The role of WNT signaling in mature T cells: TCF Is coming home

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T cell factor, the effector transcription factor of the WNT signaling pathway, was so named because of the primary observation that it is indispensable for T cell development in the thymus. Since this discovery, the role of this signaling pathway has been extensively studied in T cell development, hematopoiesis, and stem cells; however, its functional role in mature T cells has remained relatively underinvestigated. Over the last few years, various studies have demonstrated that T cell factor can directly influence T cell function and the differentiation of Th1, Th2, Th17, regulatory T cell, follicular helper CD4+ T cell subsets, and CD8+ memory T cells. In a recent review paper in Journal of Immunology with Jorg van Loosdregt, we discuss the molecular mechanisms underlying these observations and place them in the general context of immune responses. Furthermore, we explore the implications and limitations of these findings for WNT manipulation as a therapeutic approach for treating immune-related diseases. You can find out more here.

Forkhead box transcription factors as context-dependent regulators of lymphocyte homeostasis

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Lymphocytes have evolved to react rapidly and robustly to changes in their local environment by using transient adaptations and by regulating their terminal differentiation programmes. Forkhead box transcription factors (FTFs) can direct leukocyte-specific responses, and their functional diversification promotes a high degree of context-dependent specification. Many, often antagonistic, FTFs have overlapping expression patterns and can thereby compete for binding to the same chromosomal target sequences. Multiple molecular mechanisms also connect extracellular signals to the expression and functionality of specific FTFs and, in this way, fine-tune their activity. Through these diverse mechanisms, FTFs can function as context-dependent rheostats responding to diverse environmental stimuli. Focusing on the various mechanisms by which their functional activity is modulated, as well as on their mechanisms of action, we discuss how specific FTFs control lymphocyte function, allowing for the establishment and maintenance of immune homeostasis. This review, written together with Dietmar Zaiss (University of Edinburgh) has been published in Nature Immunology Reviews

STAT5 is essential for IL-7–mediated viability, growth, and proliferation of T-cell acute lymphoblastic leukemia cells

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T-cell acute lymphoblastic leukemia (T-ALL) constitutes an aggressive subset of ALL, the most frequent childhood malignancy. Whereas interleukin-7 (IL-7) is essential for normal T-cell development, it can also accelerate T-ALL development in vivo and leukemia cell survival and proliferation by activating phosphatidylinositol 3-kinase/protein kinase B/mechanistic target of rapamycin signaling. Here, we investigated whether STAT5 could also mediate IL-7 T-ALL-promoting effects. We show that IL-7 induces STAT pathway activation in T-ALL cells and that STAT5 inactivation prevents IL-7–mediated T-ALL cell viability, growth, and proliferation. At the molecular level, STAT5 is required for IL-7-induced downregulation of p27kip1and upregulation of the transferrin receptor, CD71. Surprisingly, STAT5 inhibition does not significantly affect IL-7–mediated Bcl-2 upregulation, suggesting that, contrary to normal T-cells, STAT5 promotes leukemia cell survival through a Bcl-2-independent mechanism. STAT5 chromatin immunoprecipitation sequencing and RNA sequencing reveal a diverse IL-7-driven STAT5-dependent transcriptional program in T-ALL cells, which includes BCL6 inactivation by alternative transcription and upregulation of the oncogenic serine/threonine kinase PIM1. Pharmacological inhibition of PIM1 abrogates IL-7–mediated proliferation on T-ALL cells, indicating that strategies involving the use of PIM kinase small-molecule inhibitors may have therapeutic potential against a majority of leukemias that rely on IL-7 receptor (IL-7R) signaling. Overall, our results demonstrate that STAT5, in part by upregulating PIM1 activity, plays a major role in mediating the leukemia-promoting effects of IL-7/IL-7R. 

This work was a collaboration with the Barata Lab (IMM, Lisbon) and has been published in Blood Advances

Turning an tumor suppressor into an oncogene

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SOX4 is an important component in the tumor-promoting transcriptional response induced by TGF-beta in breast cancer. Here, Stephin Vervoort and Ana Rita Lourenco performed an unbiased transcription factor interaction screen and identified SMAD3 as a novel interaction partner of SOX4. SOX4 was found to specifically control a pro-oncogenic subset of SOX4/SMAD3 co-bound TGFbeta-target genes, associated with poor-disease outcome. Our findings thus highlight a novel role of SOX4 in the TGFbeta-pathway by cooperatively regulating target genes with SMAD3 in a context-dependent manner, thereby skewing TGFbeta-responses. This work has been published in Nucleic Acid Research

