In other words, Tsg tells a primitive cell to become a brain cell, instead of say, a skin cell. But it does this indirectly by preventing BMP from relaying its message to cells. Nerve cells, which include cells of the spine and brain, constitute what's called the neural system. In addition, the researchers find that Tsg and chordin, when present together, inhibit BMP more efficiently. So far, five of these inhibitors, also called antagonists, have been identified, including chordin, noggin and follistatin, the third of which was discovered by Hemmati Brivanlou's lab in 1994.
Twisted gastrulation marks the sixth.
In addition, BMPs and their inhibitors are important regulators of bone, cartilage and joint formation and thus may be used in the treatment of bone fractures or diseases associated with skeletal defects, like osteoporosis. Hemmati Brivanlou's results in frogs have been replicated in fruit flies and zebra fish by researchers at the University of California at Irvine and at the University of Wisconsin. All three groups report their findings in the March 22 issue of Nature . Originally identified in the fruit fly Drosophila, Twisted gastrulation was named after mutant fruit flies lacking the Tsg gene, which appeared twisted while gastrulating. Gastrulation is a crucial stage of embryogenesis when the three germ layers are established and the primary body axes are constructed.