CHARACTERIZATION OF PROTEASE-ACTIVATED RECEPTOR-2 IMMUNOREACTIVITY INNORMAL HUMAN TISSUES

PAR-2 is a second member of a novel family of G-protein-coupled recept ors characterized by a proteolytic cleavage of the amino terminus, thu s exposing a tethered peptide ligand that autoactivates the receptor. The physiological and/or pathological role(s) of PAR-2 are still unkno wn. This study provides tissue-specific cellular localization of PAR-2 in normal human tissues by immunohistochemical techniques. A polyclon al antibody, PAR-2C, was raised against a peptide corresponding to the amino terminal sequence SLIGKVDGTSHVTGKGV of human PAR-2. Significant PAR-2 immunoreactivity was detected in smooth muscle of vascular and nonvascular origin and stromal cells from a variety of tissues. PAR-2 was also present in endothelial and epithelial cells independent of ti ssue type. Strong immunolabeling was observed throughout the gastroint estinal tract, indicating a possible function for PAR-2 in this system . In the CNS, PAR-2 was localized to many astrocytes and neurons, sugg esting involvement of PAR-2 in neuronal function. A role for PAR-2 in the skin was further supported by its immunolocalization in the epider mis. PAR-2C antibody exemplifies an important tool to address the phys iological role(s) of PAR-2.