The Rho family of p21 small GTPases plays important roles in regulating cytoskeleton rearrangement in the context of cell motility. The Rho GTPases directly linked to cytoskeletal reorganization in the context of cancer cell invasion and migration is the two Rho isoforms RhoA and RhoC. Literature evidence exists that these two isoforms of Rho GTPases may impart opposing effects on cancer metastasis, yet detailed analysis of signaling pathways that could contribute to such process has been acutely lacking. In this work, we elucidate the mechanism by which RhoC imparts highly specific downstream signaling effects different than RhoA and in separate cellular compartments at the leading edge of cell protrusions during EGF-stimulated motility. We will address this problem by directly visualizing multiple protein activities simultaneously in living cells, using novel biosensors that are proposed here.
Aim1 : Visualize two protein activities simultaneously in single living cell and in real-time using fully genetically encoded approach.
Aim2 : Develop new biosensors for downstream Rho effectors ROCK-1 and mDia1, amenable to simultaneous visualization together with the specific upstream Rho isoform Aim3: Investigate the spatiotemporal segregation of signaling coordinating RhoC and its downstream effector pathways at the leading edge Aim4: Investigate the spatiotemporal signaling coordinating RhoA and its downstream effector pathways at the leading edge These studies will produce new technologies valuable in direct visualization of Rho GTPase isoforms and their immediate downstream effector activations, enabling further spatiotemporal delineation of signaling mechanisms. Through these studies, we will be able to dissect the mechanism of the leading edge protrusions controlled through differential activities of Rho isoforms in breast carcinomas and enable us to address the specific role RhoC plays in producing the localized and polarized protrusions at the leading edge of breast carcinomas.

Public Health Relevance

Rho-subfamily of p21 small GTPases has been postulated to exhibit a complex coordination of their activities in space and time, depending on particular environmental cues stimulating cell motility. However, high-resolution imaging studies of these coordinated balance of GTPase activities have been acutely lacking, due primarily to the technical challenges of imaging multiple protein activities in living cells. Rho-GTPases directly linked to cytoskeletal reorganization in the context of cancer cell invasion and migration, are the two Rho isoforms RhoA and RhoC. Here, we visualize simultaneously these Rho isoform activities together with activations of their downstream effectors in a single living breast carcinoma cell and address signaling events that coordinate the leading edge protrusions in response to EGF stimulation. Our key hypothesis is that RhoC activation in breast carcinomas in response to growth factor stimulation could impart a subcellular signal polarization mechanism that promotes effective forward protrusion of the leading edge through segregation of highly active versus complete inhibitive zones of actin polymerization within the leading edge.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
Research Project (R01)
Project #
Application #
Study Section
Microscopic Imaging Study Section (MI)
Program Officer
Nie, Zhongzhen
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Albert Einstein College of Medicine
Anatomy/Cell Biology
Schools of Medicine
United States
Zip Code
Miskolci, Veronika; Hodgson, Louis; Cox, Dianne (2017) Using Fluorescence Resonance Energy Transfer-Based Biosensors to Probe Rho GTPase Activation During Phagocytosis. Methods Mol Biol 1519:125-143
Miskolci, Veronika; Wu, Bin; Moshfegh, Yasmin et al. (2016) Optical Tools To Study the Isoform-Specific Roles of Small GTPases in Immune Cells. J Immunol 196:3479-93
Ioannou, Maria S; Bell, Emily S; Girard, Martine et al. (2015) DENND2B activates Rab13 at the leading edge of migrating cells and promotes metastatic behavior. J Cell Biol 208:629-48
Wu, Bin; Miskolci, Veronika; Sato, Hanae et al. (2015) Synonymous modification results in high-fidelity gene expression of repetitive protein and nucleotide sequences. Genes Dev 29:876-86
Donnelly, Sara K; Bravo-Cordero, Jose Javier; Hodgson, Louis (2014) Rho GTPase isoforms in cell motility: Don't fret, we have FRET. Cell Adh Migr 8:526-34
Miskolci, Veronika; Hodgson, Louis; Cox, Dianne et al. (2014) Western analysis of intracellular interleukin-8 in human mononuclear leukocytes. Methods Mol Biol 1172:285-93
Hanna, Samer; Miskolci, Veronika; Cox, Dianne et al. (2014) A new genetically encoded single-chain biosensor for Cdc42 based on FRET, useful for live-cell imaging. PLoS One 9:e96469
Bravo-Cordero, Jose Javier; Hodgson, Louis; Condeelis, John S (2014) Spatial regulation of tumor cell protrusions by RhoC. Cell Adh Migr 8:263-7
Sun, Qiang; Cibas, Edmund S; Huang, Hongyan et al. (2014) Induction of entosis by epithelial cadherin expression. Cell Res 24:1288-98
Roh-Johnson, M; Bravo-Cordero, J J; Patsialou, A et al. (2014) Macrophage contact induces RhoA GTPase signaling to trigger tumor cell intravasation. Oncogene 33:4203-12

Showing the most recent 10 out of 25 publications