LMNA Knock-Down Affects Differentiation and Progression of Human Neuroblastoma Cells

Background

Neuroblastoma (NB) is one of the most aggressive tumors that occur in childhood. Although genes, such as MYCN, have been shown to be involved in the aggressiveness of the disease, the identification of new biological markers is still desirable. The induction of differentiation is one of the strategies used in the treatment of neuroblastoma. A-type lamins are components of the nuclear lamina and are involved in differentiation. We studied the role of Lamin A/C in the differentiation and progression of neuroblastoma.

Methodology/Principal Findings

Knock-down of Lamin A/C (LMNA-KD) in neuroblastoma cells blocked retinoic acid-induced differentiation, preventing neurites outgrowth and the expression of neural markers. The genome-wide gene-expression profile and the proteomic analysis of LMNA-KD cells confirmed the inhibition of differentiation and demonstrated an increase of aggressiveness-related genes and molecules resulting in augmented migration/invasion, and increasing the drug resistance of the cells. The more aggressive phenotype acquired by LMNA-KD cells was also maintained in vivo after injection into nude mice. A preliminary immunohistochemistry analysis of Lamin A/C expression in nine primary stages human NB indicated that this protein is poorly expressed in most of these cases.

Conclusions/Significance

We demonstrated for the first time in neuroblastoma cells that Lamin A/C plays a central role in the differentiation, and that the loss of this protein gave rise to a more aggressive tumor phenotype.     

Elucidation of the Interaction Mechanism with Liposomes of gH625-Peptide Functionalized Dendrimers

We have demonstrated that amide-based dendrimers functionalized with the membrane-interacting peptide gH625 derived from the herpes simplex virus type 1 (HSV-1) envelope glycoprotein H enter cells mainly through a non-active translocation mechanism. Herein, we investigate the interaction between the peptide-functionalized dendrimer and liposomes composed of PC/Chol using fluorescence spectroscopy, isothermal titration calorimetry, and surface plasmon resonance to get insights into the mechanism of internalization. The affinity for the membrane bilayer is very high and the interaction between the peptide-dendrimer and liposomes took place without evidence of pore formation. These results suggest that the presented peptidodendrimeric scaffold may be a promising material for efficient drug delivery.     

Accumulation and Response of Willow Plants Exposed to Environmental Relevant Sulfonamide Concentrations

As a result of manure application to arable lands, agricultural ecosystems are often contaminated by veterinary antibiotics. In this study the aptitude of Salix fragilis L. to accumulate and tolerate sulfadimethoxine (SDM) was evaluated, together with the antibiotic effects on the plant development, with particular attention focused on roots.Results showed an antibiotic presence in root tissues, but not in leaves, after one month of SDM exposure to 0.01, 0.1, 1 and 10 mg l^?1. A hormetic growth of the hypogeal system was observed, however stress symptoms on the root development were only noticed after treatment to the highest dose. Results obtained from a second test, where new cuttings were exposed to 10 mg SDM l^?1for different periods, suggested that willow tolerance to SDM increased with the exposure duration, probably because of the onset of particular acclimation mechanisms. Therefore, the present work indicates that this woody species could be utilized in the phytoremediation of sulfonamide antibiotics at doses comparable to that found in agricultural ecosystems once obtained appropriate confirmations through future studies at a laboratory and field scale.     

Photosynthetic capacity of field-grown durum wheat under different N availabilities: A comparative study from leaf to canopy

The effect of N availability on photosynthetic capacity, growth parameters and yield was studied in field-grown durum-wheat plants at both the leaf and canopy levels. Two contrasting nitrogen levels (120 and 0 kg ha^?1) were assayed in a randomised block design with nine replicates each. Total biomass was measured at anthesis and yield and its agronomical components at maturity. Photosynthetic measurements were performed 2 weeks after anthesis in two plots of each N treatment. Flag leaves were measured, using a LI-COR 6400 combined with the chlorophyll fluorescence meter, and the whole canopy by measuring CO₂ and H₂O fluxes in an innovative canopy-chamber system. We showed a clear increase in photosynthetic gas exchange and chlorophyll contents with N fertilisation at both canopy and leaf levels. As a consequence the increase in yield as response to N fertilisation seems the result of a larger green leaf area combined with a higher photosynthetic capacity of the leaves attributable to an increase in the maximum carboxylation velocity of Rubisco. Moreover gas-exchange measurements of the flag leaf during grain filling seem to provide a realistic characterisation, not just of the photosynthetic performance of the crop, but also about the impact of N availability on yield. Thus, measurements performed on the flag leaf matched those at the canopy level, with proportional increases in terms of gas exchange and chlorophyll content, providing a fast, cheap and reliable estimation of canopy photosynthesis and the grain yield attained by the crop.     

