Interferonβ-1b Induces the Expression of RGS1 a Negative Regulator of G-Protein Signaling

We present evidence of a link between interferonβ-1b (IFN-β) and G-protein signaling by demonstrating that IFN-β can induce the expression of the negative regulator of G-protein signaling 1 (RGS1). RGS1 reduces G-protein activation and immune cell migration by interacting with heterotrimeric G-proteins and enhancing their intrinsic GTPase activity. In this study, IFN-β treatment resulted in the induction of RGS1 in peripheral blood mononuclear cells (PBMCs), monocytes, T cells, and B cells. Induction of RGS1 by IFN-β was concentration dependent and observed at both the RNA and protein level. Other members of the RGS family were not induced by IFN-β, and induction of RGS1 required the activation of the IFN receptor. In addition, RGS1 induction was observed in PBMCs obtained from IFN-β-treated multiple sclerosis patients suggesting a possible, as yet unexplored, involvement of G-protein regulation in disease treatment. The upregulation of RGS1 by IFN-β has not been previously reported

IL-17A and Th17 Cells in Lung Inflammation: An Update on the Role of Th17 Cell Differentiation and IL-17R Signaling in Host Defense against Infection

The significance of Th17 cells and interleukin- (IL-)17A signaling in host defense and disease development has been demonstrated in various infection and autoimmune models. Numerous studies have indicated that Th17 cells and its signature cytokine IL-17A are critical to the airway’s immune response against various bacteria and fungal infection. Cytokines such as IL-23, which are involved in Th17 differentiation, play a critical role in controlling Klebsiella pneumonia (K. pneumonia) infection. IL-17A acts on nonimmune cells in infected tissues to strengthen innate immunity by inducing the expression of antimicrobial proteins, cytokines, and chemokines. Mice deficient in IL-17 receptor (IL-17R) expression are susceptible to infection by various pathogens. In this review, we summarize the recent advances in unraveling the mechanism behind Th17 cell differentiation, IL-17A/IL-17R signaling, and also the importance of IL-17A in pulmonary infection

A Novel Nuclear Function for the Interleukin-17 Signaling Adaptor Protein Act1.

In the context of the human airway, interleukin-17A (IL-17A) signaling is associated with severe inflammation, as well as protection against pathogenic infection, particularly at mucosal surfaces such as the airway. The intracellular molecule Act1 has been demonstrated to be an essential mediator of IL-17A signaling. In the cytoplasm, it serves as an adaptor protein, binding to both the intracellular domain of the IL-17 receptor as well as members of the canonical nuclear factor kappa B (NF-κB) pathway. It also has enzymatic activity, and serves as an E3 ubiquitin ligase. In the context of airway epithelial cells, we demonstrate for the first time that Act1 is also present in the nucleus, especially after IL-17A stimulation. Ectopic Act1 expression can also increase the nuclear localization of Act1. Act1 can up-regulate the expression and promoter activity of a subset of IL-17A target genes in the absence of IL-17A signaling in a manner that is dependent on its N- and C-terminal domains, but is NF-κB independent. Finally, we show that nuclear Act1 can bind to both distal and proximal promoter regions of DEFB4, one of the IL-17A responsive genes. This transcriptional regulatory activity represents a novel function for Act1. Taken together, this is the first report to describe a non-adaptor function of Act1 by directly binding to the promoter region of IL-17A responsive genes and directly regulate their transcription

A Novel Nuclear Function for the Interleukin-17 Signaling Adaptor Protein Act1

In the context of the human airway, interleukin-17A (IL-17A) signaling is associated with severe inflammation, as well as protection against pathogenic infection, particularly at mucosal surfaces such as the airway. The intracellular molecule Act1 has been demonstrated to be an essential mediator of IL-17A signaling. In the cytoplasm, it serves as an adaptor protein, binding to both the intracellular domain of the IL-17 receptor as well as members of the canonical nuclear factor kappa B (NF-kappa B) pathway. It also has enzymatic activity, and serves as an E3 ubiquitin ligase. In the context of airway epithelial cells, we demonstrate for the first time that Act1 is also present in the nucleus, especially after IL-17A stimulation. Ectopic Act1 expression can also increase the nuclear localization of Act1. Act1 can up-regulate the expression and promoter activity of a subset of IL-17A target genes in the absence of IL-17A signaling in a manner that is dependent on its N- and C-terminal domains, but is NF-kappa B independent. Finally, we show that nuclear Act1 can bind to both distal and proximal promoter regions of DEFB4, one of the IL-17A responsive genes. This transcriptional regulatory activity represents a novel function for Act1. Taken together, this is the first report to describe a non-adaptor function of Act1 by directly binding to the promoter region of IL-17A responsive genes and directly regulate their transcription.National Institute of Health [AI061695, AI113526, HL096373, T32 HL07013, ES00628, HL097087]; Clinical Innovator Award from Flight Attendant Medical Research Institute [123055-CIA]This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Further characterization of Act1 induced gene expression.

<p>(A) HBE1 cells were transfected with Act1-FLAG and harvested 24h post-transfection for RNA extraction and real-time PCR analysis of various IL-17 target genes. (B) A549 or NHBE cells were transfected with empty vector (EV) or Act1-FLAG and harvested 24h post-transfection for RNA extraction and real-time PCR analysis of <i>DEFB4</i> expression. (C) HBE1 cells were transfected with empty vector, Act1-FLAG or untagged Act1 and harvested 24h post-transfection for RNA extraction and real-time PCR analysis of <i>DEFB4</i> expression. C(t) values were normalized to <i>GAPDH</i> and calibrated to empty vector controls. Error bars represent SEM of 3 independent experiments. *p<0.05 compared to empty vector (EV) transfected cells.</p

Further characterization of Act1 induced gene expression.

<p>(A) HBE1 cells were transfected with Act1-FLAG and harvested 24h post-transfection for RNA extraction and real-time PCR analysis of various IL-17 target genes. (B) A549 or NHBE cells were transfected with empty vector (EV) or Act1-FLAG and harvested 24h post-transfection for RNA extraction and real-time PCR analysis of <i>DEFB4</i> expression. (C) HBE1 cells were transfected with empty vector, Act1-FLAG or untagged Act1 and harvested 24h post-transfection for RNA extraction and real-time PCR analysis of <i>DEFB4</i> expression. C(t) values were normalized to <i>GAPDH</i> and calibrated to empty vector controls. Error bars represent SEM of 3 independent experiments. *p<0.05 compared to empty vector (EV) transfected cells.</p

PCR Primers.

<p>PCR Primers.</p