Project description:The 5' untranslated region (UTR) sequence of eukaryotic mRNAs may contain upstream open reading frames (uORFs), which can regulate translation of the main open reading frame (mORF). The current model of translational regulation by uORFs posits that when a ribosome scans an mRNA and encounters a uORF, translation of that uORF can prevent ribosomes from reaching the mORF and cause decreased mORF translation. In this study, we first observed that rare variants in the 5' UTR dysregulate protein abundance. Upon further investigation, we found that rare variants near the start codon of uORFs can repress or derepress mORF translation, causing allelic changes in protein abundance. This finding holds for common variants as well, and common variants that modify uORF start codons also contribute disproportionately to metabolic and whole-plant phenotypes, suggesting that translational regulation by uORFs serves an adaptive function. These results provide evidence for the mechanisms by which natural sequence variation modulates gene expression, and ultimately, phenotype.
Project description:The transition metal Cu is an essential micronutrient in biological systems. The majority of Cu is taken up into the cell through the Cu transporter CTR1 and thus, deletion of Ctr1 results in Cu deficiency. Here we performed transcriptional profiling of isogenic mouse embryonic fibroblast harboring conditional alleles for Ctr1 floxed out or intact through in vitro administration of doxycycline. The goal was to elucidate gene expression changes upon knockout of Ctr1.
Project description:Human acetyltransferases MOZ and MORF are implicated in chromosomal translocations associated with aggressive leukemias. Oncogenic translocations involve the far amino terminus of MOZ/MORF, the function of which remains unclear. Here, we identified and characterized two structured winged helix domains, WH1 and WH2, in MORF and MOZ. WHs bind DNA in a cooperative manner, with WH1 specifically recognizing unmethylated CpG sequences. Structural and genomic analyses show that the DNA binding function of WHs targets MORF/MOZ to gene promoters, stimulating transcription and H3K23 acetylation, and WH1 recruits oncogenic fusions to HOXA genes that trigger leukemogenesis. Cryo-EM, NMR, mass spectrometry and mutagenesis studies provide mechanistic insight into the DNA-binding mechanism, which includes the association of WH1 with the linker DNA and binding of WH2 to the dyad of the nucleosome, with the latter being further modulated by the neighboring domain DPF and autoacetylation of MORF. The discovery of WHs in MORF and MOZ and their DNA binding functions could open a new avenue in developing therapeutics to treat diseases associated with aberrant MOZ/MORF acetyltransferase activities.
Project description:In an approach to generate Saccharomyces cerevisiae strains with increased intracellular copper amounts for technical applications we over-expressed the copper transporter CTR1 and a variant of CTR1 with a truncation in the C-terminus after the 300 amino acids (CTR1 delta-300). We determined the copper sensitivity of the generated strains and used inductively coupled plasma spectrometry (ICP-OES and ICP-MS) analysis to investigate the effects of over-expression of both constructs under excess copper on the cellular content of different elements in S. cerevisiae. In addition, we ran DNA microarray analysis to obtain the gene expression profile under the changed element contents. Over-expression of CTR1 increased the copper content in the cells up to 160% and 78 genes were differentially regulated. Over-expression of the truncated CTR1 delta-300 resulted in an increased copper, iron and zinc content of more than 200% and 980 genes showed differential expression. We found that transition metal ion homeostasis was disrupted in CTR1 delta-300 over-expressing strains under excess copper and that this was combined with a transcriptional remodelling of cellular processes
Project description:In an approach to generate Saccharomyces cerevisiae strains with increased intracellular copper amounts for technical applications we over-expressed the copper transporter CTR1 and a variant of CTR1 with a truncation in the C-terminus after the 300 amino acids (CTR1 delta-300). We determined the copper sensitivity of the generated strains and used inductively coupled plasma spectrometry (ICP-OES and ICP-MS) analysis to investigate the effects of over-expression of both constructs under excess copper on the cellular content of different elements in S. cerevisiae. In addition, we ran DNA microarray analysis to obtain the gene expression profile under the changed element contents. Over-expression of CTR1 increased the copper content in the cells up to 160% and 78 genes were differentially regulated. Over-expression of the truncated CTR1 delta-300 resulted in an increased copper, iron and zinc content of more than 200% and 980 genes showed differential expression. We found that transition metal ion homeostasis was disrupted in CTR1 delta-300 over-expressing strains under excess copper and that this was combined with a transcriptional remodelling of cellular processes Transcription profiling was performed in Saccharomyces cerevisiae BY4741 (referred to as wild type) over-expressing CTR1 and in the ctr1- deletion strain BY4741 delta-ctr1 overexpressing CTR1 delta-300 after 7 hours of culture under excess copper (0.02 mM CuCl2). Control strains contained the corresponding empty vector. Three independent experiments were performed and 12 samples were analyzed.
Project description:The RNA polymerase II (RNAPII) transcription cycle is regulated throughout its duration by protein phosphorylation. Previously, two regions phosphorylated by cyclin-dependent kinase 9 (CDK9) in elongation factor SPT5—the linker between Kyrpides-Ouzounis-Woese (KOW) x-4 and 5 domains and carboxy-terminal repeat (CTR) 1—were implicated in promoter-proximal pausing and termination, respectively. Here, we show that phosphorylations in the linker, CTR1, and a third region, CTR2, coordinately control pause release, elongation speed, and termination in HCT116 human colon cancer cells. Pausing was unaffected or increased by mutations preventing CTR1 or CTR2 phosphorylation, respectively, but attenuated when both CTRs were mutated. Whereas loss of CTR1 phosphorylation slowed elongation and repressed nascent transcription, simultaneous CTR2 mutation partially reversed both effects. Nevertheless, mutating both CTRs had additive effects on splicing, termination, steady-state mRNA levels, and cell proliferation. Therefore, tripartite SPT5 phosphorylation times pause release and tunes RNAPII elongation rate to ensure productive transcription and cell viability.
Project description:The RNA polymerase II (RNAPII) transcription cycle is regulated throughout its duration by protein phosphorylation. Previously, two regions phosphorylated by cyclin-dependent kinase 9 (CDK9) in elongation factor SPT5—the linker between Kyrpides-Ouzounis-Woese (KOW) x-4 and 5 domains and carboxy-terminal repeat (CTR) 1—were implicated in promoter-proximal pausing and termination, respectively. Here, we show that phosphorylations in the linker, CTR1, and a third region, CTR2, coordinately control pause release, elongation speed, and termination in HCT116 human colon cancer cells. Pausing was unaffected or increased by mutations preventing CTR1 or CTR2 phosphorylation, respectively, but attenuated when both CTRs were mutated. Whereas loss of CTR1 phosphorylation slowed elongation and repressed nascent transcription, simultaneous CTR2 mutation partially reversed both effects. Nevertheless, mutating both CTRs had additive effects on splicing, termination, steady-state mRNA levels, and cell proliferation. Therefore, tripartite SPT5 phosphorylation times pause release and tunes RNAPII elongation rate to ensure productive transcription and cell viability.
Project description:Arabidopsis MPK4 is involved in the control of antagonism between salicylic acid (SA) and ethylene (ET)/jasmonic acid (JA) pathways in the plant innate immune system as a repressor of the SA pathway, but an activator of the ET/JA pathway. Here we and use comparative microarray analysis of ctr1, ctr1/mpk4, mpk4 and wild type to show that MPK4 is required for only a narrow subset of ET regulated genes.