[Role of T-cell leukemia translocation-associated gene (TCTA) protein in human osteoclastogenesis].

Synovial tissues of patients with rheumatoid arthritis (RA) include factors regulating bone resorption, such as receptor activator NF-kappaB ligand (RANKL), TNF-alpha, IL-6, IL-17, and IFN-gamma. However, in addition to these cytokines, other factors expressed in synovial tissues may play a role in regulating bone resorption. In 2009, we demonstrated that novel peptides from T-cell leukemia translocation-associated gene (TCTA) protein expressed in synovial tissues from patients with RA inhibit human osteoclastogenesis, preventing cellular fusion via the interaction between TCTA protein and a putative counterpart molecule. Only a few studies on the role of TCTA protein have been reported, including our report published in 2009. In the current review paper, we summarized papers on TCTA protein before 2009 and our recent findings.