title: Cyclic strain-induced cytoskeletal rearrangement of human periodontal ligament cells via the Rho signaling pathway.
abstract: BACKGROUND
  Although mechanical stimulations are known have a significant impact on cytoskeletal rearrangement, little is known regarding the behavioral alteration of human periodontal ligament cells (hPDLCs) under cyclic strain. The aim of this study was to elucidate the role of the Rho signaling pathway on cyclic strain-induced cytoskeletal rearrangement of hPDLCs.
  
  
  METHODS
  Healthy hPDLCs obtained from teeth extracted for orthodontic purposes were subjected to cyclic strain with physiological loading (10%) at a frequency of 0.1 Hz for 6 h or 24 h using a FX-5000T system. Changes in cell morphology were examined by phase-contrast microscopy, while F-actin reorganization was observed by phalloidin staining and confocal microscopy. Protein expression was analyzed through western blot analysis.
  
  
  RESULTS
  Significant enhancement of cytoskeletal reorganization was observed following exposure to the cyclic strain. In addition, a significant increase was noted in the expression levels of GTP-Rho, Rho-associated protein kinase (ROCK) and p-cofilin, whereas the expression levels of Rho GDP dissociation inhibitors alpha (Rho-GDIa) were reduced in the hPDLCs, compared with the static control cells. More importantly, the Rock inhibitor Y-27632 suppressed cyclic strain-induced cytoskeletal rearrangement of hPDLCs. Additionally, Y-27632 and overexpression of Rho-GDIa were found to lower p-cofilin protein expressions under cyclic strain, while Rho-GDIa siRNA transfection had the opposite effect on the hPDLCs.
  
  
  CONCLUSIONS
  Cyclic strain promotes cytoskeletal rearrangement of hPDLCs by downregulating the expression levels of Rho-GDIa and upregulating the expression levels of GTP-Rho, Rock and p-cofilin. These observations may provide valuable insight into understanding orthodontic tooth movement as well as alveolar bone remodeling.
authors.affiliation: Department of Oral and Maxillofacial Surgery, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai Key Laboratory of Stomatology and Shanghai Research Institute of Stomatology, Shanghai, China.
authors.forename: Jinsong
authors.initials: J
authors.lastname: Pan
authors.affiliation: Department of Stomatology, Central Hospital of Minhang District, Shanghai, China.
authors.forename: Tingle
authors.initials: T
authors.lastname: Wang
authors.affiliation: Department of Stomatology, First People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
authors.forename: Li
authors.initials: L
authors.lastname: Wang
authors.affiliation: Department of Oral and Maxillofacial Surgery, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai Key Laboratory of Stomatology and Shanghai Research Institute of Stomatology, Shanghai, China.
authors.forename: Wantao
authors.initials: W
authors.lastname: Chen
authors.affiliation: Department of Stomatology, First People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
authors.forename: Meng
authors.initials: M
authors.lastname: Song
mesh_terms: D000577:Amides / Q000494:pharmacology; D003599:Cytoskeleton / Q000378:metabolism*; D015870:Gene Expression; D006801:Humans; D010513:Periodontal Ligament / Q000166:cytology* / Q000378:metabolism*; D011725:Pyridines / Q000494:pharmacology; D015398:Signal Transduction; D062948:rho Guanine Nucleotide Dissociation Inhibitor alpha / Q000235:genetics / Q000378:metabolism; D054460:rho-Associated Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: D000577:Amides; D011725:Pyridines; D062948:rho Guanine Nucleotide Dissociation Inhibitor alpha; C108830:Y 27632; D054460:rho-Associated Kinases