Integrin Α1β1 Participates in Chondrocyte Transduction of Osmotic Stress

Purpose: To determine the role of the collagen binding receptor integrin α1β1 in regulating chondrocyte osmotransduction.

Methods: The [Ca²⁺]_i transient response of wildtype and integrin α1-null chondrocytes to osmotic stress was measured ex vivo and in vitro using real-time confocal microscopy. Immunocytochemistry was performed to detect the presence of the osmosensor, transient receptor potential vanilloid 4 (TRPV4), and the agonist GSK1016790A (GSK101) was used to test for its functionality.

Results: Deletion of the integrin α1 subunit inhibited the ability of chondrocytes to respond to a hypoosmotic stress ex vivo and in vitro. TRPV4 protein was expressed by both wildtype and integrin α1-null chondrocytes, however TRPV4 could only be activated on wildtype chondrocytes.

Conclusion: Integrin α1β1 is a key participant in chondrocyte transduction of a hypo-osmotic stress. Furthermore, the mechanism by which integrin α1β1 influences osmotransduction is independent of matrix binding, but likely dependent on the chondrocyte osmosensor TRPV4.

Keywords:

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Year

Entry

1989

Schaffler MB, Radin EL, Burr DB. Mechanical and morphological effects of strain rate on fatigue of compact bone. Bone. 1989;10(3):207-214.

1999

Mow VC, Wang CC, Hung CT. The extracellular matrix, interstitial fluid and ions as a mechanical signal transducer in articular cartilage. Osteoarthritis Cartilage. January 1999;7(1):41-58.

2001

Erickson GR, Alexopoulos LG, Guilak F. Hyper-osmotic stress induces volume change and calcium transients in chondrocytes by transmembrane, phospholipid, and G-protein pathways. J Biomech. December 2001;34(12):1527-1535.

1979

Maroudas A. Physicochemical properties of articular cartilage. In: Freeman MAR, ed. Adult Articular Cartilage. 2nd ed. Kent, England: Pitman Medical; 1979:215-290.

1995

Buschmann MD, Gluzband YA, Grodzinsky AJ, Hunziker EB. Mechanical compression modulates matrix biosynthesis in chondrocyte/agarose culture. J Cell Sci. April 1995;108(4):1497-1508.