Proteomic Identification of Protein Targets for 15-Deoxy-I12,14-Prostaglandin J2 in Neuronal Plasma Membrane

15-deoxy-I12,14-prostaglandin J2 (15d-PGJ2) is one of factors contributed to the neurotoxicity of amyloid I2 (AI2), a causative protein of Alzheimer's disease. Type 2 receptor for prostaglandin D2 (DP2) and peroxysome-proliferator activated receptorI3 (PPARI3) are identified as the membrane receptor and the nuclear receptor for 15d-PGJ2, respectively. Previously, we reported that the cytotoxicity of 15d-PGJ2 was independent of DP2 and PPARI3, and suggested that 15d-PGJ2 induced apoptosis through the novel specific binding sites of 15d-PGJ2 different from DP2 and PPARI3. To relate the cytotoxicity of 15d-PGJ2 to amyloidoses, we performed binding assay [3H]15d-PGJ2 and specified targets for 15d-PGJ2 associated with cytotoxicity. In the various cell lines, there was a close correlation between the susceptibilities to 15d-PGJ2 and fibrillar AI2. Specific binding sites of [3H]15d-PGJ2 were detected in rat cortical neurons and human bronchial smooth muscle cells. When the binding assay was performed in subcellular fractions of neurons, the specific binding sites of [3H]15d-PGJ2 were detected in plasma membrane, nuclear and cytosol, but not in microsome. A proteomic approach was used to identify protein targets for 15d-PGJ2 in the plasma membrane. By using biotinylated 15d-PGJ2, eleven proteins were identified as biotin-positive spots and classified into three different functional proteins: glycolytic enzymes (Enolase2, pyruvate kinase M1 (PKM1) and glyceraldehyde 3-phosphate dehydrogenase (GAPDH)), molecular chaperones (heat shock protein 8 and T-complex protein 1 subunit I-), cytoskeletal proteins (Actin I2, F-actin-capping protein, Tubulin I2 and Internexin I-). GAPDH, PKM1 and Tubulin I2 are AI2-interacting proteins. Thus, the present study suggested that 15d-PGJ2 plays an important role in amyloidoses not only in the central nervous system but also in the peripheral tissues.