Project description:Ribosomal protein (RP) genes must be coordinately expressed for proper assembly of the ribosome yet the mechanisms that control expression of RP genes in metazoans are poorly understood. Recently, TATA-Binding Protein-related factor 2 (TRF2) rather than the TATA-Binding Protein (TBP) was found to function in transcription of RP genes in Drosophila. Unlike TBP, TRF2 lacks sequence-specific DNA binding activity, so the mechanism by which TRF2 is recruited to promoters is unclear. We show that the transcription factor M1BP, which associates with the core promoter region, activates transcription of RP genes. Moreover, M1BP directly interacts with TRF2 to recruit it to the RP gene promoter. High resolution ChIP-exo was used to analyze in vivo the association of M1BP, TRF2, and the TFIID subunit, TAF1. Despite recent work suggesting that TFIID does not associate with RP genes in Drosophila, we find that TAF1 is present at RP gene promoters and that its interaction might also be directed by M1BP. Although M1BP associates with thousands of genes and TRF2 associates with hundreds, their colocalization is largely restricted to RP genes, suggesting that this combination is key to coordinately regulating transcription of the majority of RP genes in Drosophila.
Project description:Taf7l (a paralogue of Taf7) and Trf2 (a TBP-related protein) are components of the core promoter complex required for gene/tissue-specific transcription of protein-coding genes by RNA polymerase II. Previous studies reported that Taf7l knockout mice exhibit structurally abnormal sperm, reduced sperm count, weakened motility and compromised fertility. Here we find that continued backcrossing of Taf7l-/Y mice from N5 to N9 produced KO males that are essentially sterile. Genome-wide expression profiling by mRNA-seq analysis of wild type (WT) and Taf7l-/Y (KO) testes revealed that Taf7l ablation impairs the expression of many post-meiotic spermatogenic specific as well as metabolic genes. Importantly, histological analysis of testes revealed that Taf7l-/Y mice develop post-meiotic arrest at the first stage of spermiogenesis, phenotypically similar to Trf2-/- mice, but distinct from Taf4b-/- mice. Indeed, we find that Taf7l and Trf2 co-regulate post-meiotic genes, but none of Taf4b-regulated germ stem cell genes in testes. Genome-wide ChIP-seq studies indicate that TAF7L binds to promoters of activated post-meiotic genes in testis. Moreover, biochemical studies show that TAF7L associates with TRF2 both in vitro and in testis suggesting that TAF7L likely cooperates directly with TRF2 at promoters of a subset of post-meiotic genes to regulate spermiogenesis. Our findings thus provide a new mechanism for cell-type specific transcriptional control involving an interaction between a ‘non-prototypic’ core promoter recognition factor (Trf2) and an orphan TAF subunit (Taf7l) in mammalian testis-specific gene transcription. Genome-wide mapping of TAF7L and Pol II in testis tissue, and mRNA-seq expression profiling wild type and Taf7l knockout testis.
Project description:Taf7l (a paralogue of Taf7) and Trf2 (a TBP-related protein) are components of the core promoter complex required for gene/tissue-specific transcription of protein-coding genes by RNA polymerase II. Previous studies reported that Taf7l knockout mice exhibit structurally abnormal sperm, reduced sperm count, weakened motility and compromised fertility. Here we find that continued backcrossing of Taf7l-/Y mice from N5 to N9 produced KO males that are essentially sterile. Genome-wide expression profiling by mRNA-seq analysis of wild type (WT) and Taf7l-/Y (KO) testes revealed that Taf7l ablation impairs the expression of many post-meiotic spermatogenic specific as well as metabolic genes. Importantly, histological analysis of testes revealed that Taf7l-/Y mice develop post-meiotic arrest at the first stage of spermiogenesis, phenotypically similar to Trf2-/- mice, but distinct from Taf4b-/- mice. Indeed, we find that Taf7l and Trf2 co-regulate post-meiotic genes, but none of Taf4b-regulated germ stem cell genes in testes. Genome-wide ChIP-seq studies indicate that TAF7L binds to promoters of activated post-meiotic genes in testis. Moreover, biochemical studies show that TAF7L associates with TRF2 both in vitro and in testis suggesting that TAF7L likely cooperates directly with TRF2 at promoters of a subset of post-meiotic genes to regulate spermiogenesis. Our findings thus provide a new mechanism for cell-type specific transcriptional control involving an interaction between a ‘non-prototypic’ core promoter recognition factor (Trf2) and an orphan TAF subunit (Taf7l) in mammalian testis-specific gene transcription.
