Examining O-xylosyltransferase in Drosophila

O-xylosyltransferase (Oxt) is a transmembrane glycosyltransferase that initiates the first step in heperan and chrondroitin sulfate (HS and CS) proteoglycan biosynthesis. HSPGs and CSPGs are abundant in the extracellular environment of many tissues, such as articular cartilage in humans. In this tissue, HSPGs and CSPGs are essential regulation of signaling pathways that maintain tissue homeostasis. If homeostasis is not preserved, joint tissue will degrade and osteoarthritis (OA) can occur. Elevated levels of circulating Oxt have been detected in human OA patients suggesting shed Oxt may have an extracellular function. Little is known about Oxt behavior or function once it is released from the plasma membrane. Cell culture experiments have shown that Oxt, normally located in the Golgi and the endoplasmic reticulum (ER), can be shed by proteolysis activity and move into the media. It is likely that the same result will be observed in vivo. The overall aim of this project is to determine if Oxt released fro...