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Licona, P; Chimal-Monroy, J; Soldevila, G (2006)

INHIBINS ARE THE MAJOR ACTIVIN LIGANDS EXPRESSED DURING EARLY THYMOCYTE DEVELOPMENT

Dev. Dyn. 235(4):1124-1132
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Activins are members of the transforming growth factor-beta (TGF?) superfamily, which regulate cell differentiation processes. Here we report the first quantitative analysis of the expression of Activin/Inhibin ligands, type I and II receptors, as well as Smad proteins in fetal (E14-E16) and adult thymic subpopulations. Our data showed that Alk4, ActRIIA, ActRIIB, and Smads 2, 3, and 4, are expressed in fetal thymus (E14 > E15 > E16) and in thymocytes from adult mice (mostly in the double negative [DN] subpopulation). Ligand expression analysis showed that ?A, ?B, and ? subunits were mainly detected in thymic stromal cells. Interestingly, ? subunits were expressed at much higher levels compared to ?A and ?B subunits, demonstrating for the first time the potential role of Inhibins as important mediators during early T cell development. Our data indicate that Activin/Inhibin signaling could regulate the process of thymus organogenesis and early thymocyte differentiation, as it has been demonstrated for other members of the TGF-? superfamily. © 2006 Wiley-Liss, Inc.