α-Dystroglycan hypoglycosylation affects cell migration by influencing ß-dystroglycan membrane clustering and filopodia length: A multiscale confocal microscopy analysis.

Dystroglycan (DG) serves as an adhesion complex linking the actin cytoskeleton to the extracellular matrix. DG is encoded by a single gene as a precursor, which is constitutively cleaved to form the α- and ß-DG subunits. α-DG is a peripheral protein characterized by an extensive glycosylation that is essential to bind laminin and other extracellular matrix proteins, while ß-DG binds the cytoskeleton proteins. The functional properties of DG depend on the correct glycosylation of α-DG and on the cross-talk between the two subunits. A reduction of α-DG glycosylation has been observed in muscular dystrophy and cancer while the inhibition of the interaction between α- and ß-DG is associated to aberrant post-translational processing of the complex. Here we used confocal microscopy based techniques to get insights into the influence of α-DG glycosylation on the functional properties of the ß-DG, and its effects on cell migration. We used epithelial cells transfected with wild-type and with a mutated DG harboring the mutation T190M that has been recently associated to dystroglycanopathy. We found that α-DG hypoglycosylation, together with an increased protein instability, reduces the membrane dynamics of the ß-subunit and its clustering within the actin-rich domains, influencing cell migration and spontaneous cell movement. These results contribute to give novel insights into the involvement of aberrant glycosylation of DG in the developing of muscular dystrophy and tumor metastasis.

The interleukin-1ß/CXCL1/2/neutrophil axis mediates host protection against group B streptococcal infection.

Previous studies have indicated that group B streptococcus (GBS), a frequent human pathogen, potently induces the release of interleukin-1ß (IL-1ß), an important mediator of inflammatory responses. Since little is known about the role of this cytokine in GBS disease, we analyzed the outcome of infection in IL-1ß-deficient mice. These animals were markedly sensitive to GBS infection, with most of them dying under challenge conditions that caused no deaths in wild-type control mice. Lethality was due to the inability of the IL-1ß-deficient mice to control local GBS replication and dissemination to target organs, such as the brain and the kidneys. Moreover, in a model of inflammation induced by the intraperitoneal injection of killed GBS, a lack of IL-1ß was associated with selective impairment in the production of the neutrophil chemokines CXCL1 and CXCL2 and in neutrophil recruitment to the peritoneal cavity. Decreased blood neutrophil counts and impaired neutrophil recruitment to the brain and kidneys were also observed during GBS infection in IL-1ß-deficient mice concomitantly with a reduction in CXCL1 and CXCL2 tissue levels. Notably, the hypersusceptibility to GBS infection observed in the immune-deficient animals was recapitulated by neutrophil depletion with anti-Gr1 antibodies. Collectively, our data identify a cytokine circuit that involves IL-1ß-induced production of CXCL1 and CXCL2 and leads the recruitment of neutrophils to GBS infection sites. Moreover, our data point to an essential role of these cells in controlling the progression and outcome of GBS disease.

Thermodynamic parameters for the formation of dimeric hydrolytic species of copper(II) in aqueous NaClO(4) solution at different ionic strengths.

The hydrolysis of copper(II) has been studied in experimental conditions for which polynuclear species are formed prevalently. The study has been carried out by the pH-metric technique at different temperatures and ionic strengths in NaClO(4) aqueous solution. As previously reported in literature, the most important hydrolytic species is Cu(2)(OH)(2)(2+). For copper(II) concentrations greater than 75 mmol dm(-3), also the species Cu(2)(OH)(3+) is formed in appreciable amount. The formation constants of these species have been determined, together with their dependence on ionic strength. The temperature coefficients of equilibrium constants allowed to obtain the relative formation enthalpies.