Stimulation of c-Rel transcriptional activity by PKA catalytic subunit ?

Deregulation of intracellular signal transduction pathways is a hallmark of cancer cells, clearly differentiating them from healthy cells. Differential intracellular distribution of the cAMP-dependent protein kinases (PKA) was previously detected in cell cultures and in vivo in glioblastoma and medulloblastoma. Our goal is to extend this observation to meningioma, to explore possible differences among tumors of different origins and prospective outcomes. The distribution of regulatory and catalytic subunits of PKA has been examined in tissue specimens obtained during surgery from meningioma patients. PKA RI subunit appeared more evenly distributed throughout the cytoplasm, but it was clearly detectable only in some tumors. RII was present in discrete spots, presumably at high local concentration; these aggregates could also be visualized under equilibrium binding conditions with fluorescent 8-substituted cAMP analogues, at variance with normal brain tissue and other brain tumors. The PKA catalytic subunit showed exactly overlapping pattern to RII and in fixed sections could be visualized by fluorescent cAMP analogues. Gene expression analysis showed that the PKA catalytic subunit revealed a significant correlation pattern with genes involved in meningioma. Hence, meningioma patients show a distinctive distribution pattern of PKA regulatory and catalytic subunits, different from glioblastoma, medulloblastoma, and healthy brain tissue. These observations raise the possibility of exploiting the PKA intracellular pathway as a diagnostic tool and possible therapeutic interventions.

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Activity, expression and function of a second Drosophila protein kinase A catalytic subunit gene.

Genetics ◽

10.1093/genetics/141.4.1507 ◽

1995 ◽

Vol 141 (4) ◽

pp. 1507-1520 ◽

Cited By ~ 5

Author(s):

A Meléndez ◽

W Li ◽

D Kalderon

Keyword(s):

Protein Kinase ◽

Protein Kinase A ◽

Essential Gene ◽

Sequence Similarity ◽

Catalytic Subunit ◽

Subunit Gene ◽

Drosophila Protein ◽

Pka Catalytic Subunit ◽

Kinase A

Abstract The DC2 gene was isolated previously on the basis of sequence similarity to DC0, the major Drosophila protein kinase A (PKA) catalytic subunit gene. We show here that the 67-kD Drosophila DC2 protein behaves as a PKA catalytic subunit in vitro. DC2 is transcribed in mesodermal anlagen of early embryos. This expression depends on dorsal but on neither twist nor snail activity. DC2 transcriptional fusions mimic this embryonic expression and are also expressed in subsets of cells in the optic lamina, wing disc and leg discs of third instar larvae. A saturation screen of a small deficiency interval containing DC2 for recessive lethal mutations yielded no DC2 alleles. We therefore isolated new deficiencies to generate deficiency trans-heterozygotes that lacked DC2 activity. These animals were viable and fertile. The absence of DC2 did not affect the viability or phenotype of imaginal disc cells lacking DC0 activity or embryonic hatching of animals with reduced DC0 activity. Furthermore, transgenes expressing DC2 from a DC0 promoter did not efficiently rescue a variety of DC0 mutant phenotypes. These observations indicate that DC2 is not an essential gene and is unlikely to be functionally redundant with DC0, which has multiple unique functions during development.

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Phosphorylation by Cyclin C/Cyclin-Dependent Kinase 2 following Mitogenic Stimulation of Murine Fibroblasts Inhibits Transcriptional Activity of LSF during G1 Progression

Molecular and Cellular Biology ◽

10.1128/mcb.00687-08 ◽

2009 ◽

Vol 29 (9) ◽

pp. 2335-2345 ◽

Cited By ~ 12

Author(s):

Utsav H. Saxena ◽

Christina M. H. Powell ◽

Jill K. Fecko ◽

Roxanne Cacioppo ◽

Hubert S. Chou ◽

...

