Human Mena Associates with Rac1 Small GTPase in Glioblastoma Cell Lines

Mammarian enabled (Mena), a member of the Enabled (Ena)/Vasodilator-stimulated phosphoprotein (VASP) family of proteins, has been implicated in cell motility through regulation of the actin cytoskeleton assembly, including lamellipodial protrusion. Rac1, a member of the Rho family GTPases, also plays a pivotal role in the formation of lamellipodia. Here we report that human Mena (hMena) colocalizes with Rac1 in lamellipodia, and using an unmixing assisted acceptor depletion fluorescence resonance energy transfer (u-adFRET) analysis that hMena associates with Rac1 in vivo in the glioblastoma cell line U251MG. Depletion of hMena by siRNA causes cells to be highly spread with the formation of lamellipodia. This cellular phenotype is canceled by introduction of a dominant negative form of Rac1. A Rac activity assay and FRET analysis showed that hMena knock-down cells increased the activation of Rac1 at the lamellipodia. These results suggest that hMena possesses properties which help to regulate the formation of lamellipodia through the modulation of the activity of Rac1

An EMT-Driven Alternative Splicing Program Occurs in Human Breast Cancer and Modulates Cellular Phenotype

Epithelial-mesenchymal transition (EMT), a mechanism important for embryonic development, plays a critical role during malignant transformation. While much is known about transcriptional regulation of EMT, alternative splicing of several genes has also been correlated with EMT progression, but the extent of splicing changes and their contributions to the morphological conversion accompanying EMT have not been investigated comprehensively. Using an established cell culture model and RNA–Seq analyses, we determined an alternative splicing signature for EMT. Genes encoding key drivers of EMT–dependent changes in cell phenotype, such as actin cytoskeleton remodeling, regulation of cell–cell junction formation, and regulation of cell migration, were enriched among EMT–associated alternatively splicing events. Our analysis suggested that most EMT–associated alternative splicing events are regulated by one or more members of the RBFOX, MBNL, CELF, hnRNP, or ESRP classes of splicing factors. The EMT alternative splicing signature was confirmed in human breast cancer cell lines, which could be classified into basal and luminal subtypes based exclusively on their EMT–associated splicing pattern. Expression of EMT–associated alternative mRNA transcripts was also observed in primary breast cancer samples, indicating that EMT–dependent splicing changes occur commonly in human tumors. The functional significance of EMT–associated alternative splicing was tested by expression of the epithelial-specific splicing factor ESRP1 or by depletion of RBFOX2 in mesenchymal cells, both of which elicited significant changes in cell morphology and motility towards an epithelial phenotype, suggesting that splicing regulation alone can drive critical aspects of EMT–associated phenotypic changes. The molecular description obtained here may aid in the development of new diagnostic and prognostic markers for analysis of breast cancer progression.National Institutes of Health (U.S.) (R01-HG002439)National Science Foundation (U.S.) (equipment grant)National Institutes of Health (U.S.) (Integrative Cancer Biology Program Grant U54-CA112967)David H. Koch Institute for Integrative Cancer Research at MIT (Ludwig Center for Metastasis Research)David H. Koch Institute for Integrative Cancer Research at MITMassachusetts Institute of Technology (Croucher Scholarship)Massachusetts Institute of Technology (Ludwig Fund postdoctoral fellowship)National Institutes of Health (U.S.) (NIH CA100324)National Institutes of Health (U.S.) (AECC9526-5267

Genome-Wide Association Analysis of Oxidative Stress Resistance in Drosophila melanogaster

Background: Aerobic organisms are susceptible to damage by reactive oxygen species. Oxidative stress resistance is a quantitative trait with population variation attributable to the interplay between genetic and environmental factors. Drosophila melanogaster provides an ideal system to study the genetics of variation for resistance to oxidative stress. Methods and Findings: We used 167 wild-derived inbred lines of the Drosophila Genetic Reference Panel for a genomewide association study of acute oxidative stress resistance to two oxidizing agents, paraquat and menadione sodium bisulfite. We found significant genetic variation for both stressors. Single nucleotide polymorphisms (SNPs) associated with variation in oxidative stress resistance were often sex-specific and agent-dependent, with a small subset common for both sexes or treatments. Associated SNPs had moderately large effects, with an inverse relationship between effect size and allele frequency. Linear models with up to 12 SNPs explained 67–79 % and 56–66 % of the phenotypic variance for resistance to paraquat and menadione sodium bisulfite, respectively. Many genes implicated were novel with no known role in oxidative stress resistance. Bioinformatics analyses revealed a cellular network comprising DNA metabolism and neuronal development, consistent with targets of oxidative stress-inducing agents. We confirmed associations of seven candidate genes associated with natural variation in oxidative stress resistance through mutational analysis. Conclusions: We identified novel candidate genes associated with variation in resistance to oxidative stress that hav

A Quantitative Approach to Innovation in Agricultural Value Chains: Evidence from Kenyan Horticulture

In less developed countries such as Kenya, trade is increasingly occurring through, and employment is found within, global and local value chains. Yet, although innovation is widely recognised as crucial for development, the endogenous relationship between small-scale innovations and participation in global value chains (GVCs) has yet to be explored sufficiently. This endogeneity is highlighted using the 3L’s of labels, linkages and learnings as key overlapping factors that affect both the processes of innovation as well as GVC participation. Drawing on a survey of 320 fresh fruit farmers and 55 interviews in Kenya, we develop a novel method to quantify small-scale agricultural innovations, which are categorised into two overarching types. The first, formal, emanate from meeting standard requirements; the second, informal, evolve from local contexts and are less codified. We find that GVC farmers perform more formal innovations, while local farmers perform similar levels of informal innovation to GVC farmers

The effect of a micronutrient powder home fortification program on anemia and cognitive outcomes among young children in rural China: a cluster randomized trial

Abstract Background Anemia early in life has been associated with delayed cognitive and motor development. The WHO recommends home fortification using multiple micronutrient powders (MNPs) containing iron as a strategy to address anemia in children under two. We evaluated the effects of a program freely distributing MNP sachets to caregivers of infants in rural China. Methods We conducted a cluster-randomized controlled trial in Shaanxi province, enrolling all children aged 6–11 months in target villages. Following a baseline survey, investigators randomly assigned each village/cluster to a control or treatment group. In the treatment group, caregivers were instructed to give MNPs daily. Follow-up was after 6, 12, and 18 months of intervention. Primary outcomes were hemoglobin concentrations and scores on the Bayley Scales of Infant Development. Results One thousand, eight hundred and-two eligible children and their caregivers were enrolled. At baseline 48% (870) of children were anemic and 29% (529) were developmentally delayed. Six hundred and-ten children (117 villages) were assigned to the control group and 1192 children (234 villages) were assigned to the treatment group. Assignment to the treatment group was associated with an improvement in hemoglobin levels (marginal effect 1.77 g/L, 95% CI 0.017–3.520, p-value = 0.048) and cognitive development (marginal effect 2.23 points, 95% CI 0.061–4.399, p-value = 0.044) after 6 months but not thereafter. There were no significant effects on motor development. Zero effects after the first 6 months were not due to low compliance, low statistical power, or changes in feeding behavior. Hemoglobin concentrations improved in both the treatment and control groups over the course of the study; however, 22% (325) of children remained anemic at endline, and 48% (721) were cognitively delayed. Conclusions Providing caregivers with MNP sachets modestly hastened improvement in hemoglobin levels that was occurring absent intervention; however, this improvement did not translate into improved developmental outcomes at endline. Trial registration ISRCTN44149146 ; prospectively registered on 15th April 2013