Brain Region Specific Alterations in the Protein and mRNA Levels of Protein Kinase A Subunits in the Post-Mortem Brain of Teenage Suicide Victims

The adipose renin-angiotensin system (RAS) has been assigned to participate in the control of adipose tissue development and in the pathogenesis of obesity-related hypertension. In adipose cells, the biological responses to β-adrenergic stimulation are mediated by an increase in intracellular cAMP. Because cAMP is known to promote adipogenesis and because an association exists between body fat mass, hypertension, and increased sympathetic stimulation, we examined the influence of cAMP on angiotensinogen (ATG) expression and secretion in rat adipose tissue. Exposure of primary cultured differentiated preadipocytes to the cAMP analog 8-bromoadenosine 3′,5′-cyclic monophosphate (8-BrcAMP) or cAMP-stimulating agents (forskolin and IBMX) results in a significant increase in ATG mRNA levels. In adipose tissue fragments, 8-BrcAMP also increases ATG mRNA levels and protein secretion, but not in the presence of the protein kinase A inhibitor H89. The addition of isoproterenol, known to stimulate the synthesis of intracellular cAMP via β-adrenoreceptors, had the same stimulatory effect on ATG expression and secretion. These results indicate that cAMP in vitro upregulates ATG expression and secretion in rat adipose tissue via the protein kinase A-dependent pathway. Further studies are required to determine whether this regulatory pathway is activated in human obesity, where increased sympathetic tone is frequently observed, and to elucidate the importance of adipose ATG to the elevated blood pressure observed in this pathological state.

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Transcript of protein kinase A knock-down modulates feeding behavior and neuropeptide Y gene expression in phenylpropanolamine-treated rats

Physiological Genomics ◽

10.1152/physiolgenomics.00110.2007 ◽

2007 ◽

Vol 31 (2) ◽

pp. 306-314 ◽

Cited By ~ 8

Author(s):

Yih-Shou Hsieh ◽

Shun-Fa Yang ◽

Shu-Chen Chu ◽

Dong-Yih Kuo

Keyword(s):

Gene Expression ◽

Protein Kinase ◽

Neuropeptide Y ◽

Protein Kinase A ◽

Mrna Level ◽

Camp Response Element Binding ◽

Antisense Oligodeoxynucleotide ◽

Mrna Levels ◽

Knock Down ◽

Kinase A

Neuropeptide Y (NPY) is an appetite-controlling neuromodulator that contributes to the appetite-suppressing effect of phenylpropanolamine (PPA). Aims of this study were to investigate whether protein kinase A (PKA) signaling is involved in regulating NPY gene expression and PPA-induced anorexia. Rats were given daily with PPA for 5 days. Changes in daily food intake and hypothalamic NPY, PKA, cAMP response element binding protein (CREB), and pro-opiomelanocortin (POMC) gene expression were measured and compared. To further determine if PKA was involved, intracerebroventricular infusions of antisense oligodeoxynucleotide were performed at 60 min before daily PPA treatment in freely moving rats. Results showed that daily PKA, CREB, and POMC expression were increased following PPA treatment, which showed a closely reverse relationship with alterations of decreased feeding behaviors and NPY mRNA levels. Results also showed that PKA knock-down could block PPA-induced anorexia as well as restore NPY mRNA level, indicating the involvement of PKA signaling in the regulation of NPY gene expression. It is suggested that hypothalamic PKA signaling may participate in the central regulation of PPA-mediated appetite suppression via the modulation of hypothalamic NPY gene expression. The present findings reveal that manipulations at the molecular level of PKA or cAMP may allow the development of therapeutic agents to improve the undesirable properties of PPA or other amphetamine-like anorectic drugs.

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Phosphorylation decreases trypsin activation and apolipoprotein AI binding to glycosylphosphatidylinositol-specific phospholipase D

Biochemistry and Cell Biology ◽

10.1139/o02-004 ◽

2002 ◽

Vol 80 (2) ◽

pp. 253-260 ◽

Cited By ~ 4

Author(s):

Mark A Deeg ◽

Rosario F Bowen

Keyword(s):

