Background Huntington’s disease (HD) is progressive neurodegenerative disorder caused by the mutation in the huntingtin gene giving rise to mutated form of huntingtin protein (mHTT). Recent findings suggest that mHTT may also affect DNA damage response. However, it is not clear whether mHTT compromises detection of double strand DNA breaks (DSBs) or repair mechanism itself.
Aims The main aim of this study is to characterise DSBs response in primary fibroblasts isolated from transgenic minipig HD model.
Methods In order to study DNA damage we monitored kinetics of γH2AX and 53BP1 by immunofluorescence in primary dermal fibroblasts isolated from wild-type and HD transgenic minipigs of age 8, 24 and 48 months after treatment with radiomimetic drug neocarzinostatin (NCS). The quantitative analysis of confocal images was done by FindFoci algorithm (available as an ImageJ plugin).
Results Analysis showed decreased number of γH2AX foci in 24 and 48 months HD fibroblasts after NCS treatment compared to wild-type fibroblasts, suggesting that the ability to recognise new DSBs in HD fibroblasts is compromised. Moreover, we observed that NCS treatment in 8 and 48 months fibroblasts caused significantly higher number of 53BP1 foci shortly after DSBs induction suggesting that the DSBs repair in HD fibroblasts is impaired.
Conclusion Taken together, we found that HD fibroblasts exhibit compromised ability to recognise new DSBs and that significant change in dynamics of loading repair factor 53BP1 is present. These data confirmed that transgenic minipig HD model exhibits similar defects in DSBs response as human patients and mouse models.
Acknowledgement This study was supported by CHDI Foundation (A-5378) and by National Sustainability Programme, project number LO1609 (Czech Ministry of Education, Youth and Sports).
The research leading to these results has received funding from the Norwegian Financial Mechanism 2009–2014 and the Ministry of Education, Youth and Sports under Project Contract no. MSMT-28477/2014 (project ID 7F14308).
- DSBs response
- transgenic minipig HD model