Actin cytoskeleton controls activation of Wnt/β-catenin signaling in mesenchymal cells on implant surfaces with different topographies

• Published in: Acta biomaterialia Vol. 8; no. 8; pp. 2963 - 2968
• Main Authors: Galli, C., Piemontese, M., Lumetti, S., Ravanetti, F., Macaluso, G.M., Passeri, G.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.08.2012
• Subjects: Actin Cytoskeleton - drug effects; Actin Cytoskeleton - metabolism; Actins - metabolism; Activation; alkaline phosphatase; Alkaline Phosphatase - genetics; Alkaline Phosphatase - metabolism; Amides - pharmacology; Animals; antagonists; beta Catenin - genetics; beta Catenin - metabolism; Biocompatibility; Biomedical materials; Cell Differentiation - drug effects; Cell Proliferation - drug effects; cell viability; Cells, Cultured; Cytoskeleton; Differentiation; fluorescence microscopy; Fluorescent Antibody Technique; Gene Expression Regulation - drug effects; genes; Luciferases - metabolism; Mesenchymal Stromal Cells - cytology; Mesenchymal Stromal Cells - drug effects; Mesenchymal Stromal Cells - metabolism; messenger RNA; Mice; microfilaments; osteocalcin; Osteocalcin - genetics; Osteocalcin - metabolism; Osteoprotegerin - genetics; Osteoprotegerin - metabolism; Polished; Prostheses and Implants; Protein Kinase Inhibitors - pharmacology; protein kinases; Pyridines - pharmacology; quantitative polymerase chain reaction; Real-Time Polymerase Chain Reaction; rho-Associated Kinases - antagonists & inhibitors; rho-Associated Kinases - metabolism; RNA, Messenger - genetics; RNA, Messenger - metabolism; ROCK; Surface chemistry; Surface Properties - drug effects; Titanium; Titanium - pharmacology; Topography; Wnt; Wnt Signaling Pathway - drug effects; Titanium; Cytoskeleton; ROCK; Wnt; Topography
• ISSN: 1742-7061; 1878-7568
• DOI: 10.1016/j.actbio.2012.04.043

Surface topography affects cell function and differentiation. It has been previously shown that rough surfaces can enhance the activation of canonical Wnt signaling, an important pathway for osteoblast differentiation and bone maintenance, but the underlying mechanisms are still poorly understood. The present paper investigates whether cytoskeletal organization contributes to regulating this pathway. Rho-associated protein kinase (ROCK), an important controller of actin microfilaments, was inhibited with 2mM specific antagonist Y-27632 in mesenchymal and osteoblastic cells growing on titanium discs with a polished or acid-etched, sand-blasted (SLA) surface. Y-27632 subverted the morphology of the cytoskeleton on polished and, to a lesser extent, on SLA surfaces, as evidenced by fluorescence microscopy. Although ROCK inhibition did not affect cell viability, it increased activation of Wnt signaling in uncommitted C2C12 mesenchymal cells on polished surfaces but not on SLA discs upon reporter assay. Consistently with this, real-time polymerase chain reaction analysis showed that MC3T3 cells on polished surfaces expressed higher mRNA levels for β-catenin and alkaline phosphatase, a known Wnt target gene, and for the osteoblastic differentiation marker osteocalcin after ROCK inhibition. Taken together, these data demonstrate that cytoskeletal organization mediates activation of Wnt canonical signaling in cells on titanium surfaces with different topographies.