Periodic Reporting for period 1 - CRISTONE (Targeting CRISPR-based HDAC inhibitors to histones: a new tool for assessing mechanisms of class I HDAC inhibitors and developing chemical probes.)
Okres sprawozdawczy: 2017-09-01 do 2019-08-31
Given their nuclear localization, class I HDACs are among the key regulators responsible for epigenetic marks. Because several studies suggest that HDAC overexpression is linked to various diseases (such as cancer, cardiovascular, and neurodegenerative disorders), HDAC inhibition has emerged as an attractive therapeutic strategy to restore the histone acetylation balance. However, it is difficult to target drugs influencing histone-modifying enzymes to specific genomic loci. Moreover, HDAC inhibitors are known to have effects on the acetylation of other proteins. To have a direct effect on histone acetylation leading to transcriptional activation, HDAC inhibitors need to cross multiple cell membranes to reach the nucleus, avoid interaction with other lysine deacetylating enzymes, and avoid binding to HDAC isoforms located in the cytoplasm. Furthermore, the cellular effects of deacetylation inhibition on non-histone proteins need to be discriminated when trying to understand the effects of the HDAC inhibitors.
HDAC inhibitors are currently used in cancer therapy and have been considered as epigenetic drugs. However, whether the therapeutic effects of HDAC inhibitors are a direct consequence of changes in chromatin accessibility and transcription remains to be proven. Together with the drug localization issue, the specific mechanisms involved in therapeutic success/failure of HDAC inhibitors remain to be investigated. These mechanisms include i) the genome-wide transcriptional effects resulting from histone deacetylation in cells overexpressing specific HDAC isoforms; ii) the effects of isoform-dependent transcriptional regulation and their association with chromatin accessibility; and iii) the effects of HDAC inhibitory drugs that are a direct consequence of loci-related chromatin remodeling. This project aimed to address the issues mentioned above through an innovative approach, using HDAC-overexpressing cells, genome-wide studies, and a new epigenetic editing tool (CRISTONE) designed to bring an HDAC inhibitor to a specific locus using the guide-RNA-targeted CRISPR/dCas9 technology. This will be useful in the search for new cancer treatment, including epigenetic therapies.