Executive Summary : | Altercation in chromatin structure caused by chromatin-modifying proteins, i.e. non-genetic influence in gene expression known as epigenetics, is emerging as a valued R&D area worldwide in both academia and industries. The histone modifications, acetylation or methylation (e.g. H3K9 methylation which is a target of this proposal and linked to acute leukemia) are considered excellent targets to study epigenetics. But, due to high complexities in chromatin architecture and dynamic context-specific cross-talk between chromatin and modifying protein partners, many of these areas are still largely unaddressed (gap areas) due to the difficulty in constructing appropriate experimental protocol. Moreover, the dynamic interactions caused by histone tails with modifying proteins are not usually visible in X-ray crystallography or electron microscopy that lead to difficulties in accessing these crucial interactions for drug discovery. This proposal aims to establish the systematic detection of such interactions that can be translated into inhibitors and molecular sensors. For this purpose, crucial epigenetic marker H3K9Me3+ and its ‘reader’ protein Hp1 are selected as targets due to their involvement in gene silencing. The basic objectives of this proposal are to develop organic molecule based fluorescent probe cum inhibitor of trimethylated histone (H3K9Me3+) which is a crucial epigenetic marker. The H3K9Me3+ tail is ‘read’ by chromodomain reader group of protein namely ‘heterochromatin protein 1 (Hp1)’ and their dynamic interaction results in the recruitment of other members of the cycle (e.g. writer G9a protein) that finally leads to gene silencing. As the reading of H3K9Me3+ by Hp1 has been linked to many malignancies including acute myeloid leukemia (AML), therefore systematic monitoring of the dynamic interaction through designed ligands is a valuable area that is still largely unexplored. The bottleneck of targeting the reading of H3K9Me3+ by Hp1 are: rapid dynamic interaction with cationic lysine tail which is challenging to monitor using X-ray/EM and the non-druggability issue of Hp1 for inhibitor design. However, this proposal aims to overcome the bottleneck using novel approach by ‘capping’ the H3K9Me3+ marker using organic macrocycles. The macrocycle calixarene can recognize cationic lysine from the protein surface and their selectivity can be specifically tuned by incorporating suitable moieties on the macrocyclic template. Based on these backgrounds, this proposal presents two different series of calixarene macrocycle based ligands: a series of fluorescent probes that can potentially monitor the dynamic interactions of H3K9Me3+-Hp1 couple and a series of inhibitors that can potentially inhibits the reading of H3K9Me3+ by Hp1 for the first time. |