Project description:MAF1 represses Pol III-mediated transcription by interfering with TFIIIB and Pol III. Herein, we found that MAF1 knockdown induced CDKN1A transcription and chromatin looping concurrently with Pol III recruitment. Simultaneous knockdown of MAF1 with Pol III or BRF1 (subunit of TFIIIB) diminished the activation and looping effect, which indicates that recruiting Pol III was required for activation of Pol II-mediated transcription and chromatin looping. ChIP analysis after MAF1 knockdown indicated enhanced binding of Pol III and BRF1, as well as of CFP1, p300, and PCAF, which are factors that mediate active histone marks, along with the binding of TBP and POLR2E to the CDKN1A promoter. Simultaneous knockdown with Pol III abolished these regulatory events. Similar results were obtained for GDF15. Our results reveal a novel mechanism by which MAF1 and Pol III regulate the activity of a protein-coding gene transcribed by Pol II.
Project description:MAF1 represses Pol III-mediated transcription by interfering with TFIIIB and Pol III. Herein, we found that MAF1 knockdown induced CDKN1A transcription and chromatin looping concurrently with Pol III recruitment. Simultaneous knockdown of MAF1 with Pol III or BRF1 (subunit of TFIIIB) diminished the activation and looping effect, which indicates that recruiting Pol III was required for activation of Pol II-mediated transcription and chromatin looping. ChIP analysis after MAF1 knockdown indicated enhanced binding of Pol III and BRF1, as well as of CFP1, p300, and PCAF, which are factors that mediate active histone marks, along with the binding of TBP and POLR2E to the CDKN1A promoter. Simultaneous knockdown with Pol III abolished these regulatory events. Similar results were obtained for GDF15. Our results reveal a novel mechanism by which MAF1 and Pol III regulate the activity of a protein-coding gene transcribed by Pol II. Knockdown assay was performed using siRNA obtained from MISSION®RNA (Sigma). Inhibition of expression of Pol III (SASI_Hs01_00046568) and MAF1 (SASI_Hs01_00135954) was achieved by transfection with LipofectamineTM RNAiMax (Invitrogen) according to the manufacturer’s protocol. MISSION® siRNA Universal Negative Control (Sigma) was used as knockdown control. Cells were transfected in serum-free medium. After 8 h, the siRNA containing medium was replaced with complete medium.
Project description:In higher eukaryotes, an important mechanism to tune translation in different tissues and conditions is mTORC1-dependent regulation of tRNAs transcription by RNA polymerase III (Pol III), as the relative amount of tRNAs tightly coordinates with the translational needs of the cell. mTORC1 contributes to regulate protein synthesis through its direct substrate MAF1, which functions as a negative regulator of Pol III transcription in response to stimuli such as serum starvation or rapamycin treatment. Here, we applied ChIP-seq to examine the Pol III occupancy profile in human fibroblasts and report evidence of a genome wide, MAF1-dependent coordinated response to favorable or stress growth conditions. Strikingly, while a set of genes is extremely responsive in terms of Pol III binding, other genes are mostly unperturbed, yet associated with transcriptionally engaged polymerases as revealed by nascent EU-labeled RNA-seq (neuRNA-seq). As shown by DamIP-seq, the responsiveness of a subset of genes is tightly connected to the rapid and transient interaction of MAF1 with DNA-bound Pol III. We performed duplicate ChIP-seq experiments for the Rpc4 (POLR3D) subunit of RNA polymerase III in IMR90hTert cells grown in the presence of fetal bovine serum (FBS), serum starved (SS), serum starved and treated with insulin (SS+I), serum starved and treated with insulin and rapamycin (SS+R+I). Additional ChIP-seq profiles were generated in cells treated with MAF1 siRNAs and serum starved. MAF1 binding was addressed by DamIP-seq, using two replicates per clone of IMR90hTert cells expressing HA-tagged MAF1-DamK9A (2 different clones) or EGFP-DamK9A (2 different clones). To monitor dynamic transcription profiles we did neusRNA-seq in IMR90hTert cells EU-labeled or mock (DMSO)-labeled. For both DamIP-seq and neusRNA-seq, cells were either unperturbed or serum starved.
