Metal-Mediated Il-8 Binding to Heparan Sulfate Evaluated by Electrochemical Impedance Spectroscopy

Heparan sulfate (HS) interactions with interleukin 8 (IL-8) are crucial for immune system response. The structural features of the HS and the environmental entities, such as metal ions, can regulate these interactions. However, it is challenging to evaluate the effect of each parameter on the interactions because of low accessibility to well-defined saccharides and the lack of characteristic features to be determined by analytical tools. We evaluated the effect of the HS structural features on IL-8 binding affinity utilizing electrochemical impedance spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS). We showed that the metal ions Ca2+ and Mg2+ dissimilarly mediate the interactions of HS and IL-8 in structure-dependent manner of the HS. We showed that in all glycans, a positive synergistic effect on IL-8 binding was observed. For several glycans, the presence of ions resulted in a dramatic increase in the affinity to IL-8, while for other glycans, a milder effect was observed. This demonstrated that both structural motifs and environmental features are crucial for maintaining the interactions between the HS and IL-8

Impaired Replication Stress Response in Cells from Immunodeficiency Patients Carrying Cernunnos/XLF Mutations

Non-Homologous End Joining (NHEJ) is one of the two major pathways of DNA Double Strand Breaks (DSBs) repair. Mutations in human NHEJ genes can lead to immunodeficiency due to its role in V(D)J recombination in the immune system. In addition, most patients carrying mutations in NHEJ genes display developmental anomalies which are likely the result of a general defect in repair of endogenously induced DSBs such as those arising during normal DNA replication. Cernunnos/XLF is a recently identified NHEJ gene which is mutated in immunodeficiency with microcephaly patients. Here we aimed to investigate whether Cernunnos/XLF mutations disrupt the ability of patient cells to respond to replication stress conditions. Our results demonstrate that Cernunnos/XLF mutated cells and cells downregulated for Cernunnos/XLF have increased sensitivity to conditions which perturb DNA replication. In addition, under replication stress, these cells exhibit impaired DSB repair and increased accumulation of cells in G2/M. Moreover Cernunnos/XLF mutated and down regulated cells display greater chromosomal instability, particularly at fragile sites, under replication stress conditions. These results provide evidence for the role of Cernunnos/XLF in repair of DSBs and maintenance of genomic stability under replication stress conditions. This is the first study of a NHEJ syndrome showing association with impaired cellular response to replication stress conditions. These findings may be related to the clinical features in these patients which are not due to the V(D)J recombination defect. Additionally, in light of the emerging important role of replication stress in the early stages of cancer development, our findings may provide a mechanism for the role of NHEJ in preventing tumorigenesis

Enzyme Mediated Encapsulation of Gold Nanoparticles by Polyaniline Nanoshell

In this contribution we describe the formation of gold nanoparticles (AuNP)and polyaniline (PANI) AuNP-PANI nanocomposite via in situ enzymaticpolymerization. The method consists of electrostatic adsorption of aniliniummonomers on AuNPs citrate stabilized surface of 50 nm diameters, followedby oxidation with horseradish peroxidase (HRP) enzyme and its cofactorH2O2. All reaction steps were monitored by UV-Vis-NIR spectroscopy includ-ing in situ detection of the polymerization process. UV-Vis-NIR, Cyclicvoltammetry (CV) and surface enhanced Raman scattering (SERS) measure-ments supported the formation of a nanoshell of PANI on the AuNP core. Two templates for anilinium assembly were compared revealing a strongdependence of the enzymatic kinetics on the template. The kinetic study hadshown that the rigid template of the AuNP contributes to higher reaction rateon the AuNP compared with the more flexible polyanion template. The mildreaction condition enables an easy and precise method for obtaining PANInano-shell on anionic templates for advanced bioelectronic applications</jats:p