PROTEIN KINASE C INHIBITS FORMATION OF VA GENE TRANSCRIPTION INITIATION COMPLEX

Engagement of the T cell receptor for antigen activates phospholipase C resulting in an increase in intracellular free calcium concentration ([Ca2+]i) and activation of protein kinase C (PKC). Increased [Ca2+]i activates Ca2+/calmodulin-dependent kinases including the multifunctional Ca2+/calmodulin-dependent protein kinase II (CaM-K II), as well as calcineurin, a type 2B protein phosphatase. Recent studies have identified calcineurin as a key enzyme for interleukin (IL)-2 and IL-4 promoter activation. However, the role of CaM-K II remains unknown. We have used mutants of these kinases and phosphatases (gamma B*CaM-K and delta CaM-AI, respectively) to explore their relative role in cytokine gene transcription and their interactions with PKC-dependent signaling systems. gamma B*CaM-K and delta CaM-AI, known to exhibit constitutive Ca(2+)-independent activity, were cotransfected (alone or in combination) in Jurkat T cells with a plasmid containing the intact IL-2 promoter driving the expression of the chloramphenicol acetyltransferase reporter gene. Cotransfection of gamma B*CaM-K with the IL-2 promoter construct downregulated its transcription in response to stimulation with ionomycin and phorbol myristate acetate (PMA). The inhibitory effect of CaM-K II on IL-2 promoter was associated with decreased transcription of its AP-1 and NF-AT transactivating pathways. Under the same conditions, delta CaM-AI superinduced IL-2 promoter activity (approximately twofold increase). When both mutants were used in combination, gamma B*CaM-K inhibited the induction of the IL-2 promoter by delta CaM-AI. Similar results were obtained when a construct containing the IL-4 promoter also was used. gamma B*CaM-K also downregulated the activation of AP-1 in response to transfection with a constitutively active mutant of PKC or stimulation with PMA. These results suggest that CaM-K II may exert negative influences on cytokine gene transcription in human T cells, and provide preliminary evidence for negative cross-talk with the calcineurin- and PKC-dependent signaling systems.

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Transcriptional Inhibition of Oxytocin Receptor Expression in Human Myometrial Cells by Melatonin Involves Protein Kinase C Signaling

The Journal of Clinical Endocrinology & Metabolism ◽

10.1210/jc.2007-1128 ◽

2007 ◽

Vol 92 (10) ◽

pp. 4015-4019 ◽

Cited By ~ 17

Author(s):

James Sharkey ◽

James Olcese

Keyword(s):

Protein Kinase C ◽

Protein Kinase ◽

Phospholipase C ◽

Gene Transcription ◽

Late Pregnancy ◽

Oxytocin Receptor ◽

Receptor Expression ◽

Human Myometrium ◽

Myometrial Cells ◽

Kinase C

Abstract Context: Our laboratory recently characterized the expression of the melatonin receptors in the human myometrium and showed that the expression of these receptors is suppressed during late pregnancy. Objective: In an effort to understand better the significance of melatonin in the human myometrium, we explored the mechanisms through which this hormone influences the expression of the oxytocin receptor in vitro. Design: The stable melatonin analog iodomelatonin was presented to cultured telomerase-immortalized myometrial cells of the human telomerase reverse transcriptase line under physiological doses and durations. Pharmacological inhibitors of melatonin binding, gene transcription, phospholipase C, and protein kinase C signaling were used to define the mechanism of melatonin action. Results: Our results reveal that melatonin significantly inhibits oxytocin receptor mRNA expression primarily via the melatonin 2 receptor. The melatonin-dependent decrease in oxytocin receptor transcripts involves suppression of gene transcription rather than enhanced rates of transcript degradation. Melatonin effects were abolished by pretreating the cells with the phospholipase C inhibitor U73122 or the protein kinase C inhibitor C1. Conclusions: Melatonin, like oxytocin, can negatively regulate oxytocin receptor transcription in human myometrial cells via modulation of protein kinase C signaling. This is consistent with the hypothesis that the reduced melatonin receptor expression during late pregnancy, which occurs at a time when oxytocin receptors are up-regulated, may be physiologically important for the subsequent timing of labor.

