Combined high-throughput library screening and next generation RNA sequencing uncover microRNAs controlling human cardiac fibroblast biology.

BACKGROUND: Myocardial fibrosis is a hallmark of the failing heart, contributing to the most common causes of deaths worldwide. Several microRNAs (miRNAs, miRs) controlling cardiac fibrosis were identified in recent years; however, a more global approach to identify miRNAs involved in fibrosis is missing. METHODS AND RESULTS: Functional miRNA mimic library screens were applied in human cardiac fibroblasts (HCFs) to identify annotated miRNAs inducing proliferation. In parallel, miRNA deep sequencing was performed after subjecting HCFs to proliferating and resting stimuli, additionally enabling discovery of novel miRNAs. In-depth in vitro analysis confirmed the pro-fibrotic nature of selected, highly conserved miRNAs miR-20a-5p and miR-132-3p. To determine downstream cellular pathways and their role in the fibrotic response, targets of the annotated miRNA candidates were modulated by synthetic siRNA. We here provide evidence that repression of autophagy and detoxification of reactive oxygen species by miR-20a-5p and miR-132-3p explain some of their pro-fibrotic nature on a mechanistic level. CONCLUSION: We here identified both miR-20a-5p and miR-132-3p as crucial regulators of fibrotic pathways in an in vitro model of human cardiac fibroblast biology.

Identification of a protein-protein interaction network downstream of molybdenum cofactor biosynthesis in Arabidopsis thaliana.

The molybdenum cofactor (Moco) is ubiquitously present in all kingdoms of life and vitally important for survival. Among animals, loss of the Moco-containing enzyme (Mo-enzyme) sulphite oxidase is lethal, while for plants the loss of nitrate reductase prohibits nitrogen assimilation. Moco is highly oxygen-sensitive, which obviates a freely diffusible pool and necessitates protein-mediated distribution. During the highly conserved Moco biosynthesis pathway, intermediates are channelled through a multi-protein complex facilitating protected transport. However, the mechanism by which Moco is subsequently transferred to apo-enzymes is still unclear. Moco user enzymes can be divided into two families: the sulphite oxidase (SO) and the xanthine oxidoreductase (XOR) family. The latter requires a final sulphurisation of Moco catalysed via ABA3. To examine Moco transfer towards apo-Mo-enzymes, two different and independent protein-protein interaction assays were performed in vivo: bimolecular fluorescence complementation and split luciferase. The results revealed a direct contact between Moco producer molybdenum insertase CNX1, which represents the last biosynthesis step, and members of the SO family. However, no protein contact was observed between Moco producer CNX1 and apo-enzymes of the XOR family or between CNX1 and the Moco sulphurase ABA3. Instead, the Moco-binding protein MOBP2 was identified as a mediator between CNX1 and ABA3. This interaction was followed by contact between ABA3 and enzymes of the XOR family. These results allow to describe an interaction matrix of proteins beyond Moco biosynthesis and to demonstrate the complexity of transferring a prosthetic group after biosynthesis.

GARP inhibits allergic airway inflammation in a humanized mouse model.

BACKGROUND: Regulatory T cells (Treg) represent a promising target for novel treatment strategies in patients with inflammatory/allergic diseases. A soluble derivate of the Treg surface molecule glycoprotein A repetitions predominant (sGARP) has strong anti-inflammatory and regulatory effects on human cells in vitro as well as in vivo through de novo induction of peripheral Treg. The aim of this study was to investigate the immunomodulatory function of sGARP and its possible role as a new therapeutic option in allergic diseases using a humanized mouse model. METHODS: To analyze the therapeutic effects of sGARP, adult NOD/Scidγc(-/-) (NSG) mice received peripheral blood mononuclear cells (PBMC) derived from allergic patients with sensitization against birch allergen. Subsequently, allergic inflammation was induced in the presence of Treg alone or in combination with sGARP. RESULTS: In comparison with mice that received Treg alone, additional treatment with sGARP reduced airway hyperresponsiveness (AHR), influx of neutrophils and macrophages into the bronchoalveolar lavage (BAL), and human CD45(+) cells in the lungs. Furthermore, the numbers of mucus-producing goblet cells and inflammatory cell infiltrates were reduced. To elucidate whether the mechanism of action of sGARP involves the TGF-ß receptor pathway, mice additionally received anti-TGF-ß receptor II (TGF-ßRII) antibodies. Blocking the signaling of TGF-ß through TGF-ßRII abrogated the anti-inflammatory effects of sGARP, confirming its essential role in inhibiting the allergic inflammation. CONCLUSION: Induction of peripheral tolerance via sGARP is a promising potential approach to treat allergic airway diseases.

