Leukotriene D4-Induced Activation and Translocation of the G-Protein αi3-Subunit in Human Epithelial Cells

• Published in: Biochemical and biophysical research communications 1996-09, Vol.226 (2), p.413-419
• Main Authors: Adolfsson, Jonas L.P., Öhd, John F., Sjölander, Anita
• Format: Article
• Language: English
• Subjects: Biological Transport; Epithelial Cells; Epithelium - metabolism; GTP-Binding Proteins - metabolism; Guanine Nucleotide Exchange Factors; Guanosine Diphosphate - metabolism; Guanosine Triphosphate - metabolism; Humans; Intestines - cytology; Intestines - metabolism; Leukotriene D4 - metabolism; Proteins - metabolism; Subcellular Fractions - metabolism
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1006/bbrc.1996.1370

The present results show that stimulation of Intestine 407 epithelial cells with LTD4(Leukotriene D4) triggers a rapid activation of the pertussis-toxin-sensitive Gi3-protein and a simultaneous translocation of its α-subunits to a crude cytoskeletal fraction. The activation of Gαi3, which was measured as the GTP/GDP exchange ratio, peaked about 15 s after the addition of LTD4. Western blot analyses of subcellular fractions showed that Gαi3-subunits accumulated in the cytoskeletal fraction and decreased in the membrane fraction, and the decrease was most marked 15 s after the exposure to LTD4. None of the other pertussis-toxin-sensitive G-proteins (Gi1-2and Gα0) were activated or translocated upon stimulation with LTD4. This agonist was also found to reduce the GTP/GDP exchange ratio of Gs-proteins without affecting the subcellular distribution of its α-subunits. These findings imply that the Gi3-protein is the pertussis-toxin-sensitive G-protein previously found to mediate several downstream LTD4-stimulated signalling events. Furthermore, the translocation of Gαi3-subunits to the cytoskeleton and the simultaneous inhibition of Gs-proteins indicate that the cytoskeleton might participate in the signalling process of human epithelial cells.