James Darnell is an American molecular cell biologist distinguished for his work to understand processes in human cells that mediate and regulate gene expression. He discovered an important cellular system that recognises changes in external circulating levels of molecules and effects rapid activation of nuclear genes in response.
Beginning his research career studying poliovirus replication in mammalian cells, James was consumed by curiosity to address the question of how genes are regulated in animal cells. He made important discoveries — in collaboration with others — about the processing of nuclear RNA into messenger RNA, the ‘instruction book’ for building proteins.
James discovered STAT proteins, which respond to external signals called cytokines that attach to the cell surface. This leads to the alteration and activation of STATs, which move into the nucleus and bind DNA to activate target genes. STAT signalling is now known to contribute to a wide variety of vital developmental and homeostatic events in animals.