RhoD regulates cytoskeletal dynamics via the actin nucleation-promoting factor WASp homologue associated with actin Golgi membranes and microtubules

The Rho GTPases have mainly been studied in association with their roles in the regulation of actin filament organization. These studies have shown that the Rho GTPases are essential for basic cellular processes, such as cell migration, contraction, and division. In this paper, we report that RhoD has a role in the organization of actin dynamics that is distinct from the roles of the better-studied Rho members Cdc42, RhoA, and Rac1. We found that RhoD binds the actin nucleation–promoting factor WASp homologue associated with actin Golgi membranes and microtubules (WHAMM), as well as the related filamin A–binding protein FILIP1. Of these two RhoD-binding proteins, WHAMM was found to bind to the Arp2/3 complex, while FILIP1 bound filamin A. WHAMM was found to act downstream of RhoD in regulating cytoskeletal dynamics. In addition, cells treated with small interfering RNAs for RhoD and WHAMM showed increased cell attachment and decreased cell migration. These major effects on cytoskeletal dynamics indicate that RhoD and its effectors control vital cytoskeleton-driven cellular processes. In agreement with this notion, our data suggest that RhoD coordinates Arp2/3-dependent and FLNa-dependent mechanisms to control the actin filament system, cell adhesion, and cell migration

Functionally Relevant Domains of the Prion Protein Identified In Vivo

The prion consists essentially of PrPSc, a misfolded and aggregated conformer of the cellular protein PrPC. Whereas PrPC deficient mice are clinically healthy, expression of PrPC variants lacking its central domain (PrPΔCD), or of the PrP-related protein Dpl, induces lethal neurodegenerative syndromes which are repressed by full-length PrP. Here we tested the structural basis of these syndromes by grafting the amino terminus of PrPC (residues 1–134), or its central domain (residues 90–134), onto Dpl. Further, we constructed a soluble variant of the neurotoxic PrPΔCD mutant that lacks its glycosyl phosphatidyl inositol (GPI) membrane anchor. Each of these modifications abrogated the pathogenicity of Dpl and PrPΔCD in transgenic mice. The PrP-Dpl chimeric molecules, but not anchorless PrPΔCD, ameliorated the disease of mice expressing truncated PrP variants. We conclude that the amino proximal domain of PrP exerts a neurotrophic effect even when grafted onto a distantly related protein, and that GPI-linked membrane anchoring is necessary for both beneficial and deleterious effects of PrP and its variants

Survival of atraumatic restorative treatment (ART) sealants and restorations: a meta-analysis

The purpose of this study is to perform a systematic investigation plus meta-analysis into survival of atraumatic restorative treatment (ART) sealants and restorations using high-viscosity glass ionomers and to compare the results with those from the 2005 ART meta-analysis. Until February 2010, four databases were searched. Two hundred four publications were found, and 66 reported on ART restorations or sealant survival. Based on five exclusion criteria, two independent reviewers selected the 29 publications that accounted for the meta-analysis. Confidence intervals (CI) and or standard errors were calculated and the heterogeneity variance of the survival rates was estimated. Location (school/clinic) was an independent variable. The survival rates of single-surface and multiple-surface ART restorations in primary teeth over the first 2 years were 93% (CI, 91–94%) and 62% (CI, 51–73%), respectively; for single-surface ART restorations in permanent teeth over the first 3 and 5 years it was 85% (CI, 77–91%) and 80% (CI, 76–83%), respectively and for multiple-surface ART restorations in permanent teeth over 1 year it was 86% (CI, 59–98%). The mean annual dentine lesion incidence rate, in pits and fissures previously sealed using ART, over the first 3 years was 1%. No location effect and no differences between the 2005 and 2010 survival rates of ART restorations and sealants were observed. The short-term survival rates of single-surface ART restorations in primary and permanent teeth, and the caries-preventive effect of ART sealants were high. Clinical relevance: ART can safely be used in single-surface cavities in both primary and permanent teeth. ART sealants have a high caries preventive effect

The Cellular Prion Protein Interacts with the Tissue Non-Specific Alkaline Phosphatase in Membrane Microdomains of Bioaminergic Neuronal Cells

BACKGROUND: The cellular prion protein, PrP(C), is GPI anchored and abundant in lipid rafts. The absolute requirement of PrP(C) in neurodegeneration associated to prion diseases is well established. However, the function of this ubiquitous protein is still puzzling. Our previous work using the 1C11 neuronal model, provided evidence that PrP(C) acts as a cell surface receptor. Besides a ubiquitous signaling function of PrP(C), we have described a neuronal specificity pointing to a role of PrP(C) in neuronal homeostasis. 1C11 cells, upon appropriate induction, engage into neuronal differentiation programs, giving rise either to serotonergic (1C11(5-HT)) or noradrenergic (1C11(NE)) derivatives. METHODOLOGY/PRINCIPAL FINDINGS: The neuronal specificity of PrP(C) signaling prompted us to search for PrP(C) partners in 1C11-derived bioaminergic neuronal cells. We show here by immunoprecipitation an association of PrP(C) with an 80 kDa protein identified by mass spectrometry as the tissue non-specific alkaline phosphatase (TNAP). This interaction occurs in lipid rafts and is restricted to 1C11-derived neuronal progenies. Our data indicate that TNAP is implemented during the differentiation programs of 1C11(5-HT) and 1C11(NE) cells and is active at their cell surface. Noteworthy, TNAP may contribute to the regulation of serotonin or catecholamine synthesis in 1C11(5-HT) and 1C11(NE) bioaminergic cells by controlling pyridoxal phosphate levels. Finally, TNAP activity is shown to modulate the phosphorylation status of laminin and thereby its interaction with PrP. CONCLUSION/SIGNIFICANCE: The identification of a novel PrP(C) partner in lipid rafts of neuronal cells favors the idea of a role of PrP in multiple functions. Because PrP(C) and laminin functionally interact to support neuronal differentiation and memory consolidation, our findings introduce TNAP as a functional protagonist in the PrP(C)-laminin interplay. The partnership between TNAP and PrP(C) in neuronal cells may provide new clues as to the neurospecificity of PrP(C) function