Degraded collagen fragments activate NF-kappa B and protect human smooth muscle cells against apoptosis through induction of inhibitor of apoptosis proteins (IAPs)

We report here that degraded type I collagen fragments activate NF-kappa B via phosphorylation and degradation of I kappa B alpha in human vascular smooth muscle cells (SMC) via alpha v beta 3 integrins. Simultanously, collagen fragments induce the expression of IAPs in a NF-kappa B-dependend manner. Inhibition of NF-kappa B results in suppression of IAP upregulation and induces apoptosis. These data identify a novel protective mechanism for SMC against apoptosis under conditions of enhanced extracellular matrix (ECM) degradation as e.g. in the atherosclerotic lesion.