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Kalinina S, Freymueller C, Naskar N, von Einem B, Reess K, Sroka R, Rueck A. Bioenergetic Alterations of Metabolic Redox Coenzymes as NADH, FAD and FMN by Means of Fluorescence Lifetime Imaging Techniques. Int J Mol Sci 2021; 22:5952. [PMID: 34073057 PMCID: PMC8199032 DOI: 10.3390/ijms22115952] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Revised: 05/26/2021] [Accepted: 05/28/2021] [Indexed: 12/15/2022] Open
Abstract
Metabolic FLIM (fluorescence lifetime imaging) is used to image bioenergetic status in cells and tissue. Whereas an attribution of the fluorescence lifetime of coenzymes as an indicator for cell metabolism is mainly accepted, it is debated whether this is valid for the redox state of cells. In this regard, an innovative algorithm using the lifetime characteristics of nicotinamide adenine dinucleotide (phosphate) (NAD(P)H) and flavin adenine dinucleotide (FAD) to calculate the fluorescence lifetime induced redox ratio (FLIRR) has been reported so far. We extended the FLIRR approach and present new results, which includes FLIM data of the various enzymes, such as NAD(P)H, FAD, as well as flavin mononucleotide (FMN). Our algorithm uses a two-exponential fitting procedure for the NAD(P)H autofluorescence and a three-exponential fit of the flavin signal. By extending the FLIRR approach, we introduced FLIRR1 as protein-bound NAD(P)H related to protein-bound FAD, FLIRR2 as protein-bound NAD(P)H related to free (unbound) FAD and FLIRR3 as protein-bound NAD(P)H related to protein-bound FMN. We compared the significance of extended FLIRR to the metabolic index, defined as the ratio of protein-bound NAD(P)H to free NAD(P)H. The statistically significant difference for tumor and normal cells was found to be highest for FLIRR1.
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Affiliation(s)
- Sviatlana Kalinina
- Core Facility Confocal and Multiphoton Microscopy, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm, Germany; (N.N.); (K.R.)
| | - Christian Freymueller
- Laser-Forschungslabor, LIFE Center, University Hospital, LMU Munich, Fraunhoferstrasse 20, 82152 Planegg, Germany; (C.F.); (R.S.)
- Department of Urology, University Hospital, LMU Munich, Marchioninistraße 15, 81377 Munich, Germany
| | - Nilanjon Naskar
- Core Facility Confocal and Multiphoton Microscopy, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm, Germany; (N.N.); (K.R.)
| | - Bjoern von Einem
- Zentrum Biomedizinische Forschung (ZBMF), Department of Neurology, Ulm University, Helmholtzstrasse, 8/1, 89081 Ulm, Germany;
| | - Kirsten Reess
- Core Facility Confocal and Multiphoton Microscopy, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm, Germany; (N.N.); (K.R.)
| | - Ronald Sroka
- Laser-Forschungslabor, LIFE Center, University Hospital, LMU Munich, Fraunhoferstrasse 20, 82152 Planegg, Germany; (C.F.); (R.S.)
- Department of Urology, University Hospital, LMU Munich, Marchioninistraße 15, 81377 Munich, Germany
| | - Angelika Rueck
- Core Facility Confocal and Multiphoton Microscopy, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm, Germany; (N.N.); (K.R.)
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