Nerves closely associate with blood vessels and help to pattern the vasculature during development. Recent work suggests that newly formed nerve fibers may regulate the tumor microenvironment, but their exact functions are unclear. Studying mouse models of prostate cancer, we show that endothelial β-adrenergic receptor signaling via adrenergic nerve-derived noradrenaline in the prostate stroma is critical for activation of an angiogenic switch that fuels exponential tumor growth. Mechanistically this occurs through alteration of endothelial cell metabolism. Endothelial cells typically rely on aerobic glycolysis for angiogenesis. We found that the loss of endothelial Adrb2, the gene encoding the β2-adrenergic receptor, leads to inhibition of angiogenesis through enhancement of endothelial oxidative phosphorylation. Co-deletion of Adrb2 and Cox10, a gene encoding a cytochrome IV oxidase assembly factor, prevented the metabolic shift induced by Adrb2 deletion and rescued prostate cancer progression. This cross-talk between nerves and endothelial metabolism could potentially be targeted as an anti-cancer therapy.

The V proteins of Nipah virus and Hendra virus have been demonstrated to bind to cellular STAT1 and STAT2 proteins to form high-molecular-weight complexes that inhibit interferon (IFN)-induced antiviral transcription by preventing STAT nuclear accumulation. Analysis of the Nipah virus V protein has revealed a region between amino acids 174 and 192 that functions as a CRM1-dependent nuclear export signal (NES).This peptide is sufficient to complement an export-defective human immunodeficiency virus Rev protein, and deletion and substitution mutagenesis revealed that this peptide is necessary for both V protein shuttling and cytoplasmic retention of STAT1 and STAT2 proteins. However, the NES is not required for V-dependent IFN signaling inhibition. IFN signaling is blocked primarily by interaction between Nipah virus V residues 100 to 160 and STAT1 residues 509 to 712. Interaction with STAT2 requires a larger Nipah virus V segment between amino acids 100 and 300, but deletion of residues 230 to 237 greatly reduced STAT2 coprecipitation. Further, V protein interactions with cellular STAT1 is a prerequisite for STAT2 binding, and sequential immunoprecipitations demonstrate that V, STAT1, and STAT2 can form a tripartite complex. These findings characterize essential regions for Henipavirus V proteins that represent potential targets for therapeutic intervention.The biological effects of alpha and beta interferon (IFN-␣ and -␤) are mediated by a transcription factor complex, ISGF3, that is comprised of the signal transducer and activator of transcription (STAT) proteins, STAT1 and STAT2, in association with a DNA-binding subunit, an IFN regulatory factor, IRF9 (1, 12). IFN-induced, ISGF3-mediated transcription results in a cellular antiviral state that provides protection against a broad range of virus types. In response to this negative selection, most viruses have evolved adaptations that allow them to evade IFN-induced innate antiviral responses (13,26).In the case of the paramyxovirus family of negative-strand RNA viruses, IFN signaling to ISGF3 is disrupted by direct targeting of STAT proteins (4). Current evidence from the study of several family members indicates that the common outcome of STAT targeting and IFN evasion is achieved by individual paramyxovirus species through a diverse range of molecular mechanisms. For example, the Rubulaviruses, simian virus 5 (SV5), human parainfluenza virus 2, and mumps virus all encode STAT-directed E3 ubiquitin ligase activities that function in combination with cellular proteins to target STAT1, STAT2, or STAT3 for proteasomal degradation (5,18,19,28,29). Distinctly, measles virus, a prototype Morbillivirus, does not induce STAT ubiquitylation and degradation but instead prevents IFN-induced ISGF3 assembly and STAT protein nuclear translocation (17, 27). These IFN evasion mechanisms rely on protein-protein interactions between STATs and the paramyxovirus-encoded V protein. The paramyxovirus V protein is characterized by a highly conserved cysteine-rich C-terminal domain (...

Transcription regulators STAT1 and STAT2 are key components of the interferon signaling system leading to innate antiviral immunity. The related STAT3 protein is a regulator of interleukin-6-type cytokine signals and can contribute to both cell growth and death important for cancer gene regulation and tumor survival. These three STAT proteins are targeted for proteasome-mediated degradation by RNA viruses in the Rubulavirus genus of the Paramyxoviridae. A single viral protein, the V protein, assembles STAT-specific ubiquitin ligase complexes from cellular components. Simian virus 5 (SV5) targets STAT1, human parainfluenza virus 2 targets STAT2, and mumps virus targets both STAT1 and STAT3. Analysis of the V-dependent degradation complex (VDC) composition and assembly revealed several features contributing to targeting specificity. SV5 and mumps V proteins require STAT2 to recruit the STAT1 target, yet mumps V protein binds STAT3 independent of STAT1 and STAT2. All Rubulavirus V proteins tested require cellular DDB1 to target STATs for degradation but differ in the use of Roc1, which is essential for mumps V STAT3 targeting. Protein interaction analysis reveals that paramyxovirus V proteins can homo-and heterooligomerize and that the conserved cysteine-rich zinc-binding C-terminal domain is necessary and sufficient for oligomerization. Purified SV5 V protein spontaneously assembles into spherical macromolecular particles, and similar particles constitute SV5 and mumps VDC preparations.

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