Interferons play key roles in mediating antiviral and antigrowth responses and in modulating immune response. The main signaling pathways are rapid and direct. They involve tyrosine phosphorylation and activation of signal transducers and activators of transcription factors by Janus tyrosine kinases at the cell membrane, followed by release of signal transducers and activators of transcription and their migration to the nucleus, where they induce the expression of the many gene products that determine the responses. Ancillary pathways are also activated by the interferons, but their effects on cell physiology are less clear. The Janus kinases and signal transducers and activators of transcription, and many of the interferon-induced proteins, play important alternative roles in cells, raising interesting questions as to how the responses to the interferons intersect with more general aspects of cellular physiology and how the specificity of cytokine responses is maintained.

http://www3.uah.es/farmamol/Public/AnnReviews/PDF/Biochemistry/Interferons.pdf

How cells respond to interferons

Interferon-gamma (IFN-gamma) coordinates a diverse array of cellular programs through transcriptional regulation of immunologically relevant genes. This article reviews the current understanding of IFN-gamma ligand, receptor, signal transduction, and cellular effects with a focus on macrophage responses and to a lesser extent, responses from other cell types that influence macrophage function during infection. The current model for IFN-gamma signal transduction is discussed, as well as signal regulation and factors conferring signal specificity. Cellular effects of IFN-gamma are described, including up-regulation of pathogen recognition, antigen processing and presentation, the antiviral state, inhibition of cellular proliferation and effects on apoptosis, activation of microbicidal effector functions, immunomodulation, and leukocyte trafficking. In addition, integration of signaling and response with other cytokines and pathogen-associated molecular patterns, such as tumor necrosis factor-alpha, interleukin-4, type I IFNs, and lipopolysaccharide are discussed.

https://jlb.onlinelibrary.wiley.com/doi/epdf/10.1189/jlb.0603252

Interferon-γ: an overview of signals, mechanisms and functions

Interferons are cytokines that play a complex and central role in the resistance of mammalian hosts to pathogens. Type I interferon (IFN-alpha and IFN-beta) is secreted by virus-infected cells. Immune, type II, or gamma-interferon (IFN-gamma) is secreted by thymus-derived (T) cells under certain conditions of activation and by natural killer (NK) cells. Although originally defined as an agent with direct antiviral activity, the properties of IFN-gamma include regulation of several aspects of the immune response, stimulation of bactericidal activity of phagocytes, stimulation of antigen presentation through class I and class II major histocompatibility complex (MHC) molecules, orchestration of leukocyte-endothelium interactions, effects on cell proliferation and apoptosis, as well as the stimulation and repression of a variety of genes whose functional significance remains obscure. The implementation of such a variety of effects by a single cytokine is achieved by complex patterns of cell-specific gene regulation: Several IFN-gamma-regulated genes are themselves components of transcription factors. The IFN-gamma response is itself regulated by interaction with responses to other cytokines including IFN-alpha/beta, TNF-alpha, and IL-4. Over 200 genes are now known to be regulated by IFN-gamma and they are listed in a World Wide Web document that accompanies this review. However, much of the cellular response to IFN-gamma can be described in terms of a set of integrated molecular programs underlying well-defined physiological systems, for example the induction of efficient antigen processing for MHC-mediated antigen presentation, which play clearly defined roles in pathogen resistance. A promising approach to the complexity of the IFN-gamma response is to extend the analysis of the less understood IFN-gamma-regulated genes in terms of molecular programs functional in pathogen resistance.

Cellular responses to interferon-gamma.

Extracellular proteins bound to cell-surface receptors can change nuclear gene expression patterns in minutes, with far-reaching consequences for development, cell growth and homeostasis. The signal transducer and activator of transcription (STAT) proteins are among the most well studied of the latent cytoplasmic signal-dependent transcription-factor pathways. In addition to several roles in normal cell decisions, dysregulation of STAT function contributes to human disease, making the study of these proteins an important topic of current research.

/pdf/stats-transcriptional-control-and-biological-impact-4uxqiluxhc.pdf

STATs: transcriptional control and biological impact

Lymphocytes were originally thought to form the basis of a 'cancer immunosurveillance' process that protects immunocompetent hosts against primary tumour development, but this idea was largely abandoned when no differences in primary tumour development were found between athymic nude mice and syngeneic wild-type mice However, subsequent observations that nude mice do not completely lack functional T cells and that two components of the immune system-IFNgamma and perforin-help to prevent tumour formation in mice have led to renewed interest in a tumour-suppressor role for the immune response Here we show that lymphocytes and IFNgamma collaborate to protect against development of carcinogen-induced sarcomas and spontaneous epithelial carcinomas and also to select for tumour cells with reduced immunogenicity The immune response thus functions as an effective extrinsic tumour-suppressor system However, this process also leads to the immunoselection of tumour cells that are more capable of surviving in an immunocompetent host, which explains the apparent paradox of tumour formation in immunologically intact individuals

IFNγ, and lymphocytes prevent primary tumour development and shape tumour immunogenicity

Role for Fes/Fps Tyrosine Kinase in Microtubule Nucleation through Its Fes/CIP4 Homology Domain

Truncation of c-fes via gene targeting results in embryonic lethality and hyperproliferation of hematopoietic cells.

Secreted signaling proteins play fundamental roles in the embryonic patterning of multicellular organisms from insects to humans. Three protein families, bone morphogenetic proteins (BMPs), Wnts, and hedgehog (Hh) are secreted cell—cell signaling molecules that have been shown to be important regulators of a wide variety of normal and pathological developmental processes. BMPs, Wnts, and Hh can all be termed as morphogens in that they act directly at a distance and induce distinct differentiation programs at different concentrations. Signaling by BMPs, Wnts, and Hh is regulated in both positive and negative fashions at the extracellular, membrane, cytoplasmic, and nuclear levels. The range of molecular strategies involved in regulating the signaling activities of these proteins in a developing embryo highlights the crucial importance of maintaining tight spatial and temporal control of morphogens during development.

Renee Hackenmiller

Papers

Role for Fes/Fps Tyrosine Kinase in Microtubule Nucleation through Its Fes/CIP4 Homology Domain

Truncation of c-fes via gene targeting results in embryonic lethality and hyperproliferation of hematopoietic cells.

Control of Development and Homeostasis Via Regulation of BMP, Wnt, and Hedgehog Signaling