Project description:In higher eukaryotes, an important mechanism to tune translation in different tissues and conditions is mTORC1-dependent regulation of tRNAs transcription by RNA polymerase III (Pol III), as the relative amount of tRNAs tightly coordinates with the translational needs of the cell. mTORC1 contributes to regulate protein synthesis through its direct substrate MAF1, which functions as a negative regulator of Pol III transcription in response to stimuli such as serum starvation or rapamycin treatment. Here, we applied ChIP-seq to examine the Pol III occupancy profile in human fibroblasts and report evidence of a genome wide, MAF1-dependent coordinated response to favorable or stress growth conditions. Strikingly, while a set of genes is extremely responsive in terms of Pol III binding, other genes are mostly unperturbed, yet associated with transcriptionally engaged polymerases as revealed by nascent EU-labeled RNA-seq (neuRNA-seq). As shown by DamIP-seq, the responsiveness of a subset of genes is tightly connected to the rapid and transient interaction of MAF1 with DNA-bound Pol III. We performed duplicate ChIP-seq experiments for the Rpc4 (POLR3D) subunit of RNA polymerase III in IMR90hTert cells grown in the presence of fetal bovine serum (FBS), serum starved (SS), serum starved and treated with insulin (SS+I), serum starved and treated with insulin and rapamycin (SS+R+I). Additional ChIP-seq profiles were generated in cells treated with MAF1 siRNAs and serum starved. MAF1 binding was addressed by DamIP-seq, using two replicates per clone of IMR90hTert cells expressing HA-tagged MAF1-DamK9A (2 different clones) or EGFP-DamK9A (2 different clones). To monitor dynamic transcription profiles we did neusRNA-seq in IMR90hTert cells EU-labeled or mock (DMSO)-labeled. For both DamIP-seq and neusRNA-seq, cells were either unperturbed or serum starved.
Project description:In higher eukaryotes, an important mechanism to tune translation in different tissues and conditions is mTORC1-dependent regulation of tRNAs transcription by RNA polymerase III (Pol III), as the relative amount of tRNAs tightly coordinates with the translational needs of the cell. mTORC1 contributes to regulate protein synthesis through its direct substrate MAF1, which functions as a negative regulator of Pol III transcription in response to stimuli such as serum starvation or rapamycin treatment. Here, we applied ChIP-seq to examine the Pol III occupancy profile in human fibroblasts and report evidence of a genome wide, MAF1-dependent coordinated response to favorable or stress growth conditions. Strikingly, while a set of genes is extremely responsive in terms of Pol III binding, other genes are mostly unperturbed, yet associated with transcriptionally engaged polymerases as revealed by nascent EU-labeled RNA-seq (neuRNA-seq). As shown by DamIP-seq, the responsiveness of a subset of genes is tightly connected to the rapid and transient interaction of MAF1 with DNA-bound Pol III. We performed duplicate ChIP-seq experiments for the Rpc4 (POLR3D) subunit of RNA polymerase III in IMR90hTert cells grown in the presence of fetal bovine serum (FBS), serum starved (SS), serum starved and treated with insulin (SS+I), serum starved and treated with insulin and rapamycin (SS+R+I). Additional ChIP-seq profiles were generated in cells treated with MAF1 siRNAs and serum starved. MAF1 binding was addressed by DamIP-seq, using two replicates per clone of IMR90hTert cells expressing HA-tagged MAF1-DamK9A (2 different clones) or EGFP-DamK9A (2 different clones). To monitor dynamic transcription profiles we did neusRNA-seq in IMR90hTert cells EU-labeled or mock (DMSO)-labeled. For both DamIP-seq and neusRNA-seq, cells were either unperturbed or serum starved.
Project description:In higher eukaryotes, an important mechanism to tune translation in different tissues and conditions is mTORC1-dependent regulation of tRNAs transcription by RNA polymerase III (Pol III), as the relative amount of tRNAs tightly coordinates with the translational needs of the cell. mTORC1 contributes to regulate protein synthesis through its direct substrate MAF1, which functions as a negative regulator of Pol III transcription in response to stimuli such as serum starvation or rapamycin treatment. Here, we applied ChIP-seq to examine the Pol III occupancy profile in human fibroblasts and report evidence of a genome wide, MAF1-dependent coordinated response to favorable or stress growth conditions. Strikingly, while a set of genes is extremely responsive in terms of Pol III binding, other genes are mostly unperturbed, yet associated with transcriptionally engaged polymerases as revealed by nascent EU-labeled RNA-seq (neuRNA-seq). As shown by DamIP-seq, the responsiveness of a subset of genes is tightly connected to the rapid and transient interaction of MAF1 with DNA-bound Pol III.
