Humans, corals share same cellular self-destruction mode

New York: What do humans and corals have in common? Both share a 500-million-year-old biomechanical pathway that tells cells when to die.

It might sound scary but killing off defective cells is essential to keeping an organism healthy. "Corals are actually much more similar to humans than we ever realised. We have a lot to learn from corals about our own immune system," said Steven Quistad, graduate student, working for the lab of US-based San Diego State University virologist Forest Rohwer. While analysing the proteins of the coral Acropora digitifera and matching them against human proteins, Quistad found a peculiar similarity. Both had receptor proteins that receive signals from another protein called tumor necrosis factor (TNF). When TNF proteins attach themselves to a cell`s TNF receptors, the cell launches into an orderly self-destruct mode. The process, known as apoptosis, plays a crucial role in cellular health. Researchers took the human version of a TNF protein and exposed it to a coral`s TNF receptors. They saw evidence that the coral cell was breaking down within 10 minutes of exposure to human TNF. Human TNF set into motion programmed cell death in corals. Next, researchers wondered if coral TNF proteins would trigger apoptosis in human cells. They coaxed E. coli bacteria to express the same. Sure enough, apoptosis occurred in the human cells. "The findings suggest that the pathway by which TNF triggers apoptosis is old. Extremely old," Quistad said. It will help biologists advance their understanding of the early evolution of multi-cellular life and medical researchers to develop new drugs to fight diseases like cancer, researchers explained. The study was published in the journal Proceedings of the National Academy of Sciences.