Elf5 is essential for early embryogenesis and mammary gland development during pregnancy and lactation

Elf5 is an epithelial-specific ETS factor. Embryos with a null mutation in the Elf5 gene died before embryonic day 7.5, indicating that Elf5 is essential during mouse embryogenesis. Elf5 is also required for proliferation and differentiation of mouse mammary alveolar epithelial cells during pregnancy and lactation. The loss of one functional allele led to complete developmental arrest of the mammary gland in pregnant Elf5 heterozygous mice. A quantitative mRNA expression study and Western blot analysis revealed that decreased expression of Elf5 correlated with the downregulation of milk proteins in Elf5(+/-) mammary glands. Mammary gland transplants into Rag(-/-) mice demonstrated that Elf5(+/-) mammary alveolar buds failed to develop in an Elf5(+/+) mammary fat pad during pregnancy, demonstrating an epithelial cell autonomous defect. Elf5 expression was reduced in Prolactin receptor (Prlr) heterozygous mammary glands, which phenocopy Elf5(+/-) glands, suggesting that Elf5 and Prlr are in the same pathway. Our data demonstrate that Elf5 is essential for developmental processes in the embryo and in the mammary gland during pregnancy.     

Premortem autophagy determines the immunogenicity of chemotherapy-induced cancer cell death

One particular strategy to render anticancer therapies efficient consists of converting the patient's own tumor cells into therapeutic vaccines, via the induction of immunogenic cell death (ICD). One of the hallmarks of ICD dwells in the active release of ATP by cells committed to undergo, but not yet having succumbed to, apoptosis. We observed that the knockdown of essential autophagy-related genes (ATG3, ATG5, ATG7 and BECN1) abolishes the pre-apoptotic secretion of ATP by several human and murine cancer cell lines undergoing ICD. Accordingly, autophagy-competent, but not autophagy-deficient, tumor cells treated with ICD inducers in vitro could induce a tumor-specific immune response in vivo. Cancer cell lines stably depleted of ATG5 or ATG7 normally generate tumors in vivo, and such autophagy-deficient neoplasms, upon systemic treatment with ICD inducers, exhibit the same levels of apoptosis (as monitored by nuclear shrinkage and caspase-3 activation) and necrosis (as determined by following the kinetics of HMGB1 release) as their autophagy-proficient counterparts. However, autophagy-incompetent cancers fail to release ATP, to recruit immune effectors into the tumor bed and to respond to chemotherapy in conditions in which autophagy-competent tumors do so. The intratumoral administration of ecto-ATPase inhibitors increases extracellular ATP concentrations, re-establishes the therapy-induced recruitment of dendritic cells and T cells into the tumor bed, and restores the chemotherapeutic response of autophagy-deficient cancers. Altogether, these results suggest that autophagy-incompetent tumor cells escape from chemotherapy-induced (and perhaps natural?) immunosurveillance because they are unable to release ATP.     

“Hypermethylation” of anthranilic acid-labeled sugars confers the selectivity required for liquid chromatography-mass spectrometry

Analysis of the monosaccharides of complex carbohydrates is often performed by liquid chromatography with fluorescence detection. Unfortunately, methylated sugars, unusual amino- or deoxysugars and incomplete hydrolysis can lead to erroneous assignments of peaks. Here, we demonstrate that a volatile buffer system is suitable for the separation of anthranilic acid labeled sugars. It allows off-line examination of peaks by electrospray mass spectrometry. Approaches towards on-line mass spectrometric detection using reversed-phase or porous graphitic carbon columns fell short of achieving sufficient separation of the relevant isobaric sugars. Adequate chromatographic performance for isomeric sugars was achieved with reversed-phase chromatography of “hyper”-methylated anthranilic acid-labeled monosaccharides. Deuteromethyl iodide facilitates the discovery of naturally methylated sugars and identification of their parent monosaccharide as demonstrated with N-glycans of the snail Achatina fulica, where two thirds of the galactoses and a quarter of the mannoses were methylated.     

Global change‐driven effects on dissolved organic matter composition: Implications for food webs of northern lakes

Northern ecosystems are experiencing some of the most dramatic impacts of global change on Earth. Rising temperatures, hydrological intensification, changes in atmospheric acid deposition and associated acidification recovery, and changes in vegetative cover are resulting in fundamental changes in terrestrial–aquatic biogeochemical linkages. The effects of global change are readily observed in alterations in the supply of dissolved organic matter (DOM)—the messenger between terrestrial and lake ecosystems—with potentially profound effects on the structure and function of lakes. Northern terrestrial ecosystems contain substantial stores of organic matter and filter or funnel DOM, affecting the timing and magnitude of DOM delivery to surface waters. This terrestrial DOM is processed in streams, rivers, and lakes, ultimately shifting its composition, stoichiometry, and bioavailability. Here, we explore the potential consequences of these global change‐driven effects for lake food webs at northern latitudes. Notably, we provide evidence that increased allochthonous DOM supply to lakes is overwhelming increased autochthonous DOM supply that potentially results from earlier ice‐out and a longer growing season. Furthermore, we assess the potential implications of this shift for the nutritional quality of autotrophs in terms of their stoichiometry, fatty acid composition, toxin production, and methylmercury concentration, and therefore, contaminant transfer through the food web. We conclude that global change in northern regions leads not only to reduced primary productivity but also to nutritionally poorer lake food webs, with discernible consequences for the trophic web to fish and humans.     

