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Mediated Transcription (mediated + transcription)
Selected AbstractsThe induction of HIF-1 reduces astrocyte activation by amyloid beta peptideEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 7 2009David Schubert Abstract Reduced glucose metabolism and astrocyte activation in selective areas of the brain are pathological features of Alzheimer's disease (AD). The underlying mechanisms of low energy metabolism and a molecular basis for preventing astrocyte activation are not, however, known. Here we show that amyloid beta peptide (A,)-dependent astrocyte activation leads to a long-term decrease in hypoxia-inducible factor (HIF)-1, expression and a reduction in the rate of glycolysis. Glial activation and the glycolytic changes are reversed by the maintenance of HIF-1, levels with conditions that prevent the proteolysis of HIF-1,. A, increases the long-term production of reactive oxygen species (ROS) through the activation of nicotinamide adenine dinucleotide phosphate oxidase and reduces the amount of HIF-1, via the activation of the proteasome. ROS are not required for glial activation, but are required for the reduction in glycolysis. These data suggest a significant role for HIF-1,-mediated transcription in maintaining the metabolic integrity of the AD brain and identify the probable cause of the observed lower energy metabolism in afflicted areas. They may also explain the therapeutic success of metal chelators in animal models of AD. [source] Salt-inducible kinase-1 represses cAMP response element-binding protein activity both in the nucleus and in the cytoplasmFEBS JOURNAL, Issue 21 2004Yoshiko Katoh Salt-inducible kinase-1 (SIK1) is phosphorylated at Ser577 by protein kinase A in adrenocorticotropic hormone-stimulated Y1 cells, and the phospho-SIK1 translocates from the nucleus to the cytoplasm. The phospho-SIK1 is dephosphorylated in the cytoplasm and re-enters the nucleus several hours later. By using green-fluorescent protein-tagged SIK1 fragments, we found that a peptide region (586,612) was responsible for the nuclear localization of SIK1. The region was named the ,RK-rich region' because of its Arg- and Lys-rich nature. SIK1s mutated in the RK-rich region were localized mainly in the cytoplasm. Because SIK1 represses cAMP-response element (CRE)-mediated transcription of steroidogenic genes, the mutants were examined for their effect on transcription. To our surprise, the cytoplasmic mutants strongly repressed the CRE-binding protein (CREB) activity, the extent of repression being similar to that of SIK1(S577A), a mutant localized exclusively in the nucleus. Several chimeras were constructed from SIK1 and from its isoform SIK2, which was localized mainly in the cytoplasm, and they were examined for intracellular localization as well as CREB-repression activity. A SIK1-derived chimera, where the RK-rich region had been replaced with the corresponding region of SIK2, was found in the cytoplasm, its CREB-modulating activity being similar to that of wild-type SIK1. On the other hand, a SIK2-derived chimera with the RK-rich region of SIK1 was localized in both the nucleus and the cytoplasm, and had a CREB-repressing activity similar to that of the wild-type SIK2. Green fluorescent protein-fused transducer of regulated CREB activity 2 (TORC2), a CREB-specific co-activator, was localized in the cytoplasm and nucleus of Y1 cells, and, after treatment with adrenocorticotropic hormone, cytoplasmic TORC2 entered the nucleus, activating CREB. The SIK1 mutants, having a strong CRE-repressing activity, completely inhibited the adrenocorticotropic hormone-induced nuclear entry of green fluorescent protein-fused TORC2. This suggests that SIK1 may regulate the intracellular movement of TORC2, and as a result modulates the CREB-dependent transcription activity. Together, these results indicate that the RK-rich region of SIK1 is important for determining the nuclear localization and attenuating CREB-repressing activity, but the degree of the nuclear localization of SIK1 itself does not necessarily reflect the degree of SIK1-mediated CREB repression. [source] TIP30 is associated with progression and metastasis of prostate cancerINTERNATIONAL JOURNAL OF CANCER, Issue 4 2008Hui Zhang Abstract Tat-interacting protein 30 (TIP30), a transcriptional repressor for ER,-mediated transcription, possesses several characteristics of a tumor suppressor in certain human and mouse cells. It is reported that deletion of TIP30 gene preferentially increases tumorigenesis in the female knockout mice. Here, we analyzed TIP30 gene expression in