Project description:The yeast ζ-crystallin Zta1p interacts specifically with RNA sequences rich in adenine and uracil (AU-rich element). We have looked for possible targets of Zta1p through a comparative transcriptional analysis of the yeast defective in ZTA1 (Δzta1) versus the wild-type by microarray. This revealed that a group of genes implicated on amino acid biosynthesis are affected by the lack of ZTA1. The effect on one of the targets ARG4 was studied in more detail, revealing a clear positive correlation between ZTA1 and ARG4 expression at the mRNA level. We demonstrate that Zta1p is able to bind specifically to the 3’UTR AU-rich elements of ARG4 mRNA in vitro, suggesting that the mechanism by which ZTA1 modulates the expression of ARG4 is probably mediated by this mRNA binding ability. Moreover, the expression of ZTA1 is also under the control of the TOR pathway, and under Gcn4p, which regulates genes implicated in the response to nutrient availability and the general amino acid control (GAAC). In summary, our results shed light on the functional role of the ζ-crystallin family as stress response proteins, with a conserved functional role, from yeast to humans, in the post-transcriptional regulation of genes that need to be rapidly activated for cell defense.
Project description:The yeast M-NM-6-crystallin Zta1p interacts specifically with RNA sequences rich in adenine and uracil (AU-rich element). We have looked for possible targets of Zta1p through a comparative transcriptional analysis of the yeast defective in ZTA1 (M-NM-^Tzta1) versus the wild-type by microarray. This revealed that a group of genes implicated on amino acid biosynthesis are affected by the lack of ZTA1. The effect on one of the targets ARG4 was studied in more detail, revealing a clear positive correlation between ZTA1 and ARG4 expression at the mRNA level. We demonstrate that Zta1p is able to bind specifically to the 3M-bM-^@M-^YUTR AU-rich elements of ARG4 mRNA in vitro, suggesting that the mechanism by which ZTA1 modulates the expression of ARG4 is probably mediated by this mRNA binding ability. Moreover, the expression of ZTA1 is also under the control of the TOR pathway, and under Gcn4p, which regulates genes implicated in the response to nutrient availability and the general amino acid control (GAAC). In summary, our results shed light on the functional role of the M-NM-6-crystallin family as stress response proteins, with a conserved functional role, from yeast to humans, in the post-transcriptional regulation of genes that need to be rapidly activated for cell defense. Triplicate biological replicate experiments were performed, where the two strains, M-bM-^HM-^Fzta1 and wild-type, were grown in the presence or absence of hydrogen peroxide. The experimental design was defined to directly compare the M-bM-^HM-^Fzta1 versus the wild-type strain in either of the two hydrogen peroxide treatment conditions (i.e. treated M-bM-^HM-^Fzta1 versus treated wt, or untreated M-bM-^HM-^Fzta1 versus untreated wt). A duplicate hybridization on a separate array with dye swapping was performed in each case to correct for dye bias effects. Thus, a total of 12 array data sets were produced as a result of processing three experimental pairs of samples, for each of two treatment conditions, with dye swap duplicates.
Project description:Tristetraprolin is a vertebrate CCCH tandem zinc finger protein that can bind to and destabilize certain mRNAs containing AU-rich element binding sites. zfs1 is the single gene in the fission yeast, Schizosaccharomyces pombe, that encodes a protein containing the critical features of the tristetraprolin zinc finger domain. zfs1 has been linked to pheromone signal transduction control and to the coordination of mitosis, but no biological function has been ascribed to the zfs1 protein. Through a functional genomics approach we compared transcript levels in wild-type and zfs1-deficient S. pombe strains; those elevated in the zfs1-deficient strain were examined for the presence of potential tristetraprolin-like binding sites. One such potential target transcript was encoded by arz1, a gene encoding a protein of unknown function that contains armadillo repeats. arz1 mRNA decay was inhibited in the zfs1-deficient strain when it was expressed under the control of a thiamine-repressible promoter. Mutations within one AU-rich element present in the arz1 3prime-untranslated region protected this transcript from zfs1-promoted decay, whereas mutating another potential binding site had no effect. Binding assays confirmed a direct interaction between zfs1 and arz1 mRNA-based probes; this interaction was eliminated when key residues were mutated in either zfs1 zinc finger. zfs1 and its targets in S. pombe represent a useful model system for studies of zinc finger protein/AU-rich element interactions that result in mRNA decay. Experiment Overall Design: S. pombe wild-type and zfs1-deficient strains were grown to 1.0 A600 in EMM+5S at 30C for steady state analysis. Total cellular RNA was prepared from four replicate cultures.
