β-Catenin expression in thymocytes accelerates thymic involution

Age-related thymic involution in mammals is accompanied by decreased generation of naive T cells without significant reduction in the number of peripheral T cells. This leads to inefficient immune responses and inadequate combating of infections and other challenges to the immune system in older mammals. The molecular mechanisms that underlie this phenomenon are not known. In this report we show that expression of β-catenin in thymocytes enhances thymic involution. The effect of β-catenin expression is seen in all the thymic sub-populations, suggesting that an age-related developmental process is accelerated. We also show that, as in normal mice, thymic involution does not lead to a drastic reduction in splenic T cells in β-catenin-transgenic mice. This study identifies β-catenin expression in thymocytes as a molecular target of age-related thymic involution.