Regenerative Medicine Utrecht looking for 29 new international PhD students

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With an aging population and rising healthcare costs, the need for organs, tissues and personalized strategies in medicine has never been greater. Recent developments in medical technologies such as 3D-bioprinting, stem cell therapy and gene editing hold the promise to provide tissues for transplantation, tailor-made medical solutions and opportunities to help the body repair and regenerate itself. However, our understanding of the fundamentals of cell, tissue and organ regeneration and their potential application for therapeutic purposes are still in its infancy. For Regenerative Medicine to fully capture its potential, a synergistic and multidisciplinary effort remains necessary to achieve essential scientific breakthroughs.

Together the University Medical Center Utrecht (coordinator) and the Utrecht University offer a unique international PhD programme, named RESCUE, for excellent PhD candidates (early stage researchers, ESRs) with 29 high level fellowships for a joint doctorate programme within the Regenerative Medicine Centre Utrecht. The RESCUE programme aims to enhance the potential and future career perspectives of researchers by providing a global training network including over 50 excellent academic and industrial partner organisations, creating a new generation of research experts, empowering them to take leading positions in the field of Regenerative Medicine world-wide.

PhD positions are for Master's students who have not worked in The Netherlands for more than 12 months in the last 3 years. Positions are available in the fields of: stem cells & organoids, cardiovascular regeneration and musculoskeletal regeneration. The Coffer Lab also has a joint position available. 

More information and the application procedure can be found here www.rescue-cofund.eu.

Targeting autophagy in T helper cells may represent a novel therapeutic approach to induce tolerance and treat autoimmune disease

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Activation of CD4+ T cells induces autophagy, a catabolic process through which cell components are sequestered into autophagosomes that fuse with lysosomes to degrade cargo. The functional role of activation-induced autophagy has not been determined yet. In this collaborative work together with Fernando Macian's group (Albert Einstein College of Medicine), we identify autophagy as a key tolerance avoidance mechanism. Data from Enric Mocholi, who has worked in both labs, has revealed that inhibition of autophagy during T cell activation induces a long-lasting state of hypo-responsiveness in effector T helper cells, accompanied by the expression of an anergic gene signature. Cells unable to induce autophagy after TCR engagement show inefficient mitochondrial respiration, and reduced TCR-mediated signaling. In vivo, inhibition of autophagy during antigen priming induces CD4+ T cell anergy and decreases the severity of disease in an experimental autoimmune encephalomyelitis model. Interestingly, CD4+ T cells isolated from the synovial fluid of juvenile idiopathic arthritis (JIA) patients, while resistant to suboptimal stimulation-induced anergy, can be tolerized with autophagy inhibitors. Autophagy constitutes, thus, a tolerance avoidance mechanism which determines CD4+ T cell fate. Targeting autophagy in T helper cells may represent a novel therapeutic approach to induce tolerance and treat autoimmune disease. This work has been published in Cell Reports

Megakaryocyte lineage development is controlled by modulation of protein acetylation

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Treatment with lysine deacetylase inhibitors (KDACi) for haematological malignancies, is accompanied by haematological side effects including thrombocytopenia, suggesting that modulation of protein acetylation affects normal myeloid development, and specifically megakaryocyte development. However, the effects of KDACi inhibitors on human hematopoiesis have not been systematically investigated.  In this study by Marije Bartels and Anita Govers, utilising ex-vivo differentiation of human haematopoietic progenitor cells, we investigated the effects of two functionally distinct KDACi, valproic acid (VPA), and nicotinamide (NAM), on megakaryocyte differentiation, and lineage choice decisions. While both being KDACi, VPA and NAM can differentially regulate cell fate decisions during megakaryocyte, and erythroid (ME) development through specific effects on promoter-acetylation of genes regulating ME-lineage development. Here, we compared the effects of VPA treatment with NAM treatment on human ME-lineage development, and further progression into the megakaryocytic lineage. Our data demonstrate for the first time that KDAC and SIRT inhibition differentially modulates the expansion and differentiation of ME-progenitors (MEP). Utilising a histone 3 lysine 27 acetylation (H3K27ac) chromatin immunoprecipitation- (ChIP) sequencing approach, we identified key regulatory genes implicated in myeloid progenitor function, and ME-lineage differentiation, directly regulated by VPA and NAM treatment. These findings increase our understanding of the effects of KDACi on normal haematopoiesis which should be considered when using KDACi in a clinical context. This work has recently been accepted for publication in PLoS ONE