Differential Effects ofStaphylococcus aureusα-Hemolysin on the Synthesis of Hyaluronan and Chondroitin Sulfate by Rat Chondrosarcoma Chondrocytes

Abstract

The plasma membranes of rat chondrosarcoma chondrocytes were permeabilized by treatment with α-hemolysin, the major toxin produced byStaphylococcus aureus,which forms small, stable, heptameric, transmembrane pores (1–2 nm in diameter) permitting influx/efflux of low-molecular-mass molecules (≤2000 Da). Treated chondrocytes were permeable to entry of trypan blue and exit of ATP. We describe the effects of α-hemolysin on the synthesis of hyaluronan (HA) and chondroitin sulfate (CS) by chondrocytes using the simple sugar [3H]glucosamine as a metabolic precursor. Chondrocytes permeabilized with α-hemolysin in serum-free media decreased intracellular ATP and synthesis of CS to ∼5% of control within 2–4 h, but synthesized HA (80% of control for 8 h; ∼65% of control at 24 h). Adding fresh medium (with or without serum) to permeabilized cells increased ATP significantly and increased HA synthesis to near initial control values. Under the same conditions, the recovery of CS synthesis approached initial levels in control but not permeabilized cells. Our model demonstrates that the biosynthesis of HA by these cellsin vitrois remarkably stable to cellular perturbations which drastically inhibit synthesis of CS on proteoglycans.