This meeting on osteopontin (OPN, an integrin-binding secreted phosphoprotein) is intended to bring together investigators who do not normally interact because they are interested in different disciplines that normally meet separately. By means of this conference we expect to acquire new insights into OPN 's role in human development, physiology, and pathology. Major foci of OPN research include its role in tissue mineralization, in calcium homeostasis, in cell signalling, in cell attachment, and in nonspecific immunity. OPN is produced by cells that generate or remodel mineralized matrix: it promotes cell attachment to hydroxyapatite via its RGD alpha-v-beta3-binding domain and is involved in bone formation, bone remodeling and stone formation. OPN is likely important in defending against certain infections, particularly rickettsia and gram negative organisms. It is expressed at high levels by many types of cancer cells, and recent evidence suggests that its importance to the tumor cell may reside in its ability to suppress nitric oxide production. OPN expression correlates with smooth muscle migration and it is implicated in the development of atherosclerotic lesions and restenosis after angioplasty. It is found in most if not all secreted body fluids, and in some (urine, bile and milk) it may be critical to the suppression of the precipitation of calcium salts. OPN is found in cochlear fluid and may play a role there in calcium homeostasis. OPN is found in certain neurons, where it may be involved in some aspect o regulating signal transduction via nitric oxide. In the decidua and placenta it could mediate calcium transport between fetal and maternal tissues. OPN up- regulation in hypoxic cells suggests a role in shielding against ischemic injury, perhaps because of its ability to bind calcium. Prominent investigators working in these different areas have agreed to participate, and young investigators new to the field will be invited to present their research in poster format. To our knowledge there are no meetings scheduled that overlap with this proposed conference. Appended is the proposed agenda for this two-day meeting.
