Production and purification of recombinant mouse cathepsin S

Unrestricted Sjögren’s syndrome (SjS) is defined as a systemic autoimmune disorder, not only characterized by the immune-mediated destruction of exocrine glands but also associated with defective protein trafficking. Previous work has suggested that the missorting of intracellular proteins from lysosomes to mature secretory vesicles (SV) might result in abnormal release of degradative proteins by SV-mediated exocytosis. In the present paper, the coding sequence of rabbit Rab27a, Rab27b, and GGA1 were obtained for future siRNA knockdown studies to evaluate their roles in SV exocytosis. Since CatS is a promising pathogenic factor involved in the progression of several diseases, and other work suggests that it may be upregulated and missorted in an animal model of SjS, reagents were generated for future studies to investigate CatS sorting including plasmid constructs and a recombinant adenovirus expressing CatS fused to GFP. The results indicate that CatS-GFP colocalizes with lysosomes in transfected Hela cells and that this expressed recombinant fusion protein seems to exist mainly as proCatS-GFP.