Diacylglycerol kinase ζ regulates RhoA activation via a kinase-independent scaffolding mechanism

Research output: Contribution to journalJournal articleResearchpeer-review

Ryan Ard, Kirk Mulatz, Hanan Abramovici, Jean-Christian Maillet, Alexandra Fottinger, Tanya Foley, Michèle-Renée Byham, Tasfia Ahmed Iqbal, Atsuko Yoneda, John R Couchman, Robin J Parks, Stephen H Gee

Rho GTPases share a common inhibitor, Rho guanine nucleotide dissociation inhibitor (RhoGDI), which regulates their expression levels, membrane localization, and activation state. The selective dissociation of individual Rho GTPases from RhoGDI ensures appropriate responses to cellular signals, but the underlying mechanisms are unclear. Diacylglycerol kinase ζ (DGKζ), which phosphorylates diacylglycerol to yield phosphatidic acid, selectively dissociates Rac1 by stimulating PAK1-mediated phosphorylation of RhoGDI on Ser-101/174. Similarly, phosphorylation of RhoGDI on Ser-34 by protein kinase Cα (PKCα) selectively releases RhoA. Here we show DGKζ is required for RhoA activation and Ser-34 phosphorylation, which were decreased in DGKζ-deficient fibroblasts and rescued by wild-type DGKζ or a catalytically inactive mutant. DGKζ bound directly to the C-terminus of RhoA and the regulatory arm of RhoGDI and was required for efficient interaction of PKCα and RhoA. DGKζ-null fibroblasts had condensed F-actin bundles and altered focal adhesion distribution, indicative of aberrant RhoA signaling. Two targets of the RhoA effector ROCK showed reduced phosphorylation in DGKζ-null cells. Collectively our findings suggest DGKζ functions as a scaffold to assemble a signaling complex that functions as a RhoA-selective, GDI dissociation factor. As a regulator of Rac1 and RhoA activity, DGKζ is a critical factor linking changes in lipid signaling to actin reorganization.
Original languageEnglish
JournalMolecular Biology of the Cell
Volume23
Issue number20
Pages (from-to)4008-19
Number of pages12
ISSN1059-1524
DOIs
Publication statusPublished - Oct 2012

    Research areas

  • Animals, Biocatalysis, Diacylglycerol Kinase, Embryo, Mammalian, Enzyme Activation, Fibroblasts, Focal Adhesions, Mice, Models, Biological, Multiprotein Complexes, Phosphorylation, Phosphoserine, Protein Binding, Protein Kinase C-alpha, Protein Stability, Protein Structure, Tertiary, Signal Transduction, Stress Fibers, rho-Specific Guanine Nucleotide Dissociation Inhibitors, rhoA GTP-Binding Protein

ID: 49106164