Disrupting DNA G-quadruplex secondary structures to revert premature ageing

The underlying cause of aging remains one of the central mysteries of biology. Recent studies in several different biological models suggest that not only can the rate of aging be modified by environmental and genetic factors, but also that the aging clock can be reversed, restoring characteristics of youthfulness to aged cells and tissues.

DNA packaging and organisation in the cell nucleus has been shown to be significantly altered thorough ageing and some accelerating ageing disorders. Treatment with small molecule ligands can interfere with nuclear organisation and revert premature ageing sings in patient-derived cells. DNA non-canonical structures, in particular DNA G-quadruplex structures, have also shown to play a role in DNA packaging in some accelerating ageing syndromes. Indeed, mutation of specific G-quadruplex unwinding proteins and accumulation of these DNA structures have been shown to be the underlying cause of accelerating ageing syndromes, such as Cockayne syndromes. Targeting DNA and its structural feature to both further our understating in fundamental ageing biology and explore potential for therapeutic intervention of rare accelerating ageing disorders, is an unexplored opportunity that needs to be investigated.

Here, I will exploit a range of chemical biology tools to both investigate the fundamental role of DNA G-quadruplex structures in ageing biology, and explore the potential for therapeutic intervention of rare accelerating ageing syndromes by developing small molecules to target and disrupt these structures. Specifically, I will combine my experience with DNA G-quadruplex targeting and genome-wide mapping with a G-quadruplex selective live-cell imaging methodology that has been developed at the chemistry department of Imperial College London in collaboration with Dr. Vilar. I intend to address these specific questions:

1) What are the global changes in G-quadruplex prevalence genome-wide in accelerating ageing disorders and how is DNA packaging affected by their formation?

2) Can targeting and disrupting the G-quadruplexes that accumulate via ageing be used to revert the ageing phenotypes by restoring correct DNA packaging?

3) What are the dynamics in living cells, with respect to transcription and replication of DNA, that cause G-quadruplex formation thorough ageing?

Addressing these questions will further our understanding of the cause and effect relationship between DNA secondary structure formation and gene mis-regulation that cause ageing. This will pave the way towards the development of novel therapeutic agents which will ultimately increase health-span and treat rare accelerating ageing syndromes.

The aim of this project is to investigate the role of DNA packaging and DNA G-quadruplex secondary structure thorough ageing and accelerating ageing disorders.

G-quadruplexes are stable non-B DNA structures that form in guanine-rich DNA sequences, acting as knots and posing a threat for polymerases processivity during transcription and replication. G-quadruplex prevalence is highly dependent on chromatin architecture and recent findings have suggested that is the lack of resolution of DNA G-quadruplex structures, particularly those formed within the guanine-rich ribosomal DNA, the underlining cause of accelerating ageing in Cockayne syndrome. However, a clear cause-effect between the buildup of unresolved G-quadruplex structures, chromatin structure alteration and ageing biology remains yet to be elucidated. Investigating chromatin architecture variation thorough lifespan and targeting age-dependent DNA structural features to revert ageing phenotypes is an unexplored opportunity that could radically improve our understanding of ageing biology.

I will develop molecular probes to target, visualise and disrupt G-quadruplex structures to study their prevalence and influence on chromatin structures during ageing, leveraging on cell-models derived from patients affected by accelerating ageing disorders. The use of these probes, in combination with live-cell imaging techniques established at Imperial College and genome-wide mapping methodologies, will provide a unique platform to unravel the changes in chromatin architecture and DNA secondary structures formation that are linked with ageing. This work will pave the way towards the targeting of DNA and chromatin structural features to revert ageing associated conditions/phenotypes and treat rare accelerating ageing disorders.

The fundamental insights gained from this project will directly benefit scientists engaged in the study of nucleic acids function, gene regulation and ageing biology.

The deliverables will include insights into molecular targets and their cognate small molecule ligands, which will provide starting points for the development of therapeutic agents that act via G-quadruplex recognition. The tools and methodologies that will be developed will have broader use in future chemical biology approaches to study and interfere with ageing-dependent chromatin remodelling for both diagnostics and therapeutic applications.

Ultimately this research aims to further the knowledge of fundamental ageing biology for increasing health-span, having a direct impact on the wider public.