Mutational Analysis of the Yeast TRAPP Subunit Trs20p Identifies Roles in Endocytic Recycling and Sporulation

Trs20p is a subunit of the evolutionarily conserved TRAPP (TRAnsport Protein Particle) complex that mediates various aspects of membrane trafficking. Three TRAPP complexes have been identified in yeast with roles in ER-to-Golgi trafficking, post-Golgi and endosomal-to-Golgi transport and in autophagy. The role of Trs20p, which is essential for viability and a component of all three complexes, and how it might function within each TRAPP complex, has not been clarified to date. To begin to address the role of Trs20p we generated different mutants by random mutagenesis but, surprisingly, no defects were observed in diverse anterograde transport pathways or general secretion in Trs20 temperature-sensitive mutants. Instead, mutation of Trs20 led to defects in endocytic recycling and a block in sporulation/meiosis. The phenotypes of different mutants appear to be separable suggesting that the mutations affect the function of Trs20 in different TRAPP complexes.     

Dissecting the transcriptional phenotype of ribosomal protein deficiency: implications for Diamond-Blackfan Anemia

Defects in genes encoding ribosomal proteins cause Diamond Blackfan Anemia (DBA), a red cell aplasia often associated with physical abnormalities. Other bone marrow failure syndromes have been attributed to defects in ribosomal components but the link between erythropoiesis and the ribosome remains to be fully defined. Several lines of evidence suggest that defects in ribosome synthesis lead to “ribosomal stress” with p53 activation and either cell cycle arrest or induction of apoptosis. Pathways independent of p53 have also been proposed to play a role in DBA pathogenesis.     

Light-modulation of nitrate reductase activity in leaves and roots of maize

The nuclear DNA content in ray cells from the 1-year-old vascular cambium of white ash ( Fraxinus americana L.) trees was determined at intervals during the annual cycle of cambial activity and dormancy by using Feulgen microspectrophotometry. By 10 September, these cells had entered dormancy in G₁ with a normal DNA distribution and a minimal average DNA content of 2.65 pg. The average amount of DNA increased to 3.51 pg by 30 November, remained at this elevated value until at least 30 March, when the cambium was still dormant, then declined to the minimum level on 1 May and 10 June, when the cells were mitotically active. The springtime decline appeared to occur both before and during cell division. Between 1 May and 10 June, the prophase (4C) and telophase (2C) DNA contents decreased significantly. The amount of nuclear DNA measured by microspectrophotometry was verified by using flow cytometry and image analysis. The results support the view that there is an annual oscillation in the nuclear genome size of shoot meristematic cells in tree species native to the northern temperate zone.     

HIV/gp120 decreases adult neural progenitor cell proliferation via checkpoint kinase-mediated cell-cycle withdrawal and G1 arrest

Impaired adult neurogenesis has been observed in several neurodegenerative diseases, including human immunodeficiency virus (HIV-1)-associated dementia (HAD). Here we report that the HIV-envelope glycoprotein gp120, which is associated with HAD pathogenesis, inhibits proliferation of adult neural progenitor cells (aNPCs) in vitro and in vivo in the dentate gyrus of the hippocampus of HIV/gp120-transgenic mice. We demonstrate that HIV/gp120 arrests cell-cycle progression of aNPCs at the G1 phase via a cascade consisting of p38 mitogen-activated protein kinase (MAPK) --> MAPK-activated protein kinase 2 (a cell-cycle checkpoint kinase) --> Cdc25B/C. Our findings define a molecular mechanism that compromises adult neurogenesis in this neurodegenerative disorder.     

Kaolin-based particle film technology affects tomato physiology,yield and quality

Environmental stress can affect development and yield of tomato plants. This study was undertaken to investigate the underlying mechanism asserted by kaolin on tomato physiology by evaluating its effect on leaf, canopy and inner fruit temperatures, gas exchange at the leaf and canopy scales, above ground biomass, yield and fruit quality.The study was carried out under field conditions in Southern Italy. Treatments were plants treated with kaolin-based particle film (Surround^® WP) suspension and untreated plants (control).Kaolin application slightly increased leaf and canopy scale temperatures by 1.0 and 0.4 °C, respectively, transpiration rate decreased at both scales. On calm days (wind speed <0.5 m s^?1) with a prevalently clear sky at midday, inner fruit temperature (t_f) of kaolin-treated plants was 4.4 °C lower than the t_f of control plants, while in days with clear sky-windy, and cloudy-calm, the t_f did not differ.At leaf scale, net assimilation was reduced by 26% in kaolin-coated treatments. Stomatal conductance decreased by 53%, resulting in reductions of 34 and 15% in transpiration and internal CO₂ concentration, respectively. Gas exchange parameters measured at canopy scale were similarly affected. In kaolin-treated plants, assimilation and evapotranspiration rates were reduced by 17 and 20%, respectively, while dark respiration was not affected. Above ground dry biomass decreased by 6.4%.Marketable yield in kaolin-treated plants was 21% higher than those measured in control plants; this is possibly related to the 96 and 79% reduction in sunburned fruit and those damaged by insects, respectively, and to the 9% increase in mean fruit weight. Kaolin treatment increased lycopene fruit content by 16%, but did not affect total soluble solids content, fruit dry matter, juice pH, titratable acidity or tomato fruit firmness. The use of kaolin-based particle film technology would be an effective tool to alleviate heat stress and to reduce water stress in tomato production under arid and semi-arid conditions.