Response of human macrophages to gamma radiation is mediated via expression of endogenous retroviruses.

Ionizing radiation-induced tissue damage recruits monocytes into the exposed area where they are differentiated to macrophages. These implement phagocytic removal of dying cells and elicit an acute inflammatory response, but can also facilitate tumorigenesis due to production of anti-inflammatory cytokines. Using primary human monocyte-derived macrophages (MDMs) and the THP1 monocytic cell line, we demonstrate that gamma radiation triggers monocyte differentiation toward the macrophage phenotype with increased expression of type I interferons (IFN-I) and both pro- and anti-inflammatory macrophage activation markers. We found that these changes correlate with significantly upregulated expression of 622 retroelements from various groups, particularly of several clades of human endogenous retroviruses (HERVs). Elevated transcription was detected in both sense and antisense directions in the HERV subgroups tested, including the most genetically homogeneous clade HML-2. The level of antisense transcription was three- to five-fold higher than of the sense strand levels. Using a proximity ligation assay and immunoprecipitation followed by RNA quantification, we identified an increased amount of the dsRNA receptors MDA-5 and TLR3 bound to an equivalent number of copies of sense and antisense chains of HERVK HML-2 RNA. This binding triggered MAVS-associated signaling pathways resulting in increased expression of IFN-I and inflammation related genes that enhanced the cumulative inflammatory effect of radiation-induced senescence. HML-2 knockdown was accompanied with reduced expression and secretion of IFNα, pro-inflammatory (IL-1β, IL-6, CCL2, CCL3, CCL8, and CCL20) and anti-inflammatory (IL10) modulators in irradiated monocytes and MDMs. Taken together, our data indicate that radiation stress-induced HERV expression enhances the IFN-I and cytokine response and results in increased levels of pro-inflammatory modulators along with expression of anti-inflammatory factors associated with the macrophage tumorigenic phenotype

Genome Sequence of Azotobacter vinelandii , an Obligate Aerobe Specialized To Support Diverse Anaerobic Metabolic Processes

Azotobacter vinelandii is a soil bacterium related to the Pseudomonas genus that fixes nitrogen under aerobic conditions while simultaneously protecting nitrogenase from oxygen damage. In response to carbon availability, this organism undergoes a simple differentiation process to form cysts that are resistant to drought and other physical and chemical agents. Here we report the complete genome sequence of A. vinelandii DJ, which has a single circular genome of 5,365,318 bp. In order to reconcile an obligate aerobic lifestyle with exquisitely oxygen-sensitive processes, A. vinelandii is specialized in terms of its complement of respiratory proteins. It is able to produce alginate, a polymer that further protects the organism from excess exogenous oxygen, and it has multiple duplications of alginate modification genes, which may alter alginate composition in response to oxygen availability. The genome analysis identified the chromosomal locations of the genes coding for the three known oxygen-sensitive nitrogenases, as well as genes coding for other oxygen-sensitive enzymes, such as carbon monoxide dehydrogenase and formate dehydrogenase. These findings offer new prospects for the wider application of A. vinelandii as a host for the production and characterization of oxygen-sensitive proteins.Fil: Setubal, João C.. Virginia Polytechnic Institute; Estados UnidosFil: Dos Santos, Patricia Carolina. Wake Forest University; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario; ArgentinaFil: Goldman, Barry S.. Monsanto Company; Estados UnidosFil: Ertesvag, Helga. Norwegian University of Science and Technology; NoruegaFil: Espin, Guadelupe. Universidad Nacional Autónoma de México; MéxicoFil: Rubio, Luis M.. Instituto Imdea Energia; EspañaFil: Valla, Svein. Norwegian University of Science and Technology; NoruegaFil: Almeida, Nalvo F.. Virginia Polytechnic Institute; Estados Unidos. Universidade Federal do Mato Grosso do Sul; BrasilFil: Balasubramanian, Divya. Hiram College; Estados UnidosFil: Cromes, Lindsey. Hiram College; Estados UnidosFil: Curatti, Leonardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario; Argentina. Fundación para Investigaciones Biológicas Aplicadas. Centro de Estudios de Biodiversidad y Biotecnología; ArgentinaFil: Du, Zijin. Monsanto Company; Estados UnidosFil: Godsy, Eric. Monsanto Company; Estados UnidosFil: Goodner, Brad. Hiram College; Estados UnidosFil: Hellner Burris, Kaitlyn. Hiram College; Estados UnidosFil: Hernandez, José A.. Midwestern University; Estados UnidosFil: Houmiel, Katherine. Seattle Pacific University; Estados UnidosFil: Imperial, Juan. Centro de Biotecnologia y Genomica de Plantas; EspañaFil: Kennedy, Christina. University of Arizona; Estados UnidosFil: Larson, Timothy J.. Virginia Polytechnic Institute; Estados UnidosFil: Latreille, Phil. Monsanto Company; Estados UnidosFil: Ligon, Lauren S.. Virginia Polytechnic Institute; Estados UnidosFil: Lu, Jing. Monsanto Company; Estados UnidosFil: Mærk, Mali. Norwegian University of Science and Technology; NoruegaFil: Miller, Nancy M.. Monsanto Company; Estados UnidosFil: Norton, Stacie. Monsanto Company; Estados UnidosFil: O'Carroll, Ina P.. Virginia Polytechnic Institute; Estados UnidosFil: Paulsen, Ian. Macquarie University; AustraliaFil: Raulfs, Estella C.. Virginia Polytechnic Institute; Estados UnidosFil: Roemer, Rebecca. Hiram College; Estados Unido

A Proposed Role for the Azotobacter vinelandii NfuA Protein as an Intermediate Iron-Sulfur Cluster Carrier*

Iron-sulfur clusters ([Fe-S] clusters) are assembled on molecular scaffolds and subsequently used for maturation of proteins that require [Fe-S] clusters for their functions. Previous studies have shown that Azotobacter vinelandii produces at least two [Fe-S] cluster assembly scaffolds: NifU, required for the maturation of nitrogenase, and IscU, required for the general maturation of other [Fe-S] proteins. A. vinelandii also encodes a protein designated NfuA, which shares amino acid sequence similarity with the C-terminal region of NifU. The activity of aconitase, a [4Fe-4S] cluster-containing enzyme, is markedly diminished in a strain containing an inactivated nfuA gene. This inactivation also results in a null-growth phenotype when the strain is cultivated under elevated oxygen concentrations. NifU has a limited ability to serve the function of NfuA, as its expression at high levels corrects the defect of the nfuA-disrupted strain. Spectroscopic and analytical studies indicate that one [4Fe-4S] cluster can be assembled in vitro within a dimeric form of NfuA. The resultant [4Fe-4S] cluster-loaded form of NfuA is competent for rapid in vitro activation of apo-aconitase. Based on these results a model is proposed where NfuA could represent a class of intermediate [Fe-S] cluster carriers involved in [Fe-S] protein maturation