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Updated: Aug 15, 2025

Laser Microirradiation to Study In Vivo Cellular Responses to Simple and Complex DNA Damage
Published on: January 31, 2018
Dynamics of endogenous PARP1 and PARP2 during DNA damage revealed by live-cell single-molecule imaging
Jyothi Mahadevan1, Asmita Jha2, Johannes Rudolph1
1Department of Biochemistry, University of Colorado Boulder, Boulder, CO 80309, USA.
Abstract:
PARP1 contributes to genome architecture and DNA damage repair through its dynamic association with chromatin. PARP1 and PARP2 (PARP1/2) recognize damaged DNA and recruit the DNA repair machinery. Using single-molecule microscopy in live cells, we monitored the movement of PARP1/2 on undamaged and damaged chromatin. We identify two classes of freely diffusing PARP1/2 and two classes of bound PARP1/2. The majority (>60%) of PARP1/2 diffuse freely in both undamaged and damaged nuclei and in the presence of inhibitors of PARP1/2 used for cancer therapy (PARPi). Laser-induced DNA damage results in a small fraction of slowly diffusing PARP1 and PARP2 to become transiently bound. Treatment of cells with PARPi in the presence of DNA damage causes subtle changes in the dynamics of bound PARP1/2, but not the high levels of PARP1/2 trapping seen previously. Our results imply that next-generation PARPi could specifically target the small fraction of DNA-bound PARP1/2.
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