Signal proteins inside a cell are called kinases. Each kinase consists of a long chain of atoms with different responsibilities; some atoms receive messages and direct the kinase to a specific location, while other atoms deliver the message. The work of a kinase is both complex and crucial and may spell the difference between health and disease. Now, Stanford bioengineers have invented a new technique for observing and reporting on the behavior of kinases as they labor within cells. The reason this new process is important is it will speed the development of new drugs based on kinase irregularities, two dozen of which already exist or are in development.
"Cancers can occur when a kinase inappropriately tells a cell to 'grow, grow, grow'," said Dr. Markus Covert, an assistant professor of bioengineering at Stanford and lead author of the new study. "The reverse can also be true, if a cell reaches what should be the end of its normal life-span but the kinase never says 'die, die, die.'” He further explained the new technique has enabled him and his colleagues to “observe multiple kinases functioning in living cells, which is something no one else has ever seen.”
To track the activity of the kinase signaling system in living cells, Dr. Sergi Regot, a postdoctoral scholar in Covert's lab, dreamed up the idea of a Kinase Translocation Reporter (KTR). He tagged the KTRs with a fluorescent protein so he could track their locations inside the cell and added a molecular switch to indicate whether the kinase was active or inactive. Over a year’s laboratory work enabled the team of researchers to perfect the technique, enabling them to see how specific levels of kinase activity either promote health or trigger disease inside a living cell.
So far Covert and his team have successfully applied the KTR approach to five kinases, and they believe it is possible to extend KTR technology to others. "Imagine you wanted to discover a new drug," Covert said. "You could throw KTRs into a cell culture and observe kinase activity under different conditions." Covert explained how researchers might use KTRs to observe and compare kinase activity in healthy versus diseased cells and, after introducing an experimental drug, continue to watch, by way of KTRs, how the proposed remedy affects the living cell. Compared to former methods involving multiple, painstakingly-grown cell cultures, the new technique is swift and efficient and should enable discovery and production of more, better drugs.
Source: Regot S, Hughey JJ, Bajar BT, Carrasco S, Covert MW. High-sensitivity measurements of multiple kinase activities in live single cells. Cell. 2014.