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Angiotensin II inhibits renin gene transcription via the protein kinase C pathway

Pflügers Archiv - European Journal of Physiology ◽

10.1007/s00424-002-0835-8 ◽

2002 ◽

Vol 444 (4) ◽

pp. 499-505 ◽

Cited By ~ 27

Author(s):

Markus Müller ◽

Bernhard Krämer ◽

Armin Kurtz ◽

Vladimir Todorov

Keyword(s):

Protein Kinase C ◽

Angiotensin Ii ◽

Protein Kinase ◽

Gene Transcription ◽

Kinase C ◽

Renin Gene

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Protein kinase C-ζ mediates TNF-α-induced ICAM-1 gene transcription in endothelial cells

AJP Cell Physiology ◽

10.1152/ajpcell.2000.279.4.c906 ◽

2000 ◽

Vol 279 (4) ◽

pp. C906-C914 ◽

Cited By ~ 96

Author(s):

Arshad Rahman ◽

Khandaker N. Anwar ◽

Asrar B. Malik

Keyword(s):

Endothelial Cells ◽

Protein Kinase C ◽

Protein Kinase ◽

Gene Transcription ◽

Critical Role ◽

Dominant Negative Mutant ◽

Kinase C ◽

Tnf Α ◽

Pkc Isozymes ◽

Pkc Ζ

We addressed the role of protein kinase C (PKC) isozymes in mediating tumor necrosis factor-α (TNF-α)-induced oxidant generation in endothelial cells, a requirement for nuclear factor-κB (NF-κB) activation and intercellular adhesion molecule-1 (ICAM-1) gene transcription. Depletion of the conventional (c) and novel (n) PKC isozymes following 24 h exposure of human pulmonary artery endothelial (HPAE) cells with the phorbol ester, phorbol 12-myristate 13-acetate (500 nM), failed to prevent TNF-α-induced oxidant generation. In contrast, inhibition of PKC-ζ synthesis by the antisense oligonucleotide prevented the oxidant generation following the TNF-α stimulation. We observed that PKC-ζ also induced the TNF-α-induced NF-κB binding to the ICAM-1 promoter and the resultant ICAM-1 gene transcription. We showed that expression of the dominant negative mutant of PKC-ζ prevented the TNF-α-induced ICAM-1 promoter activity, whereas overexpression of the wild-type PKC-ζ augmented the response. These data imply a critical role for the PKC-ζ isozyme in regulating TNF-α-induced oxidant generation and in signaling the activation of NF-κB and ICAM-1 transcription in endothelial cells.

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Protein Kinase C δ Induces Transcription of the TP53 Tumor Suppressor Gene by Controlling Death-Promoting Factor Btf in the Apoptotic Response to DNA Damage

Molecular and Cellular Biology ◽

10.1128/mcb.01126-07 ◽

2007 ◽

Vol 27 (24) ◽

pp. 8480-8491 ◽

Cited By ~ 62

Author(s):

Hanshao Liu ◽

Zheng-Guang Lu ◽

Yoshio Miki ◽

Kiyotsugu Yoshida

Keyword(s):

Dna Damage ◽

Protein Kinase C ◽

Protein Kinase ◽

Tumor Suppressor ◽

Gene Transcription ◽

Core Promoter ◽

Genotoxic Stress ◽

Tp53 Gene ◽

Transcriptional Level ◽

Kinase C

ABSTRACT Expression of the TP53 tumor suppressor is tightly controlled for its ability to function as a critical regulator of cell growth, proliferation, and death in response to DNA damage. However, little is known about the mechanisms and contributions of the transcriptional regulation of TP53. Here we report that protein kinase C δ (PKCδ), a ubiquitously expressed member of the novel subfamily of PKC isoforms, transactivates TP53 expression at the transcriptional level. Reporter assays demonstrated that PKCδ induces the promoter activity of TP53 through the TP53 core promoter element (CPE-TP53) and that such induction is enhanced in response to DNA damage. The results also demonstrate that, upon exposure to genotoxic stress, PKCδ activates and interacts with the death-promoting transcription factor Btf to co-occupy CPE-TP53. Inhibition of PKCδ activity decreases the affinity of Btf for CPE-TP53, thereby reducing TP53 expression at both the mRNA and the protein levels. In concert with these results, we show that disruption of Btf-mediated TP53 gene transcription by RNA interference leads to suppression of TP53-mediated apoptosis following genotoxic stress. These findings provide evidence that activation of TP53 gene transcription by PKCδ triggers TP53-dependent apoptosis in response to DNA damage.

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