Transcriptional Induction (transcriptional + induction)

Distribution by Scientific Domains


Selected Abstracts


The ecdysteroidogenic P450 Cyp302a1/disembodied from the silkworm, Bombyx mori, is transcriptionally regulated by prothoracicotropic hormone

INSECT MOLECULAR BIOLOGY, Issue 5 2005
R. Niwa
Abstract During larval and pupal development of insects, ecdysone is synthesized in the prothoracic gland (PG). Although several Drosophila genes, including Halloween P450 genes, are known to be important for ecdysteroidogenesis in PG, little is known of the ecdysteroidogenic genes in other insects. Here we report on Cyp302a1/disembodied (dib-Bm), one of the Halloween P450s in the silkworm Bombyx mori that is a carbon-22 hydroxylase. dib-Bm is predominantly expressed in PG and its developmental expression profile is correlated with a change in the ecdysteroid titre in the haemolymph. Furthermore, dib-Bm expression in cultured PGs is significantly induced by treatment with prothoracicotropic hormone. This is the first report on the transcriptional induction of a steroidogenic gene by the tropic hormone in insects. [source]


Ochratoxin A impairs Nrf2-dependent gene expression in porcine kidney tubulus cells

JOURNAL OF ANIMAL PHYSIOLOGY AND NUTRITION, Issue 5 2009
C. Boesch-Saadatmandi
Summary The mycotoxin, ochratoxin A (OTA), which is produced by Aspergillus and Penicillium subspecies, is frequently present in feedstuffs. Ochratoxin A exhibits a wide range of toxic activities including nephrotoxicity. However, the underlying molecular mechanisms of OTA-induced cellular nephrotoxicity have yet not been fully elucidated. Nrf2 is a basic leucine zipper transcriptional activator essential for the coordinated transcriptional induction of antioxidant and xenobiotic metabolizing enzymes in the kidney. Therefore, in the present study, the effects of OTA on the nuclear translocation and transactivation of the transcription factor Nrf2 as well as mRNA levels of Nrf2 target genes including glutathione- S -transferase and ,-glutamylcysteinyl synthetase have been studied in cultured porcine kidney tubulus cells (LLC-PK1). Nrf2 was induced by sulforaphane, a well-known activator of this transcription factor. Ochratoxin A significantly decreased ,-glutamylcysteinyl synthetase and glutathione- S -transferase mRNA levels in LLC-PK1 cells. Decreased mRNA levels of ,-glutamylcysteinyl synthetase and glutathione- S -transferase were accompanied by a lowered nuclear translocation and transactivation of Nrf2. Furthermore, OTA also lowered Nrf2 mRNA levels. Current data indicate that OTA nephrotoxicity may be, at least partly, mediated by an Nrf2-dependent signal transduction pathway. [source]


Copper-mediated reversal of defective laccase in a ,vph1 avirulent mutant of Cryptococcus neoformans

MOLECULAR MICROBIOLOGY, Issue 4 2003
Xudong Zhu
Summary Previous studies have shown that a ,vph1 Cryptococcus neoformans mutant defective in vesicular acidification lacked several important virulence factors including a copper-containing laccase and was avirulent in a mouse model. In the present studies, we characterized laccase transcription and protein production to obtain insights into the mechanism of the vph1 mutation in this pathogen. Although transcription and protein expression were somewhat reduced, laccase protein was found to be successfully translated and correctly targeted to the cell wall in the ,vph1 mutant as shown by Western blot and immuno-electron microscopy, despite a complete lack of laccase activity. Laccase activity was substantially restored in metabolically active ,vph1 cells at 30°C by addition of 100 µM copper sulphate. This restoration by copper was found to occur through both transcriptional and post-translational mechanisms. Laccase transcriptional induction by copper was found to be dependent on enhancer region II within the 5,-untranslated region of CNLAC1. Copper was also found to restore partial activity to ,vph1 cells at 0°C, suggesting that cell wall laccase was expressed in the mutant as an apo-enzyme. Apo-laccase restoration by copper was found to be facilitated by an acidic environment, consistent with a role for the vacuolar (H+)-ATPase proton pump in copper assembly of laccase in C. neoformans. [source]


Identification of QTL controlling root growth response to phosphate starvation in Arabidopsis thaliana

