Direct regulation of Gata3 expression determines the T helper differentiation potential of Notch

CD4(+) T helper cells differentiate into T helper 1 (Th1) or Th2 effector lineages, which orchestrate immunity to different types of microbes. Both Th1 and Th2 differentiation can be induced by Notch, but what dictates which of these programs is activated in response to Notch is not known. By using T cell-specific gene ablation of the Notch effector RBP-J or the Notch1 and 2 receptors, we showed here that Notch was required on CD4(+) T cells for physiological Th2 responses to parasite antigens. GATA-3 was necessary for Notch-induced Th2 differentiation, and we identified an upstream Gata3 promoter as a direct target for Notch signaling. Moreover, absence of GATA-3 turned Notch from a Th2 inducer into a powerful inducer of Th1 differentiation. Therefore, Gata3 is a critical element determining inductive Th2 differentiation and limiting Th1 differentiation by Notch

Notch Signaling Regulates Follicular Helper T Cell Differentiation

Floriane Auderset, Nicolas Fasnacht, Ute Koch, Freddy Radtke, Anne Wilson

Follicular helper T (TFH) cells are specialized in providing help for B cell differentiation and Ab secretion. Several positive and negative regulators of TFH cell differentiation have been described but their control is not fully understood. In this study, we show that Notch signaling in T cells is a major player in the development and function of TFH cells. T cell-specific gene ablation of Notch1 and Notch2 impaired differentiation of TFH cells in draining lymph nodes of mice immunized with T-dependent Ags or infected with parasites. Impaired TFH cell differentiation correlated with deficient germinal center development and the absence of high-affinity Abs. The impact of loss of Notch on TFH cell differentiation was largely independent of its effect on IL-4. These results show a previously unknown role for Notch in the regulation of TFH cell differentiation and function with implications for the control of this T cell population.

American Association of Immunologists2013

Essential role of the Wnt pathway effector Tcf-1 for the establishment of functional CD8 T cell memory

Immune protection from intracellular pathogens depends on the generation of terminally differentiated effector and of multipotent memory precursor CD8 T cells, which rapidly regenerate effector and memory cells during recurrent infection. The identification of factors and pathways involved in CD8 T cell differentiation is of obvious importance to improve vaccination strategies. Here, we show that mice lacking T cell factor 1 (Tcf-1), a nuclear effector of the canonical Wingless/Integration 1 (Wnt) signaling pathway, mount normal effector and effector memory CD8 T cell responses to infection with lymphocytic choriomeningitis virus (LCMV). However, Tcf-1-deficient CD8 T cells are selectively impaired in their ability to expand upon secondary challenge and to protect from recurrent virus infection. Tcf-1-deficient mice essentially lack CD8 memory precursor T cells, which is evident already at the peak of the primary response, suggesting that Tcf-1 programs CD8 memory cell fate. The function of Tcf-1 to establish CD8 T cell memory is dependent on the catenin-binding domain in Tcf-1 and requires the Tcf-1 coactivators and Wnt signaling intermediates beta-catenin and gamma-catenin. These findings demonstrate that the canonical Wnt signaling pathway plays an essential role for CD8 central memory T cell differentiation under physiological conditions in vivo. They raise the possibility that modulation of Wnt signaling may be exploited to improve the generation of CD8 memory T cells during vaccination or for therapies designed to promote sustained cytotoxic CD8 T cell responses against tumors.

National Academy of Sciences2010

Mechanisms underlying cell-fate determination in the mammary gland development

Duje Buric

Notch signaling pathway is an important developmental pathway and has been implicated in both mammary gland development and tumorigenesis. Several studies investigating Notch signaling in mouse mammary gland implied that Notch signaling is an important factor in the determination of the luminal cell type. Clinical studies on breast tumors as well as studies in transgenic mouse models overexpressing active Notch receptors suggested an oncogenic function of Notch in the mammary gland connecting it to the poor breast cancer prognosis. However the physiological role of Notch signaling and its downstream mechanisms remain unclear. Analysis of Transgenic-EGFP Notch reporter mouse mammary epithelium revealed that Notch signaling is active specifically in a subset of hormone receptor positive cells. More sensitive FACS analysis consistently shows EGFP expression in HR+ luminal cells and reveals a weaker signal in a subset of basal (CD24lo) cells. Additionally mRNA analysis revealed that Notch active luminal cells are expressing Wnt4 ligand. To unveil the role of the Notch signaling in the Wnt4 expressing HR+ cells, we conditionally deleted RBP-Jκ, Notch signaling mediator, in Wnt4 expressing subpopulation of hormone receptor positive cells via Wnt4Cre. Abrogation of RBP-Jκ resulted in loss of progesterone receptor expression in 90% of cells bearing the RBP-Jκ deletion while estrogen receptor expression remained intact, implicating RBP-Jκ in regulation of progesterone receptor expression. To test whether Notch signaling regulates PR expression in the entire HR+ population, we analyzed mammary epithelium in which RBP-Jκ has been conditionally deleted via MMTV-Cre in progenitor cells revealing the presence of a subpopulation of luminal hormone receptor positive cells that differentiate independently of Notch signaling. Time directed deletion of RBP-Jκ via intraductally injected Adeno-Cre virus into the adult mouse mammary ductal system through the nipple additionally confirmed that RBP-Jκ is required for progesterone receptor expression. Chromatin immunoprecipitation assay showed that RBP-Jκ binds two out of four putative RBPJκ binding sites in the progesterone receptor promoter. Inhibition of Notch signaling in vivo via intraductal injection of γ-secretase inhibitor, DAPT, resulted in reduced progesterone receptor expression strongly suggesting that Notch-related RBP-Jκ signaling is responsible for PR expression. In this project we are proposing that there are two different populations of HR+ cells: one defined as Wnt4 expressing subpopulation of HR+ cells in which PR expression is dependent of Notch signaling, and another one defined as Wnt4 non expressing subpopulation of HR+ cells which is independent of Notch signaling. Since Notch signaling is able to replace ER signaling and activate ER target genes in the endocrine therapy resistant cell lines, Wnt4 expressing population of HR+ luminal cells might play a crucial role in the acquiring of the resistance.

EPFL2015

Mechanisms underlying cell-fate determination in the mammary gland development

Duje Buric

EPFL2015