Identification of Ndfip1 as a novel negative regulator for spatial memory formation associated with increased ubiquitination of Beclin 1 and PTEN.

Long-term memory formation requires de novo RNA and protein synthesis. By using the differential display-polymerase chain reaction strategy, we have presently identified the Nedd4 family interacting protein 1 (Ndfip1) cDNA fragment that is differentially expressed between the slow learners and the fast learners from the water maze learning task in rats. Further, the fast learners show decreased Ndfip1 mRNA and protein expression levels than the slow learners. Spatial training similarly decreases the Ndfip1 mRNA and protein expression levels. Conversely, the Ndfip1 conditional heterozygous (cHet) mice show enhanced spatial memory performance compared to the Ndfip1flox/WT control mice. Result from co-immunoprecipitation experiment indicates that spatial training decreases the association between Ndfip1 and the E3 ubiquitin ligase Nedd4 (Nedd4-1), and we have shown that both Beclin 1 and PTEN are endogenous ubiquitination targets of Nedd4 in the hippocampus. Further, spatial training decreases endogenous Beclin 1 and PTEN ubiquitination, and increases Beclin 1 and PTEN expression in the hippocampus. On the other hand, the Becn1 conditional knockout (cKO) mice and the Pten cKO mice both show impaired spatial learning and memory performance. Moreover, the expression level of Beclin 1 and PTEN is higher in the Ndfip1 cHet mice compared with the Ndfip1flox/WT control mice. Here, we have identified Ndfip1 as a candidate novel negative regulation for spatial memory formation and this is associated with increased ubiquitination of Beclin 1 and PTEN in the hippocampus.

Galectin-3 promotes Aß oligomerization and Aß toxicity in a mouse model of Alzheimer's disease.

Amyloid-ß (Aß) oligomers largely initiate the cascade underlying the pathology of Alzheimer's disease (AD). Galectin-3 (Gal-3), which is a member of the galectin protein family, promotes inflammatory responses and enhances the homotypic aggregation of cancer cells. Here, we examined the role and action mechanism of Gal-3 in Aß oligomerization and Aß toxicities. Wild-type (WT) and Gal-3-knockout (KO) mice, APP/PS1;WT mice, APP/PS1;Gal-3+/- mice and brain tissues from normal subjects and AD patients were used. We found that Aß oligomerization is reduced in Gal-3 KO mice injected with Aß, whereas overexpression of Gal-3 enhances Aß oligomerization in the hippocampi of Aß-injected mice. Gal-3 expression shows an age-dependent increase that parallels endogenous Aß oligomerization in APP/PS1 mice. Moreover, Aß oligomerization, Iba1 expression, GFAP expression and amyloid plaque accumulation are reduced in APP/PS1;Gal-3+/- mice compared with APP/PS1;WT mice. APP/PS1;Gal-3+/- mice also show better acquisition and retention performance compared to APP/PS1;WT mice. In studying the mechanism underlying Gal-3-promoted Aß oligomerization, we found that Gal-3 primarily co-localizes with Iba1, and that microglia-secreted Gal-3 directly interacts with Aß. Gal-3 also interacts with triggering receptor expressed on myeloid cells-2, which then mediates the ability of Gal-3 to activate microglia for further Gal-3 expression. Immunohistochemical analyses show that the distribution of Gal-3 overlaps with that of endogenous Aß in APP/PS1 mice and partially overlaps with that of amyloid plaque. Moreover, the expression of the Aß-degrading enzyme, neprilysin, is increased in Gal-3 KO mice and this is associated with enhanced integrin-mediated signaling. Consistently, Gal-3 expression is also increased in the frontal lobe of AD patients, in parallel with Aß oligomerization. Because Gal-3 expression is dramatically increased as early as 3 months of age in APP/PS1 mice and anti-Aß oligomerization is believed to protect against Aß toxicity, Gal-3 could be considered a novel therapeutic target in efforts to combat AD.

Dysregulated Translation in Neurodevelopmental Disorders: An Overview of Autism-Risk Genes Involved in Translation.

