Phosphorylation of NHERF1 S279 and S301 differentially regulates breast cancer cell phenotype and metastatic organotropism

Metastatic cancer cells are highly plastic for the expression of different tumor phenotype hallmarks and organotropism. This plasticity is highly regulated but the dynamics of the signaling processes orchestrating the shift from one cell phenotype and metastatic organ pattern to another are still largely unknown. The scaffolding protein NHERF1 has been shown to regulate the expression of different neoplastic phenotypes through its PDZ domains, which forms the mechanistic basis for metastatic organotropism. This reprogramming activity was postulated to be dependent on its differential phosphorylation patterns. Here, we show that NHERF1 phosphorylation on S279/S301 dictates several tumor phenotypes such as in vivo invasion, NHE1-mediated matrix digestion, growth and vasculogenic mimicry. Remarkably, injecting mice with cells having differential NHERF1 expression and phosphorylation drove a shift from the predominantly lung colonization (WT NHERF1) to predominately bone colonization (double S279A/S301A mutant), indicating that NHERF1 phosphorylation also acts as a signaling switch in metastatic organotropism.     

Identification of genes responsive to sodium butyrate in colonic epithelial cells

We identified genes responsive to sodium butyrate (SB) in colonic epithelial cells using cDNA microarrays. Treatment with 2 mM SB of colonic epithelial cells (MCE301), which was derived from transgenic mice harboring a temperature-sensitive simian virus 40 large T-antigen, arrested cell growth and showed a differentiated phenotype accompanying an increase in alkaline phosphatase activity. Of the approximately 900 genes analyzed, SB down-regulated 25 genes and up-regulated 88 genes by a factor of 2.0 or greater. Northern blot or TaqMan and Western blot analyses confirmed that the mRNA and protein levels of cyclin D1 and the level of proliferating cell nuclear antigen decreased, whereas the levels of integrin beta1 and osteopontin increased. The present results regarding the changes in gene expression, arrived at using microarrays, will provide a basis for a further understanding of the molecular mechanisms of cell growth arrest and differentiation in response to SB in colonic epithelial cells.     

Removing endogenous tau does not prevent tau propagation yet reduces its neurotoxicity

In Alzheimer's disease and tauopathies, tau protein aggregates into neurofibrillary tangles that progressively spread to synaptically connected brain regions. A prion‐like mechanism has been suggested: misfolded tau propagating through the brain seeds neurotoxic aggregation of soluble tau in recipient neurons. We use transgenic mice and viral tau expression to test the hypotheses that trans‐synaptic tau propagation, aggregation, and toxicity rely on the presence of endogenous soluble tau. Surprisingly, mice expressing human P301Ltau in the entorhinal cortex showed equivalent tau propagation and accumulation in recipient neurons even in the absence of endogenous tau. We then tested whether the lack of endogenous tau protects against misfolded tau aggregation and toxicity, a second prion model paradigm for tau, using P301Ltau‐overexpressing mice with severe tangle pathology and neurodegeneration. Crossed onto tau‐null background, these mice had similar tangle numbers but were protected against neurotoxicity. Therefore, misfolded tau can propagate across neural systems without requisite templated misfolding, but the absence of endogenous tau markedly blunts toxicity. These results show that tau does not strictly classify as a prion protein.     

ZmGrp3: identification of a novel marker for root initiation in maize and development of a robust assay to quantify allele-specific contribution to gene expression in hybrids

This study comprises a comprehensive gene expression analysis of the root tip specific maize gene ZmGrp3. In the first part of this paper expression of ZmGrp3 was studied in maize inbred lines. First, RNA in situ hybridization experiments confined the expression of ZmGrp3 to the columella and the epidermis of all embryonic and postembryonic root types. Second, Northern-blot analyses of the maize root initiation mutants rtcs and lrt1 revealed that the ZmGrp3 gene is not expressed prior to root initiation, thus providing a novel marker for this developmental process. Finally, a comprehensive expression profiling in 42 tissues via the Lynx MPSS system revealed almost exclusive expression of ZmGrp3 in maize roots. In the second part of this survey, ZmGrp3 expression was assayed in maize hybrids. In this context, a novel approach to quantify allele-specific contribution to gene expression in maize hybrids was developed. This assay combines RT–PCR amplification of polymorphisms between two alleles and subsequent quantification of allele-specific gene expression via a combination of didesoxyterminator assays and capillary electrophoresis. Allelic expression of the ZmGrp3 gene in six reciprocal hybrids generated from three ZmGrp3 alleles was analyzed via a new statistical mixed model approach.Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users.     

Nitrogen fixation by hydrogen-utilizing bacteria

Seventeen strains of nitrogen-fixing bacteria, isolated from different habitats on hydrogen and carbon dioxide as well as on other substrates, morphologically resembled each other. All strains, including Mycobacterium flavum 301, grew autotrophically with hydrogen. The isolate strain 6 was sensitive to oxygen when dependent on N₂ as nitrogen source, a consequence of the sensitivity of its nitrogenase towards oxygen. At the same time, strain 6 was sensitive to hydrogen when growing autotrophically on N₂ as nitrogen source, but hydrogen did not affect acetylene reduction by these cells.Abbreviations MPN Most probable number - BS medium basal salts medium     

Complete DNA sequence and gene analysis of the virulence plasmid pCP301 of Shigella flexneri 2a

The complete nucleotide sequence and organization of the large virulence plasmid pCP301 (termed by us) of Shigella flexneri 2a strain 301 were determined and analyzed. The result showed that the entire DNA sequence of pCP301 is composed of 221618 bp which form a circular plasmid. Sequence analysis identified 272 open reading frames (ORFs), among which, 194 correspond to the proteins described previously, 61 have low identity (<60%) to known proteins and the rest 17 have no regions of significant homology with proteins in database. The genes of pCP301 mainly include the genes associated with bacterial virulence, the genes associated with regulation and the genes relating to plasmid maintenance, stability and DNA metabolism. Insertion sequence (IS) elements are 68 kb in length and account for 30 percent of complete sequence of the plasmid which indicates that gene multiple rearrangements of the pCP301 have taken place in Shigella flexneri evolution history. The research result is helpful for interpreting the pathogenesis of Shigella, as well as the genetics and evolution of the plasmid.     

Complete DNA sequence and gene analysis of the virulence plasmid pCP301 of Shigella flexneri 2a

Bacteria Shigella spp. are highly contagious, severely harmful and gram-negative facultative intracellular pathogens. They may cause shigellosis characterized by fever, dehydration and hematochezia in clinic, and shigellosis has been remaining a leading cause of infant mortality in the world. Shigella belongs to the family Enterobacteriaceae and the group Escherichiaeae, which are divided into four species and at least 47 serotypes: Shigella dysenteriae (13 serotypes), Shigella flexneri (15 …