Selective Disruption of Insulin-like Growth Factor-1 (IGF-1) Signaling via Phosphoinositide-dependent Kinase-1 Prevents the Protective Effect of IGF-1 on Human Cancer Cell Death

Insulin-like growth factor-1 (IGF-1) signaling system exerts a broad antiapoptotic function and plays a crucial role in resistance to anticancer therapies. Exposure of MCF-7 breast cancer cells to IGF-1 rapidly and transiently induced tyrosine phosphorylation and activation of phosphoinositide-dependent kinase-1 (PDK1). This was paralleled by Akt/protein kinase B and protein kinase C-ζ phosphorylation, at Thr³⁰⁸ and Thr⁴¹⁰, respectively. IGF-1 treatment also enhanced PDK1 interaction with IGF-1 receptor (IGF-1R) in intact MCF-7 cells. Pulldown assays revealed that PDK1 bound IGF-1R in vitro and that the region encompassing amino acids 51–359 of PDK1 was necessary for the interaction. Synthetic peptides corresponding to IGF-1R C terminus amino acids 1295–1337 (C43) and to PDK1 amino acids 114–141 reduced in vitro IGF-1R/PDK1 interaction in a concentration-dependent manner. Loading of fluoresceinated-C43 (fluorescein isothiocyanate (FITC)-C43) into MCF-7 cells significantly reduced IGF-1R/PDK1 interaction and phosphorylation of PDK1 substrates. Moreover, FITC-C43 intracellular loading reverted the protective effect of IGF-1 on growth factor deprivation-induced cell death. Finally, the inhibition of IGF-1R/PDK1 interaction and signaling by FITC-C43 was accompanied by 2-fold enhanced killing capacity of cetuximab in human GEO colon adenocarcinoma cells and was sufficient to restore cell death in cetuximab-resistant cell clones. Thus, disruption of PDK1 interaction with IGF-1R reduces IGF-1 survival effects in cancer cells and may enhance cell death by anticancer agents.     

Role of the Ca-pectates on the accumulation of heavy metals in the root apoplasm

In order to better understand the processes that regulate the accumulation in the apoplasm of heavy metals and their mobilization by the plant metabolites it is essential to study the mechanisms that regulate the interactions between metal ions and pectins. In such a context, the sorption of Cd(II), Zn(II), Cu(II) and Pb(II) from single and multi-metal solutions, by a Ca-polygalacturonate gel with a degree of esterification of 18.0 (PGAM₁) and 65.5% (PGAM₂) was studied in the 3.0–6.0 pH range in the presence of CaCl₂ 2.5 mM. The sorption of Cr(III) from single metal solution was also considered. The results show that the amount of each metal ion sorbed increases with increasing the initial metal ion concentration and pH. The data from the single metal solution tests show that at pH 6.0 the affinity of the metal ions towards the PGAM₁ matrix follows the order: Cr(III) > Cu(II) ? Pb(II) ? Zn(II) ? Cd(II). The simultaneous sorption of the bivalent metal ions by the PGAM₁ gels indicates that Pb(II) is selectively sorbed. The FT-IR spectra show that the carboxylate groups are mainly responsible for the metal ion coordination. The ability of PGAM₂ to accumulate Cr(III), Cu(II), and Pb(II) was lower than that found in the PGAM₁ systems whereas the sorption of Zn(II) and Cd(II) was negligible.     

Insertional variability of four transposable elements and population structure of the midge Chironomus riparius (Diptera)

The dipteran Chironomus riparius is found across the entire Palearctic region; its larvae are among the most abundant macroinvertebrates inhabiting inland waterbodies. Chironomid larvae have been extensively used in ecotoxicological and cytogenetic research, but relatively little is known on the population structure of this species. Transposable elements (TEs) are DNA sequences that are capable of autonomous replication; the number and genomic location of TE insertions varies across individuals; this variability is increasingly being used in population studies. Several TEs had been characterized in Chironomids; this enabled the analysis of insertional variability of four different TEs in six natural populations of C. riparius from Italy, Bulgaria and Russia using a PCR-based method, transposon insertion display (TID). The method allows to obtain dominant markers, similar to AFLP. In all populations, TE insertions showed high individual polymorphism, while median copy numbers of the same TEs did not vary between populations. Analysis of molecular variance (AMOVA) detected significant differentiation between populations for three of the TEs; although no correlation between genetic and geographic distances was found, the corresponding population structures were found to be significantly correlated and indicate a degree of isolation by distance. TEs belonging to different classes have different mechanisms of replication, resulting in different transposition rates of mobilization; the finding of mostly concordant population structuring for three of the TEs indicates that population dynamics contributed significantly in shaping the detected insertional polymorphism.     

