 April 2007

Academic Editor: Z. Elizabeth Floyd

Copyright © 2007 K. R. Shockley et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Bone formation and hematopoiesis are anatomically juxtaposed and share common regulatory mechanisms. Bone marrow mesenchymal stromal/stem cells (MSC) contain a compartment that provides progeny with bone forming osteoblasts and fat laden adipocytes as well as fibroblasts, chondrocytes, and muscle cells. In addition, marrow MSC provide an environment for support of hematopoiesis, including the development of bone resorbing osteoclasts. The PPARγ2 nuclear receptor is an adipocyte-specific transcription factor that controls marrow MSC lineage allocation toward adipocytes and osteoblasts. Increased expression of PPARγ2 with aging correlates with changes in the MSC status in respect to both their intrinsic differentiation potential and production of signaling molecules that contribute to the formation of a specific marrow microenvironment. Here, we investigated the effect of PPARγ2 on MSC molecular signature in respect to the expression of gene markers associated exclusively with stem cell phenotype, as well as genes involved in the formation of a stem cell supporting marrow environment. We found that PPARγ2 is a powerful modulator of stem cell-related gene expression. In general, PPARγ2 affects the expression of genes specific for the maintenance of stem cell phenotype, including LIF, LIF receptor, Kit ligand, SDF-1, Rex-1/Zfp42, and Oct-4. Moreover, the antidiabetic PPARγ agonist TZD rosiglitazone specifically affects the expression of “stemness” genes, including ABCG2, Egfr, and CD44. Our data indicate that aging and antidiabetic TZD therapy may affect mesenchymal stem cell phenotype through modulation of PPARγ2 activity. These observations may have important therapeutic consequences and indicate a need for more detailed studies of PPARγ2 role in stem cell biology.