Fluorescent Protein-Based Biosensors and Their Clinical Applications - Progress in Molecular Biology and Translational Science - page 313

Abstract
Green fluorescent protein and its relatives have shed their light on a wide range of
biological problems. To date, with a color palette consisting of fluorescent proteins with
different spectra, researchers can “ paint ” living cells as they desire. Moreover, sophisti-
cated biosensors engineered to contain single or multiple fluorescent proteins, includ-
ing FRET-based biosensors, spatiotemporally unveil molecular mechanisms underlying
physiological processes. Although such molecules have contributed considerably to
basic research, their abilities to be used in applied life sciences have yet to be fully
explored. Here, we review the molecular bases of fluorescent proteins and fluorescent
protein-based biosensors and focus on approaches aimed at applying such proteins to
the clinic.
1. INTRODUCTION
Green fluorescent protein (GFP) is a fluorescent protein that was orig-
inally isolated from the luminous organ of the jellyfish Aequorea victoria by
Dr. Osamu Shimomura. 1 It is probably no exaggeration to say that GFP
has continued to shed light on cell biology since its cDNA was isolated in
1992. 2 The main reason why GFP is so revolutionary is its ability to be easily
introduced into cells by transfection, which is dependent on a key feature
of GFP, that is, its ability to generate the intrinsic chromophore without
cofactors or enzymatic components. 3
It was not long before color variants of GFP were developed and fluo-
rescent proteins were distributed worldwide. 3 Following these innovations,
fluorescent proteins were isolated from organisms other than jellyfish
(although mainly from Cnidaria ) 4 ; together, these proteins constitute a pal-
ette that can provide colorful decoration to living cells. Not only do these
tools serve as markers of protein localization but they can also be used for
monitoring intracellular environments under various physiological condi-
tions. In addition, via use of the principles of reconstitution of protein frag-
ments or a physicochemical energy transfer phenomenon, protein-protein
interactions or conformational changes can be monitored, widening the po-
tential applications of fluorescent proteins.
More recently, our research group has begun to further expand the po-
tential of fluorescent proteins from basic biological research to the clinic. 5 As
in basic research, biosensors engineered on the basis of fluorescent proteins
have provided solutions for hitherto arduous tasks and may offer innovative
technological advances in clinical laboratory examinations when used in