SCRG1, a Potential Marker of Autophagy in TSE

The Scrg1 gene was initially discovered as one of the genes up-regulated in transmissible spongiform encephalopathies (TSE). Scrg1 encodes a highly conserved, cysteine-rich protein expressed principally in the central nervous system. The protein is targeted to the Golgi apparatus and large dense-core vesicles/secretory granules in neurons. We have recently shown that the Scrg1 protein is widely induced in neurons of scrapie-infected mice, suggesting that Scrg1 is involved in the host response to stress and/or the death of neurons. At the ultrastructural level, Scrg1 is associated with dictyosomes of the Golgi apparatus and autophagic vacuoles of degenerative neurons. It is well known that apoptosis plays a major role in the events leading to neuronal cell death in TSE. However, autophagy has been identified in experimentally induced scrapie a long time ago and was recently re-evaluated as a possible cell death program in prion diseases. The consistent association of Scrg1 with autophagic structures typical of scrapie is in agreement with the recruitment of Golgi-specific proteins in this degradation process and we suggest that Scrg1 might be used as a specific probe to identify neuronal autophagy in TSE. Addenda to: Scrg1 is Induced in TSE and Brain injuries, and Associated with Autophagy M. Dron, Y. Bailly, V. Beringue, A.-M. Haeberlé, B. Griffond, P.-Y. Risold, M.G. Tovey, H. Laude and F. Dandoy-Dron. Eur J Neurosci 2005; 22:133-46