The dark sides of amyloid in Alzheimer’s disease pathogenesis

Although widely explored, the pathogenesis of Alzheimer’s disease (AD) has yet to be cleared. Over the past twenty years the so call amyloid cascade hypothesis represented the main research paradigm in AD pathogenesis. In spite of its large consensus, the proposed role of β-amyloid (Aβ) remain to be elucidated. Many evidences are starting to cast doubt on Aβ as the primary causative factor in AD. For instance, Aβ is deposited in the brain following many different kinds of injury. Also, concentration of Aβ needed to induce toxicity in vitro are never reached in vivo. In this review we propose an amyloid-independent interpretation of several AD pathogenic features, such as synaptic plasticity, endo-lysosomal trafficking, cell cycle regulation and neuronal survival.     

The last stage in the life history of the European conger eel Conger conger: a transformation before death

The taxonomic, morphological and meristic features of a dark eel caught by commercial trawling off the Gulf of Patti, southern Tyrrhenian Sea, Mediterranean Sea, February 17, 2017, showed it to be a female Conger conger. Histological analysis of gonads demonstrated that the individual was in a post-spawning phase. X-ray radiographs showed widespread decalcification of skeleton and teeth loss, confirming a strong mobilisation of somatic energy reserves needed for reproductive development.     

Antioxidant Dps protein from the thermophilic cyanobacterium Thermosynechococcus elongatus

DNA-binding proteins from starved cells (Dps proteins) protect bacteria primarily from oxidative damage. They are composed of 12 identical subunits assembled with 23-symmetry to form a compact cage-like structure known to be stable at temperatures > 70 degrees C and over a wide pH range. Thermosynechococcus elongatus Dps thermostability is increased dramatically relative to mesophilic Dps proteins. Hydrophobic interactions at the dimeric and trimeric interfaces called Dps-like are replaced by salt bridges and hydrogen bonds, a common strategy in thermophiles. Moreover, the buried surface area at the least-extended Dps-like interface is significantly increased. A peculiarity of T. elongatus Dps is the presence of a chloride ion coordinated with threefold symmetry-related arginine residues lining the opening of the Dps-like pore toward the internal cavity. T. elongatus Dps conserves the unusual intersubunit ferroxidase centre that allows the Dps protein family to oxidize Fe(II) with hydrogen peroxide, thereby inhibiting free radical production via Fenton chemistry. This catalytic property is of special importance in T. elongatus (which lacks the catalase gene) in the protection of DNA and photosystems I and II from hydrogen peroxide-mediated oxidative damage.     

c-Flip(L) is expressed in undifferentiated mouse male germ cells

Apoptosis represents a fundamental process during fetal/post-natal testis development. Therefore pro- and anti-apoptotic proteins are essential to regulate testis physiology. c-Flip(L) is a known inhibitor of caspase 8/10 activity; in this study its perinatal expression in mouse male germ cells was investigated. In testis sections and seminiferous tubule whole mount c-Flip(L) was found to be expressed in undifferentiated spermatogonia and to co-localize with germ stem cells markers. In vivo investigations in the vitamin-A deficient mouse, lacking differentiated germ cells, confirmed c-Flip(L) expression in undifferentiated spermatogonia. Further analyses showed Fas expression but no significant caspase 8/10 activity when c-Flip(L) was highly expressed. Altogether these data suggest that c-Flip may control the survival rate of undifferentiated spermatogonia.     

New fused benzazepine as selective D3 receptor antagonists. Synthesis and biological evaluation. Part 2: [g]-fused and hetero-fused systems

The synthesis and the SAR of a new series of potent and selective dopamine D(3) receptor antagonists is reported. The new scaffolds of the [g]-fused and the hetero-fused tricyclic benzazepine are here reported together with their pharmacokinetic profile.     

Human anti-IgG1 hinge autoantibodies reconstitute the effector functions of proteolytically inactivated IgGs

A number of proteases of potential importance to human physiology possess the ability to selectively degrade and inactivate Igs. Proteolytic cleavage within and near the hinge domain of human IgG1 yielded products including Fab and F(ab')(2) possessing full Ag binding capability but absent several functions needed for immune destruction of cellular pathogens. In parallel experiments, we showed that the same proteolytically generated Fabs and F(ab')(2)s become self-Ags that were widely recognized by autoantibodies in the human population. Binding analyses using various Fab and F(ab')(2), as well as single-chain peptide analogues, indicated that the autoantibodies targeted the newly exposed sequences where proteases cleave the hinge. The point of cleavage may be less of a determinant for autoantibody binding than the exposure of an otherwise cryptic stretch of hinge sequence. It was noted that the autoantibodies possessed an unusually high proportion of the IgG3 isotype in contrast to Abs induced against foreign immunogens in the same human subjects. In light of the recognized potency of IgG3 effector mechanisms, we adopted a functional approach to determine whether human anti-hinge (HAH) autoantibodies could reconstitute the (missing) Fc region effector functions to Fab and F(ab')(2). Indeed, in in vitro cellular assays, purified HAH autoantibodies restored effector functions to F(ab')(2) in both Ab-dependent cellular cytotoxicity and complement-dependent cytotoxicity assays. The results indicate that HAH autoantibodies selectively bind to proteolytically cleaved IgGs and can thereby provide a surrogate Fc domain to reconstitute cell lytic functions.     

Cellular Trafficking of Thymosin Beta-4 in HEPG2 Cells Following Serum Starvation

Thymosin beta-4 (Tβ4) is an ubiquitous multi-functional regenerative peptide, related to many critical biological processes, with a dynamic and flexible conformation which may influence its functions and its subcellular distribution. For these reasons, the intracellular localization and trafficking of Tβ4 is still not completely defined and is still under investigation in in vivo as well as in vitro studies.In the current study we used HepG2 cells, a human hepatoma cell line; cells growing in normal conditions with fetal bovine serum expressed high levels of Tβ4, restricted to the cytoplasm until 72 h. At 84 h, a diffuse Tβ4 cytoplasmic immunostaining shifted to a focal perinuclear and nuclear reactivity. In the absence of serum, nuclear reactivity was localized in small granules, evenly dispersed throughout the entire nuclear envelop, and was observed as earlier as at 48 h. Cytoplasmic immunostaining for Tβ4 in HepG2 cells under starvation appeared significantly lower at 48 h and decreased progressively at 72 and at 84 h. At these time points, the decrease in cytoplasmic staining was associated with a progressive increase in nuclear reactivity, suggesting a possible translocation of the peptide from the cytoplasm to the nuclear membrane. The normal immunocytochemical pattern was restored when culture cells submitted to starvation for 84 h received a new complete medium for 48 h.Mass spectrometry analysis, performed on the nuclear and cytosolic fractions of HepG2 growing with and without serum, showed that Tβ4 was detectable only in the cytosolic and not in the intranuclear fraction. These data suggest that Tβ4 is able to translocate from different cytoplasmic domains to the nuclear membrane and back, based on different stress conditions within the cell.The punctuate pattern of nuclear Tβ4 immunostaining associated with Tβ4 absence in the nucleoplasm suggest that this peptide might be localized in the nuclear pores, where it could regulate the pore permeability.