Papers Published

1. GR Erickson, DL Northrup, F Guilak, Hypo-osmotic stress induces calcium-dependent actin reorganization in articular chondrocytes., Osteoarthritis and cartilage / OARS, Osteoarthritis Research Society, England, vol. 11 no. 3 (March, 2003), pp. 187-97 .
   (last updated on 2006/06/06)

   Abstract:
   OBJECTIVE: The aim of this study was to investigate the effects of hypo-osmotically induced calcium (Ca(2+)) transients on the organization of the actin cytoskeleton in articular chondrocytes. The secondary hypothesis tested was that actin restructuring following hypo-osmotic stress is mediated by gelsolin. METHODS: Isolated porcine chondrocytes were exposed to hypo-osmotic stress, and [Ca(2+)](i)was monitored using laser scanning microscopy. Calcium transients were monitored using fluorescent ratiometric imaging. The intracellular distribution of actin was examined using fluorescent immunohistochemistry and transient transfection with the pEGFP-actin plasmid. The intracellular distribution of gelsolin was investigated using fluorescent immunohistochemistry. RESULTS: Osmotic stress induced transient increases in [Ca(2+)](i)caused reorganization of intracellular actin through a mechanism that required Ca(2+)in the extracellular media. Fluorescence microscopy revealed that gelsolin was colocalized with F-actin immediately following hypo-osmotic stress but dissociated over time. CONCLUSION: These results indicate that hypo-osmotic stress induces a gelsolin-mediated reorganization of actin through a transient increase in [Ca(2+)](i).

   Keywords:
   Actins • Animals • Calcium • Cartilage, Articular • Chondrocytes • Cytoskeleton • Fluorescent Antibody Technique • Gelsolin • Green Fluorescent Proteins • Indicators and Reagents • Inositol 1,4,5-Trisphosphate • Luminescent Proteins • Microscopy, Confocal • Osmosis • Swine • analysis • metabolism • metabolism* • pharmacokinetics* • physiology