|Cancer||Cell death||Cell cycle||Cytoskeleton||Exo/endocytosis||Differentiation||Division||Organelles||Signalling||Stem cells||Trafficking|
Mechanical loading modulates chondrocyte primary cilia incidence and length
Susan R McGlashan*1, Martin M Knight†, Tina T Chowdhury†, Purva Joshi*, Cynthia G Jensen*, Sarah Kennedy* and Charles A Poole*‡
*Department of Anatomy with Radiology, University of Auckland, Auckland, New Zealand, †School of Engineering and Materials Science, Queen Mary, University of London, London, U.K., and ‡Section of Orthopaedic Surgery, Department of Medical and Surgical Sciences, Dunedin School of Medicine, University of Otago, Dunedin, New Zealand
The pathways by which chondrocytes of articular cartilage sense their mechanical environment are unclear. Compelling structural evidence suggests that chondrocyte primary cilia are mechanosensory organelles. This study used a 3D agarose culture model to examine the effect of compressive strain on chondrocyte cilia. Chondrocyte/agarose constructs were subjected to cyclic compression (0–15%; 1 Hz) for 0.5–48 h. Additional constructs were compressed for 48 h and allowed to recover for 72 h in uncompressed free-swelling conditions. Incidence and length of cilia labelled with anti-acetylated α-tubulin were examined using confocal microscopy. In free-swelling chondrocytes, these parameters increased progressively, but showed a significant decrease following 24 or 48 h compression. A 72 h recovery partially reversed this effect. The reduced cilia incidence and length were not due to increased cell division. We therefore propose that control of primary cilia length is an adaptive signalling mechanism in response to varying levels and duration of mechanical loads during joint activity.
Key words: three-dimensional agarose culture, articular cartilage, cilia resorption, compressive strain, primary cilium
Abbreviations: DIC, differential interference contrast, DMEM, Dulbecco’s minimal essential medium, ECM, extracellular matrix, FCS, fetal calf serum, IFT, intraflagellar transport, PCNA, proliferating cell nuclear antigen
1To whom correspondence should be addressed (email firstname.lastname@example.org).
Received 28 July 2009/9 December 2009; accepted 25 January 2010
Published as Cell Biology International Immediate Publication 25 January 2010, doi:10.1042/CBI20090094
© The Author(s) Journal compilation © 2010 Portland Press Limited