Project description:The intestinal epithelium ensures uptake of vital nutrients and acts as a barrier between luminal contents and the underlying immune system. In inflammatory bowel diseases, such as ulcerative colitis (UC), this barrier is compromised, and patients experience debilitating symptoms. Here, we perform single-cell RNA profiling of epithelial cells and outline patterns of cell fate decisions in healthy individuals and UC patients. We demonstrate that patterns of hierarchical behavior are altered in UC patients and identify unique cellular states associated with Janus kinase/signal transducer and activator of transcription (JAK/STAT) activation in ulcerated and non-ulcerated areas of the colonic epithelium. These transcriptional changes could be recapitulated in human colonic organoids, wherein cytokine-mediated activation of JAK/STAT led to the emergence of cell populations with augmented regenerative properties. Altogether, our findings indicate that intricate relationships between epithelial and cytokine signaling regulate cell fate during epithelial tissue regeneration in humans and have important implications for the understanding of UC biology.
Project description:In 2018, the pan-Janus kinase (JAK) inhibitor tofacitinib was launched for the treatment of ulcerative colitis (UC). Although tofacitinib has proven efficacious in patients with active UC, it failed in patients with Crohn's disease (CD). This finding strongly hints at a different contribution of JAK signaling in both entities. Here, we review the current knowledge on the interplay between the JAK/signal transducer and activator of transcription (STAT) pathway and inflammatory bowel diseases (IBD). In particular, we provide a detailed overview of the differences and similarities of JAK/STAT-signaling in UC and CD, highlight the impact of the JAK/STAT pathway in experimental colitis models and summarize the published evidence on JAK/STAT-signaling in immune cells of IBD as well as the genetic association between the JAK/STAT pathway and IBD. Finally, we describe novel treatment strategies targeting JAK/STAT inhibition in UC and CD and comment on the limitations and challenges of the new drug class.
Project description:The JAK-STAT pathway represents a finely tuned orchestra capable of rapidly facilitating an exquisite symphony of responses from a complex array of extracellular signals. This review explores the evolution of the JAK-STAT pathway: the origins of the individual domains from which it is constructed, the formation of individual components from these basic building blocks, the assembly of the components into a functional pathway, and the subsequent reiteration of this basic template to fulfill a variety of roles downstream of cytokine receptors.
Project description:Hexanucleotide repeat expansion in the gene C9ORF72 is a leading cause of amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD). C9ORF72 deficiency leads to severe inflammatory phenotypes in mice, but exactly how C9ORF72 regulates inflammation remains to be fully elucidated. Here, we report that loss of C9ORF72 leads to the hyperactivation of the JAK-STAT pathway and an increase in the protein levels of STING, a transmembrane adaptor protein involved in immune signaling in response to cytosolic DNA. Treatment with a JAK inhibitor rescues the enhanced inflammatory phenotypes caused by C9ORF72 deficiency in cell culture and mice. Furthermore, we showed that the ablation of C9ORF72 results in compromised lysosome integrity, which could contribute to the activation of the JAK/STAT-dependent inflammatory responses. In summary, our study identifies a mechanism by which C9ORF72 regulates inflammation, which might facilitate therapeutic development for ALS/FTLD with C9ORF72 mutations.
Project description:Liver cancer is the second most lethal cancer in the world with limited treatment options. Hepatocellular carcinoma (HCC), which accounts for more than 80% of all liver cancers, has had increasing global incidence over the past few years. There is an urgent need for novel and better therapeutic intervention for HCC patients. The JAK/STAT signaling pathway plays a multitude of important biological functions in both normal and malignant cells. In a subset of HCC, JAK/STAT signaling is aberrantly activated, leading to dysregulation of downstream target genes that controls survival, angiogenesis, stemness, immune surveillance, invasion and metastasis. In this review, we will focus on the role of JAK/STAT signaling in HCC and discuss the current clinical status of several JAK/STAT inhibitors.
