13 research outputs found
Stoichiometric expression of mtHsp40 and mtHsp70 modulates mitochondrial morphology and cristae structure via Opa1L cleavage
Green Supply Chain Management and Its Impact on Consumer Purchase Decision as a Marketing Strategy: Applying the Theory of Planned Behavior
This study examines the impact of green supply chain management (GSCM) on consumers environmentally friendly purchase behavior. We surveyed 283 consumers and analyzed the data using SPSS 18.0, AMOS 18.0, and verified them with structural equation modeling. To support the primary data analysis results, we conducted focus group interviews (FGIs) of 16 consumers. According to the primary data analysis, consumers’ subjective norms and perceived behavioral control positively influence GSCM. However, attitude did not have a significant influence. In the FGI, consumers show a highly positive attitude and purchase intention toward the GSCM of companies. However, they exhibit mistrust and lower purchase intentions toward advertising or marketing campaigns promoting GSCM to consumers. In contrast, the influence of subjective norms was found to be different for different products. In addition, a high price—regarded as the biggest barrier among perceived control factors—raises purchase intentions if consumers are provided with good and transparent information about green products. Thus, this study buttresses the fact that if a company uses GSCM practices as an eco-friendly marketing strategy that reduces consumer distrust and considers product characteristics, it can have a positive effect on consumers’ decision to purchase eco-friendly products
Ras/ERK-signalling promotes tRNA synthesis and growth via the RNA polymerase III repressor Maf1 in <i>Drosophila</i>
<div><p>The small G-protein Ras is a conserved regulator of cell and tissue growth. These effects of Ras are mediated largely through activation of a canonical RAF-MEK-ERK kinase cascade. An important challenge is to identify how this Ras/ERK pathway alters cellular metabolism to drive growth. Here we report on stimulation of RNA polymerase III (Pol III)-mediated tRNA synthesis as a growth effector of Ras/ERK signalling in <i>Drosophila</i>. We find that activation of Ras/ERK signalling promotes tRNA synthesis both in vivo and in cultured <i>Drosophila</i> S2 cells. We also show that Pol III function is required for Ras/ERK signalling to drive proliferation in both epithelial and stem cells in <i>Drosophila</i> tissues. We find that the transcription factor Myc is required but not sufficient for Ras-mediated stimulation of tRNA synthesis. Instead we show that Ras signalling promotes Pol III function and tRNA synthesis by phosphorylating, and inhibiting the nuclear localization and function of the Pol III repressor Maf1. We propose that inhibition of Maf1 and stimulation of tRNA synthesis is one way by which Ras signalling enhances protein synthesis to promote cell and tissue growth.</p></div
Brf1 is required for intestinal stem cells (ISCs) homeostasis and for Ras-induced cell proliferation.
<p>(A, B) <i>UAS-Brf1 RNAi</i> was expressed adult ISCs and EBs using the <i>esg-GAL4</i><sup><i>ts</i></sup> system. Control flies were <i>esg-GAL4</i><sup><i>ts</i></sup> flies crossed to <i>w</i><sup><i>1118</i></sup>. Flies were then fed with sucrose or sucrose plus DSS (A) or Bleomycin (B) for 2 days. Intestines were then dissected and stained for phospho-histone H3 positive cells. Data represent the mean number of phospho-histone H3 cells per intestine +/ SEM. N >15 intestines per condition. (C) A UAS-Ras<sup>V12</sup> transgene was expressed in adult intestines using the <i>esg-GAL4</i><sup><i>ts</i></sup> driver. Control samples (WT) expressed <i>UAS-GFP</i> alone. Total RNA was isolated and levels of pre-tRNAs measured by qRT-PCR. N = 4 independent samples per condition. Data are presented as mean +/- SEM. (D) <i>UAS-Raf</i><sup><i>gof</i></sup> and <i>UAS-Brf1 RNAi</i> were expressed, either alone or together, in the adult ISCs and EBs using the <i>esg-Gal4</i><sup><i>ts</i></sup> system. <i>esg</i> positive cells are marked with GFP and DNA is stained with Hoechst dye. Knockdown of Brf 1(<i>UAS-Brf RNAi</i>) suppresses the increased proliferation seen with <i>UAS-Raf</i><sup><i>gof</i></sup> expression.</p
dMyc is required but not sufficient for Ras-induced tRNA synthesis.
<p>(A) Ras<sup>V12</sup> expression was induced in <i>Drosophila</i> S2 cells for 24 hours in either control cells or dMyc knockdown cells. dMyc was knocked down by incubating cells with dsRNA against <i>dMyc</i>. Control cells were treated with dsRNA to GFP. Total RNA was isolated with Trizol and analyzed by northern blotting using DIG-labelled antisense probes to tRNA<sup>iMet</sup> or tRNA<sup>Arg</sup>. Ethidium bromide stained 5S rRNA band was used as a loading control. (B, C and D) dMyc expression was induced in S2 cells for 24hrs, and then cells were treated with 10 μM U0126 or DMSO for 2 hours. Total RNA was isolated with Trizol and analyzed by qRT-PCR to measure levels of (B) pre-tRNAs, (C) <i>dMyc</i> mRNA, or (D) mRNA levels of three dMyc target genes—<i>NOP60B</i>, <i>PPAN</i> and <i>NOP5</i>. N = 4 independent samples per condition. Data are presented as mean +/-SEM.</p
Brf1 is required for Ras-induced tRNA synthesis and growth in both wing imaginal discs and adult midgut progenitor cells (AMPs).
