Dr. Erdjan Salih, associate professor in the Department of Molecular & Cell Biology, has published his second paper of 2013 on the egg yolk protein phosvitin in the journal Development Biology. The new research has implications for evolution, ex vivo egg embryo development, and regenerative medicine and provides a new understanding of vitamin C (ascorbate). “The study culminated in providing paradigm shifting alternative mechanism to synthesis of collagen, hydroxyproline formation and general connective tissue and bone organogenesis which has been classically known for almost a century to occur through a mechanism involving only vitamin C (ascorbate),” said Dr. Salih.
The paper, “Novel bioactivity of phosvitin in connective tissue and bone organogenesis revealed by live calvarial bone organ culture models,” highlights yet-unknown biological functions of egg phosvitin:
- Phosvitin inhibits PTH-induced osteoclast formation/differentiation in live calvarial bone organ cultures.
- Phosvitin induced osteoblast differentiation, synthesis of collagens, and new bone formation, of particular interest in the fields of tissue engineering and regenerative medicine and dentistry.
- Biological functions of egg phosvitin mirror those of ascorbate as an anti-oxidant/reducing agent. Previously, ascorbate was thought to be the only molecule with such properties.
This last point makes phosvitin critical in ex vivo embryo development in birds, fish, and reptiles that lack Vitamin C. Dr. Salih explains:
“Similar to humans and primates, who are incapable of synthesizing vitamin C and hence completely dependent on nutritional intake of this crucial biomolecule, several species of birds, fish, and reptiles also lost the capacity to synthesize vitamin C. That indicates that their ex vivo egg embryos should never develop and hatch. Despite this, they do.”
Contributing to the paper are masters candidates Drs. Jess Liu and Drew Czernick, and Shin-Chun Lin; DSc student Dr. Abeer Alasmari; and Chair of Periodontology Dr. Serge Dibart.
“Dr. Salih’s recent work on the abundant egg yolk protein phosvitin suggests that it may play an anti-oxidant role similar to ascorbate in the development of collagen and bone in egg-laying species such as birds, reptiles, and fish,” said Professor and Chair in the Department of Molecular & Cell Biology Dr. David E. Levin. He continued, “This work reveals an important biological function for phosvitin and may explain how the skeletal system of these animals is able to develop in the absence of ascorbate. Dr. Salih’s contributions shed new light on the mechanisms underlying bone and connective tissue development. ”