Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:4.1.1.6 (CAD)
 4,420 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Hypoxia-inducible factor 1 alpha (HIF1alpha) and its related factor, HLF, activate expression of a group of genes such as erythropoietin in response to low oxygen. Transfection analysis using fusion genes of GAL4DBD with various fragments of the two factors delineated two transcription activation domains which are inducible in response to hypoxia and are localized in the C-terminal half. Their sequences are conserved between HLF and HIF1alpha. One is designated NAD (N-terminal activation domain), while the other is CAD (C-terminal activation domain). Immunoblot analysis revealed that NADs, which were rarely detectable at normoxia, became stabilized and accumulated at hypoxia, whereas CADs were constitutively expressed. In the mammalian two-hybrid system, CAD and NAD baits enhanced the luciferase expression from a reporter gene by co-transfection with CREB-binding protein (CBP) prey, whereas CAD, but not NAD, enhanced beta-galactosidase expression in yeast by CBP co-expression, suggesting that NAD and CAD interact with CBP/p300 by a different mechanism. Co-transfection experiments revealed that expression of Ref-1 and thioredoxin further enhanced the luciferase activity expressed by CAD, but not by NAD. Amino acid replacement in the sequences of CADs revealed a specific cysteine to be essential for their hypoxia-inducible interaction with CBP. Nuclear translocation of thioredoxin from cytoplasm was observed upon reducing O2 concentrations.
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PMID:Molecular mechanisms of transcription activation by HLF and HIF1alpha in response to hypoxia: their stabilization and redox signal-induced interaction with CBP/p300. 1020 54

The cAMP-response element-binding protein (CREB)-binding protein and p300 are two highly conserved transcriptional coactivators and histone acetyltransferases that integrate signals from diverse signal transduction pathways in the nucleus and also link chromatin remodeling with transcription. In this report, we have examined the role of p300 in the control of the G(1) phase of the cell cycle in nontransformed immortalized human breast epithelial cells (MCF10A) and fibroblasts (MSU) by using adenovirus vectors expressing p300-specific antisense sequences. Quiescent MCF10A and MSU cells expressing p300-specific antisense sequences synthesized p300 at much reduced levels and exited G(1) phase without serum stimulation. These cells also showed an increase in cyclin A and cyclin A- and E-associated kinase activities characteristic of S phase induction. Further analysis of the p300-depleted quiescent MCF10A cells revealed a 5-fold induction of c-MYC and a 2-fold induction of c-JUN. A direct target of c-MYC, CAD, which is required for DNA synthesis, was also found to be up-regulated, indicating that up-regulation of c-MYC functionally contributed to DNA synthesis. Furthermore, S phase induction in p300-depleted cells was reversed when antisense c-MYC was expressed in these cells, indicating that up-regulation of c-MYC may directly contribute to S phase induction. Adenovirus E1A also induced DNA synthesis and increased the levels of c-MYC and c-JUN in serum-starved MCF10A cells in a p300-dependent manner. Our results suggest an important role of p300 in cell cycle regulation at G(1) and raise the possibility that p300 may negatively regulate early response genes, including c-MYC and c-JUN, thereby preventing DNA synthesis in quiescent cells.
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PMID:Antisense-mediated depletion of p300 in human cells leads to premature G1 exit and up-regulation of c-MYC. 1129 95

Hypoxia-inducible factors (HIF) are a family of heterodimeric transcriptional regulators that play pivotal roles in the regulation of cellular utilization of oxygen and glucose and are essential transcriptional regulators of angiogenesis in solid tumor and ischemic disorders. The transactivation activity of HIF complexes requires the recruitment of p300/CREB-binding protein (CBP) by HIF-1 alpha and HIF-2 alpha that undergo oxygen-dependent degradation. HIF activation in tumors is caused by several factors including mitogen-activated protein kinase (MAPK) signaling. Here we investigated the molecular basis for HIF activation by MAPK. We show that MAPK is required for the transactivation activity of HIF-1 alpha. Furthermore, inhibition of MAPK disrupts the HIF-p300 interaction and suppresses the transactivation activity of p300. Overexpression of MEK1, an upstream MAPK activator, stimulates the transactivation of both p300 and HIF-1 alpha. Interestingly, the C-terminal transactivation domain of HIF-1 alpha is not a direct substrate of MAPK, and HIF-1 alpha phosphorylation is not required for HIF-CAD/p300 interaction. Taken together, our data suggest that MAPK signaling facilitates HIF activation through p300/CBP.
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PMID:MAPK signaling up-regulates the activity of hypoxia-inducible factors by its effects on p300. 1258 75

The transcription factor Hypoxia-Inducible Factor (HIF) complexes with the coactivator p300, activating the hypoxia response pathway and allowing tumors to grow. The CH1 and CAD domains of each respective protein form the interface between p300 and HIF. Small molecule compounds are in development that target and inhibit HIF/p300 complex formation, with the goal of reducing tumor growth. High resolution NMR spectroscopy is necessary to study ligand interaction with p300-CH1, and purifying high quantities of properly folded p300-CH1 is needed for pursuing structural and biophysical studies. p300-CH1 has 3 zinc fingers and 9 cysteine residues, posing challenges associated with reagent compatibility and protein oxidation. A protocol has been developed to overcome such issues by incorporating zinc during expression and streamlining the purification time, resulting in a high yield of optimally folded protein (120 mg per 4 L expression media) that is suitable for structural NMR studies. The structural integrity of the final recombinant p300-CH1 has been verified to be optimal using onedimensional 1H NMR spectroscopy and circular dichroism. This protocol is applicable for the purification of other zinc finger containing proteins.
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PMID:Purifying Properly Folded Cysteine-rich, Zinc Finger Containing Recombinant Proteins for Structural Drug Targeting Studies: the CH1 Domain of p300 as a Case Example. 2896 47

Staphylococcal nuclease domain-containing protein 1 (SND1) has been reported as an oncoprotein in a variety of cancers involving multiple processes, including proliferation, angiogenesis, and metastasis. However, the mechanisms underlying metastasis remain largely unknown. Herein, by using the ovarian cancer cell line SKOV3, which has high metastasis ability, we showed that loss-of-function of SND1 dramatically suppressed the invasion and migration of SKOV3 cells. We then performed gene expression profiles and further verified (by use of quantitative PCR and Western blot analysis) that loss-of-function of SND1 resulted in up-regulation of epithelial markers, such as epithelial cadherin and claudin 1, and down-regulation of mesenchymal markers, including neural cadherin and vimentin. Moreover, we illustrated that SLUG, a key transcription factor implicated in epithelial-mesenchymal transition and metastasis, acts as an essential effector of the SND1-promoted epithelial-mesenchymal transition process via regulating N-CAD and VIM expression (or E-CAD and CLDN1). The underlying molecular mechanisms illustrated that SND1 regulates the gene transcriptional activation of SLUG by increasing chromatin accessibility through the recruitment of the acetyltransferases GCN5 and CBP/p300 to the SLUG promoter proximal region. Overall, SND1 was identified as a novel upstream regulator of SLUG, which plays important roles in regulating the E-CAD/N-CAD expression switch.-Xin, L., Zhao, R., Lei, J., Song, J., Yu, L., Gao, R., Ha, C., Ren, Y., Liu, X., Liu, Y., Yao, Z., Yang, J. SND1 acts upstream of SLUG to regulate the epithelial-mesenchymal transition (EMT) in SKOV3 cells.
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PMID:SND1 acts upstream of SLUG to regulate the epithelial-mesenchymal transition (EMT) in SKOV3 cells. 3050 25