Keyword(s):

Transcriptional Activity ◽

Target Genes ◽

Cyclin Dependent Kinase ◽

Mitogenic Stimulation ◽

Mouse Fibroblasts ◽

Cyclin C ◽

Murine Fibroblasts ◽

Interfering Rna ◽

Stimulation Of

ABSTRACT Transcription factor LSF is required for progression from quiescence through the cell cycle, regulating thymidylate synthase (Tyms) expression at the G1/S boundary. Given the constant level of LSF protein from G0 through S, we investigated whether LSF is regulated by phosphorylation in G1. In vitro, LSF is phosphorylated by cyclin E/cyclin-dependent kinase 2 (CDK2), cyclin C/CDK2, and cyclin C/CDK3, predominantly on S309. Phosphorylation of LSF on S309 is maximal 1 to 2 h after mitogenic stimulation of quiescent mouse fibroblasts. This phosphorylation is mediated by cyclin C-dependent kinases, as shown by coimmunoprecipitation of LSF and cyclin C in early G1 and by abrogation of LSF S309 phosphorylation upon suppression of cyclin C with short interfering RNA. Although mouse fibroblasts lack functional CDK3 (the partner of cyclin C in early G1 in human cells), CDK2 compensates for this absence. By transient transfection assays, phosphorylation at S309, mediated by cyclin C overexpression, inhibits LSF transactivation. Moreover, overexpression of cyclin C and CDK3 inhibits induction of endogenous Tyms expression at the G1/S transition. These results identify LSF as only the second known target (in addition to pRb) of cyclin C/CDK activity during progression from quiescence to early G1. Unexpectedly, this phosphorylation prevents induction of LSF target genes until late G1.

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Serum stimulation of the c-fos enhancer induces reversible changes in c-fos chromatin structure

Molecular and Cellular Biology ◽

10.1128/mcb.10.3.1126-1133.1990 ◽

1990 ◽

Vol 10 (3) ◽

pp. 1126-1133

Author(s):

J L Feng ◽

B Villeponteau

Keyword(s):

Growth Factors ◽

Dna Sequences ◽

Chromatin Structure ◽

Transcriptional Activity ◽

Dnase I ◽

Enhancer Activity ◽

Serum Stimulation ◽

Fos Protein ◽

Dnase I Sensitivity ◽

Stimulation Of

Transcription of the proto-oncogene c-fos is known to be activated by growth factors in serum and subsequently repressed by the Fos protein. We show that generalized DNase I sensitivity of c-fos chromatin correlates closely with enhancer activity during induction, repression, and superinduction of the c-fos gene. Within 90 s of serum stimulation, proximal DNA sequences on both sides of the enhancer exhibit increased DNase I sensitivity. Within 5 min, elevated DNase I sensitivity spreads to chromatin at the distal 3' end of the c-fos gene. These results suggest that an open state of chromatin is propagated in both directions from the enhancer. The induced alterations in chromatin structure precede the increased transcriptional activity of the c-fos gene, suggesting that these changes in chromatin structure potentiate transcription.

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Positive and Negative Regulation of Phosphoinositide 3-Kinase-Dependent Signaling Pathways by Three Different Gene Products of the p85α Regulatory Subunit

Molecular and Cellular Biology ◽

10.1128/mcb.20.21.8035-8046.2000 ◽

2000 ◽

Vol 20 (21) ◽

pp. 8035-8046 ◽

Cited By ~ 109

Author(s):

Kohjiro Ueki ◽

Petra Algenstaedt ◽

Franck Mauvais-Jarvis ◽

C. Ronald Kahn

Keyword(s):