Protein Kinase ◽

Human Serum ◽

Protein Kinase A ◽

Phospholipase D ◽

Density Lipoprotein ◽

Fold Increase ◽

Mrna Levels ◽

Apolipoprotein Ai ◽

Kinase A

Glycosylphosphatidylinositol-specific phospholipase D (GPI-PLD) is present in plasma as an apolipoprotein and as a cell-associated lipase. GPI-PLD mRNA levels are regulated, but it is unclear if posttranslational mechanisms also regulate GPI-PLD function. We examined the effect of protein kinase A phosphorylation on human serum GPI-PLD activity, trypsin activation, and apolipoprotein AI binding. Protein kinase A phosphorylation did not activate GPI-PLD activity in vitro, nor did phosphorylated GPI-PLD cleave a GPI-anchored protein from intact porcine erythrocytes. Trypsin cleaves the C-terminal β propeller of purified human serum GPI-PLD to generate three immunodetectable fragments (75, 28, and 18 kDa) in association with a 12-fold increase in enzyme activity. After phosphorylation, the amounts of 28- and 18-kDa fragments were markedly decreased with trypsin treatment, and activity was only increased five-fold. Phosphorylation also inhibits binding of GPI-PLD to apolipoprotein AI. These data are the first demonstrating that phosphorylation may regulate GPI-PLD interaction with other proteins.Key words: apolipoprotein AI, high-density lipoprotein, glycosylphosphatidylinositol, trypsin, phospholipase D.

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Mechanism of interferon action: alpha and gamma interferons differentially affect mRNA levels of the catalytic subunit of protein kinase A and protein Mx in human cells.

Journal of Virology ◽

10.1128/jvi.66.4.2519-2522.1992 ◽

1992 ◽

Vol 66 (4) ◽

pp. 2519-2522 ◽

Cited By ~ 9

Author(s):

D C Thomas ◽

C E Samuel

Keyword(s):

Protein Kinase ◽

Protein Kinase A ◽

Human Cells ◽

Catalytic Subunit ◽

Mrna Levels ◽

Kinase A

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Calcitonin Induces 25-Hydroxyvitamin D31α-Hydroxylase mRNA Expression via Protein Kinase C Pathway in LLC-PK1Cells

Journal of the American Society of Nephrology ◽

10.1681/asn.v10122474 ◽

1999 ◽

Vol 10 (12) ◽

pp. 2474-2479

Author(s):

NORIKO YOSHIDA ◽

TADASHI YOSHIDA ◽

AKIRA NAKAMURA ◽

TOSHIAKI MONKAWA ◽

MATSUHIKO HAYASHI ◽

...

Keyword(s):

Vitamin D ◽

Protein Kinase C ◽

Protein Kinase ◽

Mrna Expression ◽

Protein Kinase A ◽

Mrna Levels ◽

Hydroxyvitamin D ◽

Kinase C ◽

25 Hydroxyvitamin D ◽

Kinase A

Abstract. The biosynthesis of 1α, 25-dihydroxyvitamin D3from 25-hydroxyvitamin D3is catalyzed by 25-hydroxyvitamin D31α-hydroxylase (CYP27B1) in renal proximal tubules. It was recently demonstrated that LLC-PK1cells express CYP27B1 mRNA, which is regulated by intracellular cAMP but not vitamin D3. To clarify the effect of calcitonin on vitamin D3metabolismin vitro, LLC-PK1cells were incubated with hormonal factors, and expression of CYP27B1 mRNA was measured by quantitative reverse transcription-PCR. Calcitonin at 100 nmol/L significantly increased CYP27B1 mRNA expression by 24 h (271 ± 21% of control). Incubation with calcitonin over a range of 1 μmol/L to 1 pmol/L resulted in a concentration-dependent increase in CYP27B1 mRNA levels. It is known that the calcitonin receptor has dual intracellular signaling pathways, via protein kinases A and C. Both 500 μmol/L 8-bromo-cAMP, a protein kinase A activator, and 100 nmol/L phorbol 12-myristate 13-acetate, a protein kinase C activator, increased CYP27B1 mRNA levels at 24 h (207 ± 54 and 246 ± 58% of control, respectively). However, calcitonin-induced CYP27B1 mRNA expression was only inhibited by the protein kinase C inhibitors staurosporine and calphostin C. The protein kinase A inhibitors Rp-cAMPS at 10 and 100 μmol/L and H-89 at 10 μmol/L had no effect on the action of calcitonin, in spite of cAMP-activation by calcitonin. The present data suggest that calcitonin upregulates CYP27B1 mRNA expression via the protein kinase C pathway in LLC-PK1cells.

