Interaction of the receptor for advanced glycation end products (RAGE) with transthyretin triggers nuclear transcription factor kB (NF-kB) activation

Mutated transthyretin (TTR) fibrils are associated with the pathology of familial amyloidotic polyneuropathy (FAP), in which extracellular amyloid deposits lead to degeneration of cells and tissues, in particular neurons of the peripheral nerve. Here we present evidence that the receptor for advanced glycation end products (RAGE), previously associated with Alzheimer's disease, acts as a selective cell surface acceptor site for both soluble and fibrillar TTR. Immunohistochemical studies demonstrating increased expression of RAGE in FAP tissues suggested the relevance of this receptor to TTR-induced fibrillar pathology. In vitro studies using soluble RAGE showed saturable specific interaction with soluble and fibrillar TTR with a K-d of similar to 120 nM. However, no binding was observed when soluble TTR was combined with retinol-binding protein, which represents the form in which TTR normally circulates in plasma. Specific binding of TTR to RAGE-transfected Chinese hamster ovary cells (which was completely blocked by anti-RAGE) was observed, confirming that RAGE could mediate TTR binding to cellular surfaces. RAGE-dependent activation of nuclear transcription factor kB (NF-kB) by TTR fibrils was shown in PC-12 cells stably transfected to overexpress the receptor. Furthermore, FAP nerves showed up-regulation of p50, one of the NF-kB subunits, when compared with age-matched controls. From these observations we predict that, in vivo, the presence of TTR fibrils associated with cellular surfaces of FAP patients, by contributing to NF-kB activation, leads to the pathogenesis of neurodegeneration. Further insights into the consequences of the interaction of fibrillar TTR with RAGE may therefore provide a better understanding of neurodegeneration associated with FAP.