The researchers, Howard Hughes Medical Institute investigator Joan A. Steitz and Yale University School of Medicine colleague Imed-Eddine Gallouzi, described their findings in the November 30, 2001, issue of Science.
Export of mRNA from the nucleus to the cytoplasm takes place through a pore complex in the membrane of the nucleus. Export is believed to involve the attachment of an adapter protein to the mRNA. The adapter protein binds both the mRNA and a receptor that in turn interacts with pores in the nuclear membrane and thus serves as a shuttle to enable export of mRNA. Steitz and Gallouzi reported that they had selectively blocked the action of several adapter proteins. The function of one such adapter, called HuR, was explored in detail.
The problem has been that many different proteins have been identified that bind to mRNA in the nucleus and that are known to shuttle to the cytoplasm, said Steitz Many of them are very abundant, and bind virtually every message in the cell. Also, every mRNA in the nucleus is coated with all sorts of RNA-binding proteins.
So, what seems almost miraculous about these results is that by just inhibiting the interactions with the receptor of one or a couple of these adapters, we can keep the particular mRNA entirely in the nucleus. Thats quite remarkable, and something we still dont understand.
Steitz and her colleagues had begun studying the HuR protein because it is involved in preventing the degradation of mRNA. However, evidence was also mounting that the RNA-binding prote
Contact: Jim Keeley
Howard Hughes Medical Institute