the databases of several DNA microarray studies of human prostate cancer and show that TIP30 is specifically overexpressed in metastatic prostate cancers. We demonstrate that TIP30 nuclear expression is associated with prostate cancer progression and metastasis by immunohistochemical analysis in primary and metastatic prostate cancers. Consistent with these data, we also show that knockdown of TIP30 expression, through use of a short hairpin RNA-expressing plasmid, suppresses the cellular growth of PC3 and LNCaP prostate cancer cells. Ectopic overexpression of TIP30 stimulates metastatic potential of prostate cancer cells in an in vitro invasion assay, whereas knockdown of TIP30 inhibits the prostate cancer cells invasion. Finally, we demonstrate that ectopic overexpression of TIP30 enhances androgen receptor mediated transcription, whereas knockdown of TIP30 results in a decreased transcription activity. These data provide evidence that TIP30 plays a role in prostate cancer progression and that TIP30 overexpression may promote prostate cancer cell growth and metastasis. © 2008 Wiley-Liss, Inc. [source] Constitutive activation of the mitogen-activated protein kinase pathway impairs vitamin D signaling in human prostate epithelial cellsJOURNAL OF CELLULAR PHYSIOLOGY, Issue 2 2010Zhentao Zhang We studied the effect of prolonged activation of mitogen-activated protein kinase (MAPK) signaling on 1,25 dihydroxyvitamin D (1,25(OH)2D3) action in the immortalized human prostate epithelial cell line RWPE1 and its Ki-Ras transformed clone RWPE2. 1,25(OH)2D3 -treatment caused growth arrest and induced gene expression in both cell lines but the response was blunted in RWPE2 cells. Vitamin D receptor (VDR) levels were lower in RWPE2 cells but VDR over-expression did not increase vitamin-D-mediated gene transcription in either cell line. In contrast, MAPK inhibition restored normal vitamin D transcriptional responses in RWPE2 cells and MAPK activation with constitutively active MEK1R4F reduced vitamin-D-regulated transcription in RWPE1 cells. 1,25(OH)2D3 -mediated transcription depends upon the VDR and its heterodimeric partner the retinoid X receptor (RXR) so we studied whether changes in the VDR,RXR transcription complex occur in response to MAPK activation. Mutation of putative phosphorylation sites in the activation function 1 (AF-1) domain (S32A, T82A) of RXR, restored 1,25(OH)2D3 -mediated transactivation in RWPE2 cells. Mammalian two-hybrid and co-immunoprecipitation assays revealed a vitamin-D-independent interaction between steroid receptor co-activator-1 (SRC-1) and RXR, that was reduced by MAPK activation and was restored in RWPE2 cells by mutating S32 and T82 in the RXR, AF-1 domain. Our data show that a common contributor to cancer development, prolonged activation of MAPK signaling, impairs 1,25(OH)2D3 -mediated transcription in prostate epithelial cells. This is due in part to the phosphorylation of critical amino acids in the RXR, AF-1 domain and impaired co-activator recruitment. J. Cell. Physiol. 224: 433,442, 2010. © 2010 Wiley-Liss, Inc. [source] In vitro transcription of PrfA-dependent and -independent genes of Listeria monocytogenesMOLECULAR MICROBIOLOGY, Issue 1 2001M. Lalic-Mülthaler In vitro transcription starting from the promoters of the Listeria monocytogenes genes hly, plcA, actA, mpl, prfA and iap has been studied. Whereas transcription from Phly, PplcA and PactA is strictly PrfA-dependent, that from Piap, PprfA1/2 and, unexpectedly, also from Pmpl is independent. Initiation of in vitro transcription at all tested promoters except PprfA requires high concentrations of ATP but not GTP. The nucleotides required in higher concentrations for efficient in vitro transcription are always included in the first three nucleotides of the corresponding transcript. RNA polymerase prepared from L. monocytogenes cultured either in rich culture medium (RNAPBHI), exposed to heat shock conditions (RNAP48) or conditioned in minimal essential medium (RNAPMEM) shows significant differences in the transcription efficiencies when transcription is initiated at these promoters. Transcription starting from the PrfA-dependent promoters PactA and Phly is enhanced with RNAP48 and RNAPMEM (in relation to Piap,mediated transcription), while transcription from the other promoters is reduced when compared with RNAPBHI. These data suggest that in vivo transcription of the genes actA and hly may not function optimally with RNA polymerase loaded with the vegetative sigma factor 43, but may require a modified RNA polymerase, possibly loaded with an alternative sigma factor. [source] | ||||||||||