Antisense oligonucleotide-based inhibition of DNA damage response at telomeres improves the detrimental phenotypes of human accelerated ageing
IFOM Foundation - FIRC Institute of Molecular Oncology Foundation, Milan, Italy
Present address: Australian Institute for Bioengineering and Nanotechnology, University of Queensland, Queensland, Australia
So far DNA damage response (DDR) pathways have been studied as a proteins-only network. Recently, the role of RNA has emerged as a novel key regulator of DDR pathways. We have shown that damage-induced long non-coding RNAs (dilncRNAs) are generated at sites of DNA double-strand breaks (DSBs) and are processed into shorter DNA damage response RNAs (DDRNAs) (Francia et al Nature 2012, Michelini et al Nature Cell Biology 2017). These RNAs, by interacting and retaining DDR protein factors at the lesion, are key to mount a full DDR and their inhibition by sequence-specific antisense oligonucleotides (ASOs) allows site-specific DDR inhibition. Dysfunctional telomeres resemble DSBs and telomere deprotection upon TRF2 knockout or inhibition leads to the transcription of telomeric non-coding RNAs (tncRNAs). Inhibition of such tncRNAs by ASOs prevents DDR activation at dysfunctional telomeres in cultured cells and in vivo in mice (Rossiello et al. Nature Communications 2017, Nguyen et al. Nature Protocols 2018). The ability to specifically inhibit DDR activation at telomeres allows for the first time to determine the contribution of telomeric DDR in physiological and pathological contexts, including accelerated ageing conditions. Hutchinson-Gilford Progeria Syndrome (HGPS) is caused by the expression of a mutant form of lamin A, called progerin, that leads to telomere dysfunction and DDR activation. Presently, the contribution of telomeric dysfunction and consequent DDR activation in HGPS pathogenesis is unknown. We will show that progerin-induced telomere dysfunction induces the transcription of tncRNAs. Their functional inhibition by telomeric ASOs prevents full DDR activation, proliferative defects and premature cellular senescence in various HGPS cell systems. We also show in vivo that tASO treatment significantly improves the detrimental phenotypes of a transgenic HGPS mouse model.