Project description:In higher eukaryotes, an important mechanism to tune translation in different tissues and conditions is mTORC1-dependent regulation of tRNAs transcription by RNA polymerase III (Pol III), as the relative amount of tRNAs tightly coordinates with the translational needs of the cell. mTORC1 contributes to regulate protein synthesis through its direct substrate MAF1, which functions as a negative regulator of Pol III transcription in response to stimuli such as serum starvation or rapamycin treatment. Here, we applied ChIP-seq to examine the Pol III occupancy profile in human fibroblasts and report evidence of a genome wide, MAF1-dependent coordinated response to favorable or stress growth conditions. Strikingly, while a set of genes is extremely responsive in terms of Pol III binding, other genes are mostly unperturbed, yet associated with transcriptionally engaged polymerases as revealed by nascent EU-labeled RNA-seq (neuRNA-seq). As shown by DamIP-seq, the responsiveness of a subset of genes is tightly connected to the rapid and transient interaction of MAF1 with DNA-bound Pol III.
Project description:In higher eukaryotes, an important mechanism to tune translation in different tissues and conditions is mTORC1-dependent regulation of tRNAs transcription by RNA polymerase III (Pol III), as the relative amount of tRNAs tightly coordinates with the translational needs of the cell. mTORC1 contributes to regulate protein synthesis through its direct substrate MAF1, which functions as a negative regulator of Pol III transcription in response to stimuli such as serum starvation or rapamycin treatment. Here, we applied ChIP-seq to examine the Pol III occupancy profile in human fibroblasts and report evidence of a genome wide, MAF1-dependent coordinated response to favorable or stress growth conditions. Strikingly, while a set of genes is extremely responsive in terms of Pol III binding, other genes are mostly unperturbed, yet associated with transcriptionally engaged polymerases as revealed by nascent EU-labeled RNA-seq (neuRNA-seq). As shown by DamIP-seq, the responsiveness of a subset of genes is tightly connected to the rapid and transient interaction of MAF1 with DNA-bound Pol III.
Project description:RNA polymerase III (pol III) synthesizes short non-coding RNAs, many of which, including tRNAs, Rpph1 RNA, Rn5s rRNA, and Rmrp RNA, are essential for translation. Accordingly, pol III activity is tightly regulated with cell growth and proliferation by factors such as MYC, RB1, TRP53, and MAF1. MAF1 is a repressor of pol III transcription whose activity is controlled by phosphorylation; in particular, it is inactivated through phosphorylation by mTORC1 kinase, a sensor of nutrient availability. Pol III regulation is thus sensitive to environmental cues, yet a diurnal profile of pol III transcription activity is so far lacking. Here we document pol III occupancy of its target genes in mouse liver during the diurnal cycle and show that pol III occupancy rises before the onset of the night, stays high during the night, when mice normally ingest food and when translation is increased, and decreases in daytime. By comparing diurnal pol III occupancy in wild-type mice, arrhythmic mice owing to inactivation of the Arntl gene, mice fed at regular intervals during both night and day, and mice lacking the Maf1 gene, we show that whereas higher pol III occupancy during the night reflects a MAF1-dependent response to feeding, the rise of pol III occupancy before the onset of the night reflects a circadian clock-dependent response. Thus, pol III transcription during the diurnal cycle is regulated both in response to nutrients and by the circadian clock, which allows anticipatory pol III transcription.
Project description:RNA polymerase III (pol III) synthesizes short non-coding RNAs, many of which, including tRNAs, Rpph1 RNA, Rn5s rRNA, and Rmrp RNA, are essential for translation. Accordingly, pol III activity is tightly regulated with cell growth and proliferation by factors such as MYC, RB1, TRP53, and MAF1. MAF1 is a repressor of pol III transcription whose activity is controlled by phosphorylation; in particular, it is inactivated through phosphorylation by mTORC1 kinase, a sensor of nutrient availability. Pol III regulation is thus sensitive to environmental cues, yet a diurnal profile of pol III transcription activity is so far lacking. Here we document pol III occupancy of its target genes in mouse liver during the diurnal cycle and show that pol III occupancy rises before the onset of the night, stays high during the night, when mice normally ingest food and when translation is increased, and decreases in daytime. By comparing diurnal pol III occupancy in wild-type mice, arrhythmic mice owing to inactivation of the Arntl gene, mice fed at regular intervals during both night and day, and mice lacking the Maf1 gene, we show that whereas higher pol III occupancy during the night reflects a MAF1-dependent response to feeding, the rise of pol III occupancy before the onset of the night reflects a circadian clock-dependent response. Thus, pol III transcription during the diurnal cycle is regulated both in response to nutrients and by the circadian clock, which allows anticipatory pol III transcription.