Expression analysis in yeast model of Huntington's disease (HD)
ABSTRACT: Expressing a mutant fragment of huntingtin (Htt) in yeast produces several HD-relevant phenotypes. We used microarrays to study global change in expression induced by this mutant htt fragment. Expression was also analysed in three suppressor deletion strains expressing a toxic mutant htt fragment: bna4Δ, mbf1Δ, and ume1Δ. Overall design: Yeast samples expressing either a wild-type or mutant htt fragment (Htt25Q or Htt103Q, respectively), and suppressor deletion strains expressing Htt103Q: bna4Δ, mbf1Δ, and ume1Δ.
Project description:Expressing a mutant fragment of huntingtin (Htt) in yeast produces several HD-relevant phenotypes. We used microarrays to study global change in expression induced by this mutant htt fragment. Expression was also analysed in three suppressor deletion strains expressing a toxic mutant htt fragment: bna4Δ, mbf1Δ, and ume1Δ. Yeast samples expressing either a wild-type or mutant htt fragment (Htt25Q or Htt103Q, respectively), and suppressor deletion strains expressing Htt103Q: bna4Δ, mbf1Δ, and ume1Δ.
Project description:Primary neuron model of Huntington's Disease. 2 treatment groups: A) Infected 4 weeks prior with TRE-Htt-N853-18Q-expressing recombinant lentivirus, B) Infected 4 weeks prior with TRE-Htt-N853-82Q-expressing recombinant lentivirus Keywords: gene expression study Overall design: Primary neurons samples infected with TRE-Htt-N853-18Q or -82Q.
Project description:Transcriptional dysregulation in a primary cortical neuron model of Huntington's disease Overall design: RNA-seq of primary cortical neurons transduced with control vector, wildtype Htt or Mutant Htt.
Project description:Despite extensive progress in Huntington’s Disease (HD) research, very little is known about the association of epigenetic variation and HD pathogenesis in human brain tissues. Moreover, its contribution to the tissue-specific transcriptional regulation of the huntingtin gene (HTT), in which HTT expression levels are highest in brain and testes, is currently unknown. To investigate the role of DNA methylation in HD pathogenesis and tissue-specific expression of HTT, we utilized the Illumina HumanMethylation450K BeadChip array to measure DNA methylation in a cohort of age-matched HD and control human cortex and liver tissues. In cortex samples, we found minimal evidence of HD-associated DNA methylation at probed sites after correction for cell heterogeneity but did observe an association to age of disease onset. By contrast, comparison of matched cortex and liver samples revealed tissue-specific DNA methylation of the HTT gene region at 38 sites (FDR < 0.05). Importantly, we identified a novel differentially methylated binding site in the HTT proximal promoter for the transcription factor CTCF. This CTCF site displayed increased occupancy in cortex, where HTT expression is higher, compared to liver. Additionally, CTCF silencing reduced the activity of a HTT promoter-reporter construct, suggesting that CTCF plays a role in regulating HTT promoter function. Overall, although we were unable to detect HD-associated DNA methylation alterations at queried sites, we found that DNA methylation may be correlated to age of disease onset in cortex tissues. Moreover, our data suggest that DNA methylation may, in part, contribute to tissue-specific HTT transcription through differential CTCF occupancy. The Illumina Infinium HumanMethylation450 Beadchip was used to obtain genome-wide DNA methylation measures in human cortex tissue (n = 13), with a subset of matched liver tissues (n = 5) , from a cohort of HD (n = 7) and control (n = 6) individuals in order to identify potential HD-related DNA methylation aberration in the brain as well as tissue-specific DNA methylation variation at the HTT gene locus.
