A Fragment-based Approach to Identify Small Molecule Inhibitors of Shelterin Complex Assembly
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Embargo End Date
2025-04-07
ICR Authors
Authors
Casale, G
Document Type
Thesis or Dissertation
Date
2024-10-07
Date Accepted
Abstract
Shelterin is a six-subunit complex that binds to telomeres where it protects the chromosome ends
from an unwarranted activation of the DNA damage response and, in collaboration with telomerase,
mediates homeostatic telomere length maintenance. Restored telomere length homeostasis is a
hallmark of cancer initiation and progression, which makes shelterin a promising therapeutic target.
The aim of this thesis work is to use a fragment-based screening approach to find small-molecule
inhibitors of the protein-protein interactions driving shelterin complex assembly. Such inhibitors would
be useful tool compounds to dissect the precise functions of subunits and subcomplexes of shelterin
and may, depending on their cellular impact, form the foundation for the development of novel
therapeutic anti-cancer strategies. The particular focus of this thesis is on the TRF homology (TRFH)
domain of the shelterin subunit TRF1 (TRF1 TRFH). This domain is crucial for the recruitment of
TRF1 to shelterin through a domain-peptide interaction with a flexible region of TIN2 (TIN2 TBM), the
central scaffold of the shelterin complex. Using a combination of ligand-observed (LO-)NMR and Xray
crystallography fragment screening, a series of fragment hits were found to bind at the TIN2 TBM
binding site of TRF1 TRFH. A novel crystal system of TRF1TRFH was discovered that allowed
routine soaking of fragment hits into the TIN2TBM binding site of TRF1 TRFH. Using a structurebased
in silico approach, further analogues were designed, including compound 58. This compound
was shown to bind to TRF1 TRFH with a KD of 29 μM (95% CI: 20 – 41 μM), as measured by the LONMR
R2KD assay, and displaced a TIN2TBM probe with an IC50 of 74 ± 20 μM in a fluorescence
polarisation assay. The hit matter and the TRF1-TIN2 hot spot characterised in this thesis will serve
as a starting point for the structure-guided development of potent inhibitors of TRF1 protein-protein
interactions to disrupt shelterin complex assembly.
Citation
2024
DOI
Source Title
Publisher
Institute of Cancer Research (University Of London)
ISSN
eISSN
Collections
Research Team
Struct Biol Cell Signal