Project description:Pioneer transcription factors (TFs) exhibit a special ability to bind to and open closed chromatin, facilitating engagement by other regulatory factors involved in gene activation or repression. Chemical probes are lacking for pioneer TFs, which has hindered their mechanistic investigation in cells. Here, we report electrophilic small molecules that stereoselectively and site-specifically bind the pioneer TF, FOXA1, at a cysteine (C258) within the forkhead DNA-binding domain. We show that these covalent ligands react with FOXA1 in a DNA-dependent manner and rapidly remodel its pioneer activity in prostate cancer cells reflected in redistribution of FOXA1 binding across the genome and directionally correlated changes in chromatin accessibility. Motif analysis supports a mechanism where the covalent ligands relax the canonical DNA binding preference of FOXA1 by strengthening interactions with suboptimal ancillary sequences in predicted proximity to C258. Our findings reveal a striking plasticity underpinning the pioneering function of FOXA1 that can be controlled by small molecules.
Project description:Pioneer transcription factors (TFs) exhibit a special ability to bind to and open closed chromatin, facilitating engagement by other regulatory factors involved in gene activation or repression. Chemical probes are lacking for pioneer TFs, which has hindered their mechanistic investigation in cells. Here, we report electrophilic small molecules that stereoselectively and site-specifically bind the pioneer TF, FOXA1, at a cysteine (C258) within the forkhead DNA-binding domain. We show that these covalent ligands react with FOXA1 in a DNA-dependent manner and rapidly remodel its pioneer activity in prostate cancer cells reflected in redistribution of FOXA1 binding across the genome and directionally correlated changes in chromatin accessibility. Motif analysis supports a mechanism where the covalent ligands relax the canonical DNA binding preference of FOXA1 by strengthening interactions with suboptimal ancillary sequences in predicted proximity to C258. Our findings reveal a striking plasticity underpinning the pioneering function of FOXA1 that can be controlled by small molecules.
Project description:Pioneer transcription factors (TFs) exhibit a special ability to bind to and open closed chromatin, facilitating engagement by other regulatory factors involved in gene activation or repression. Chemical probes are lacking for pioneer TFs, which has hindered their mechanistic investigation in cells. Here, we report electrophilic small molecules that stereoselectively and site-specifically bind the pioneer TF, FOXA1, at a cysteine (C258) within the forkhead DNA-binding domain. We show that these covalent ligands react with FOXA1 in a DNA-dependent manner and rapidly remodel its pioneer activity in prostate cancer cells reflected in redistribution of FOXA1 binding across the genome and directionally correlated changes in chromatin accessibility. Motif analysis supports a mechanism where the covalent ligands relax the canonical DNA binding preference of FOXA1 by strengthening interactions with suboptimal ancillary sequences in predicted proximity to C258. Our findings reveal a striking plasticity underpinning the pioneering function of FOXA1 that can be controlled by small molecules.
Project description:Pioneer transcription factors (TFs) exhibit a special ability to bind to and open closed chromatin, facilitating engagement by other regulatory factors involved in gene activation or repression. Chemical probes are lacking for pioneer TFs, which has hindered their mechanistic investigation in cells. Here, we report electrophilic small molecules that stereoselectively and site-specifically bind the pioneer TF, FOXA1, at a cysteine (C258) within the forkhead DNA-binding domain. We show that these covalent ligands react with FOXA1 in a DNA-dependent manner and rapidly remodel its pioneer activity in prostate cancer cells reflected in redistribution of FOXA1 binding across the genome and directionally correlated changes in chromatin accessibility. Motif analysis supports a mechanism where the covalent ligands relax the canonical DNA binding preference of FOXA1 by strengthening interactions with suboptimal ancillary sequences in predicted proximity to C258. Our findings reveal a striking plasticity underpinning the pioneering function of FOXA1 that can be controlled by small molecules.
Project description:Pioneer transcription factors (TFs) exhibit a special ability to bind to and open closed chromatin, facilitating engagement by other regulatory factors involved in gene activation or repression. Chemical probes are lacking for pioneer TFs, which has hindered their mechanistic investigation in cells. Here, we report electrophilic small molecules that stereoselectively and site-specifically bind the pioneer TF, FOXA1, at a cysteine (C258) within the forkhead DNA-binding domain. We show that these covalent ligands react with FOXA1 in a DNA-dependent manner and rapidly remodel its pioneer activity in prostate cancer cells reflected in redistribution of FOXA1 binding across the genome and directionally correlated changes in chromatin accessibility. Motif analysis supports a mechanism where the covalent ligands relax the canonical DNA binding preference of FOXA1 by strengthening interactions with suboptimal ancillary sequences in predicted proximity to C258. Our findings reveal a striking plasticity underpinning the pioneering function of FOXA1 that can be controlled by small molecules.
Project description:We report that the winged helix transcription factor FOXA1 is unexpectedly associated with components of single and double stranded-DNA repair complexes. Biochemical studies and high-throughput approaches validated the hierarchical composition of this FOXA1-nucleated machinery and revealed the dependency on FOXA1 for global targeting of the key repair polymerase POLB. Genome-wide DNA methylomes at single-base resolution demonstrated that FOXA1-DNA repair complex is functionally linked to DNA demethylation in a lineage specific fashion. Loss-of-function studies indicate that a significant portion of FOXA1-bound regions display localized reestablishment of methylation and that the subsets with most consistent hypermethylation are represented by active promoters and enhancers that also exhibit the greatest depletion of POLB following FOXA1 removal. Consistently, forced expression of FOXA1 commits its binding sites to an active DNA demethylation in a POLB dependent manner. Finally, we showed that FOXA1-associated DNA demethylation is tightly coupled with genomic targeting of estrogen receptor and estrogen responsiveness. Together, our results link FOXA1-associated DNA demethylation to its transcriptional pioneering.
Project description:We report that the winged helix transcription factor FOXA1 is unexpectedly associated with components of single and double stranded-DNA repair complexes. Biochemical studies and high-throughput approaches validated the hierarchical composition of this FOXA1-nucleated machinery and revealed the dependency on FOXA1 for global targeting of the key repair polymerase POLB. Genome-wide DNA methylomes at single-base resolution demonstrated that FOXA1-DNA repair complex is functionally linked to DNA demethylation in a lineage specific fashion. Loss-of-function studies indicate that a significant portion of FOXA1-bound regions display localized reestablishment of methylation and that the subsets with most consistent hypermethylation are represented by active promoters and enhancers that also exhibit the greatest depletion of POLB following FOXA1 removal. Consistently, forced expression of FOXA1 commits its binding sites to an active DNA demethylation in a POLB dependent manner. Finally, we showed that FOXA1-associated DNA demethylation is tightly coupled with genomic targeting of estrogen receptor and estrogen responsiveness. Together, our results link FOXA1-associated DNA demethylation to its transcriptional pioneering.