title: Immunocytochemical localization of MAPKAPK-2 and Hsp25 in the rat temporomandibular joint.
abstract: One series of our research has shown an intense expression of immunoreaction for heat shock protein 25 (Hsp25) in various cellular elements in the rat temporomandibular joint (TMJ). This protein is the major substrate of mitogen-activated protein kinase-activated protein kinase-2 (MAPKAPK-2), which mediates an intracellular stress-activated signaling pathway to stimulate cytosolic actin reorganization under various stresses. The present study was undertaken to examine the localization of MAPKAPK-2 in the rat TMJ by immunocytochemical techniques. Furthermore, confocal microscopy with double staining was employed to demonstrate the colocalization of MAPKAPK-2 and Hsp25. Immunocytochemistry for MAPKAPK-2 showed an intense immunoreaction in the cytoplasm of the synovial lining cells, the endothelial cells, and the fibroblasts in the synovial membrane of the rat TMJ. Double immunostaining under a confocal microscope succeeded in demonstrating the colocalization of MAPKAPK-2 and Hsp25 immunoreactions in the cytoplasm of fibroblastic type B synoviocytes in the TMJ. On the other hand, the macrophage-like type A-cells expressed MAPKAPK-2 immunoreactions but lacked Hsp25 immunoreactivity. The cells in the articular disk and the chondrocytes in the maturative and hypertrophic layer of the mandibular cartilage also showed intense immunoreactions for MAPKAPK-2 and Hsp25. In addition to cytoplasmic localization, MAPKAPK-2 immunoreactions were found in the nucleus of some synovial lining cells, cells in the articular disk, and chondrocytes. Current observations imply the presence of the phosphorylation of Hsp25 via activated MAPKAPK-2 in the cytoplasm. MAPKAPK-2 and Hsp25 possibly participate in the induction of cytoskeletal changes to the various cellular elements in rat TMJ under normal conditions.
authors.affiliation: Division of Oral Anatomy, Department of Oral Biological Science, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan. nozawa@dent.niigata-u.ac.jp
authors.forename: Kayoko
authors.initials: K
authors.lastname: Nozawa-Inoue
authors.forename: Norio
authors.initials: N
authors.lastname: Amizuka
authors.forename: Akiko
authors.initials: A
authors.lastname: Suzuki
authors.forename: Takeyasu
authors.initials: T
authors.lastname: Maeda
mesh_terms: D000818:Animals; D014408:Biomarkers, Tumor / Q000276:immunology / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D004730:Endothelium, Vascular / Q000378:metabolism; D005347:Fibroblasts / Q000378:metabolism; D055551:HSP27 Heat-Shock Proteins; D006360:Heat-Shock Proteins / Q000276:immunology / Q000378:metabolism*; D007124:Immunoenzyme Techniques; D047908:Intracellular Signaling Peptides and Proteins; D009363:Neoplasm Proteins / Q000276:immunology / Q000378:metabolism*; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000276:immunology / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D013583:Synovial Membrane / Q000737:chemistry* / Q000648:ultrastructure; D013704:Temporomandibular Joint / Q000737:chemistry* / Q000648:ultrastructure; D000099190:MAP-Kinase-Activated Kinase 2
chemical_list: D014408:Biomarkers, Tumor; D055551:HSP27 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D047908:Intracellular Signaling Peptides and Proteins; D009363:Neoplasm Proteins; D017346:Protein Serine-Threonine Kinases; D000099190:MAP-Kinase-Activated Kinase 2; C486114:Hspb1 protein, rat