Regulated local translation-whereby specific mRNAs are transported and localized in subcellular domains where they are translated in response to regional signals-allows for remote control of gene expression to concentrate proteins in subcellular compartments. Neurons are highly polarized cells with unique features favoring local control for axonal pathfinding and synaptic plasticity, which are key processes involved in constructing functional circuits in the developing brain. Neurodevelopmental disorders are caused by genetic or environmental factors that disturb the nervous system's development during prenatal and early childhood periods. The growing list of genetic mutations that affect mRNA translation raises the question of whether aberrant translatomes in individuals with neurodevelopmental disorders share common molecular features underlying their stereotypical phenotypes and, vice versa, cause a certain degree of phenotypic heterogeneity. Here, we briefly give an overview of the role of local translation during neuronal development. We take the autism-risk gene list and discuss the molecules that (perhaps) are involved in mRNA transport and translation. Both exaggerated and suppressed translation caused by mutations in those genes have been identified or suggested. Finally, we discuss some proof-of-principle regimens for use in autism mouse models to correct dysregulated translation.

Galectin-3 Negatively Regulates Hippocampus-Dependent Memory Formation through Inhibition of Integrin Signaling and Galectin-3 Phosphorylation.

Galectin-3, a member of the galectin protein family, has been found to regulate cell proliferation, inhibit apoptosis and promote inflammatory responses. Galectin-3 is also expressed in the adult rat hippocampus, but its role in learning and memory function is not known. Here, we found that contextual fear-conditioning training, spatial training or injection of NMDA into the rat CA1 area each dramatically decreased the level of endogenous galectin-3 expression. Overexpression of galectin-3 impaired fear memory, whereas galectin-3 knockout (KO) enhanced fear retention, spatial memory and hippocampal long-term potentiation. Galectin-3 was further found to associate with integrin α3, an association that was decreased after fear-conditioning training. Transfection of the rat CA1 area with small interfering RNA against galectin-3 facilitated fear memory and increased phosphorylated focal adhesion kinase (FAK) levels, effects that were blocked by co-transfection of the FAK phosphorylation-defective mutant Flag-FAKY397F. Notably, levels of serine-phosphorylated galectin-3 were decreased by fear conditioning training. In addition, blockade of galectin-3 phosphorylation at Ser-6 facilitated fear memory, whereas constitutive activation of galectin-3 at Ser-6 impaired fear memory. Interestingly galectin-1 plays a role in fear-memory formation similar to that of galectin-3. Collectively, our data provide the first demonstration that galectin-3 is a novel negative regulator of memory formation that exerts its effects through both extracellular and intracellular mechanisms.

Synthesis of sub-nanosized Pt particles on mesoporous SBA-15 material and its application to the CO oxidation reaction.

In this work, we show that the size and shape of Pt nanoparticles in SBA-15 can be controlled through vacuum and air calcination. The vacuum-calcination/H2-reduction process is used to thermally treat a 0.2 wt% Pt(4+)/SBA-15 sample to obtain small 2D clusters and single atoms that can significantly increase Pt dispersion in SBA-15. Compared with thermal treatments involving air-calcination/H2-reduction, which result in ∼4.6 nm rod-like Pt particles, vacuum-calcination/H2-reduction can dramatically reduce the size of the Pt species to approximately 0.5-0.8 nm. The Pt particles undergoing air-calcination/H2-reduction have poor conversion efficiency because the fraction of terrace sites, the major sites for CO oxidation, on the rod-like Pt particles is small. In contrast, a large amount of low-coordinated Pt sites associated with 2D Pt species and single Pt atoms in SBA-15 is effectively generated through the vacuum-calcination/H2-reduction process, which may facilitate CO adsorption and induce strong reactivity toward CO oxidation. We investigated the effect of vacuum-calcination/H2-reduction on the formation of tiny 2D clusters and single atoms by characterizing the particles, elucidating the mechanism of formation, determining the active sites for CO oxidation and measuring the heat of CO adsorption.