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Inhibition of Thromboxane A Synthase Activity Enhances Steroidogenesis and Steroidogenic Acute Regulatory Gene Expression in MA-10 Mouse Leydig Cells

Endocrinology ◽

10.1210/en.2007-0470 ◽

2007 ◽

Vol 149 (2) ◽

pp. 851-857 ◽

Cited By ~ 6

Author(s):

XingJia Wang ◽

Xiangling Yin ◽

Randolph B. Schiffer ◽

Steven R. King ◽

Douglas M. Stocco ◽

...

Keyword(s):

Rna Interference ◽

Protein Kinase ◽

Protein Kinase A ◽

Leydig Cells ◽

Steroid Hormone ◽

Mrna Levels ◽

Star Protein ◽

Steroidogenic Acute Regulatory ◽

Star Gene ◽

Kinase A

The cyclooxygenase-2 (COX2)-dependent inhibition of Leydig cell steroidogenesis has been demonstrated. To understand the mechanism for this effect of COX2, the present study examined the role of an enzyme downstream of COX2, namely thromboxane A synthase (TBXAS), in steroidogenesis. Inhibition of TBXAS activity with the inhibitor furegrelate induced a concentration-dependent increase in cAMP-induced steroidogenic acute regulatory (StAR) protein in MA-10 mouse Leydig cells. The increase in StAR protein occurred concomitantly with a significant increase in steroid hormone production. Similar results were obtained in StAR promoter activity assays and RT-PCR analyses of StAR mRNA levels, suggesting that inhibition of TBXAS activity enhanced StAR gene transcription. These observations were corroborated when TBXAS expression was specifically inhibited by RNA interference. Although the RNA interference reduced mRNA levels of TBXAS, it increased StAR mRNA levels, StAR protein, and steroidogenesis. Additional studies indicated that inhibition of TBXAS activity reduced DAX-1 protein, a repressor in StAR gene transcription. In the absence of cAMP, inhibition of TBXAS activity did not induce a significant increase in steroid hormone and StAR protein. However, addition of a low level of cAMP analogs dramatically increased steroidogenesis. Lastly, inhibition of protein kinase A activity essentially abolished the steroidogenic effect of the TBXAS inhibitor. Thus, the results from the present study suggest that a minimal level of protein kinase A activity is required for the steroidogenic effect of the TBXAS inhibitor and that inhibition of TBXAS activity or its expression increase the steroidogenic sensitivity of MA-10 mouse Leydig cells to cAMP stimulation.

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Mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase promoter contains a CREB binding site that regulates cAMP action in Caco-2 cells

Biochemical Journal ◽

10.1042/bj3450201 ◽

2000 ◽

Vol 345 (2) ◽

pp. 201-206 ◽

Cited By ~ 4

Author(s):

Anke EGGERS ◽

Concha CAUDEVILLA ◽

Guillermina ASINS ◽

Fausto G. HEGARDT ◽

Dolors SERRA

Keyword(s):

Protein Kinase ◽

Protein Kinase A ◽

Phosphoenolpyruvate Carboxykinase ◽

Camp Response Element Binding ◽

Dominant Negative ◽

Dominant Negative Mutant ◽

Mrna Levels ◽

Camp Response Element ◽

Response Element ◽

Kinase A

cAMP increases transcription of the mitochondrial (mit.) gene for 3-hydroxy-3-methylglutaryl (HMG)-CoA synthase, which encodes an enzyme that has been proposed as a control site of ketogenesis. The incubation of Caco-2 cells with cAMP increased mit.HMG-CoA synthase mRNA levels 4-fold within 24 h. We have identified an active cAMP-response element (CRE) located 546 bp upstream of the mit.HMG-CoA synthase promoter that is necessary for the induction of expression by dibutyryl cAMP. Co-transfections of constructs, containing the CRE element of the mit.HMG-CoA synthase promoter fused to the gene for chloramphenicol acetyltransferase, with protein kinase A and a dominant-negative mutant of cAMP-response-element-binding protein (CREB) show that the response to cAMP is mediated by the transcription factor CREB. The CRE element confers responsiveness of protein kinase A to a heterologous promoter in transfection assays in Caco-2 cells. Gel-retardation assays revealed that the mit.HMG-CoA synthase CRE binds to recombinant CREB. The shifted band obtained with the putative mit.HMG-CoA synthase CRE sequence and nuclear proteins from Caco-2 cells competed with CRE sequences of other genes such as somatostatin and phosphoenolpyruvate carboxykinase. We conclude that the regulation of the expression of the gene for mit.HMG-CoA synthase in Caco-2 cells by cAMP is mediated by a CRE sequence in the promoter.

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