IFN-Lambda (IFN-λ) Is Expressed in a Tissue-Dependent Fashion and Primarily Acts on Epithelial Cells In Vivo

Interferons (IFN) exert antiviral, immunomodulatory and cytostatic activities. IFN-α/β (type I IFN) and IFN-λ (type III IFN) bind distinct receptors, but regulate similar sets of genes and exhibit strikingly similar biological activities. We analyzed to what extent the IFN-α/β and IFN-λ systems overlap in vivo in terms of expression and response. We observed a certain degree of tissue specificity in the production of IFN-λ. In the brain, IFN-α/β was readily produced after infection with various RNA viruses, whereas expression of IFN-λ was low in this organ. In the liver, virus infection induced the expression of both IFN-α/β and IFN-λ genes. Plasmid electrotransfer-mediated in vivo expression of individual IFN genes allowed the tissue and cell specificities of the responses to systemic IFN-α/β and IFN-λ to be compared. The response to IFN-λ correlated with expression of the α subunit of the IFN-λ receptor (IL-28Rα). The IFN-λ response was prominent in the stomach, intestine and lungs, but very low in the central nervous system and spleen. At the cellular level, the response to IFN-λ in kidney and brain was restricted to epithelial cells. In contrast, the response to IFN-α/β was observed in various cell types in these organs, and was most prominent in endothelial cells. Thus, the IFN-λ system probably evolved to specifically protect epithelia. IFN-λ might contribute to the prevention of viral invasion through skin and mucosal surfaces

Regulation of STIM1 and SOCE by the Ubiquitin-Proteasome System (UPS)

The ubiquitin proteasome system (UPS) mediates the majority of protein degradation in eukaryotic cells. The UPS has recently emerged as a key degradation pathway involved in synapse development and function. In order to better understand the function of the UPS at synapses we utilized a genetic and proteomic approach to isolate and identify novel candidate UPS substrates from biochemically purified synaptic membrane preparations. Using these methods, we have identified Stromal interacting molecule 1 (STIM1). STIM1 is as an endoplasmic reticulum (ER) calcium sensor that has been shown to regulate store-operated Ca2+ entry (SOCE). We have characterized STIM1 in neurons, finding STIM1 is expressed throughout development with stable, high expression in mature neurons. As in non-excitable cells, STIM1 is distributed in a membranous and punctate fashion in hippocampal neurons. In addition, a population of STIM1 was found to exist at synapses. Furthermore, using surface biotinylation and live-cell labeling methods, we detect a subpopulation of STIM1 on the surface of hippocampal neurons. The role of STIM1 as a regulator of SOCE has typically been examined in non-excitable cell types. Therefore, we examined the role of the UPS in STIM1 and SOCE function in HEK293 cells. While we find that STIM1 is ubiquitinated, its stability is not altered by proteasome inhibitors in cells under basal conditions or conditions that activate SOCE. However, we find that surface STIM1 levels and thapsigargin (TG)-induced SOCE are significantly increased in cells treated with proteasome inhibitors. Additionally, we find that the overexpression of POSH (Plenty of SH3′s), an E3 ubiquitin ligase recently shown to be involved in the regulation of Ca2+ homeostasis, leads to decreased STIM1 surface levels. Together, these results provide evidence for previously undescribed roles of the UPS in the regulation of STIM1 and SOCE function

Type I Interferons and Interferon Regulatory Factors Regulate TNF-Related Apoptosis-Inducing Ligand (TRAIL) in HIV-1-Infected Macrophages

TNF-related apoptosis-inducing ligand (TRAIL) is a member of the TNF family that participates in HIV-1 pathogenesis through the depletion of CD4+ T cells. TRAIL is expressed on the cell membrane of peripheral immune cells and can be cleaved into a soluble, secreted form. The regulation of TRAIL in macrophages during HIV-1 infection is not completely understood. In this study, we investigated the mechanism(s) of TRAIL expression in HIV-1-infected macrophages, an important cell type in HIV-1 pathogenesis. A human monocyte-derived macrophage (MDM) culture system was infected with macrophage-tropic HIV-1ADA, HIV-1JR-FL, or HIV-1BAL strains. TRAIL, predominantly the membrane-bound form, increased following HIV-1 infection. We found that HIV-1 infection also induced interferon regulatory factor (IRF)-1, IRF-7 gene expression and signal transducers and activators of transcription 1 (STAT1) activation. Small interfering RNA knockdown of IRF-1 or IRF-7, but not IRF-3, reduced STAT1 activation and TRAIL expression. Furthermore, the upregulation of IRF-1, IRF-7, TRAIL, and the activation of STAT1 by HIV-1 infection was reduced by the treatment of type I interferon (IFN)-neutralizing antibodies. In addition, inhibition of STAT1 by fludarabine abolished IRF-1, IRF-7, and TRAIL upregulation. We conclude that IRF-1, IRF-7, type I IFNs, and STAT1 form a signaling feedback loop that is critical in regulating TRAIL expression in HIV-1-infected macrophages