CREB SUMOylation by the E3 ligase PIAS1 enhances spatial memory.

cAMP-responsive element binding protein (CREB) phosphorylation and signaling plays an important role in long-term memory formation, but other posttranslational modifications of CREB are less known. Here, we found that CREB1Δ, the short isoform of CREB, could be sumoylated by the small ubiquitin-like modifier (SUMO) E3 ligase protein inhibitor of activated STAT1 (PIAS1) at Lys271 and Lys290 and PIAS1 SUMOylation of CREB1Δ increased the expression level of CREB1Δ. CREB1Δ could also be sumoylated by other PIAS family proteins, but not by the E3 ligases RanBP2 and Pc2 or by the E2 ligase Ubc9. Furthermore, water maze training increased the level of endogenous CREB SUMOylation in rat CA1 neurons determined by in vitro SUMOylation assay, but this effect was not observed in other brain areas. Moreover, transduction of Lenti-CREBWT to rat CA1 area facilitated, whereas transduction of Lenti-CREB double sumo-mutant (CREBK271RK290R) impaired, spatial learning and memory performance. Transduction of Lenti-CREBWT-SUMO1 fusion vector to rat CA1 area showed a more significant effect in enhancing spatial learning and memory and CREB SUMOylation. Lenti-CREBWT transduction increased, whereas Lenti-CREBK271RK290R transduction decreased, CREB DNA binding to the brain-derived neurotrophic factor (bdnf) promoter and decreased bdnf mRNA expression. Knock-down of PIAS1 expression in CA1 area by PIAS1 siRNA transfection impaired spatial learning and memory and decreased endogenous CREB SUMOylation. In addition, CREB SUMOylation was CREB phosphorylation dependent and lasted longer. Therefore, CREB phosphorylation may be responsible for signal transduction during the early phase of long-term memory formation, whereas CREB SUMOylation sustains long-term memory.

A predicted protein, KIAA0247, is a cell cycle modulator in colorectal cancer cells under 5-FU treatment.

BACKGROUND: Colorectal cancer (CRC) is the predominant gastrointestinal malignancy and the leading cause of cancer death. The identification of genes related to CRC is important for the development of successful therapies and earlier diagnosis. METHODS: Molecular analysis of feces was evaluated as a potential method for CRC detection. Expression of a predicted protein with unknown function, KIAA0247, was found in feces evaluated using specific quantitative real-time polymerase chain reaction. Its cellular function was then analyzed using immunofluorescent staining and the changes in the cell cycle in response to 5-fluorouracil (5-FU) were assessed. RESULTS: Gastrointestinal tissues and peripheral blood lymphocytes ubiquitously expressed KIAA0247. 56 CRC patients fell into two group categories according to fecal KIAA0247 mRNA expression levels. The group with higher fecal KIAA0247 (n=22; ≥0.4897) had a significantly greater five-year overall survival rate than the group with lower fecal KIAA0247 (n = 30; <0.4897) (66.0 ± 11.6%; p=0.035, log-rank test). Fecal expression of KIAA0247 inversely related to CRC tumor size (Kendall's tau-b=-0.202; p=0.047). Immunofluorescent staining revealed that the cytoplasm of CRC cells evenly expresses KIAA0247 without 5-FU treatment, and KIAA0247 accumulates in the nucleus after 40 µM 5-FU treatment. In HCT116 p53(-/-) cells, which lack p53 cell cycle control, the proportion of cells in the G2/M phase was larger (13%) in KIAA0247-silent cells than in the respective shLuc control (10%) and KIAA0247-overexpressing cells (7%) after the addition of low dose (40 µM) 5-FU. Expression of three cyclin genes (cyclin A2, cyclin B1, and cyclin B2) also downregulated in the cells overexpressing KIAA0247. CONCLUSIONS: This is the first description of a linkage between KIAA0247 and CRC. The study's data demonstrate overexpression of KIAA0247 associates with 5-FU therapeutic benefits, and also identify the clinical significance of fecal KIAA0247 in CRC.