Analysis of bacterial RNase P RNA and protein interaction by a magnetic biosensor technique.

A magnetic sensor technique was applied to analyze the interaction of immobilized bacterial RNase P protein and 3'-biotinylated RNase P RNA bound to streptavidin-coated magnetic beads. Our measurements with three types of beads from different suppliers resulted in K(d) values of about 1-2 nM (at 4.5 mM Mg(2+) and 150 mM NH(4)(+)) for Escherichia coli RNase P RNA and protein, consistent with previous analyses using different techniques. We further measured affinity of the E. coli RNase P protein to chimeric RNase P RNA variants, consisting of an E. coli specificity domain and an engineered archaeal catalytic domain. A "bacterial-like" 1-bp insertion and 2-nt deletion in the helix P2/P3 region largely improved affinity, providing independent evidence that these elements are crucial for interaction of the two RNase P subunits. Moreover, our study documents that the properties of the streptavidin-coated magnetic beads decide on success or failure of the technique.

A haem cofactor is required for redox and light signalling by the AppA protein of Rhodobacter sphaeroides.

The AppA protein of Rhodobacter sphaeroides is unique in its ability to sense and transmit redox signals as well as light signals. By functioning as antagonist to the PpsR transcriptional repressor, it regulates the expression of photosynthesis genes in response to these environmental stimuli. Here we show binding of the cofactor haem to a domain in the C-terminal part of AppA and redox activity of bound haem. This is supported by the findings that: (i) the C-terminal domain of AppA (AppADeltaN) binds to haemin agarose, (ii) AppADeltaN isolated from Escherichia coli shows absorbance at 411 nm and absorbances at 424 nm and 556 nm after reduction with dithionite and (iii) AppADeltaN can be reconstituted with haem in vitro. Expression of AppA variants in R. sphaeroides reveals that the haem binding domain is important for normal expression levels of photosynthesis genes and for normal light regulation in the presence of oxygen. The haem cofactor affects the interaction of the C-terminal part of AppA to PpsR but also its interaction to the N-terminal light sensing AppA-BLUF domain. Based on this we present a model for the transmission of light and redox signals by AppA.

Magnetic biosensor for the detection of Yersinia pestis.

A novel type of magnetic-beads based magnetic biosensor is described for the detection of Yersinia pestis. Experiments were performed with the antigen fraction F1 of these bacteria. The magnetic sensor platform offers easy and reliable detection of Y. pestis by the use of magnetic beads for labelling and quantification in a single step due to their paramagnetic features. The system uses antiYPF1 antibodies as capture element on ABICAP columns as core element of the magnetic sensor. Several immobilization methods for antibodies on polyethylene were exploited. The established biosensor has a linear detection range of 25-300 ng/ml Y. pestis antigen F1 and a detection limit of 2.5 ng/ml in buffer and human blood serum. The presented sensor system is small, simple, portable and therefore usable as off-lab detection unit for medical and warfare analytes.

CRP determination based on a novel magnetic biosensor.

The c-reactive protein (CRP) is a very significant human blood marker for inflammatory processes and is routinely determined for many clinical purposes. The widespread and well established detection method for this approximately 115 kDa hepatic protein is the high-sensitivity ELISA assay (hsCRP-ELISA) in blood serum. New approaches in medical CRP diagnosis (e.g. for CVD, inflammatory bowel disease) require rapid quantification in native matrices. A novel CRP determination method based on magnetic detection is described and tested for human blood serum, saliva and urine. The detection principle is based on two different anti-CRP antibodies (monoclonal, IgG) for CRP trapment and labelling. The linear detection range of this immunosensor ranged from 25 ng/ml to 2.5 microg/ml and is therefore much more sensitive than typical hsCRP-ELISA-assays.

SPR-based immunosensor for the CRP detection--a new method to detect a well known protein.

The c-reactive protein (CRP) is one of the significant human blood serum markers for inflammatory processes. The serum presence of this hepatic approximately 115 kDa protein of five identical subunits accompanies several diseases (e.g. CVD, inflammatory bowel diseases) and is nowadays detected by high-sensitivity ELISA assays in blood serum. To enable CRP detection in other matrices, an SPR-based (surface plasmon resonance) immunosensor for the CRP detection has been established. A linear detection range of 2-5 microg CRP per ml was found, using two different antiCRP antibodies (monoclonal, IgG) for CRP trapment and detection. Furthermore, the kinetic antibody association and dissociation constants of one antibody (antiCRP, clone C2) could be determined.