title: RASSF1A Suppresses Cell Migration through Inactivation of HDAC6 and Increase of Acetylated α-Tubulin.
abstract: OBJECTIVE
  The RAS association domain family protein 1 (RASSF1) has been implicated in a tumor-suppressive function through the induction of acetylated α-tubulin and modulation of cell migration. However, the mechanisms of how RASSF1A is associated with acetylation of α-tubulin for controlling cell migration have not yet been elucidated. In this study, we found that RASSF1A regulated cell migration through the regulation of histon deacetylase 6 (HDAC6), which functions as a tubulin deacetylase.
  
  
  METHODS
  The cell migration was assessed using wound-healing and transwell assays. The role of RASSF1A on cell migration was examined by immunofluorescence staining, HDAC activity assay and western blot analysis.
  
  
  RESULTS
  Cell migration was inhibited and cell morphology was changed in RASSF1A-transfected H1299 cells, compared with controls, whereas HDAC6 protein expression was not changed by RASSF1A transfection in these cells. However, RASSF1A inhibited deacetylating activity of HDAC6 protein and induced acetylated α-tubulin expression. Furthermore, acetylated α-tubulin and HDAC6 protein were co-localized in the cytoplasm in RASSF1A-transfected H1299 cells. Conversely, when the endogenous RASSF1A expression in HeLa cells was blocked with RASSF1A siRNA treatment, acetylated α-tubulin was co-localized with HDAC6 protein throughout the whole cells, including the nucleus, compared with scramble siRNA-treated HeLa cells. The restoration of RASSF1A by 5-Aza-dC treatment also induced acetylated α-tubulin through inhibition of HDAC6 activity that finally resulted in suppressing cell migration in H1299 cells. To further confirm the role of HDAC6 in RASSF1A-mediated cell migration, the HDAC6 expression in H1299 cells was suppressed by using HDAC6 siRNA, and cell motility was found to be decreased through enhanced acetylated α-tubulin.
  
  
  CONCLUSIONS
  The results of this study suggest that the inactivation of HDAC6 by RASSF1A regulates cell migration through increased acetylated α-tubulin protein.
authors.affiliation: Brain Korea 21 Project for Biomedical Science, Korea University College of Medicine, Seoul, Korea. ; Genomic Research Center for Lung and Breast/Ovarian Cancers, Korea University College of Medicine, Seoul, Korea.
authors.forename: Hae-Yun
authors.initials: HY
authors.lastname: Jung
authors.forename: Jun Seok
authors.initials: JS
authors.lastname: Jung
authors.forename: Young Mi
authors.initials: YM
authors.lastname: Whang
authors.forename: Yeul Hong
authors.initials: YH
authors.lastname: Kim
keywords: Cell movement; HDAC6; Lung neoplasms; RASSF1A; Tumor suppressor genes