Project description:Telomere binding factor 2 (TRF2), is a protein that plays a major role in the maintenance of telomere integrity. In mitotic normal and transformed cells, TRF2 inhibition triggers a rapid telomere DNA damage response that results in cell senescence or apoptosis. Here we provide evidence that TRF2 plays a role suppressing neuronal differentiation. TRF2 interacts with the RE1-silencing transcription factor (REST) in nuclear PML protein-containing compartments of neuronal cells in vivo. Inhibition of TRF2 function with a dominant-negative form of TRF2 elicits a telomeric DNA damage response, and disrupts the TRF2-REST complex resulting in proteasomal degradation of REST. Overexpression of REST impairs the ability of DN-TRF2 to induce neuronal differentiation, indicating that enhanced degradation of REST is sufficient to account for the differentiation-inducing effect of DN-TRF2. REST degradation derepresses RE1-regulated genes (L1CAM, BDNF, b3-tubulin, syntaxin and others) resulting in morphological and functional differentiation of neurons. Our findings identify a novel interaction between the telomeric protein TRF2 and REST which regulates the molecular differentiation program of neurons. Keywords: transfection and molecular inhibition
Project description:The transcriptional mechanisms that allow neural stem cells (NSC) to balance self-renewal with differentiation are not well understood. We identify here a unique subset of TATA -binding protein associated factors (TAFs) as NSC identity genes in Drosophila. We found that depletion of any one of nine TAFs or the TBP-related factor 2 (TRF2), resulted in fewer NSCs exhibiting delayed cell cycle progression without impacting NSC survival. In contrast, depletion of TBP led to a delay in NSC cell cycle progression without loss of self-renewal. An integrated RNA-seq and DamID analysis revealed that TAFs function with both TBP and TRF2, and that TAF-TBP and TAF-TRF2 shared targets genes encode different subsets of transcription factors and RNA-binding proteins with established or emerging roles in NSC identity and brain development. Taken together, our results demonstrate that core promoter factors are selectively required for NSC identity in vivo by promoting cell cycle progression, NSC cell polarity and by preventing premature differentiation. Because pathogenic variants in TAF1, TAF2, TAF6, TAF8 and TAF13 have all been linked to human neurological disorders, this work may stimulate and inform future animal models of TAF-linked neurological disorders.
Project description:The transcriptional mechanisms that allow neural stem cells (NSC) to balance self-renewal with differentiation are not well understood. We identify here a unique subset of TATA -binding protein associated factors (TAFs) as NSC identity genes in Drosophila. We found that depletion of any one of nine TAFs or the TBP-related factor 2 (TRF2), resulted in fewer NSCs exhibiting delayed cell cycle progression without impacting NSC survival. In contrast, depletion of TBP led to a delay in NSC cell cycle progression without loss of self-renewal. An integrated RNA-seq and DamID analysis revealed that TAFs function with both TBP and TRF2, and that TAF-TBP and TAF-TRF2 shared targets genes encode different subsets of transcription factors and RNA-binding proteins with established or emerging roles in NSC identity and brain development. Taken together, our results demonstrate that core promoter factors are selectively required for NSC identity in vivo by promoting cell cycle progression, NSC cell polarity and by preventing premature differentiation. Because pathogenic variants in TAF1, TAF2, TAF6, TAF8 and TAF13 have all been linked to human neurological disorders, this work may stimulate and inform future animal models of TAF-linked neurological disorders.
