Commensurate with their roles in regulating cytokine-dependent inflammation and immunity, signal transducer and activator of transcription (STAT) proteins are central in determining whether immune responses in the tumour microenvironment promote or inhibit cancer. Persistently activated STAT3 and, to some extent, STAT5 increase tumour cell proliferation, survival and invasion while suppressing anti-tumour immunity. The persistent activation of STAT3 also mediates tumour-promoting inflammation. STAT3 has this dual role in tumour inflammation and immunity by promoting pro-oncogenic inflammatory pathways, including nuclear factor-kappaB (NF-kappaB) and interleukin-6 (IL-6)-GP130-Janus kinase (JAK) pathways, and by opposing STAT1- and NF-kappaB-mediated T helper 1 anti-tumour immune responses. Consequently, STAT3 is a promising target to redirect inflammation for cancer therapy.

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STATs in cancer inflammation and immunity: a leading role for STAT3

The mitogen-activated protein kinase signal transduction pathway.

Maximal activation of transcription by Stat1 and Stat3 requires both tyrosine and serine phosphorylation.

Publisher Summary The chapter introduces the mitogen-activated protein (MAP) kinase (MAPK) module. The identification of MAP kinase pathways exemplifies the power of combining biochemical and genetic approaches to molecular problems. The chapter discusses the mammalian MAPK pathways—ERKl/2 and MKKl/2 pathways—and stress-activated protein kinase pathways. The regulation of MAPK pathways by protein phosphatases is discussed in the chapter describing in detail about dual specificity phosphatases, serinenhreonine phosphatases, and protein tyrosine phosphatases. The chapter explores the cellular substrates of MAP kinases, wherein it discusses about protein kinase substrates for MAPKS, nuclear transcription factors, signaling components, and cytoskeletal proteins. Responses to MAPK pathways, regulation of cell growth and transformation, and regulation of cell differentiation and development have also been summarized in the chapter. The chapter describes the yeast MAPK pathways of saccharomyces cerevisiae (Budding Yeast) and Schizosaccharomyces pombe (Fission Yeast). The chapter provides the description of the intracellular targeting and spatial regulation of MAPK pathway components, signaling complexes, and the nuclear translocation of MAPK and MKK. Eukaryotic MAPK cascades provide excellent examples of signal transduction mechanisms that embody key principles common to many, if not all, signaling pathways. Many fundamental questions remain for future studies to investigate the mechanisms by which these pathways are regulated as well as the cellular responses that they control.

Signal transduction through MAP kinase cascades.

Cytokines and interferons are molecules that play central roles in the regulation of a wide array of cellular functions in the lympho-hematopoietic system. These factors stimulate proliferation, differentiation, and survival signals, as well as specialized functions in host resistance to pathogens. Although cytokines are known to activate multiple signaling pathways that together mediate these important functions, one of these pathways, the Jak-STAT pathway, is the focus of this chapter. This pathway is triggered by both cytokines and interferons, and it very rapidly allows the transduction of an extracellular signal into the nucleus. The pathway uses a novel mechanism in which cytosolic latent transcription factors, known as signal transducers and activators of transcription (STATs), are tyrosine phosphorylated by Janus family tyrosine kinases (Jaks), allowing STAT protein dimerization and nuclear translocation. STATs then can modulate the expression of target genes. The basic biology of this system, including the range of known Jaks and STATs, is discussed, as are the defects in animals and humans lacking some of these signaling molecules.

/pdf/jaks-and-stats-biological-implications-23mq0jx75j.pdf

JAKS AND STATS: Biological Implications*

https://www.cell.com/cell/pdf/0092-8674(94)90235-6.pdf

Molecular cloning of APRF, a novel IFN-stimulated gene factor 3 p91-related transcription factor involved in the gp130-mediated signaling pathway

NF-IL6, a member of the basic leucine zipper (bZIP) family transcription factors, is involved in expression of inducible genes involved in immune and inflammatory responses. We observed that coexpression of oncogenic p21ras stimulated the transactivating activity of NF-IL6 and induced phosphorylation of Thr-235 located just N-terminal to the DNA binding domain of NF-IL6. Recently, mitogen-activated protein (MAP) kinases have been shown to be implicated in the cellular response to activated ras. Purified MAP kinases specifically phosphorylated Thr-235 of NF-IL6 in vitro. Mutation of Thr-235 abolished the ras-dependent activation of NF-IL6. From these results, we conclude that NF-IL6 is regulated through phosphorylation by MAP kinases in response to activated ras.

https://www.pnas.org/content/pnas/90/6/2207.full.pdf

Phosphorylation at threonine-235 by a ras-dependent mitogen-activated protein kinase cascade is essential for transcription factor NF-IL6.

We investigated the pathophysiological role of a potent macrophage (M(phi)) chemotactic cytokine (chemokine), monocyte chemotactic and activating factor/monocyte chemoattractant protein-1 (MCAF/MCP-1), in an animal model of crescentic glomerulonephritis. Administration of a small dose of nephrotoxic sera induced severe proliferative and necrotizing glomerulonephritis, with crescentic formation in the early phase and glomerulosclerosis in the later phase, in Wistar-Kyoto rats. MCAF/MCP-1 protein was detected immunohistochemically in glomeruli, vascular endothelial cells, and tubular epithelial cells in the early phase of injured kidney tissues but not in normal ones. Anti-MCAF/MCP-1 antibodies decreased the number of M(phi) in glomeruli, and prevented crescentic formation and the fusion of epithelial cell foot process in nephritic rats, thereby decreasing the excreted amounts of protein to normal levels on days 3 and 6. Furthermore, anti-MCAF/MCP-1 antibodies remarkably reduced glomerulosclerosis and impro...

Intervention of crescentic glomerulonephritis by antibodies to monocyte chemotactic and activating factor (MCAF/MCP-1)

Identification of interleukin-8 converting enzyme as cathepsin L.

A drug for prevention and therapy of diseases caused by fibrinoid formation or thrombus formation, as well as a model animal of fibrinoid formation or thrombus formation in the lung is disclosed. The drug for preventing and treating diseases caused by fibrinoid formation or thrombus formation in the lung according to the present invention comprises an inhibitor of interleukin 6 as an effective ingredient. The model animal of the diseases caused by fibrinoid formation or thrombus formation in the lung is a rat in which fibrinoid formation or thrombus formation actually occurs by induction with interleukin 6.

Masanobu Naruto

Papers

Molecular cloning of APRF, a novel IFN-stimulated gene factor 3 p91-related transcription factor involved in the gp130-mediated signaling pathway

Phosphorylation at threonine-235 by a ras-dependent mitogen-activated protein kinase cascade is essential for transcription factor NF-IL6.

Intervention of crescentic glomerulonephritis by antibodies to monocyte chemotactic and activating factor (MCAF/MCP-1)

Identification of interleukin-8 converting enzyme as cathepsin L.

Drug for prevention and therapy of diseases caused by fibrinoid formation or thrombus formation in the lung and model animals of the diseases