Project description:The histone deacetylase HDAC3 is associated with the NCoR/SMRT co-repressor complex and its canonical function is in transcriptional repression, but it can also activate transcription. Here we show that the repressor and activator functions of HDAC3 can be genetically separated in Drosophila. A lysine substitution in the N-terminus (K26A) disrupts its catalytic activity and activator function, whereas a combination of substitutions (HEBI) abrogating the interaction with SMRTER enhance repressor activity beyond wild-type in the early embryo. We conclude that the critical functions of HDAC3 in embryo development involve catalytic-dependent gene activation and non-enzymatic repression by several mechanisms, including tethering of loci to the nuclear periphery.
Project description:The histone deacetylase HDAC3 is associated with the NCoR/SMRT co-repressor complex and its canonical function is in transcriptional repression, but it can also activate transcription. Here we show that the repressor and activator functions of HDAC3 can be genetically separated in Drosophila. A lysine substitution in the N-terminus (K26A) disrupts its catalytic activity and activator function, whereas a combination of substitutions (HEBI) abrogating the interaction with SMRTER enhance repressor activity beyond wild-type in the early embryo. We conclude that the critical functions of HDAC3 in embryo development involve catalytic-dependent gene activation and non-enzymatic repression by several mechanisms, including tethering of loci to the nuclear periphery.
Project description:The histone deacetylase HDAC3 is associated with the NCoR/SMRT co-repressor complex, and its canonical function is in transcriptional repression, but it can also activate transcription. Here, we show that the repressor and activator functions of HDAC3 can be genetically separated in Drosophila. A lysine substitution in the N terminus (K26A) disrupts its catalytic activity and activator function, whereas a combination of substitutions (HEBI) abrogating the interaction with SMRTER enhances repressor activity beyond wild type in the early embryo. We conclude that the crucial functions of HDAC3 in embryo development involve catalytic-dependent gene activation and non-enzymatic repression by several mechanisms, including tethering of loci to the nuclear periphery.
Project description:Histone deacetylase 3 (HDAC3) is unique among the HDAC superfamily of chromatin modifiers that silence transcription through enzymatic modification of histones, because interaction with nuclear receptor corepressors (NCoR1/2) is required for engagement of its catalytic activity. However, loss of HDAC3 also represses transcription. Here we report that, during lipopolysaccharide (LPS) activation of macrophages, the deacetylase activity of HDAC3 is selectively engaged at ATF3-bound enhancers that repress anti-inflammatory genes. By contrast, LPS-stimulated recruitment of HDAC3 to ATF2-bound sites without NCoR1/2 activates pro-inflammatory genes by a non-canonical mechanism whereby catalytically inactive HDAC3 stably interacts with p65. Consistent with this bimodal inflammatory modulation, deletion of HDAC3 in macrophages safeguards mice from lethal exposure to LPS, but this protection is not conferred by genetic or pharmacological abolition of HDAC3 catalytic activity. Thus, HDAC3 is a dichotomous transcriptional activator and repressor whose deacetylase-independent functions are critical in priming the innate immune system.
Project description:Histone deacetylase 3 (HDAC3) is unique among the HDAC superfamily of chromatin modifiers that silence transcription through enzymatic modification of histones, because interaction with nuclear receptor corepressors (NCoR1/2) is required for engagement of its catalytic activity. However, loss of HDAC3 also represses transcription. Here we report that, during lipopolysaccharide (LPS) activation of macrophages, the deacetylase activity of HDAC3 is selectively engaged at ATF3-bound enhancers that repress anti-inflammatory genes. By contrast, LPS-stimulated recruitment of HDAC3 to ATF2-bound sites without NCoR1/2 activates pro-inflammatory genes by a non-canonical mechanism whereby catalytically inactive HDAC3 stably interacts with p65. Consistent with this bimodal inflammatory modulation, deletion of HDAC3 in macrophages safeguards mice from lethal exposure to LPS, but this protection is not conferred by genetic or pharmacological abolition of HDAC3 catalytic activity. Thus, HDAC3 is a dichotomous transcriptional activator and repressor whose deacetylase-independent functions are critical in priming the innate immune system.
Project description:Histone deacetylase 3 (HDAC3) is unique among the HDAC superfamily of chromatin modifiers that silence transcription through enzymatic modification of histones, because interaction with nuclear receptor corepressors (NCoR1/2) is required for engagement of its catalytic activity. However, loss of HDAC3 also represses transcription. Here we report that, during lipopolysaccharide (LPS) activation of macrophages, the deacetylase activity of HDAC3 is selectively engaged at ATF3-bound enhancers that repress anti-inflammatory genes. By contrast, LPS-stimulated recruitment of HDAC3 to ATF2-bound sites without NCoR1/2 activates pro-inflammatory genes by a non-canonical mechanism whereby catalytically inactive HDAC3 stably interacts with p65. Consistent with this bimodal inflammatory modulation, deletion of HDAC3 in macrophages safeguards mice from lethal exposure to LPS, but this protection is not conferred by genetic or pharmacological abolition of HDAC3 catalytic activity. Thus, HDAC3 is a dichotomous transcriptional activator and repressor whose deacetylase-independent functions are critical in priming the innate immune system.