12-Lipoxygenase in A431 cells: genetic identity, modulation of expression, and intracellular localization.
Exp Cell Res
; 228(2): 197-205, 1996 Nov 01.
Article
en En
| 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.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Araquidonato 12-Lipooxigenasa
/
Regulación Enzimológica de la Expresión Génica
Límite:
Humans
Idioma:
En
Revista:
Exp Cell Res
Año:
1996
Tipo del documento:
Article
País de afiliación:
Estados Unidos