A Microfluidic Platform for Precision Small-volume Sample Processing and Its Use to Size Separate Biological Particles with an Acoustic Microdevice

A major advantage of microfluidic devices is the ability to manipulate small sample volumes, thus reducing reagent waste and preserving precious sample. However, to achieve robust sample manipulation it is necessary to address device integration with the macroscale environment. To realize repeatable, sensitive particle separation with microfluidic devices, this protocol presents a complete automated and integrated microfluidic platform that enables precise processing of 0.15–1.5 ml samples using microfluidic devices. Important aspects of this system include modular device layout and robust fixtures resulting in reliable and flexible world to chip connections, and fully-automated fluid handling which accomplishes closed-loop sample collection, system cleaning and priming steps to ensure repeatable operation. Different microfluidic devices can be used interchangeably with this architecture. Here we incorporate an acoustofluidic device, detail its characterization, performance optimization, and demonstrate its use for size-separation of biological samples. By using real-time feedback during separation experiments, sample collection is optimized to conserve and concentrate sample. Although requiring the integration of multiple pieces of equipment, advantages of this architecture include the ability to process unknown samples with no additional system optimization, ease of device replacement, and precise, robust sample processing.     

DNA ligase III promotes alternative nonhomologous end-joining during chromosomal translocation formation

Nonhomologous end-joining (NHEJ) is the primary DNA repair pathway thought to underlie chromosomal translocations and other genomic rearrangements in somatic cells. The canonical NHEJ pathway, including DNA ligase IV (Lig4), suppresses genomic instability and chromosomal translocations, leading to the notion that a poorly defined, alternative NHEJ (alt-NHEJ) pathway generates these rearrangements. Here, we investigate the DNA ligase requirement of chromosomal translocation formation in mouse cells. Mammals have two other DNA ligases, Lig1 and Lig3, in addition to Lig4. As deletion of Lig3 results in cellular lethality due to its requirement in mitochondria, we used recently developed cell lines deficient in nuclear Lig3 but rescued for mitochondrial DNA ligase activity. Further, zinc finger endonucleases were used to generate DNA breaks at endogenous loci to induce translocations. Unlike with Lig4 deficiency, which causes an increase in translocation frequency, translocations are reduced in frequency in the absence of Lig3. Residual translocations in Lig3-deficient cells do not show a bias toward use of pre-existing microhomology at the breakpoint junctions, unlike either wild-type or Lig4-deficient cells, consistent with the notion that alt-NHEJ is impaired with Lig3 loss. By contrast, Lig1 depletion in otherwise wild-type cells does not reduce translocations or affect microhomology use. However, translocations are further reduced in Lig3-deficient cells upon Lig1 knockdown, suggesting the existence of two alt-NHEJ pathways, one that is biased toward microhomology use and requires Lig3 and a back-up pathway which does not depend on microhomology and utilizes Lig1.     

Innate defense against influenza A virus: activity of human neutrophil defensins and interactions of defensins with surfactant protein D

Surfactant protein D (SP-D) plays important roles in innate host defense against influenza A virus (IAV) infection, in part by modifying interactions with neutrophils. Human neutrophil defensins (HNPs) inhibit infectivity of enveloped viruses, including IAV. Our goal in this study was to characterize antiviral interactions between SP-D and HNPs. Recombinant and/or natural forms of SP-D and related collectins and HNPs were tested for antiviral activity against two different strains of IAV. HNPs 1 and 2 did not inhibit viral hemagglutination activity, but they interfered with the hemagglutination-inhibiting activity of SP-D. HNPs had significant viral neutralizing activity against divergent IAV strains. However, the HNPs generally had competitive effects when combined with SP-D in assays using an SP-D-sensitive IAV strain. In contrast, cooperative antiviral effects were noted in some instances when relatively SP-D-resistant strains were treated with SP-D and HNPs. HNPs were found to bind to the neck and/or carbohydrate recognition domain of SP-D. This binding was specific because no, or minimal, binding to other collectins was found. HNPs precipitated SP-D from bronchoalveolar lavage fluid and reduced the antiviral activity of bronchoalveolar lavage fluid. HNP-1 and -2 differed somewhat in their independent antiviral activity and their binding to SP-D. These results are relevant to the early phase of host defense against IAV, and suggest a complex interplay between SP-D and HNPs at sites of active inflammation.