Project description:Calcineurin (Cn) is a protein phosphatase that regulates the activation of the nuclear factor of activated T-cells (NFAT) family of transcription factors, which are key regulators of T-cell development and function. Here, we generated a conditional Cnb1 mouse model in which Cnb1 was specifically deleted in CD4+ T cells (Cnb1CD4 mice) to delineate the role of the Cn-NFAT pathway in immune homeostasis of the intestine. The Cnb1CD4 mice developed severe, spontaneous colitis characterized at the molecular level by an increased T helper-1-cell response but an unaltered regulatory T-cell compartment. Antibiotic treatment ameliorated the intestinal inflammation observed in Cnb1CD4 mice, suggesting that the microbiota contributes to the onset of colitis. CD4+ T cells isolated from Cnb1CD4 mice produced high levels of IFNγ due to increased activation of the JAK2/STAT4 pathway induced by IL-12. Our data highlight that Cn signaling in CD4+ T cells is critical for intestinal immune homeostasis in part by inhibiting IL-12 responsiveness of CD4+ T cells.
Project description:JAK-STAT signaling pathway plays an important role in the cells' development and homeostasis. Over the past decades, the studies have identified the role of the JAK-STAT pathway in cell proliferation and apoptosis. Here, we want to discuss that whether and how the JAK-STAT pathway affects the lipid metabolism of adipose tissue. A host of cytokines and hormones can regulate lipid metabolism through activating the JAK-STAT signaling pathway. Activated STATs can regulate lipid metabolism directly by influencing the expression of enzymes. We have summarized the relevant research and articles of JAK-STAT during the recent years. Within this review, we will introduce you the recent research and highlight the unresolved problems in understanding how JAK-STAT signaling pathway contribute to the lipid metabolism in mature adipocytes and preadipocytes. Dysregulation of the JAK-STAT pathway would lead to a multiple metabolism disorders and medicines for this signaling pathway maybe become a new idea for diseases such as metabolic syndrome, especially in children.
Project description:BackgroundThe JAK/STAT pathway transduces signals from multiple cytokines and controls haematopoiesis, immunity and inflammation. In addition, pathological activation is seen in multiple malignancies including the myeloproliferative neoplasms (MPNs). Given this, drug development efforts have targeted the pathway with JAK inhibitors such as ruxolitinib. Although effective, high costs and side effects have limited its adoption. Thus, a need for effective low cost treatments remains.Methods & findingsWe used the low-complexity Drosophila melanogaster pathway to screen for small molecules that modulate JAK/STAT signalling. This screen identified methotrexate and the closely related aminopterin as potent suppressors of STAT activation. We show that methotrexate suppresses human JAK/STAT signalling without affecting other phosphorylation-dependent pathways. Furthermore, methotrexate significantly reduces STAT5 phosphorylation in cells expressing JAK2 V617F, a mutation associated with most human MPNs. Methotrexate acts independently of dihydrofolate reductase (DHFR) and is comparable to the JAK1/2 inhibitor ruxolitinib. However, cells treated with methotrexate still retain their ability to respond to physiological levels of the ligand erythropoietin.ConclusionsAminopterin and methotrexate represent the first chemotherapy agents developed and act as competitive inhibitors of DHFR. Methotrexate is also widely used at low doses to treat inflammatory and immune-mediated conditions including rheumatoid arthritis. In this low-dose regime, folate supplements are given to mitigate side effects by bypassing the biochemical requirement for DHFR. Although independent of DHFR, the mechanism-of-action underlying the low-dose effects of methotrexate is unknown. Given that multiple pro-inflammatory cytokines signal through the pathway, we suggest that suppression of the JAK/STAT pathway is likely to be the principal anti-inflammatory and immunosuppressive mechanism-of-action of low-dose methotrexate. In addition, we suggest that patients with JAK/STAT-associated haematological malignancies may benefit from low-dose methotrexate treatments. While the JAK1/2 inhibitor ruxolitinib is effective, a £43,200 annual cost precludes widespread adoption. With an annual methotrexate cost of around £32, our findings represent an important development with significant future potential.