U of MN researchers identify protein that causes cell nucleoli to disassemble

Protein used during cell development important in cloning technique

Researchers at the University of Minnesota have identified the protein responsible for disassembly of donor nucleoli in the context of nuclear cloning. Although it was already known that nucleoli, essential structures for protein synthesis, normally disassemble or disappear for a period of time in the early animal development and also during nuclear cloning, it was not known until this study what causes this phenomenon. Researchers hope the identification of the protein will lead to advances in cloning techniques and potential therapies. The study will be published in the journal Nature Cell Biology on Feb. 17 (www.nature.com/ncb)

“The nucleolus, one of the largest structures found within the cell’s nucleus, contains numerous proteins that have essential roles in cell biology, for cancer, stem cells, and aging,” said lead researcher Nobuaki Kikyo, M.D, Ph.D., assistant professor of medicine, Stem Cell Institute. “By understanding how the nucleolus disassembles and reassembles, we hope to learn more about normal cell development, the roles of specific proteins, and their impact on human diseases.”

In the cloning process, the genetic material is removed from an egg cell, and then the nucleus containing the genetic material from a somatic (or body-associated) cell is transplanted into the egg cell. Kikyo and his team recreated the normal procedure by mixing somatic cell nuclei and protein extract from frog eggs to purify the proteins responsible for nucleolar disassembly. Kikyo identified the proteins, FRGY2a and FRGY2b, that disassemble nucleoli without help of other proteins. The nucleoli are later reassembled as they normally would be.

“The study shows that FRGY2 proteins may be able to transform adult cells into something more like embryonic cells—young and actively proliferating cells with flexibility to turn into many types of cells,” said Kikyo. “Furthermore, this work shows that it is possible to dissect the very mysterious process – cloning – with a biochemical approach and identify key players in it.”