Details

Autor(en) / Beteiligte

• Chen, Jeffrey C
• Zhuang, Shunhui
• Nguyen, Tony H
• Boss, Gerry R
• Pilz, Renate B

Titel

Oncogenic Ras Leads to Rho Activation by Activating the Mitogen-activated Protein Kinase Pathway and Decreasing Rho-GTPase-activating Protein Activity

Ist Teil von

• The Journal of biological chemistry, 2003-01, Vol.278 (5), p.2807-2818

Ort / Verlag

United States: American Society for Biochemistry and Molecular Biology

Erscheinungsjahr

2003

Quelle

MEDLINE

Beschreibungen/Notizen

• Transformation by oncogenic Ras requires signaling through Rho family proteins including RhoA, but the mechanism(s) whereby oncogenic Ras regulates the activity of RhoA is (are) unknown. We examined the effect of Ras on RhoA activity in NIH 3T3 cells either stably transfected with H-Ras(V12) under control of an inducible promoter or transiently expressing the activated H-Ras. Using a novel method to quantitate enzymatically the GTP bound to Rho, we found that expression of the oncogenic Ras increased Rho activity ∼2-fold. Increased Rho activity was associated with increased plasma membrane binding of RhoA and decreased activity of the Rho/Ras-regulated p21 WAF1/CIP1 promoter. RhoA activation by oncogenic Ras could be explained by a decrease in cytosolic p190 Rho-GAP activity and translocation of p190 Rho-GAP from the cytosol to a detergent-insoluble cytoskeletal fraction. Pharmacologic inhibition of the Ras/Raf/MEK/ERK pathway prevented Ras-induced activation of RhoA and translocation of p190 Rho-GAP; expression of constitutively active Raf-1 kinase or MEK was sufficient to induce p190 Rho-GAP translocation. We conclude that in NIH 3T3 cells oncogenic Ras activates RhoA through the Raf/MEK/ERK pathway by decreasing the cytosolic activity and changing the subcellular localization of p190 Rho-GAP.