@article{a290b5162eb543619994a31d43716dae,
title = "Coupling S100A4 to Rhotekin alters Rho signaling output in breast cancer cells",
abstract = "Rho signaling is increasingly recognized to contribute to invasion and metastasis. In this study, we discovered that metastasis-associated protein S100A4 interacts with the Rho-binding domain (RBD) of Rhotekin, thus connecting S100A4 to the Rho pathway. Glutathione S-transferase pull-down and immunoprecipitation assays demonstrated that S100A4 specifically and directly binds to Rhotekin RBD, but not the other Rho effector RBDs. S100A4 binding to Rhotekin is calcium-dependent and uses residues distinct from those bound by active Rho. Interestingly, we found that S100A4 and Rhotekin can form a complex with active RhoA. Using RNA interference, we determined that suppression of both S100A4 and Rhotekin leads to loss of Rho-dependent membrane ruffling in response to epidermal growth factor, an increase in contractile F-actin 'stress' fibers and blocks invasive growth in three-dimensional culture. Accordingly, our data suggest that interaction of S100A4 and Rhotekin permits S100A4 to complex with RhoA and switch Rho function from stress fiber formation to membrane ruffling to confer an invasive phenotype.",
keywords = "Rho, Rhotekin, S100A4/metastasin, invasive growth, lamellipodia",
author = "M. Chen and Bresnick, {A. R.} and O'Connor, {K. L.}",
note = "Funding Information: S100A4 and Rhotekin leads to a functional switch in Rho function. When both Rhotekin and S100A4 are expressed, growth factor stimulation of Rho activity leads to the coupling of Rho to S100A4. Under these conditions, myosin II oligomerization is restricted in close proximity to active Rho, thus limiting stress fiber formation. The inhibition of myosin-mediated actin contractility then permits membrane ruffling and lamellae formation to predominate downstream of Rho effectors such as ROCK (Figure 8a). When Rhotekin is absent, S100A4 and Rho are uncoupled. Under this condition, Rho activation is not restricted to the leading edge, which allows for the formation of membrane ruffles at the leading edge and stress fibers in the cell body (Figure 8b). This concept is supported by the presence of both membrane ruffles and stress fibers with RNAi-mediated reduction in Rhotekin (Figure 5b) and the altered distribution of pMLC (Figure 6). Without S100A4, membrane ruffles are unable to form (Figure 5c) due to the increase in oligomeric myosin and absence of monomeric myosin at the leading edge (Figure 6). Notably, the loss of both S100A4 and Rhotekin exacerbates the thickness and number of stress fibers.",
year = "2013",
month = aug,
day = "8",
doi = "10.1038/onc.2012.383",
language = "English (US)",
volume = "32",
pages = "3754--3764",
journal = "Oncogene",
issn = "0950-9232",
publisher = "Nature Publishing Group",
number = "32",
}