Involvement of protein kinase C in the regulation of ornithine decarboxylase mRNA by phorbol esters in rat hepatoma cells

Butler, Andrew C.; Mar, Penny K.; McDonald, Frances F.; Ramsay, Raechelle L.

doi:10.1016/0014-4827(91)90129-i

Cited by 25 publications

(8 citation statements)

References 33 publications

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“…As shown in Figures 1 and 2, the highest PKC levels in Raji cells were induced (2.77 fold expression and 175.21 % activity) by 20 nM of PMA and the expression reached a maximum response at 6 h (2.74 fold expression and 221.86 % activity) treatment. This transient PKC activation pattern is consistent with other studies reporting that higher PMA concentrations and prolonged exposure to PMA could cause PKC depletion (Butler et al, 1991;Chang et al, 2002). Similar findings showed that highest PKC induction in B cells was obtained with 20 nM PMA and 6 hours incubation time (Kwon et al, 2006).…”

Section: Resultssupporting

confidence: 92%

Suppressive Effect of Maslinic Acid on PMA-induced Protein Kinase C in Human B-Lymphoblastoid Cells

Lim

Yew

Yap

et al. 2012

Asian Pacific Journal of Cancer Prevention

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Section: Resultssupporting

confidence: 92%

Suppressive Effect of Maslinic Acid on PMA-induced Protein Kinase C in Human B-Lymphoblastoid Cells

Lim

Yew

Yap

et al. 2012

Asian Pacific Journal of Cancer Prevention

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“…Under similar conditions, we have observed a threefold to sixfold increase in ODCsteady-state mRNA [351. As we failed to observe any significant alteration in ODC mRNA half- life in H35 cells [35], the slight discrepancy may be due to the contributions of potential cis-acting sites in the first intron of ODC [21]. On the other hand, TPA caused little or no increase in ODC promoter activity in Rat2 fibroblasts ( Figure 2) under conditions under which TPA increased ODC mRNA levels by fivefold to sixfold (data not shown).…”

Section: Discussioncontrasting

confidence: 53%

Characterization of novel phorbol ester‐ and serum‐responsive sequences of the rat ornithine decarboxylase gene promoter

Mar

Kumar

Kang

et al. 1995

Molecular Carcinogenesis

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Ornithine decarboxylase (ODC), the key regulatory enzyme in mammalian polyamine biosynthesis, is rapidly induced by mitogens and tumor promoters. We used transient expression assays and DNA-protein binding studies to examine the regulation of ODC promoter activity by phorbol esters and serum growth factors. A fragment of the ODC 5' flanking region (nt-1156 to +13) was sufficient to confer 12-O-tetradecanoylphorbol-13-acetate (TPA)-responsive expression to a luciferase reporter gene when transfected into H35 cells. However, induction by TPA was not observed in Rat2 fibroblasts, although refeeding of serum-starved Rat2 cells with fresh serum-containing medium rapidly induced a fivefold to sixfold increase in ODC promoter activity, maximal about 8 h after refeeding. Deletion analysis demonstrated that several sequences contributed to basal ODC promoter activity but that nt -92 to +13 was sufficient for induction by TPA or by serum. This sequence lacked canonical TPA-responsive elements, and an activator protein-1 (AP-1) consensus oligonucleotide failed to compete effectively for proteins binding to this region. Two of four protein complexes observed by gel-shift analysis of nt -92 to +13 were competitively inhibited by wild-type but not mutant oligonucleotides encompassing a variant cyclic AMP-response element (CRE) (ODC nt -50 to -42); however, a consensus CRE did not compete. Mutagenesis of this site demonstrated that it contributes to basal expression of the ODC promoter but not to TPA or serum responsiveness. Thus, we conclude that the proximal ODC promoter (nt -92 to +13) responds to TPA and serum stimulation in a cell-type-specific manner that is not mediated by canonical AP-1 elements.

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“…This is in line with many other reports that a chronic exposure of electromagnetic radiation affects learning and memory functions [39] by affecting hippocampus. Butler et al [40] reported that cells might be functionally depleted of protein kinase by prolonged exposure to biologically active phorbol esters. They reported that the activity was reduced to 92% as compared to control [40].…”

Section: Discussionmentioning

confidence: 98%

“…Butler et al [40] reported that cells might be functionally depleted of protein kinase by prolonged exposure to biologically active phorbol esters. They reported that the activity was reduced to 92% as compared to control [40]. An earlier study from our laboratory also suggests that there was a decrease in the activity of PKC in rats exposed to 147-MHz amplitude-modulated at 16 Hz as compared to the control group [22].…”

Section: Discussionmentioning

confidence: 98%

Fifty-gigahertz Microwave Exposure Effect of Radiations on Rat Brain

Kesari

Behari

2008

Appl Biochem Biotechnol

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The object of this study is to investigate the effects of 50-GHz microwave radiation on the brain of Wistar rats. Male rats of the Wistar strain were used in the study. Animals of 60-day age were divided into two groups-group 1, sham-exposed, and group 2, experimental (microwave-exposed). The rats were housed in a temperature-controlled room (25 degrees C) with constant humidity (40-50%) and received food and water ad libitum. During exposure, rats were placed in Plexiglas cages with drilled ventilation holes and kept in an anechoic chamber. The animals were exposed for 2 h a day for 45 days continuously at a power level of 0.86 microW/cm(2) with nominal specific absorption rate 8.0 x 10(-4) w/kg. After the exposure period, the rats were killed and homogenized, and protein kinase C (PKC), DNA double-strand break, and antioxidant enzyme activity [superoxides dismutase (SOD), catalase, and glutathione peroxidase (GPx)] were estimated in the whole brain. Result shows that the chronic exposure to these radiations causes DNA double-strand break (head and tail length, intensity and tail migration) and a significant decrease in GPx and SOD activity (p = or<0.05) in brain cells, whereas catalase activity shows significant increase in the exposed group of brain samples as compared with control (p = or<0.001). In addition to these, PKC decreased significantly in whole brain and hippocampus (p < 0.05). All data are expressed as mean +/- standard deviation. We conclude that these radiations can have a significant effect on the whole brain.

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Involvement of protein kinase C in the regulation of ornithine decarboxylase mRNA by phorbol esters in rat hepatoma cells

Cited by 25 publications

References 33 publications

Suppressive Effect of Maslinic Acid on PMA-induced Protein Kinase C in Human B-Lymphoblastoid Cells

Suppressive Effect of Maslinic Acid on PMA-induced Protein Kinase C in Human B-Lymphoblastoid Cells

Characterization of novel phorbol ester‐ and serum‐responsive sequences of the rat ornithine decarboxylase gene promoter

Fifty-gigahertz Microwave Exposure Effect of Radiations on Rat Brain

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