Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 1 de 1
Filter
Add more filters










Database
Language
Publication year range
1.
Exp Cell Res ; 228(2): 197-205, 1996 Nov 01.
Article in English | MEDLINE | ID: mdl-8912711

ABSTRACT

Human A431 epidermoid carcinoma cells express 12-lipoxygenase enzymatic activity. However, the isoform identity based on cDNA sequence data is not known. Further, the simultaneous characterization of the intracellular distribution of 12-lipoxygenase protein and activity is lacking. Here we report that the cDNA sequence from RT-PCR-amplified 12-lipoxygenase mRNA is identical with the platelet-type 12-lipoxygenase isoform, and the leukocyte-type isoform of 12-lipoxygenase is not expressed in A431 cells. The predominant amount (78%) of 12-lipoxygenase protein resides in the cytosol. In contrast, the predominant (98%) 12-lipoxygenase activity is localized in the membrane fraction. Western blot and immunofluorescence data demonstrate that epidermal growth factor increases total cellular 12-lipoxygenase protein and enhances the association of 12-lipoxygenase protein with perinuclear or nuclear membrane sites. In addition, epidermal growth factor stimulates 12-lipoxygenase activity resulting in generation of 12(S)-hydroxyeicosatetraenoic acid from cellular arachidonate. In contrast, both 12-lipoxygenase protein and activity decrease approximately 80% within 24 h during serum starvation. The recovery of 12-lipoxygenase expression in serum-deprived cells can be induced by readdition of epidermal growth factor or serum. Further, the basal expression of 12-lipoxygenase depends on signal pathways requiring protein tyrosine kinase activity, since genistein, herbimycin A, and tyrphostin 25 reduce the expression of 12-lipoxygenase protein in A431 cells.


Subject(s)
Arachidonate 12-Lipoxygenase/biosynthesis , Arachidonate 12-Lipoxygenase/genetics , Gene Expression Regulation, Enzymologic , Arachidonate 12-Lipoxygenase/analysis , Base Sequence , Blood Platelets/enzymology , Carcinoma, Squamous Cell , Cell Line , Cell Membrane/enzymology , Culture Media, Serum-Free , Cytosol/enzymology , DNA Primers , DNA, Complementary , Epidermal Growth Factor/pharmacology , Exons , Gene Expression Regulation, Enzymologic/drug effects , Gene Expression Regulation, Neoplastic/drug effects , Humans , Molecular Sequence Data , Polymerase Chain Reaction , Protein-Tyrosine Kinases/metabolism , RNA, Messenger/biosynthesis , Sequence Homology, Nucleic Acid , Signal Transduction , Transcription, Genetic
SELECTION OF CITATIONS
SEARCH DETAIL
...