Access rate to the emergency department for venous thromboembolism in relationship with coarse and fine particulate matter air pollution

Particulate matter (PM) air pollution has been associated with cardiovascular and respiratory disease. Recent studies have proposed also a link with venous thromboembolism (VTE) risk. This study was aimed to evaluate the possible influence of air pollution-related changes on the daily flux of patients referring to the Emergency Department (ED) for VTE, dissecting the different effects of coarse and fine PM. From July 1(st), 2007, to June 30(th), 2009, data about ED accesses for VTE and about daily concentrations of PM air pollution in Verona district (Italy) were collected. Coarse PM (PM(10-2.5)) was calculated by subtracting the finest PM(2.5) from the whole PM(10). During the index period a total of 302 accesses for VTE were observed (135 males and 167 females; mean age 68.3 ± 16.7 years). In multiple regression models adjusted for other atmospheric parameters PM(10-2.5), but not PM(2.5), concentrations were positively correlated with VTE (beta-coefficient = 0.237; P = 0.020). During the days with high levels of PM(10-2.5) (≥ 75(th) percentile) there was an increased risk of ED accesses for VTE (OR 1.69 with 95%CI 1.13-2.53). By analysing days of exposure using distributed lag non-linear models, the increase of VTE risk was limited to PM(10-2.5) peaks in the short-term period. Consistently with these results, in another cohort of subjects without active thrombosis (n = 102) an inverse correlation between PM(10-2.5) and prothrombin time was found (R = -0.247; P = 0.012). Our results suggest that short-time exposure to high concentrations of PM(10-2.5) may favour an increased rate of ED accesses for VTE through the induction of a prothrombotic state.     

Guinea pig acylphosphatase: The amino acid sequence

We determined the primary structure of guinea pig skeletal muscle acylphosphatase, using the high degree of homology with several vertebrate acylphosphatases to obtain correct alignment of the complete series of tryptic peptides. Their sequences were obtained mainly by Edman degradation; FAB mass spectrometry was used to identify the acyl group blocking the NH₂-terminal residue and to elucidate the structure of the NH₂-terminal tryptic peptide. The comparison among acylphosphatase sequences from skeletal muscle of several vertebrate species is presented and discussed.     

Zooplankton Community Structure and Inter‐Annual Dynamics in Two Sand‐Pit Lakes with Different Dredging Impact

Zooplankton seasonal and inter‐annual dynamics were investigated in two neighbouring sand‐pit lakes with similar morphological features but different exploitation regime. We hypothesized that the dredging activities affected the zooplankton communities and the hydrochemical conditions of the studied lakes. Significant differences in zooplankton abundance were found. The analysis of similarity (ANOSIM) revealed that plankton communities were different between lakes and that the microcrustaceans largely contributed to the average dissimilarity. In particular, the lower densities of cladocerans and the presence of large‐size species in the lake still under dredging during this study appeared to be related to the resuspension of sand in the water column. We report how the zooplankton communities evolved toward an higher taxonomical and functional diversity after conclusion of the dredging activities. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Conformational switching and fibrillogenesis in the amyloidogenic fragment of apolipoprotein a-I

The N-terminal portion of apolipoprotein A-I corresponding to the first 93 residues has been identified as the main component of apolipoprotein A-I fibrils in a form of systemic amyloidosis. We have been able to characterize the process of conformational switching and fibrillogenesis in this fragment of apolipoprotein A-I purified directly from ex vivo amyloid material. The peptide exists in an unstructured form in aqueous solution at neutral pH. The acidification of the solution provokes a collapse into a more compact, intermediate state and the transient appearance of a helical conformation that rapidly converts to a stable, mainly beta-structure in the fibrils. The transition from helical to sheet structure occurs concomitantly with peptide self-aggregation, and fibrils are detected after 72 h. The alpha-helical conformation is induced by the addition of trifluoroethanol and phospholipids. Interaction of the amyloidogenic polypeptide with phospholipids prevents the switching from helical to beta-sheet form and inhibits fibril formation. The secondary structure propensity of the apolipoprotein A-I fragment appears poised between helix and the beta-sheet. These findings reinforce the idea of a delicate balance between natively stabilizing interactions and fatally stabilizing interactions and stress the importance of cellular localization and environment in the maintenance of protein conformation.     

Effect of Pomphorhynchus laevis (Acanthocephala) on putative neuromodulators in the intestine of naturally infected Salmo trutta

Immunohistochemical and pathological studies were carried out on the digestive tract of parasitized and uninfected specimens of Salmo trutta (L.). A total of 124 brown trout were collected on several occasions from 3 tributaries of the Brenta River, northern Italy. Twenty-eight individuals of S. trutta (22.6%) were parasitized with Pomphorhynchus laevis (Miller, 1776). The occurrence of P. laevis in the trout gut significantly increased the number of endocrine cells immunoreactive to calcitonin gene-related peptide (CGRP), beta-endorphin, met-enkephalin, neuropeptide Y (NPY) and Substance P (SP) antisera. Moreover, bombesin-, cholecistokinin-8- (CCK-8), leu-enkephalin- and serotonin- (5-HT)-like immunoreactive cells were less numerous in the intestine of the parasitized brown trout. A strong positive immunoreactivity was observed in nerve fibres and neurones of the myenteric plexus of the parasitized fish; the antisera involved in this positive reactivity were bombesin, met-enkephalin, SP and vasoactive intestinal peptide (VIP). More neurones immunoreactive to anti-CGRP and anti-5-HT sera were noted in the myenteric plexus and in the inner layer of the tunica muscularis of the infected fish. Most of the above-mentioned neuromodulators are known to control gut motility, digestive/absorptive processes, as well as the immune response. The changes induced by parasites in the neuroendocrine system of the brown trout are discussed.