Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P05412 (c-Jun)
 11,453 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The alpha chain of the nascent polypeptide-associated complex (alpha-NAC) coactivator was shown to potentiate the activity of the homodimeric c-Jun activator, while transcription mediated by the c-Fos/c-Jun heterodimer was unaffected. The use of deletion mutants in pull-down assays revealed that alpha-NAC interacted with amino acids 1 to 89 of the c-Jun protein and that the coactivator could interact with both the unphosphorylated and the serine 73-phosphorylated form of c-Jun. N-terminal-deleted c-Jun protein failed to interact with alpha-NAC in mammalian two-hybrid assays, while mutant c-Jun proteins lacking the leucine zipper or the basic domain retained interaction with alpha-NAC in vivo. Kinetics studies with purified c-Jun homodimer and recombinant alpha-NAC proteins allowed determination of the mechanism of coactivation by alpha-NAC: the coactivator stabilized the AP-1 complex formed by the c-Jun homodimer on its DNA recognition sequence through an eightfold reduction in the dissociation constant (kd) of the complex. This effect of alpha-NAC was specific, because alpha-NAC could not stabilize the interactions of JunB or Sp1 with their cognate binding sites. Interestingly, the expression of alpha-NAC was first detected at 14.5 to 15 days postconception, concomitantly with the onset of ossification during embryogenesis. The alpha-NAC protein was specifically expressed in differentiated osteoblasts at the centers of ossification. Thus, the alpha-NAC gene product exhibits the properties of a developmentally regulated, bone-specific transcriptional coactivator.
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PMID:Bone-specific expression of the alpha chain of the nascent polypeptide-associated complex, a coactivator potentiating c-Jun-mediated transcription. 948 46

Nascent polypeptide-associated complex (NAC) protein, a heterodimeric complex of alpha- and beta-subunits, prevents mistargeting of nascent polypeptide chains to the endoplasmic reticulum membranes. alpha-NAC has sequence similarities with transcription-regulating proteins and has been reported to function as a transcriptional coactivator potentiating c-Jun-mediated transcription. Performing gene hunting using differential display-polymerase chain reaction, a downregulated sequence in the frontal cortex of patients with Alzheimer's disease (AD) and Down syndrome (DS) with AD-like neuropathology was identified as a-NAC with 100% homology. The significant decrease in alpha-NAC mRNA was shown by semiquantitative reverse transcription-polymerase chain reaction, and in parallel, the significant decrease of alpha-NAC protein, which was even more pronounced when related to either actin or neuron-specific enolase levels, was also observed in both disorders. Linear regression analysis revealed a strong, significant correlation between alpha-NAC protein and mRNA expression. In fetal DS brain, however, mRNA levels of alpha-NAC were comparable between DS and controls, suggesting that the decrease in alpha-NAC might be involved in the pathology of neurodegenerative diseases. The decrease in alpha-NAC as a transcriptional coactivator could contribute to the characteristic decline of the c-Jun-mediated transcriptional machinery and could function as the complementary mechanism in c-Jun-mediated apoptosis. Decreased alpha-NAC may result in the mistargeting, mistranslation, and proteolysis of proteins by affecting overall NAC function.
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PMID:Human brain nascent polypeptide-associated complex alpha subunit is decreased in patients with Alzheimer' s disease and Down syndrome. 1210 94

Overexpression of the integrin-linked kinase (ILK) was shown to increase c-Jun-dependent transcription. We now show that this effect of ILK involves the c-Jun transcriptional coactivator, nascent polypeptide-associated complex and coactivator alpha (alpha-NAC). ILK phosphorylated alpha-NAC on residue Ser-43 upon adhesion of cells to fibronectin. Co-expression of constitutively active ILK with alpha-NAC led to the nuclear accumulation of the coactivator. Conversely, alpha-NAC remained in the cytoplasm of cells transfected with a dominant-negative ILK mutant, and a mutated alpha-NAC at phosphoacceptor position Ser-43 (S43A) also localized outside of the nucleus. The S43A alpha-NAC mutant could not potentiate the effect of ILK on c-Jun-dependent transcription. We conclude that ILK-dependent phosphorylation of alpha-NAC induced the nuclear accumulation of the coactivator and that phosphorylation of alpha-NAC by ILK is required for the potentiation of c-Jun-mediated responses by the kinase. The results represent one of the rare examples of a transcriptional coactivator shuttling between the cytosol and the nucleus.
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PMID:Integrin-linked kinase regulates the nuclear entry of the c-Jun coactivator alpha-NAC and its coactivation potency. 1529 25