Project description:Immune cells need to sustain a state of constant alertness over a lifetime. Yet, little is known about the regulatory processes that control the fluent and fragile balance that is called homeostasis. Here we demonstrate that JAK-STAT signaling, beyond its role in immune responses, is a major regulator of immune cell homeostasis. We investigated JAK-STAT-mediated transcription and chromatin accessibility across 12 mouse models, including knockouts of all STAT transcription factors and of the TYK2 kinase. Baseline JAK-STAT signaling was detected in CD8+ T cells and macrophages of unperturbed mice – but abrogated in the knockouts and in unstimulated immune cells deprived of their normal tissue context. We observed diverse transcription-regulatory programs, including gene regulation by STAT2 and IRF9 independent of STAT1. In summary, our large-scale dataset and integrative analysis of JAK-STAT mutant and wildtype mice uncovered a crucial role of JAK-STAT signaling in unstimulated immune cells, where it contributes to a poised epigenetic and transcription-regulatory state and helps prepare these cells for rapid response to immune stimuli.
Project description:Immune cells need to sustain a state of constant alertness over a lifetime. Yet, little is known about the regulatory processes that control the fluent and fragile balance that is called homeostasis. Here we demonstrate that JAK-STAT signaling, beyond its role in immune responses, is a major regulator of immune cell homeostasis. We investigated JAK-STAT-mediated transcription and chromatin accessibility across 12 mouse models, including knockouts of all STAT transcription factors and of the TYK2 kinase. Baseline JAK-STAT signaling was detected in CD8+ T cells and macrophages of unperturbed mice – but abrogated in the knockouts and in unstimulated immune cells deprived of their normal tissue context. We observed diverse transcription-regulatory programs, including gene regulation by STAT2 and IRF9 independent of STAT1. In summary, our large-scale dataset and integrative analysis of JAK-STAT mutant and wildtype mice uncovered a crucial role of JAK-STAT signaling in unstimulated immune cells, where it contributes to a poised epigenetic and transcription-regulatory state and helps prepare these cells for rapid response to immune stimuli.
Project description:Immune cells need to sustain a state of constant alertness over a lifetime. Yet, little is known about the regulatory processes that control the fluent and fragile balance that is called homeostasis. Here we demonstrate that JAK-STAT signaling, beyond its role in immune responses, is a major regulator of immune cell homeostasis. We investigated JAK-STAT-mediated transcription and chromatin accessibility across 12 mouse models, including knockouts of all STAT transcription factors and of the TYK2 kinase. Baseline JAK-STAT signaling was detected in CD8+ T cells and macrophages of unperturbed mice – but abrogated in the knockouts and in unstimulated immune cells deprived of their normal tissue context. We observed diverse transcription-regulatory programs, including gene regulation by STAT2 and IRF9 independent of STAT1. In summary, our large-scale dataset and integrative analysis of JAK-STAT mutant and wildtype mice uncovered a crucial role of JAK-STAT signaling in unstimulated immune cells, where it contributes to a poised epigenetic and transcription-regulatory state and helps prepare these cells for rapid response to immune stimuli.
Project description:Tumor-associated macrophages contribute to tumor progression and therapeutic resistance in breast cancer. Within the tumor microenvironment, tumor-derived factors activate pathways that modulate macrophage function. Using in vitro and in vivo models, we find that tumor-derived factors induce activation of the Janus kinase (JAK)/signal transducer and activator of transcription 3 (STAT3) pathway in macrophages. We also demonstrate that loss of STAT3 in myeloid cells leads to enhanced mammary tumorigenesis. Further studies show that macrophages contribute to resistance of mammary tumors to the JAK/STAT inhibitor ruxolitinib in vivo and that ruxolitinib-treated macrophages produce soluble factors that promote resistance of tumor cells to JAK inhibition in vitro. Finally, we demonstrate that STAT3 deletion and JAK/STAT inhibition in macrophages increases expression of the pro-tumorigenic factor cyclooxygenase-2 (COX-2) and that COX-2 inhibition enhances responsiveness of tumors to ruxolitinib. These findings define a novel mechanism through which macrophages promote therapeutic resistance and highlight the importance of understanding the impact of targeted therapies on the tumor microenvironment.
Project description:Here we investigated the effects of JAK/STAT pharmacological inhibition on cHL cell models using ruxolitinib, a JAK 1/2 inhibitor. We use five classical Hodgkin lymphoma cell lines: L428, L1236, L540, KMH2, L591
Project description:The JAK/STAT pathway is an essential signalling cascade required for multiple processes during both development and for adult homeostasis. A key question in understanding this pathway is how it is regulated in different cell contexts. Here we have examined how endocytic processing contributes to signalling by the single cytokine receptor, Domeless, in Drosophila melanogaster cells. We identify an evolutionarily conserved di-Leu motif that is required for Domeless internalisation and show that endocytosis is required for activation of a subset of Domeless targets. Our data indicate that endocytosis both qualitatively and quantitatively regulates Domeless signalling. STAT92E, the single STAT transcription factor in Drosophila, appears to be the target of endocytic regulation and our studies show that phosphorylation of STAT92E on Tyr704, while necessary, is not always sufficient for target transcription. Finally, we identify a conserved residue, Thr702, which is essential for Tyr704 phosphorylation. Taken together, our findings identify previously unknown aspects of JAK/STAT pathway regulation likely to play key roles in the spatial and temporal regulation of signalling in vivo.