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Schmalz M, Liang XX, Wieser I, Gruschel C, Muskalla L, Stöckl MT, Nitschke R, Linz N, Leitenstorfer A, Vogel A, Ferrando-May E. Dissection of DNA damage and repair pathways in live cells by femtosecond laser microirradiation and free-electron modeling. Proc Natl Acad Sci U S A 2023; 120:e2220132120. [PMID: 37307476 DOI: 10.1073/pnas.2220132120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Accepted: 05/08/2023] [Indexed: 06/14/2023] Open
Abstract
Understanding and predicting the outcome of the interaction of light with DNA has a significant impact on the study of DNA repair and radiotherapy. We report on a combination of femtosecond pulsed laser microirradiation at different wavelengths, quantitative imaging, and numerical modeling that yields a comprehensive picture of photon-mediated and free-electron-mediated DNA damage pathways in live cells. Laser irradiation was performed under highly standardized conditions at four wavelengths between 515 nm and 1,030 nm, enabling to study two-photon photochemical and free-electron-mediated DNA damage in situ. We quantitatively assessed cyclobutane pyrimidine dimer (CPD) and γH2AX-specific immunofluorescence signals to calibrate the damage threshold dose at these wavelengths and performed a comparative analysis of the recruitment of DNA repair factors xeroderma pigmentosum complementation group C (XPC) and Nijmegen breakage syndrome 1 (Nbs1). Our results show that two-photon-induced photochemical CPD generation dominates at 515 nm, while electron-mediated damage dominates at wavelengths ≥620 nm. The recruitment analysis revealed a cross talk between nucleotide excision and homologous recombination DNA repair pathways at 515 nm. Numerical simulations predicted electron densities and electron energy spectra, which govern the yield functions of a variety of direct electron-mediated DNA damage pathways and of indirect damage by •OH radicals resulting from laser and electron interactions with water. Combining these data with information on free electron-DNA interactions gained in artificial systems, we provide a conceptual framework for the interpretation of the wavelength dependence of laser-induced DNA damage that may guide the selection of irradiation parameters in studies and applications that require the selective induction of DNA lesions.
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Affiliation(s)
- Michael Schmalz
- Department of Physics, University of Konstanz, 78457 Konstanz, Germany
- Department of Biology, University of Konstanz, 78457 Konstanz, Germany
- Center for Applied Photonics, University of Konstanz, 78457 Konstanz, Germany
| | - Xiao-Xuan Liang
- Institute of Biomedical Optics, University of Lübeck, 23562 Lübeck, Germany
| | - Ines Wieser
- Department of Biology, University of Konstanz, 78457 Konstanz, Germany
| | - Caroline Gruschel
- Department of Biology, University of Konstanz, 78457 Konstanz, Germany
| | - Lukas Muskalla
- Department of Biology, University of Konstanz, 78457 Konstanz, Germany
| | | | - Roland Nitschke
- Life Imaging Center and Centre for Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany
| | - Norbert Linz
- Institute of Biomedical Optics, University of Lübeck, 23562 Lübeck, Germany
| | - Alfred Leitenstorfer
- Department of Physics, University of Konstanz, 78457 Konstanz, Germany
- Center for Applied Photonics, University of Konstanz, 78457 Konstanz, Germany
| | - Alfred Vogel
- Institute of Biomedical Optics, University of Lübeck, 23562 Lübeck, Germany
| | - Elisa Ferrando-May
- Department of Biology, University of Konstanz, 78457 Konstanz, Germany
- Center for Applied Photonics, University of Konstanz, 78457 Konstanz, Germany
- Department Enabling Technology, German Cancer Research Center, 69120 Heidelberg, Germany
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