Development of FRET Biosensors to Detect Kinase Activity in Living Cells
Jenny Okáľová, Undergraduate Research Assistant and CURO Honors Scholar
Dr. Neil J. Grimsey, Pharmaceutical and Biomedical Sciences, College of Pharmacy
G-protein-coupled receptors (GPCRs) are a group of over 800 membrane receptors that induce intracellular signaling cascades to interpret an array of external signals. The p38 mitogen-activated protein kinase (MAPK) pathway plays a key role in inflammatory responses found in many diseases. Our group discovered a family of GPCRs that regulate an atypical pathway for p38 activation in vascular cells. This atypical pathway specifically requires transforming growth factor-β (TGFβ) activated kinase-1 binding protein-1 (TAB1) to bind directly to p38, ultimately inducing p38 auto-activation via autophosphorylation. Anti-inflammatory therapeutics, targeting p38 have been widely underwhelming in clinical trials, mostly due to the broad physiological and pathophysiological pathway controlled by p38. Atypical p38 signalling appears to control just the pathophysiological pathway, suggesting that selective therapeutics that target atypical p38 signaling would be more effective. We have developed subcellular targeted fluorescence resonance energy transfer (FRET) biosensors, which consist of two fluorescent proteins, cyan fluorescent protein (CFP) and yellow fluorescent protein (YFP), joined by a linker peptide that changes shape upon p38 phosphorylation. These FRET biosensors enable real-time detection of p38 kinase activity at specific organelles by measuring changes in fluorescence ratios. When in close proximity CFP will donate energy to YFP changing the mean fluorescent from 485 to 527 nm. Through the use of endosome, nucleus, plasma membrane or cytosol targeting motifs we can assess the spatiotemporal ketetics of p38 activation. These studies represent a fundamental advancement to our knowledge or p38 activation. Additionally, future expansion of this platform will enable the screening of small molecule inhibitors of the pathway to regulate the progression of vascular inflammation.