Interleukin-18 as a Therapeutic Target in Acute Myocardial Infarction and Heart Failure

Interleukin 18 (IL-18) is a proinflammatory cytokine in the IL-1 family that has been implicated in a number of disease states. In animal models of acute myocardial infarction (AMI), pressure overload, and LPS-induced dysfunction, IL-18 regulates cardiomyocyte hypertrophy and induces cardiac contractile dysfunction and extracellular matrix remodeling. In patients, high IL-18 levels correlate with increased risk of developing cardiovascular disease (CVD) and with a worse prognosis in patients with established CVD. Two strategies have been used to counter the effects of IL-18:IL-18 binding protein (IL-18BP), a naturally occurring protein, and a neutralizing IL-18 antibody. Recombinant human IL-18BP (r-hIL-18BP) has been investigated in animal studies and in phase I/II clinical trials for psoriasis and rheumatoid arthritis. A phase II clinical trial using a humanized monoclonal IL-18 antibody for type 2 diabetes is ongoing. Here we review the literature regarding the role of IL-18 in AMI and heart failure and the evidence and challenges of using IL-18BP and blocking IL-18 antibodies as a therapeutic strategy in patients with heart disease.     

Selectivity of Ni(II) and Zn(II) binding to Sporosarcina pasteurii UreE, a metallochaperone in the urease assembly: a calorimetric and crystallographic study

Urease is a nickel-dependent enzyme that plays a critical role in the biogeochemical nitrogen cycle by catalyzing the hydrolysis of urea to ammonia and carbamate. This enzyme, initially synthesized in the apo form, needs to be activated by incorporation of two nickel ions into the active site, a process driven by the dimeric metallochaperone UreE. Previous studies reported that this protein can bind different metal ions in vitro, beside the cognate Ni(II). This study explores the metal selectivity and affinity of UreE from Sporosarcina pasteurii (Sp, formerly known as Bacillus pasteurii) for cognate [Ni(II)] and noncognate [Zn(II)] metal ions. In particular, the thermodynamic parameters of SpUreE Ni(II) and Zn(II) binding have been determined using isothermal titration calorimetry. These experiments show that two Ni(II) ions bind to the protein dimer with positive cooperativity. The high-affinity site involves the conserved solvent-exposed His¹⁰⁰ and the C-terminal His¹⁴⁵, whereas the low-affinity site comprises also the C-terminal His¹⁴⁷. Zn(II) binding to the protein, occurring in the same protein regions and with similar affinity as compared to Ni(II), causes metal-driven dimerization of the protein dimer. The crystal structure of the protein obtained in the presence of equimolar amounts of both metal ions indicates that the high-affinity metal binding site binds Ni(II) preferentially over Zn(II). The ability of the protein to select Ni(II) over Zn(II) was confirmed by competition experiments in solution as well as by analysis of X-ray anomalous dispersion data. Overall, the thermodynamics and structural parameters that modulate the metal ion specificity of the different binding sites on the protein surface of SpUreE have been established.     

A statistical approach for detecting genomic aberrations in heterogeneous tumor samples from single nucleotide polymorphism genotyping data

We describe a statistical method for the characterization of genomic aberrations in single nucleotide polymorphism microarray data acquired from cancer genomes. Our approach allows us to model the joint effect of polyploidy, normal DNA contamination and intra-tumour heterogeneity within a single unified Bayesian framework. We demonstrate the efficacy of our method on numerous datasets including laboratory generated mixtures of normal-cancer cell lines and real primary tumours.     

Comparative analysis of different biofactories for the production of a major diabetes autoantigen

The 65-kDa isoform of human glutamic acid decarboxylase (hGAD65) is a major diabetes autoantigen that can be used for the diagnosis and (more recently) the treatment of autoimmune diabetes. We previously reported that a catalytically-inactive version (hGAD65mut) accumulated to tenfold higher levels than its active counterpart in transgenic tobacco plants, providing a safe and less expensive source of the protein compared to mammalian production platforms. Here we show that hGAD65mut is also produced at higher levels than hGAD65 by transient expression in Nicotiana benthamiana (using either the pK7WG2 or MagnICON vectors), in insect cells using baculovirus vectors, and in bacterial cells using an inducible-expression system, although the latter system is unsuitable because hGAD65mut accumulates within inclusion bodies. The most productive of these platforms was the MagnICON system, which achieved yields of 78.8 μg/g fresh leaf weight (FLW) but this was substantially less than the best-performing elite transgenic tobacco plants, which reached 114.3 μg/g FLW after six generations of self-crossing. The transgenic system was found to be the most productive and cost-effective although the breeding process took 3 years to complete. The MagnICON system was less productive overall, but generated large amounts of protein in a few days. Both plant-based systems were therefore advantageous over the baculovirus-based production platform in our hands.     

The methyltransferase Set7/9 (Setd7) is dispensable for the p53-mediated DNA damage response in vivo

p53 is the central regulator of cell fate following genotoxic stress and oncogene activation. Its activity is controlled by several posttranslational modifications. Originally defined as a critical layer of p53 regulation in human cell lines, p53 lysine methylation by Set7/9 (also called Setd7) was proposed to fulfill a similar function in?vivo in the mouse, promoting p53 acetylation, stabilization, and activation upon DNA damage (Kurash et?al., 2008). We tested the physiological relevance of this circuit in an independent Set7/9 knockout mouse strain. Deletion of Set7/9 had no effect on p53-dependent cell-cycle arrest or apoptosis following sublethal or lethal DNA damage induced by radiation or genotoxic agents. Set7/9 was also dispensable for p53 acetylation following irradiation. c-myc oncogene-induced apoptosis was also independent of Set7/9, and analysis of p53 target genes showed that Set7/9 is not required for the p53-dependent gene expression program. Our data indicate that Set7/9 is dispensable for p53 function in the mouse.     

Acoustic communication at the water's edge: evolutionary insights from a mudskipper

Coupled behavioural observations and acoustical recordings of aggressive dyadic contests showed that the mudskipper Periophthalmodon septemradiatus communicates acoustically while out of water. An analysis of intraspecific variability showed that specific acoustic components may act as tags for individual recognition, further supporting the sounds' communicative value. A correlative analysis amongst acoustical properties and video-acoustical recordings in slow-motion supported first hypotheses on the emission mechanism. Acoustic transmission through the wet exposed substrate was also discussed. These observations were used to support an "exaptation hypothesis", i.e. the maintenance of key adaptations during the first stages of water-to-land vertebrate eco-evolutionary transitions (based on eco-evolutionary and palaeontological considerations), through a comparative bioacoustic analysis of aquatic and semiterrestrial gobiid taxa. In fact, a remarkable similarity was found between mudskipper vocalisations and those emitted by gobioids and other soniferous benthonic fishes.