TY - JOUR
T1 - Thymic epithelial cells provide Wnt signals to developing thymocytes
AU - Pongracz, J
AU - Hare, Katherine
AU - Harman, Ben
AU - Anderson, Graham
AU - Jenkinson, Eric
PY - 2003/7/1
Y1 - 2003/7/1
N2 - Interactions with thymic stromal cells are known to be critical for the development of T cells from progenitors entering the thymus, yet the molecular mechanisms of stromal cell function remain poorly understood. Accumulating evidence has highlighted the importance of beta-catenin-mediated activation of T cell factor (TCF)/lymphoid enhancer factor (LEF) transcription during thymocyte development. As regulation of this signaling pathway is controlled by binding of soluble Wnt proteins to cell surface Frizzled (Fz) receptors, we studied components of Wnt/Fz-mediated signaling in thecontext of stromal cell regulation of thymocyte development. We show that mRNA for a variety of Wnt family members, notably Wnt-4, Wnt-7a and 7b, and Wnt-10a and 10b, are expressed by thymic epithelium rather then by thymocytes, while thymocytes demonstrate a developmentally regulated pattern of Fz receptor expression. Collectively these findings suggest (1) a functional role for Wnt-producing thymic epithelium in determining TCF/LEF-mediated transcriptional regulation in Fz-bearing thymocytes, and (2) a role for defined Wnt-Fz interactions at successive stages of thymocyte maturation. In support of this we show that separation of thymocytes from Wnt-producing epithelial cells and the thymic microenvironment, triggers beta-catenin phosphorylation and degradation in thymocytes. Thus, sustained exposure to Wnt in the context of an intact stromal microenvironment is necessary for stabilization of beta-catenin-mediated signaling in thymocytes.
AB - Interactions with thymic stromal cells are known to be critical for the development of T cells from progenitors entering the thymus, yet the molecular mechanisms of stromal cell function remain poorly understood. Accumulating evidence has highlighted the importance of beta-catenin-mediated activation of T cell factor (TCF)/lymphoid enhancer factor (LEF) transcription during thymocyte development. As regulation of this signaling pathway is controlled by binding of soluble Wnt proteins to cell surface Frizzled (Fz) receptors, we studied components of Wnt/Fz-mediated signaling in thecontext of stromal cell regulation of thymocyte development. We show that mRNA for a variety of Wnt family members, notably Wnt-4, Wnt-7a and 7b, and Wnt-10a and 10b, are expressed by thymic epithelium rather then by thymocytes, while thymocytes demonstrate a developmentally regulated pattern of Fz receptor expression. Collectively these findings suggest (1) a functional role for Wnt-producing thymic epithelium in determining TCF/LEF-mediated transcriptional regulation in Fz-bearing thymocytes, and (2) a role for defined Wnt-Fz interactions at successive stages of thymocyte maturation. In support of this we show that separation of thymocytes from Wnt-producing epithelial cells and the thymic microenvironment, triggers beta-catenin phosphorylation and degradation in thymocytes. Thus, sustained exposure to Wnt in the context of an intact stromal microenvironment is necessary for stabilization of beta-catenin-mediated signaling in thymocytes.
KW - thymic epithelium
KW - Wnt
KW - thymocyte development
KW - frizzled
UR - http://www.scopus.com/inward/record.url?scp=0041967288&partnerID=8YFLogxK
U2 - 10.1002/eji.200323564
DO - 10.1002/eji.200323564
M3 - Article
C2 - 12884861
SN - 0014-2980
VL - 33
SP - 1949
EP - 1956
JO - European Journal of Immunology
JF - European Journal of Immunology
ER -