PLANT CELL & ENVIRONMENT, Issue 1 2006
MATTHIEU REYMOND
ABSTRACT One of the responses of plants to low sources of external phosphorus (P) is to modify root architecture. In Arabidopsis thaliana plantlets grown on low P, the primary root length (PRL) is reduced whereas lateral root growth is promoted. By using the Bay-0 × Shahdara recombinant inbred line (RIL) population, we have mapped three quantitative trait loci (QTL) involved in the root growth response to low P. The Shahdara alleles at these three QTL promote the response of the primary root to low P (i.e. root length reduction). One of these QTL, LPR1, located in a 2.8 Mb region at the top of chromosome 1, explains 52% of the variance of the PRL. We also detected a single QTL associated with primary root cell elongation in response to low P which colocalizes with LPR1. LPR1 does not seem to be involved in other typical P-starvation responses such as growth and density of root hairs, excretion of acid phosphatases, anthocyanin accumulation or the transcriptional induction of the P transporter Pht1;4. LPR1 might highlight new aspects of root growth that are revealed specifically under low P conditions. [source]


Calcium requirement for ethylene-dependent responses involving 1-aminocyclopropane-1-carboxylic acid oxidase in radicle tissues of germinated pea seeds,

PLANT CELL & ENVIRONMENT, Issue 5 2003
L. PETRUZZELLI
ABSTRACT The Ca2+ requirements of ethylene-dependent responses were investigated in germinating seeds of Pisum sativum L. using 1-aminocyclopropane-1-carboxylic acid (ACC) oxidase (Ps-ACO1), ACC synthase (Ps-ACS2) and class I , -1,3-glucanase as molecular markers. Ethylene biosynthesis and responsiveness are localized to the elongation and differentiation zones of the pea radicle. Ethylene treatment induced ectopic root hair formation in the cell elongation zone and promoted root hair elongation growth in the radicles of germinated seeds. Characterized Ca2+ antagonists, including EGTA, lanthanum, verapamil, ruthenium red, W-7, lithium and neomycin, were used to test for the involvement of the apoplastic and the intracellular Ca2+ -pool, the Ca2+/calmodulin complex and the phoshoinositide (PI) cycle in the ethylene responses. Ca2+ release from internal pools, but no appreciabe apoplastic Ca2+, is involved in the transcriptional induction by ethylene of Ps-ACO1 and in ectopic root hair formation in the radicle elongation zone of germinated pea seeds. Furthermore, the Ca2+/calmodulin complex and the PI cycle seem to be involved in these ethylene responses. In contrast, both the intracellular and the apoplastic Ca2+ -pools are required for the negative and positive ethylene responses to the gene expression of PS-ACS2 and class I , -1,3-glucanase, respectively; and, apoplastic Ca2+ also promotes root hair elongation growth. Tissues from adult plants and germinating seeds exhibit temporal and spatial differences in the signal/response coupling by Ca2+ of ethylene-regulated processes. [source]


The Ca2+ -dependent protein kinase CPK3 is required for MAPK-independent salt-stress acclimation in Arabidopsis

THE PLANT JOURNAL, Issue 3 2010
Norbert Mehlmer
Summary Plants use different signalling pathways to respond to external stimuli. Intracellular signalling via calcium-dependent protein kinases (CDPKs) or mitogen-activated protein kinases (MAPKs) present two major pathways that are widely used to react to a changing environment. Both CDPK and MAPK pathways are known to be involved in the signalling of abiotic and biotic stresses in animal, yeast and plant cells. Here, we show the essential function of the CDPK CPK3 (At4g23650) for salt stress acclimation in Arabidopsis thaliana, and test crosstalk between CPK3 and the major salt-stress activated MAPKs MPK4 and MPK6 in the salt stress response. CPK3 kinase activity was induced by salt and other stresses after transient overexpression in Arabidopsis protoplasts, but endogenous CPK3 appeared to be constitutively active in roots and leaves in a strictly Ca2+ -dependent manner. cpk3 mutants show a salt-sensitive phenotype comparable with mutants in MAPK pathways. In contrast to animal cells, where crosstalk between Ca2+ and MAPK signalling is well established, CPK3 seems to act independently of those pathways. Salt-induced transcriptional induction of known salt stress-regulated and MAPK-dependent marker genes was not altered, whereas post-translational protein phosphorylation patterns from roots of wild type and cpk3 plants revealed clear differences. A significant portion of CPK3 was found to be associated with the plasma membrane and the vacuole, both depending on its N -terminal myristoylation. An initial proteomic study led to the identification of 28 potential CPK3 targets, predominantly membrane-associated proteins. [source]