Project description:Tristetraprolin is a vertebrate CCCH tandem zinc finger protein that can bind to and destabilize certain mRNAs containing AU-rich element binding sites. zfs1 is the single gene in the fission yeast, Schizosaccharomyces pombe, that encodes a protein containing the critical features of the tristetraprolin zinc finger domain. zfs1 has been linked to pheromone signal transduction control and to the coordination of mitosis, but no biological function has been ascribed to the zfs1 protein. Through a functional genomics approach we compared transcript levels in wild-type and zfs1-deficient S. pombe strains; those elevated in the zfs1-deficient strain were examined for the presence of potential tristetraprolin-like binding sites. One such potential target transcript was encoded by arz1, a gene encoding a protein of unknown function that contains armadillo repeats. arz1 mRNA decay was inhibited in the zfs1-deficient strain when it was expressed under the control of a thiamine-repressible promoter. Mutations within one AU-rich element present in the arz1 3’-untranslated region protected this transcript from zfs1-promoted decay, whereas mutating another potential binding site had no effect. Binding assays confirmed a direct interaction between zfs1 and arz1 mRNA-based probes; this interaction was eliminated when key residues were mutated in either zfs1 zinc finger. zfs1 and its targets in S. pombe represent a useful model system for studies of zinc finger protein/AU-rich element interactions that result in mRNA decay. Keywords: knockout comparison, steady-state analysis
Project description:Regulation of mRNA stability by RNA-protein interactions contributes significantly to quantitative aspects of gene expression. We have identified potential mRNA targets of the AU-rich element binding protein AUF1. Myc-tagged AUF1 p42 was induced in mouse NIH-3T3 cells and RNA-protein complexes isolated using anti-myc tag antibody beads. Bound mRNAs were analyzed with Affymetrix microarrays. We have identified 508 potential target mRNAs that were at least 3-fold enriched compared to control cells without myc-AUF1. 22.3% of the enriched mRNAs had an AU-rich cluster in the ARED Organism database, against 16.3% of non-enriched control mRNAs. The enrichment towards AU-rich elements was also visible by AREScore with an average value of 5.2 in the enriched mRNAs versus 4.2 in the control group. Yet, many mRNAs were enriched without a high ARE score suggesting that AUF1 has a broader binding spectrum than standard AUUUA repeats. AUF1 did not preferentially bind to unstable mRNAs. Still, some enriched mRNAs were highly unstable, as those of TNFSF11 (known as RANKL), KLF10, HES1, CCNT2, SMAD6, and BCL6. We have mapped some of the instability determinants. HES1 mRNA appeared to have a coding region determinant. Detailed analysis of the RANKL and BCL6 3’UTR revealed for both that full instability required two elements, which are conserved in evolution. In RANKL mRNA both elements are AU-rich and separated by 30 bases, while in BCL6 mRNA one is AU-rich and 60 bases from a non AU-rich element that potentially forms a stem-loop structure.
Project description:Members of the tristetraprolin (TTP) family of CCCH tandem zinc finger proteins can bind directly to AU-rich elements in mRNAs and promote transcript deadenylation and decay. The yeast Schizosaccharomyces pombe expresses a single TTP family member, Zfs1p, that has been linked to the mating response pathway and septum formation. We showed previously that Zfs1p can bind to and promote the destabilization of AU-rich element-containing transcripts. In this study, we identified additional target transcripts by comparing transcript levels in wild type and zfs1 mutant yeast, using deep sequencing and microarray approaches. We also used direct RNA sequencing to determine the locations of the polyA tails in both wild type and mutant strains, and to confirm the presence of potential Zfs1p target sequences within the mRNA. These studies identified a set of transcripts containing potential Zfs1p binding sites that accumulated significantly in the zfs1 mutants; a subset of these turned over more slowly in the zfs1 mutant strain, and bound directly to Zfs1p in co-immunoprecipitations. One apparent direct target encodes the transcription factor Cbf12p, which is known to increase cell-cell adhesion and flocculation when over-expressed. Studies of zfs1 and cbf12 double mutants demonstrated that the increased flocculation seen in zfs1 mutants is due, at least in part, to a direct effect on the turnover of cbf12 mRNA, leading in turn to changes in the levels of its transcriptionally regulated genes. These data suggest that Zfs1p can both directly and indirectly regulate the levels of transcripts involved in cell-cell adhesion in this species. Strains were grown in YES media to approximately OD600=1.0 and total RNA was harvested from two biological replicates each of WT and zfs1 deletion.
Project description:We analyzed liver gene expression from male and female ARE-Del mice, which have prolonged and chronic expression of IFN gamma through deletion of the IFN gamma 3’ UTR AU-rich element.
Project description:Telomere chromatin structure is pivotal for maintaining genome stability by regulating the binding of telomere-associated proteins and inhibition of a DNA damage response. In yeast, the silent information regulator (Sir) proteins bind to terminal telomeric repeats and to subtelomeric X-elements resulting in histone deacetylation and transcriptional silencing. Herein, we show that sir2 mutant strains display a very specific loss of a nucleosome residing in the X-element. Most yeast telomeres contain an X-element and the nucleosome occupancy defect in sir2 mutants is remarkably consistent between different telomeres.
Project description:Members of the tristetraprolin (TTP) family of CCCH tandem zinc finger proteins can bind directly to AU-rich elements in mRNAs and promote transcript deadenylation and decay. The yeast Schizosaccharomyces pombe expresses a single TTP family member, Zfs1p, that has been linked to the mating response pathway and septum formation. We showed previously that Zfs1p can bind to and promote the destabilization of AU-rich element-containing transcripts. In this study, we identified additional target transcripts by comparing transcript levels in wild type and zfs1 mutant yeast, using deep sequencing and microarray approaches. We also used direct RNA sequencing to determine the locations of the polyA tails in both wild type and mutant strains, and to confirm the presence of potential Zfs1p target sequences within the mRNA. These studies identified a set of transcripts containing potential Zfs1p binding sites that accumulated significantly in the zfs1 mutants; a subset of these turned over more slowly in the zfs1 mutant strain, and bound directly to Zfs1p in co-immunoprecipitations. One apparent direct target encodes the transcription factor Cbf12p, which is known to increase cell-cell adhesion and flocculation when over-expressed. Studies of zfs1 and cbf12 double mutants demonstrated that the increased flocculation seen in zfs1 mutants is due, at least in part, to a direct effect on the turnover of cbf12 mRNA, leading in turn to changes in the levels of its transcriptionally regulated genes. These data suggest that Zfs1p can both directly and indirectly regulate the levels of transcripts involved in cell-cell adhesion in this species.