<p>(A). Ras<sup>V12</sup> expression was induced in <i>Drosophila</i> S2 cells for 24 hours in either control cells or Brf1 knockdown cells, Brf1 was knocked down by incubating cells with dsRNA against Brf1. Control cells were treated with dsRNA to GFP. Total RNA was isolated with Trizol and analyzed by northern blotting using DIG-labelled antisense probes to tRNA<sup>iMet</sup> or tRNA<sup>Arg</sup>. Ethidium bromide stained 5S rRNA band was used as a loading control. (B, C) <i>UAS-EGFR</i> and <i>UAS-Brf1 RNAi</i> were expressed, either alone or together, in the dorsal compartment of larval wing imaginal discs using an <i>ap-Gal4</i> driver. Control discs were from <i>ap-Gal4</i> crossed to <i>w</i><sup><i>1118</i></sup>. Wing discs were dissected at the wandering L3 larval stage and the area of the GFP-marked dorsal compartment quantified using NIH imaging software (n > 50 wings per genotype, data presented as mean +/- SEM). Representative images are shown in (B), quantification of tissue area is shown in (C). (D) <i>UAS-EGFR</i> and <i>UAS-Brf1 RNAi</i> were expressed, either alone or together, in the <i>Drosophila</i> larval AMPs using the <i>esg-Gal4</i><sup><i>ts</i></sup> system. Larvae were shifted to 29°C at 24 hrs of development to induce transgene expression and dissected as L3 larvae. AMPs are marked <i>by UAS-GFP</i> expression. DNA is stained with Hoechst dye (blue). (E) The number of cells in each AMP cluster was quantified for each of the genotypes in D (left), and an additional similar experiment in which the Ras pathway was activated by expression of a <i>UAS-Raf</i><sup><i>gof</i></sup> transgene (right). Data are presented as box plots (25%, median and 75% values) with error bars indicating the min and max values.</p
Ras signalling regulates dMaf1 phosphorylation.
<p>(A) <i>Drosophila</i> S2 cells were treated with 10 ÎĽM U0126 for 2 hours. Cells were then lysed and processed for SDS-PAGE and western blotting using the phos-tag reagent, as described in the Methods. The blots were then probed with an anti-dMaf1 antibody (top panel), an anti-total ERK antibody (middle panel) or an anti-phospho ERK antibody (lower panel) (B) Ras<sup>V12</sup> expression was induced in <i>Drosophila</i> S2 cells for 24 hours. Cells were then lysed and processed for SDS-PAGE and western blotting using the phos-tag reagent, as described in the Methods. The blots were then probed with an anti-dMaf1 antibody (top panel), an anti-total ERK antibody (middle panel) or an anti-phospho ERK antibody (lower panel). (C) A model for how Ras signalling may regulate Pol III and tRNA synthesis.</p
The Ras/ERK signalling pathway stimulates tRNA synthesis.
<p>(A, B) <i>Drosophila</i> S2 cells were treated with 10 μM U0126 for 2 hours. Total RNA was isolated and levels of either pre-tRNAs (A), or total tRNAs (B) measured by qRT-PCR. N = 15 independent samples per condition. (C, D) Raf was knocked down in <i>Drosophila</i> S2 cells by incubating cells with dsRNAs against <i>Raf</i>. Control cells were treated with dsRNA to GFP. Total RNA was isolated and levels of either pre-tRNAs (C), or total tRNAs (D) measured by qRT-PCR. N = 4 independent samples per condition. (E, F) Ras<sup>V12</sup> expression was induced in <i>Drosophila</i> S2 cells for 24 hours. Total RNA was isolated and levels of either pre-tRNAs (E), or total tRNAs (F) measured by qRT-PCR. N = 9 independent samples per condition. (G) <i>UAS-Raf</i><sup><i>gof</i></sup> was expressed in imaginal tissues using the <i>esg-GAL4</i><sup><i>ts</i></sup> system. Control flies were <i>esg-GAL4</i><sup><i>ts</i></sup> flies crossed to <i>w</i><sup><i>1118</i></sup>. Transgenes were induced by shifting larvae to 29°C at 48hrs of larval development, and then discs were dissected from wandering L3 stage larvae. Total RNA was isolated and levels of pre-tRNAs measured by qRT-PCR. N = 4 independent samples per condition. Data are presented as mean +/- SEM.</p