title: γ-Actin regulates cell migration and modulates the ROCK signaling pathway.
abstract: Cell migration plays a crucial role in numerous cellular functions, and alterations in the regulation of cell migration are required for invasive transformation of a tumor cell. While the mechanistic process of actin-based migration has been well documented, little is known as to the specific function of the nonmuscle actin isoforms in mammalian cells. Here, we present a comprehensive examination of γ-actin's role in cell migration using an RNAi approach. The partial suppression of γ-actin expression in SH-EP neuroblastoma cells resulted in a significant decrease in wound healing and transwell migration. Similarly, the knockdown of γ-actin significantly reduced speed of motility and severely affected the cell's ability to explore, which was, in part, due to a loss of cell polarity. Moreover, there was a significant increase in the size and number of paxillin-containing focal adhesions, coupled with a significant decrease in phosphorylated paxillin in γ-actin-knockdown cells. In addition, there was a significant increase in the phosphorylation of cofilin and myosin regulatory light chain, suggesting an overactivated Rho-associated kinase (ROCK) signaling pathway in γ-actin-knockdown cells. The alterations in the phosphorylation of paxillin and myosin regulatory light chain were unique to γ-actin and not β-actin knockdown. Inhibition of the ROCK pathway with the inhibitor Y-27632 restored the ability of γ-actin-knockdown cells to migrate. This study demonstrates γ-actin as a potential upstream regulator of ROCK mediated cell migration.
authors: Children's Cancer Institute Australia, Lowy Cancer Research Centre, UNSW, PO Box 81, Randwick NSW Australia.
authors: Michael S Y
authors: MS
authors: Shum
authors: Eddy
authors: E
authors: Pasquier
authors: Sela T
authors: ST
authors: Po'uha
authors: Geraldine M
authors: GM
authors: O'Neill
authors: Christine
authors: C
authors: Chaponnier
authors: Peter W
authors: PW
authors: Gunning
authors: Maria
authors: M
authors: Kavallaris
mesh_terms: D000199:Actins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D000577:Amides / Q000494:pharmacology; D001483:Base Sequence; D002460:Cell Line; D002465:Cell Movement / Q000502:physiology*; D016764:Cell Polarity / Q000502:physiology; D022001:Focal Adhesions / Q000502:physiology; D055785:Gene Knockdown Techniques; D006801:Humans; D008954:Models, Biological; D018994:Myosin Light Chains / Q000378:metabolism; D051419:Paxillin / Q000378:metabolism; D010766:Phosphorylation; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011725:Pyridines / Q000494:pharmacology; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics; D015398:Signal Transduction; D014945:Wound Healing / Q000502:physiology; D054460:rho-Associated Kinases / Q000378:metabolism*
chemical_list: D000199:Actins; D000577:Amides; D018994:Myosin Light Chains; D051419:Paxillin; D047428:Protein Kinase Inhibitors; D011725:Pyridines; D034741:RNA, Small Interfering; C108830:Y 27632; D054460:rho-Associated Kinases