No abstract

The microenvironments of the thymus are generated by thymic epithelial cells (TECs) and are essential for inducing immune self-tolerance or developing T cells. However, the molecular mechanisms that underlie the differentiation of TECs and thymic compartmentalization are not fully understood. Here we show that deficiency in the tumor necrosis factor receptor-associated factor (TRAF) 6 results in disorganized distribution of medullary TECs (mTECs) and the absence of mature mTECs. Engraftment of thymic stroma of TRAF6(-/-) embryos into athymic nude mice induced autoimmunity. Thus, TRAF6 directs the development of thymic stroma and represents a critical point of regulation for self-tolerance and autoimmunity.

Although the majority of smooth muscle neoplasms found in the uterus are benign, uterine leiomyosarcoma (LMS) is extremely malignant, with high rates of recurrence and metastasis. We earlier reported that mice with a homozygous deficiency for LMP2, an interferon (IFN)-γ-inducible factor, spontaneously develop uterine LMS. The IFN-γ pathway is important for control of tumor growth and invasion and has been implicated in several cancers. In this study, experiments with human and mouse uterine tissues revealed a defective LMP2 expression in human uterine LMS that was traced to the IFN-γ pathway and the specific effect of JAK-1 somatic mutations on the LMP2 transcriptional activation. Furthermore, analysis of a human uterine LMS cell line clarified the biological significance of LMP2 in malignant myometrium transformation and cell cycle, thus implicating LMP2 as an anti-tumorigenic candidate. This role of LMP2 as a tumor suppressor may lead to new therapeutic targets in human uterine LMS.