Genes, Vol. 11, Pages 356: Small Molecules Targeting H3K9 Methylation Prevent Silencing of Reactivated FMR1 Alleles in Fragile X Syndrome Patient Derived Cells

Genes, Vol. 11, Pages 356: Small Molecules Targeting H3K9 Methylation Prevent Silencing of Reactivated FMR1 Alleles in Fragile X Syndrome Patient Derived Cells Genes doi: 10.3390/genes11040356 Authors: Daman Kumari Nicholas Sciascia Karen Usdin In fragile X syndrome (FXS), expansion of a CGG repeat tract in the 5′-untranslated region of the FMR1 gene to >200 repeats causes transcriptional silencing by inducing heterochromatin formation. Understanding the mechanism of FMR1 silencing is important as gene reactivation is a potential treatment approach for FXS. To date, only the DNA demethylating drug 5-azadeoxycytidine (AZA) has proved effective at gene reactivation; however, this drug is toxic. The repressive H3K9 methylation mark is enriched on the FMR1 gene in FXS patient cells and is thus a potential druggable target. However, its contribution to the silencing process is unclear. Here, we studied the effect of small molecule inhibitors of H3K9 methylation on FMR1 expression in FXS patient cells. Chaetocin showed a small effect on FMR1 gene reactivation and a synergistic effect on FMR1 mRNA levels when used in combination with AZA. Additionally, chaetocin, BIX01294 and 3-Deazaneplanocin A (DZNep) were able to significantly delay the re-silencing of AZA-reactivated FMR1 alleles. These data are consistent with the idea that H3K9 methylation precedes DNA methylation and that removal of DNA methylation is necessary to see the optimal effect of...
Source: Genes - Category: Genetics & Stem Cells Authors: Tags: Article Source Type: research