Selective blockade of interferon-α and -β reveals their non-redundant functions in a mouse model of West Nile virus infection

Although type I interferons (IFNs) were first described almost 60 years ago, the ability to monitor and modulate the functional activities of the individual IFN subtypes that comprise this family has been hindered by a lack of reagents. The major type I IFNs, IFN-β and the multiple subtypes of IFN-α, are expressed widely and induce their effects on cells by interacting with a shared heterodimeric receptor (IFNAR). In the mouse, the physiologic actions of IFN-α and IFN-β have been defined using polyclonal anti-type I IFN sera, by targeting IFNAR using monoclonal antibodies or knockout mice, or using Ifnb-/- mice. However, the corresponding analysis of IFN-α has been difficult because of its polygenic nature. Herein, we describe two monoclonal antibodies (mAbs) that differentially neutralize murine IFN-β or multiple subtypes of murine IFN-α. Using these mAbs, we distinguish specific contributions of IFN-β versus IFN-α in restricting viral pathogenesis and identify IFN-α as the key mediator of the antiviral response in mice infected with West Nile virus. This study thus suggests the utility of these new reagents in dissecting the antiviral and immunomodulatory roles of IFN-β versus IFN-α in murine models of infection, immunity, and autoimmunity

Thrombospondin-2 and SPARC/osteonectin are critical regulators of bone remodeling

Thrombospondin-2 (TSP2) and osteonectin/BM-40/SPARC are matricellular proteins that are highly expressed by bone cells. Mice deficient in either of these proteins show phenotypic alterations in the skeleton, and these phenotypes are most pronounced under conditions of altered bone remodeling. For example, TSP2-null mice have higher cortical bone volume and are resistant to bone loss associated with ovariectomy, whereas SPARC-null mice have decreased trabecular bone volume and fail to demonstrate an increase in bone mineral density in response to a bone-anabolic parathyroid hormone treatment regimen. In vitro, marrow stromal cell (MSC) osteoprogenitors from TSP2-null mice have increased proliferation but delayed formation of mineralized matrix. Similarly, in cultures of SPARC-null MSCs, osteoblastic differentiation and mineralized matrix formation are decreased. Overall, both TSP2 and SPARC positively influence osteoblastic differentiation. Intriguingly, both of these matricellular proteins appear to impact MSC fate through mechanisms that could involve the Notch signaling system. This review provides an overview of the role of TSP2 and SPARC in regulating bone structure, function, and remodeling, as determined by both in vitro and in vivo studies

Ecdysone response element in a baculovirus immediate-early gene, ie1, promoter

A computer-assisted analysis identified tentative target sequences for regulatory proteins including ecdysone-inducible factors such as BmFTZF1 and Broad-Complex Z4 (BR-C Z4) in the ie1 promoter of BmNPV. A transient expression experiment using BmN cells and a series of truncated ie1 promoter constructs demonstrated that the activity of the ie1 promoter responded to alpha-ecdysone and 20-hydroxyecdysone, which required a tridecameric nucleotide stretch (ie1EcRE, 5'-GTGTTATCGACCT-3') homologous to the ecdysone response element reported for Drosophila (DmEcRE). RT-PCR demonstrated the expression of BmEcR and BmUSP, which are required as ecdysone-specific activators for EcRE-mediated activation, in BmN cells. Furthermore, the ie1 EcRE-mediated response was confirmed by using a recombinant BmNPV possessing a luciferase gene under the control of the ie1 promoter with or without ie1 EcRE. This is the first report of an ecdysone response element in a baculoviral gene promoter. These results also suggested that the regulation of the iel by ecdysone may militate viral replication at least under certain conditions during natural infections in vivo

Higher activity of an aldehyde oxidase in the auxin-overproducing superroot1 mutant of Arabidopsis thaliana

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Two Autopsy Cases Assessing the Association of Rare Tumors Adjacent to the Sella turcica with Cause of Death and a Review of the Literature

Case 1 is an 80 year-old female, who consumed alcohol in a bar, fell down the stairs upon returning home, and was later found deceased. A postmortem CT did not confirm the presence of a tumor. An autopsy confirmed diffuse subarachnoid hemorrhage and a tumor, with a white surface covered by microvasculature pressing on the optic chiasma. The cause of death was traumatic subarachnoid hemorrhage due to an injury to the head while under the influence of alcohol. However, given the formation of a tumor pressing on the optic nerve, a possible causal relationship between the epidermoid cyst and the head injury cannot be excluded. Case 2 is a 60 year-old male, discovered dead in his own home. The autopsy confirmed subarachnoid hemorrhage around the base of the brain, and there was a hematoma-like tumor connected to the pituitary gland. The cause of death was determined to be pituitary bleeding due to pituitary adenoma. As seen in these cases, it is possible that a tumor at the base of the brain, which is a difficult location for identification, would impact the process of death; therefore, studying the grade of tumor, stage, and its involvement in the cause of death are diagnostically critical in forensic autopsies