Elevated Phospholipase D Activity in H-Ras- but Not K-Ras-Transformed Cells by the Synergistic Action of RalA and ARF6
AUTOR(ES)
Xu, Lizhong
FONTE
American Society for Microbiology
RESUMO
Phospholipase D (PLD) activity is elevated in response to the oncogenic stimulus of H-Ras but not K-Ras. H-Ras and K-Ras have been reported to localize to different membrane microdomains, with H-Ras localizing to caveolin-enriched light membrane fractions. We reported previously that PLD activity elevated in response to mitogenic stimulation is restricted to the caveolin-enriched light membrane fractions. PLD activity in H-Ras-transformed cells is dependent upon RalA, and consistent with a lack of elevated PLD activity in K-Ras-transformed cells, RalA was not activated in K-Ras-transformed cells. Although H-Ras-induced PLD activity is dependent upon RalA, an activated mutant of RalA is not sufficient to elevate PLD activity. We reported previously that RalA interacts with PLD activating ADP ribosylation factor (ARF) proteins. In cells transformed by H-Ras, we found increased coprecipitation of ARF6 with RalA. Moreover, ARF6 colocalized with RalA in light membrane fractions. Interestingly, ARF6 protein levels were elevated in H-Ras- but not K-Ras-transformed cells. A dominant-negative mutant of ARF6 inhibited PLD activity in H-Ras-transformed NIH 3T3 cells. Activated mutants of either ARF6 or RalA were not sufficient to elevate PLD activity in NIH 3T3 cells; however, expression of both activated RalA and activated ARF6 in NIH 3T3 cells led to increased PLD activity. These data suggest a model whereby H-Ras stimulates the activation of both RalA and ARF6, which together lead to the elevation of PLD activity.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=151535Documentos Relacionados
- Functional association between Arf and RalA in active phospholipase D complex
- RalA but Not RalB Enhances Polarized Delivery of Membrane Proteins to the Basolateral Surface of Epithelial Cells
- H-ras but Not K-ras Traffics to the Plasma Membrane through the Exocytic Pathway
- Novel revertants of H-ras oncogene-transformed R6-PKC3 cells.
- Phospholipase D and RalA Cooperate with the Epidermal Growth Factor Receptor To Transform 3Y1 Rat Fibroblasts