Our Research

 

 DNA damage and mitochondria feedback loop

Our work has shown that telomeres and mitochondria play an important role in cellular ageing.

We have demonstrated the existence of a positive feedback loop between telomeres and Reactive Oxygen Species produced in mitochondria. This mechanism is essential for keeping senescent cells in a permanent cell cycle arrest, through continuous generation of DNA damage and activation of a DNA damage response.

We have shown that this feedback loop is important in vivo, since mice with dysfunctional telomeres (Late generation TERC-/-) showed a p21 dependent increase in ROS production and DNA damage (Passos et al. 2010)

Also, our work has demonstrated that telomere shortening can be accelerated due to faulty mitochondria (Passos et al. 2007) and that telomeres are particularly susceptible to ROS-induced damage and that this damage is irreparable (Hewitt et al. 2012).

We hypothesise that telomeres may act as sensors of stress in cells and this may occur irrespectively of telomere length. Research by our group indicates that telomeres can activate a DNA damage response as a response to stress, irrespectively of telomere length (Hewitt et al. 2012). We have also shown that factors such as chronic low grade inflammation can accelerate telomere dysfunction in mice (Jurk et al. 2014).


Se animation video narrated by Rhys Anderson describing some of our work:

https://www.youtube.com/watch?v=SR3MJYbOmKo

 


The team is now exploring the signalling pathways between the nucleus and mitochondria and its role in cellular ageing in vitro and in vivo. We are also investigating how these processes impact on age-dependent tissue degeneration and age-related diseases (Correia-Melo et al. 2014).

For this our lab is equipped with state-of-the-art equipment and expertise in telomere biology, including measurements of telomere dysfunction by Immuno-FISH in cultured cells and tissues from mice, humans and zebrafish, telomere length by Q-FISH and Real-Time PCR, analysis and visualisation of telomere-loops by STORM microscopy (Ylli Doksani et al. 2013), Live-cell imaging of telomeres and DNA damage response proteins dynamics in mammalian cells. We have extensive expertise in assessing mitochondrial function and ROS generation using fluorescent dyes by both flow cytometry and confocal microscopy, Seahorse analysis of mitochondrial function in cells and isolated mitochondria, measurements of Amplex Red fluorescence in isolated mitochondria, cultured cells and tissues.

Finally, we are experts in characterising senescence in vitro (we use a number of different models of senescence including oxidative stress, genotoxic damage, oncogene and replicatively-induced senescence) and in vivo (we use ageing mice models including TERC-/- and NF-kB1-/-).