Factors influencing RhoA protein distribution in the nucleus.

The aim of the present study was to observe the influence of various factors on the nuclear distribution of the RhoA protein in the SGC-7901 human gastric cancer cell line. Immunofluorescence microscopy was used to detect the localization of the RhoA protein, and Western blotting was used to determine the quantity of RhoA in the nucleus, cytosol and membrane. The results showed that H2O2-mediated damage and a lipopolysaccharide (LPS)-mediated inflammatory reaction caused the translocation of RhoA from the cytosol toward the nucleus. A P38 mitogen-activated protein kinase (MAPK) inhibitor effectively hindered the LPS-triggered translocation of RhoA into the nucleus at the initial stage. Furthermore, the microtubule-targeted anticancer drug Taxol triggered the translocation of RhoA from the nucleus toward the cytosol and membrane, and Lysophosphatidic acid (LPA) enhanced this translocation. A protein modification inhibitor and a nucleus export inhibitor had no obvious effect on RhoA distribution in the nucleus. The results revealed that the distribution of RhoA protein in the nucleus was influenced by factors related to cell activities but was not affected by the modification of the protein. The translocation of RhoA into the nucleus was not dependent on the active nuclear import system.