A Highly Selective Mitochondria-Targeting Fluorescent K+ Sensor

• Published in: Angewandte Chemie International Edition Vol. 54; no. 41; pp. 12053 - 12057
• Main Authors: Kong, Xiangxing, Su, Fengyu, Zhang, Liqiang, Yaron, Jordan, Lee, Fred, Shi, Zhengwei, Tian, Yanqing, Meldrum, Deirdre R.
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 05-10-2015; WILEY‐VCH Verlag; Wiley Subscription Services, Inc
• Edition: International ed. in English
• Subjects: BODIPY; Boron Compounds - chemistry; Cations, Monovalent - analysis; Cations, Monovalent - metabolism; Cell Line; Fluorescent Dyes - chemistry; fluorescent probes; HeLa Cells; Humans; ion channels; Microscopy, Fluorescence - methods; Mitochondria; Mitochondria - metabolism; Optical Imaging - methods; potassium; Potassium - analysis; Potassium - metabolism; Potassium Channels - metabolism; BODIPY; potassium; mitochondria; fluorescent probes; ion channels
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.201506038

Regulation of intracellular potassium (K+) concentration plays a key role in metabolic processes. So far, only a few intracellular K+ sensors have been developed. The highly selective fluorescent K+ sensor KS6 for monitoring K+ ion dynamics in mitochondria was produced by coupling triphenylphosphonium, borondipyrromethene (BODIPY), and triazacryptand (TAC). KS6 shows a good response to K+ in the range 30–500 mM, a large dynamic range (Fmax/F0≈130), high brightness (ϕf=14.4 % at 150 mM of K+), and insensitivity to both pH in the range 5.5–9.0 and other metal ions under physiological conditions. Colocalization tests of KS6 with MitoTracker Green confirmed its predominant localization in the mitochondria of HeLa and U87MG cells. K+ efflux/influx in the mitochondria was observed upon stimulation with ionophores, nigericin, or ionomycin. KS6 is thus a highly selective semiquantitative K+ sensor suitable for the study of mitochondrial potassium flux in live cells.
A lamp to light the K: An intracellular mitochondria‐specific K+ sensor, KS6, was developed. KS6 shows a K+ response range of 30–500 mM, sensitive fluorescence enhancement (Fmax/F0≈130), high brightness (ϕf=14.4 % at 150 mM of K+), and insensitivity to both pH (in the range 5.5–9.0) and other metal ions under physiological conditions. KS6 is thus the first sensor that can be used for monitoring K+ ion flux in the mitochondria of live cells