Overexpression of Rho kinase 1 (ROCK1) and the G protein RhoA is implicated in breast cancer progression, but oncogenic mutations are rare, and the molecular mechanisms that underlie increased ROCK1 and RhoA expression have not been determined. RhoA-bound ROCK1 phosphorylates myosin light chain (MLC), which is required for actin-myosin contractility. RhoA also activates focal adhesion kinase (F...

Pang, Haiyan, and Khalil N. Bitar. Direct association of RhoA with specific domains of PKC. Am J Physiol Cell Physiol 289: C982–C993, 2005. First published June 1, 2005; doi:10.1152/ajpcell.00364.2004.— Previous studies performed at our laboratory have shown that agonistinduced contraction of smooth muscle is associated with translocation of protein kinase C (PKC)and RhoA to the membrane and th...

Peripheral nerve injury triggers the activation of RhoA in spinal motor and peripheral sensory neurons. RhoA activates a number of effector proteins including the Rho-associated kinase, ROCK, which targets the cytoskeleton and leads to inhibition of neurite outgrowth. Blockade of the Rho/ROCK pathway by pharmacological means improves axon regeneration after experimental injury. C3(bot) transfer...

Although RhoA plays an important role in cell proliferation and in Ras transformation in fibroblasts and mammary epithelial cells, its role in intestinal epithelial cells is unknown. In a previous study, we showed that polyamine depletion (DL-alpha-difluoromethylornithine, DFMO, treatment) strongly inhibits the proliferation of intestinal epithelial cells (IEC-6). In this report, we examined th...

MicroRNAs (miRNAs) function as genetic modulators that regulate gene expression and are involved in a wide range of biological roles, including tumor cell migration and invasion. In the present study, we demonstrated that the migration and invasion activity in MDA-MB-231 breast cancer cells could be directly influenced by altering miR-146a expression. The expression of RhoA and miR-146a in the ...

e already knew the players—MgcRacGAP, Aurora B, and RhoA—and that knocking out any one of them caused failure of cytokinesis; but it wasn’t clear how they were connected. Now, it appears that Aurora B phosphorylates the GAP domain of MgcRacGAP, allowing it to turn its GAP activity toward RhoA, according to data from Yukinori Minoshima, Toshiyuki Kawashima, Toshio Kitamura (University of Tokyo, ...

The focal adhesion-associated signaling protein HEF1 undergoes a striking relocalization to the spindle at mitosis, but a function for HEF1 in mitotic signaling has not been demonstrated. We here report that overexpression of HEF1 leads to failure of cells to progress through cytokinesis, whereas depletion of HEF1 by small interfering RNA (siRNA) leads to defects earlier in M phase before cleav...

MOTIVATION Small GTPase RhoA regulates cell-cycle progression via several mechanisms. Apart from its actions via ROCK, RhoA has recently been found to activate a scaffold protein MEKK1 known to promote ERK activation. We examined whether RhoA can substantially affect ERK activity via this MEKK1-mediated crosstalk between RhoA and EGFR-ERK pathway. By extending the published EGFR-ERK simulation ...

Cytokinesis requires activation of the GTPase RhoA. ECT-2, the exchange factor responsible for RhoA activation, is regulated to ensure spatiotemporal control of contractile ring assembly. Centralspindlin, composed of the Rho family GTPase-activating protein (RhoGAP) MgcRacGAP/CYK-4 and the kinesin MKLP1/ZEN-4, is known to activate ECT-2, but the underlying mechanism is not understood. We report...

Colorectal cancer is one of the most common cancers and is the fourth leading cause of cancer death in Korea. Mortality of colorectal cancer is strongly associated with the metastatic spread of the disease. As such, it is important to find and characterize signaling pathways involved in colon cancer metastasis. We investigated the functional importance of RhoA using human cell lines as well as ...