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The tumor promoter pristane activates transcription by a cAMP dependent mechanism (1992)

Lee, S. -H. ; Ackland-Berglund, C. E. ; Jones, C. J.

Springer

Molecular and cellular biochemistry 110 (1992), S. 75-81

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ISSN: 1573-4919

Keywords: pristane ; tumor promoter ; cAMP response element

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Chemistry and Pharmacology , Medicine

Notes: Abstract Pristane is a naturally occurring isoprenoid which is believed to be derived from the phytyl moiety of chlorophyll. Thus it is not surprising that pristane is present in many common fruits or vegetables and furthermore can be detected in tissues of fish and mammals. Using the rat as an animal model, pristane can function as a potent tumor promoter. It is conceivable that pristane could play a role in the development of certain malignancies in higher mammals since it is commonly found in the diet. At the molecular level, pristane can induce changes in the plasma membrane, alter the conformation of chromatin, as well as selectively activate gene expression. This study was undertaken to identify specific transcriptional motifs which are responsive to pristane. A transcriptional promoter which contained a cAMP response element (CRE) was consistently stimulated by pristane in several mouse and primate cell lines. A promoter construct which contained a single copy of the TPA response element (TRE) was also activated by pristane but surprisingly a promoter which contained multiple copies of the TRE was not. Activation of the TRE required 10 fold higher concentrations of pristane relative to activation of the CRE. Within two hours after addition of pristane to monkey fibroblasts (CV-1) levels of cAMP were increased more than two fold relative to controls. These data indicated that pristane can increase the level of cAMP in CV-1 cells and consequently stimulate transcriptional promoters which contain a CRE.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF02385008

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Recombinant human secretory phospholipase A2: Purification and characterization of the enzyme for active site studies (1992)

Stadel, J. M. ; Jones, C. ; Livi, G. P. ; [et al.]

Chicester [u.a.] : Wiley-Blackwell

Journal of Molecular Recognition 5 (1992), S. 145-153

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ISSN: 0952-3499

Keywords: Chemistry ; Biochemistry and Biotechnology

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Medicine

Notes: A secreted form of phospholipase A2 (PLA2) is thought to play an important role in inflammatory diseases. To characterize this enzyme the cDNA encoding a low molecular weight PLA2 was cloned from a human placental cDNA library. The cDNA encoding the human PLA2 was subcloned into an expression vector and subsequently transfected into Chinese hamster ovary (CHO) cells. A stable CHO cell clone, secreting ca I mg/L of recombinant PLA2 into the medium, was scaled up in culture to 180L. The recombinant enzyme was purified from the cell supernatant to apparent homogeneity by a novel procedure combining adsorption to poly(vinylidene difluoride) membranes, ion exchange chromatography and size exclusion chromatography. The final recovery of PLA2 activity was 58%. A direct comparison between the purified recombinant human PLA2 and PLA2 purified from human synovial fluid, including molecular weight, antigenicity, ionic dependence, substrate specificity and sensitivity to know PLA2 inhibitors, indicated that the two enzymes exhibit identical biochemical properties. These results show that the recombinant PLA2 can be efficiently expressed and purified in sufficient quantities to characterize the enzyme active site, to aid in the rational development of PLA2 inhibitors as potential anti-inflammatory drugs, and to investigate further the role of PLA2 in inflammatory disease.

Additional Material: 8 Ill.