Project description:Biochemical crosstalk between two or more histone modifications is often observed in epigenetic enzyme regulation but its functional significance in cells has been difficult to discern. Prior enzymatic studies have revealed that Lys14 acetylation of histone H3 can inhibit Lys4 demethylation by lysine specific demethylase 1 (LSD1). Here we have engineered a mutant form of LSD1, Y391K, which renders the nucleosome demethylase activity of LSD1 insensitive to Lys14 acetylation. Y391K LSD1 knockin cells show increased repression of a set of genes associated with cellular adhesion. Chromatin profiling revealed that the cis-regulatory regions of these silenced genes display a higher level of H3 Lys14 acetylation than the baseline in unedited, parental cells. Y391K LSD1 knockin cells show diminished H3 mono-methyl Lys4 in the vicinity of these silenced genes, consistent with a role for enhanced LSD1 demethylase activity in these regions. These findings illuminate the functional consequences of disconnecting histone modification crosstalk for a key epigenetic enzyme in gene and chromatin regulation.
Project description:Biochemical crosstalk between two or more histone modifications is often observed in epigenetic enzyme regulation but its functional significance in cells has been difficult to discern. Prior enzymatic studies have revealed that Lys14 acetylation of histone H3 can inhibit Lys4 demethylation by lysine specific demethylase 1 (LSD1). Here we have engineered a mutant form of LSD1, Y391K, which renders the nucleosome demethylase activity of LSD1 insensitive to Lys14 acetylation. Y391K LSD1 knockin cells show increased repression of a set of genes associated with cellular adhesion. Chromatin profiling revealed that the cis-regulatory regions of these silenced genes display a higher level of H3 Lys14 acetylation than the baseline in unedited, parental cells. Y391K LSD1 knockin cells show diminished H3 mono-methyl Lys4 in the vicinity of these silenced genes, consistent with a role for enhanced LSD1 demethylase activity in these regions. These findings illuminate the functional consequences of disconnecting histone modification crosstalk for a key epigenetic enzyme in gene and chromatin regulation.
Project description:We report changes in ER and GR binding profiles genome-wide upon co-treatment with Dex and E2 when compared to Dex or E2 treatments alone. We examine ER and GR binding under four different treatments (unt, Dex, E2, and Dex + E2).
Project description:KDM1A-mediated H3K4 demethylation is a well-established mechanism underlying transcriptional gene repression, but its role in gene activation is less clear. Here we report a critical function and novel mechanism of action of KDM1A in glucocorticoid receptor (GR)-mediated gene transcription. Biochemical purification of the nuclear GR complex revealed KDM1A as an integral component. In cell-free assays, GR modulates KDM1A-catalyzed H3K4 progressive demethylation by limiting loss of H3K4me1. Similarly, in cells KDM1A binds to most GR binding sites where it removes preprogrammed H3K4me2 but leaves H3K4me1 untouched. Blocking KDM1A catalytic activity prevents H3K4me2 removal, severely impairs GR binding to chromatin, and dysregulates GR-targeted genes. Taken together, these data suggest KDM1A-mediated H3K4me2 demethylation at GRBSs promotes GR binding and plays an important role in glucocorticoid-induced gene transcription, offering a new mechanism contributing to nuclear receptor mediated gene activation.
Project description:We report changes in ER and GR binding profiles genome-wide upon co-treatment with Dex and E2 when compared to Dex or E2 treatments alone.
Project description:Long-term glucocorticoid treatment in multiple myeloma is hampered by deleterious side effects. Glucocorticoids bind to the glucocorticoid receptor (GR), which is a crucial drug target because its activation triggers myeloma cell death. The mineralocorticoid receptor (MR) is a closely related nuclear receptor but its impact on glucocorticoid responsiveness in myeloma is unknown. Here we reveal a functional crosstalk between GR and MR that culminates in improved myeloma cell killing. We show that the GR agonist Dexamethasone (Dex) downregulates MR levels in a GR-dependent way in myeloma cells. Co-treatment of Dex with the MR antagonist Spironolactone enhances Dex-induced cell killing in (primary) myeloma cells. The crosstalk is further evidenced by an endogenous interaction between GR and MR in myeloma cells that is ligand-inducible and by a distinctive gene expression profile. Our study demonstrates that GR-MR crosstalk is therapeutically relevant in myeloma and presents a glucocorticoid-based dose-reduction strategy that could diminish glucocorticoid-related side effects in patients.
