TY - JOUR A1 - Klein-Hessling, Stefan A1 - Rudolf, Ronald A1 - Muhammad, Khalid A1 - Knobeloch, Klaus-Peter A1 - Maqbool, Muhammad Ahmad A1 - Cauchy, Pierre A1 - Andrau, Jean-Christophe A1 - Avots, Andris A1 - Talora, Claudio A1 - Ellenrieder, Volker A1 - Screpanti, Isabella A1 - Serfling, Edgar A1 - Patra, Amiya Kumar T1 - A threshold level of NFATc1 activity facilitates thymocyte differentiation and opposes notch-driven leukaemia development JF - Nature Communications N2 - NFATc1 plays a critical role in double-negative thymocyte survival and differentiation. However, the signals that regulate Nfatc1 expression are incompletely characterized. Here we show a developmental stage-specific differential expression pattern of Nfatc1 driven by the distal (P1) or proximal (P2) promoters in thymocytes. Whereas, preTCR-negative thymocytes exhibit only P2 promoter-derived Nfatc1β expression, preTCR-positive thymocytes express both Nfatc1β and P1 promoter-derived Nfatc1α transcripts. Inducing NFATc1α activity from P1 promoter in preTCR-negative thymocytes, in addition to the NFATc1β from P2 promoter impairs thymocyte development resulting in severe T-cell lymphopenia. In addition, we show that NFATc1 activity suppresses the B-lineage potential of immature thymocytes, and consolidates their differentiation to T cells. Further, in the pTCR-positive DN3 cells, a threshold level of NFATc1 activity is vital in facilitating T-cell differentiation and to prevent Notch3-induced T-acute lymphoblastic leukaemia. Altogether, our results show NFATc1 activity is crucial in determining the T-cell fate of thymocytes. KW - acute lymphocytic leukaemia KW - transcription factors KW - lymphocyte differentiation Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-172974 VL - 7 ER - TY - JOUR A1 - Barahona de Brito, Carlotta A1 - Patra, Amiya Kumar T1 - NFAT factors are dispensable for the development but are critical for the maintenance of Foxp3\(^+\) regulatory T cells JF - Cells N2 - The transcription factors of the nuclear factor of activated T cell (NFAT) family play a crucial role in multiple aspects of T cell function. It has recently been reported that NFATs play an important role in the suppressive function of CD4\(^+\)CD25\(^+\)Foxp3\(^+\) regulatory T (T\(_{reg}\)) cells. In this study, we have investigated the role of NFATs in the thymic development of T\(_{reg}\) cells in mice. We show that NFAT factors are dispensable for the development of Foxp3\(^+\) T\(_{reg}\) cells in the thymus but are critical for the maintenance of both the phenotype and survival of T\(_{reg}\) cells in the thymus as well as in peripheral lymphoid organs. Specifically, the homeostasis of CD4\(^+\)CD25\(^+\)Foxp3\(^+\) but not the CD4\(^+\)CD25\(^-\)Foxp3\(^+\) fraction is severely perturbed when NFAT signaling is blocked, leading to a strongly reduced T\(_{reg}\) population. We underscored this intriguing effect of NFAT on CD4\(^+\)CD25\(^+\)Foxp3\(^+\) T\(_{reg}\) cells to the disruption of survival signals provided by interleukin 2 (IL-2). Accordingly, blocking T\(_{reg}\) cell death by abolishing the activity of pro-apoptotic Bcl-2 family member Bim, compensated for the survival defects induced due to a lack of NFAT-IL-2-IL-2R signaling. Inhibition of NFAT activity led to a strong reduction in the number of Foxp3\(^+\) T\(_{reg}\) cells; however, it did not influence the level of Foxp3 expression on an individual cell basis. In addition, we show a differential effect of IL-2 and IL-7 signaling on Foxp3\(^+\) T\(_{reg}\) versus CD4\(^+\)CD25\(^-\) T cell development, again underlining the dispensability of NFAT signaling in the development, but not in the maintenance of Foxp3\(^+\) T\(_{reg}\) cells. KW - thymocytes KW - NFAT KW - cyclosporine A KW - T\(_{reg}\) and Foxp3 Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-270668 SN - 2073-4409 VL - 11 IS - 9 ER - TY - JOUR A1 - Barahona de Brito, Carlotta A1 - Klein-Hessling, Stefan A1 - Serfling, Edgar A1 - Patra, Amiya Kumar T1 - Hematopoietic stem and progenitor cell maintenance and multiple lineage differentiation is an integral function of NFATc1 JF - Cells N2 - Hematopoietic stem and progenitor cell (HSPC) maintenance and the differentiation of various lineages is a highly complex but precisely regulated process. Multiple signaling pathways and an array of transcription factors influence HSPC maintenance and the differentiation of individual lineages to constitute a functional hematopoietic system. Nuclear factor of activated T cell (NFAT) family transcription factors have been studied in the context of development and function of multiple mature hematopoietic lineage cells. However, until now their contribution in HSPC physiology and HSPC differentiation to multiple hematopoietic lineages has remained poorly understood. Here, we show that NFAT proteins, specifically NFATc1, play an indispensable role in the maintenance of HSPCs. In the absence of NFATc1, very few HSPCs develop in the bone marrow, which are functionally defective. In addition to HSPC maintenance, NFATc1 also critically regulates differentiation of lymphoid, myeloid, and erythroid lineage cells from HSPCs. Deficiency of NFATc1 strongly impaired, while enhanced NFATc1 activity augmented, the differentiation of these lineages, which further attested to the vital involvement of NFATc1 in regulating hematopoiesis. Hematopoietic defects due to lack of NFATc1 activity can lead to severe pathologies such as lymphopenia, myelopenia, and a drastically reduced lifespan underlining the critical role NFATc1 plays in HSPC maintenance and in the differentaion of various lineages. Our findings suggest that NFATc1 is a critical component of the myriad signaling and transcriptional regulators that are essential to maintain normal hematopoiesis. KW - hematopoiesis KW - HSC KW - lineage differentiation KW - NFATc1 Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-278809 SN - 2073-4409 VL - 11 IS - 13 ER -