Project description:Despite considerable evidence that RNA-binding proteins (RBPs) regulate mRNA transport and local translation in dendrites, roles for axonal RBPs are poorly understood. Here we demonstrate that a nontelomeric isoform of telomere repeat-binding factor 2 (TRF2-S) is a novel RBP that regulates axonal plasticity. TRF2-S interacts directly with target mRNAs to facilitate their axonal delivery. The process is antagonized by fragile X mental retardation protein (FMRP). Distinct from the current RNA-binding model of FMRP, we show that FMRP occupies the GAR domain of TRF2-S protein to block the assembly of TRF2-S-mRNA complexes. Overexpressing TRF2-S and silencing FMRP promotes mRNA entry to axons, and enhances axonal outgrowth and neurotransmitter release from presynaptic terminals. Our findings suggest a pivotal role for TRF2-S in an axonal mRNA localization pathway that enhances axon outgrowth and neurotransmitter release.
Project description:Background: The Telomeric Repeat binding Factor 2 (TRF2), a key protein involved in telomere integrity, is over-expressed in several human cancers and promotes tumor formation and progression. Recently, TRF2 has been also found outside telomeres where it can affect gene expression. Here we provide evidence that TRF2 is able to modulate the expression of microRNAs (miRNAs), small non-coding RNAs altered in human tumors. Among the miRNAs regulated by TRF2, we focused on the miR-193b-3p, an oncomiRNA that positively correlates with TRF2 expression in human colorectal cancer patients. At the mechanistic level, the control of miR-193b-3p expression requires the cooperative activity between TRF2 and the chromatin organization factor CTCF. We found that CTCF physically interacts with TRF2, thus driving the proper positioning of TRF2 on a binding site located upstream the miR-193b-3p host-gene. The binding of TRF2 on the identified region is necessary for promoting the expression of miR-193b3p which, in turn, inhibits the translation of the onco-suppressive methyltransferase SUV39H1 and promotes tumor cell proliferation. The translational relevance of the oncogenic properties of miR-193b-3p was confirmed in patients, in whom the association between TRF2 and miR-193b-3p has a prognostic value.
Project description:Despite considerable evidence that RNA-binding proteins (RBPs) regulate mRNA transport and local translation in dendrites, roles for axonal RBPs are poorly understood. Here we demonstrate that a nontelomeric isoform of telomere repeat-binding factor 2 (TRF2-S) is a novel RBP that regulates axonal plasticity. TRF2-S interacts directly with target mRNAs to facilitate their axonal delivery. The process is antagonized by fragile X mental retardation protein (FMRP). Distinct from the current RNA-binding model of FMRP, we show that FMRP occupies the GAR domain of TRF2-S protein to block the assembly of TRF2-S-mRNA complexes. Overexpressing TRF2-S and silencing FMRP promotes mRNA entry to axons, and enhances axonal outgrowth and neurotransmitter release from presynaptic terminals. Our findings suggest a pivotal role for TRF2-S in an axonal mRNA localization pathway that enhances axon outgrowth and neurotransmitter release. RNA immunoprecipitated samples using either anti-rat TRF2-S or rabbit IgG antibodies were used to generate biotin-labeled RNA using the Illumina Total Prep RNA Amplification Kit (Ambion), which was hybridized to Illumina's rat Ref-12 Expression BeadChips (Illumina, San Diego, CA), containing 22,523 well-annotated RefSeq transcripts with ~30-fold redundancy. The arrays were scanned using an Illumina BeadStation 500X Genetic Analysis Systems scanner and the image data extracted using Illumina BeadStudio software, version 1.5, normalized by Z-score transformation and used to calculate differences in signal intensities. Significant values were calculated from two groups of independent experiments, using a two-tailed Z-test with P < 0.05, a false discovery rate <0.30, a z ratio absolute value not less than 1.5, and an average signal intensity not less than zero. The results also had to pass the filtering and one-way independent ANOVA test by sample groups less than 0.05, and detection p-value for any probe in the comparison group less than 0.02.
Project description:Here we use ChIP-seq in Drosophila embryos to determine the genome-wide binding pattern of TBP and Trf2 using two different antibodies for each factor. ChIP-seq using anti-Trf2 and anti-TBP antibodies in Drosophila embryos