Sialidase NEU3 Dinamically Associates to Different Membrane Domains Specifically Modifying Their Ganglioside Pattern and Triggering Akt Phosphorylation

Lipid rafts are known to regulate several membrane functions such as signaling, trafficking and cellular adhesion. The local enrichment in sphingolipids and cholesterol together with the low protein content allows their separation by density gradient flotation after extraction with non-ionic detergent at low temperature. These structures are also referred to as detergent resistant membranes (DRM). Among sphingolipids, gangliosides play important roles in different biological events, including signal transduction and tumorigenesis. Sialidase NEU3 shows high enzymatic specificity toward gangliosides. Moreover, the enzyme is present both at the cell surface and in endosomal structures and cofractionates with caveolin. Although changes in the expression level of NEU3 have been correlated to different tumors, little is known about the precise distribution of the protein and its ability in modifying the ganglioside composition of DRM and non-DRM, thus regulating intracellular events. By means of inducible expression cell system we found that i) newly synthesized NEU3 is initially associated to non-DRM; ii) at steady state the protein is equally distributed between the two membrane subcompartments, i.e., DRM and non-DRM; iii) NEU3 is degraded via the proteasomal pathway; iv) the enzyme specifically modifies the ganglioside composition of the membrane areas where it resides; and v) NEU3 triggers phosphorylation of Akt, even in absence of exogenously administered EGF. Taken together our data demonstrate that NEU3 regulates the DRM ganglioside content and it can be considered as a modulator of Akt phosphorylation, further supporting the role of this enzyme in cancer and tumorigenesis

Impaired photosystem I oxidation induces STN7-dependent phosphorylation of the light-harvesting complex I protein Lhca4 in Arabidopsis thaliana

Reduction of the plastoquinone (PQ) pool is known to activate phosphorylation of thylakoid proteins. In the Arabidopsis thaliana mutants psad1-1 and psae1-3, oxidation of photosystem I (PSI) is impaired, and the PQ pool is correspondingly over-reduced. We show here that, under these conditions, the antenna protein Lhca4 of PSI becomes a target for phosphorylation. Phosphorylation of the mature Lhca4 protein at Thr16 is suppressed in stn7 psad1 and stn7 psae1 double mutants. Thus, under extreme redox conditions, hyperactivation of thylakoid protein kinases and/or reorganization of thylakoid protein complex distribution increase the susceptibility of PSI to phosphorylation

Role of Plastid Protein Phosphatase TAP38 in LHCII Dephosphorylation and Thylakoid Electron Flow

Regulation of photosynthesis efficiency involves reversible phosphorylation of the light-harvesting complex through the activity of the newly identified phosphatase TAP38

Natural History and Outcome of Hepatic Vascular Malformations in a Large Cohort of Patients with Hereditary Hemorrhagic Teleangiectasia

BACKGROUND: Hereditary hemorrhagic telangiectasia is a genetic disease characterized by teleangiectasias involving virtually every organ. There are limited data in the literature regarding the natural history of liver vascular malformations in hemorrhagic telangiectasia and their associated morbidity and mortality. AIM: This prospective cohort study sought to assess the outcome of liver involvement in hereditary hemorrhagic telangiectasia patients. METHODS: We analyzed 16 years of surveillance data from a tertiary hereditary hemorrhagic telangiectasia referral center in Italy. We considered for inclusion in this study 502 consecutive Italian patients at risk of hereditary hemorrhagic telangiectasia who presented at the hereditary hemorrhagic telangiectasia referral center and underwent a multidisciplinary screening protocol for the diagnosis of hereditary hemorrhagic telangiectasia. Of the 502 individuals assessed in the center, 154 had hepatic vascular malformations and were the subject of the study; 198 patients with hereditary hemorrhagic telangiectasia and without hepatic vascular malformations were the controls. Additionally, we report the response to treatment of patients with complicated hepatic vascular malformations. RESULTS: The 154 patients were included and followed for a median period of 44 months (range 12-181); of these, eight (5.2%) died from VM-related complications and 39 (25.3%) experienced complications. The average incidence rates of death and complications were 1.1 and 3.6 per 100 person-years, respectively. The median overall survival and event-free survival after diagnosis were 175 and 90 months, respectively. The rate of complete response to therapy was 63%. CONCLUSIONS: This study shows that substantial morbidity and mortality are associated with liver vascular malformations in hereditary hemorrhagic telangiectasia patients

Conceptual Design of a Soft X‐ray SASE‐FEL Source

FELs based on SASE are believed to be powerful tools to explore the frontiers of basic sciences, from physics to chemistry to biology. Intense R&D programs have started in the USA and Europe in order to understand the SASE physics and to prove the feasibility of these sources. The allocation of considerable resources in the Italian National Research Plan (PNR) brought about the formation of a CNR‐ENEA‐INFN‐University of Roma "Tor Vergata" study group. A conceptual design study has been developed and possible schemes for linac sources have been investigated, bringing to the SPARX proposal. We report in this paper the results of a preliminary start to end simulation concerning one option we are considering based on an S‐band normal conducting linac with high brightness photoinjector integrated in a RF compressor

Distribution of SNVs in secondary structural elements of NEU1 protein.

<p>Numbers in brackets represent the p-value associated to the enrichment of SNVs in the corresponding category calculated as described in Methods. Classification of variants: mis, missense; syn, synonymous.</p

Distribution of variants identified in NEU1.

<p>Schematic representation of NEU1 protein, with amino acid position on the X axis. Black vertical lines divide the 6 exons of <i>NEU1</i> gene. Line graph indicates the conservation score for each amino acid position as calculated by ScoreCons. The identified missense variants are represented as squares, with Y values corresponding to PolyPhen score. The missense variants already identified as pathological alleles in sialidosis are represented as diagonal crosses. Below the graph, schematic representation of NEU1 structural elements: full color blocks represent beta-strand elements, while crossed blocks represent helices. Color code identifies the 6 blades of the β-propeller structure as described in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0104229#pone.0104229-Chavas1" target="_blank">[35]</a>. Gray boxes represent the Asp-box elements and essential catalytic residues are indicated with dots and their residue number. Positions of all elements are relative to the amino acid position in the graph above.</p

Subcellular localization study of V217A and D234N NEU1 mutant proteins.

<p>Confocal microscopy images showing the subcellular distribution of NEU1 wild-type, V217A and D234N mutants. NEU1 proteins were detected using specific rabbit anti-NEU1 antibody and revealed with Alexa-555 secondary antibody. Wild-type NEU1 labeling resulted in a vesicular pattern (A), mainly colocalizing with the lysosomal marker LAMP1 detected with mouse anti-LAMP1 and revealed with Alexa-405 secondary antibody (B, merge in C). The V217A (D) and D234N (G) mutant proteins showed a tubulo-reticular localization. Almost no colocalization between V217A and D234N mutants and LAMP1 (E–F and H–I) could be detected. Insets represent enlargement of the indicated areas.</p

Distribution of SNVs in the exon of <i>NEU1</i> gene.

<p>Based on <i>NEU1</i> cDNA sequence NM_000434.3. Numbers in brackets represent the p-value associated to the enrichment of SNVs in the corresponding exon calculated as described in Methods. Classification of variants: mis, missense; syn, synonymous; UTR, located in the untranslated regions.</p