Osteopontin/SPP1 (E9Z1D) Rabbit mAb #88742

Osteopontin is a highly phosphorylated secreted glycoprotein expressed in a variety of cell types. Osteopontin, encoded by the gene secreted phosphoprotein 1 (SPP1), was originally isolated and cloned from a rat osteosarcoma cell line (1). Osteopontin is a highly negatively charged protein that likely regulates extracellular matrix turnover and remodeling, both in bone and other tissue (2). Osteopontin also has three highly conserved receptor-binding domains, otherwise known as arginine-glycine-aspartic acid (RGD) domains. Binding of osteopontin to cell surface integrins likely activates cell signaling pathways that regulate cell proliferation, adhesion, invasion, migration, and fibrosis (3,4). Osteopontin may be regulated by posttranslational regulation, including phosphorylation, glycosylation, and proteolytic cleavage (5). Osteopontin is also linked to several human diseases. For example, cleaved osteopontin is higher in patients suffering with cirrhosis, a disease involving fibrosis of the liver (5). Its role in the brain is unclear, but SPP1 expression in microglia, the resident macrophages of the brain, is upregulated in mouse neurodegenerative disease models, including Alzheimer’s disease (6). Osteopontin’s role in disease likely involve its function as a key mediator of inflammatory responses (4).