Glucose Transport ◽

Kinase Activity ◽

Glycogen Synthesis ◽

Catalytic Subunit ◽

Regulatory Subunit ◽

Regulatory Subunits ◽

Irs Proteins ◽

Terminal Structure ◽

Stimulation Of ◽

In Cells

ABSTRACT Phosphoinositide (PI) 3-kinase is a key mediator of insulin-dependent metabolic actions, including stimulation of glucose transport and glycogen synthesis. The gene for the p85α regulatory subunit yields three splicing variants, p85α, AS53/p55α, and p50α. All three have (i) a C-terminal structure consisting of two Src homology 2 domains flanking the p110 catalytic subunit-binding domain and (ii) a unique N-terminal region of 304, 34, and 6 amino acids, respectively. To determine if these regulatory subunits differ in their effects on enzyme activity and signal transduction from insulin receptor substrate (IRS) proteins under physiological conditions, we expressed each regulatory subunit in fully differentiated L6 myotubes using adenovirus-mediated gene transfer with or without coexpression of the p110α catalytic subunit. PI 3-kinase activity associated with p50α was greater than that associated with p85α or AS53. Increasing the level of p85α or AS53, but not p50α, inhibited both phosphotyrosine-associated and p110-associated PI 3-kinase activities. Expression of a p85α mutant lacking the p110-binding site (Δp85) also inhibited phosphotyrosine-associated PI 3-kinase activity but not p110-associated activity. Insulin stimulation of two kinases downstream from PI-3 kinase, Akt and p70 S6 kinase (p70S6K), was decreased in cells expressing p85α or AS53 but not in cells expressing p50α. Similar inhibition of PI 3-kinase, Akt, and p70S6K was observed, even when p110α was coexpressed with p85α or AS53. Expression of p110α alone dramatically increased glucose transport but decreased glycogen synthase activity. This effect was reduced when p110α was coexpressed with any of the three regulatory subunits. Thus, the three different isoforms of regulatory subunit can relay the signal from IRS proteins to the p110 catalytic subunit with different efficiencies. They also negatively modulate the PI 3-kinase catalytic activity but to different extents, dependent on the unique N-terminal structure of each isoform. These data also suggest the existence of a mechanism by which regulatory subunits modulate the PI 3-kinase-mediated signals, independent of the kinase activity, possibly through subcellular localization of the catalytic subunit or interaction with additional signaling molecules.

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Rapid Effects of Retinoic Acid on CREB and ERK Phosphorylation in Neuronal Cells

Molecular Biology of the Cell ◽

10.1091/mbc.e04-05-0439 ◽

2004 ◽

Vol 15 (12) ◽

pp. 5583-5592 ◽

Cited By ~ 127

Author(s):

Estela Cañón ◽

Jose Miguel Cosgaya ◽

Sona Scsucova ◽

Ana Aranda

Keyword(s):

Retinoic Acid ◽

Transcriptional Activity ◽

Target Genes ◽

Primary Cultures ◽

Neuronal Cells ◽

Neuronal Cell ◽

Direct Stimulation ◽

Creb Phosphorylation ◽

Response Elements ◽

Stimulation Of

Retinoic acid (RA) is a potent regulator of neuronal cell differentiation. RA normally activates gene expression by binding to nuclear receptors that interact with response elements (RAREs) in regulatory regions of target genes. We show here that in PC12 cell subclones in which the retinoid causes neurite extension, RA induces a rapid and sustained phosphorylation of CREB (cyclic AMP response element binding protein), compatible with a nongenomic effect. RA also causes a rapid increase of CREB phosphorylation in primary cultures of cerebrocortical cells and of dorsal root ganglia neurons from rat embryos. RA-mediated phosphorylation of CREB leads to a direct stimulation of CREB-dependent transcriptional activity and to activation of the expression of genes such as c-fos, which do not contain RAREs but contain cAMP response elements (CREs) in their promoters. CREB is a major target of extracellular signal regulated kinase ERK1/2 signaling in neuronal cells, and we demonstrate here that RA induces an early stimulation of ERK1/2, which is required both for CREB phosphorylation and transcriptional activity. These results demonstrate that RA, by a nongenomic mechanism, stimulates signaling pathways that lead to phosphorylation of transcription factors, which in turn activate the transcription of genes involved in neuronal differentiation.

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