Project description:Huntington's disease (HD) is a dominantly inherited genetic disease caused by mutant huntingtin (htt) protein with expanded polyglutamine tracts. A neuropathological hallmark of HD is the presence of neuronal inclusions of mutant htt. p62 is an important regulatory protein in selective autophagy, a process by which aggregated proteins are degraded, and it is associated with several neurodegenerative disorders including HD. Here we investigated the effect of p62 depletion in three HD model mice: R6/2, HD190QG and HD120QG mice. We found that loss of p62 in these models led to longer lifespans and reduced nuclear inclusions, although cytoplasmic inclusions increased with polyglutamine length. In mouse embryonic fibroblasts (MEFs) with or without p62, mutant htt with a nuclear localization signal (NLS) showed no difference in nuclear inclusion between the two MEF types. In the case of mutant htt without NLS, however, p62 depletion increased cytoplasmic inclusions. Furthermore, to examine the effect of impaired autophagy in HD model mice, we crossed R6/2 mice with Atg5 conditional knockout mice. These mice also showed decreased nuclear inclusions and increased cytoplasmic inclusions, similar to HD mice lacking p62. These data suggest that the genetic ablation of p62 in HD model mice enhances cytoplasmic inclusion formation by interrupting autophagic clearance of polyQ inclusions. This reduces polyQ nuclear influx and paradoxically ameliorates disease phenotypes by decreasing toxic nuclear inclusions. Gene expression profiles were analyzed to examine the effects of p62 depletion in mouse with or without mutant huntingtin exon 1 To examine the effect of p62 depletion on the transcriptome of Huntington's disease model mice, we crossed p62 knockout mice with HD model mice. We extracted total RNA from the striatum of these mice at 8 weeks and used for a microaaray analysis. The samples are HD transgenic mice with p62 knockout (HD_p62KO), HD mice with normal p62 (HD_p62WT), non-HD-transgenic mice with p62 knockout (NT_p62KO), and non-HD-transgenic mice with normal p62 (NT_p62WT).
Project description:ChIP-on chip assays to measure the change in histone acetylation over the yeast genome, in ASF1, SET2 and ASF1 SET2 deletion yeast strains compared to the wild-type control. ChIPs of AcH4 from wild-type, ASF1, SET2 and ASF1 SET2 deletion yeast strains were normalized to the H3 enrichment. Overall design: Two color experiment. Deletion mutant vs. WT cells. Biological replicates=3 per IP per cell type.
Project description:Epigenetic mechanisms including histone post-translational modifications control longevity in diverse organisms. Relatedly, loss of proper transcriptional regulation on a global scale is an emerging aspect of shortened lifespan, but the specific mechanisms linking these observations remain to be uncovered. Here, we describe a lifespan screen in S. cerevisiae, designed to identify altered amino acid residues of histones that alter yeast replicative aging. Our results reveal that lack of sustained H3K36 methylation is commensurate with increased cryptic transcription in a set of genes in old cells and shorter lifespan. Deletion of the K36me2/3 demethylase Rph1 increases H3K36me3 within these genes and suppresses cryptic transcript initiation to extend lifespan. We show that this aging phenomenon is conserved, as cryptic transcription also increases in old worms. We propose that epigenetic misregulation in aging cells leads to an increase in transcriptional noise that is detrimental to lifespan, and, importantly, this acceleration in aging can be reversed by restoring transcriptional fidelity. Overall design: This study examines transcription in yeast aging using a WT or Rph1 mutant background over a sequence of time-dependent FACS sorts of old cells. Cryptic transcripts are detected using a small fragment sequencing approach. The youngest WT yeast (designated S1Y, S2Y) are represented in seven biological replicates and one technical replicate, five small fragment and three others; the oldest WT yeast (designated S4O) are also represented in seven biological replicates and one technical replicate, again composed of five small fragment samples and three others. Intermediate WT yeast aging sorts (S2O and S3O) are each represented by five biological replicates and one technical replicate, three small fragment and three others. For mutant yeast, each stage in the time series is represented by five biological replicates and one technical replicate, three small fragment and three others. Experiment 4 is a technical replicate of experiment 3.
Project description:This goal of these experiments is to assess steady-state transcript levels in a set of E. coli mutants (ppk, dgk, zwf, entC, and dapF null strains) that grow slowly in M9 glucose, and to compare these transcript levels to corresponding synthetic rescue strains (i.e. spontaneous suppressor strains in which slow growth is rescued to wild-type levels). Overall design: To isolate total RNA, all strains were grown in triplicate to an equivalent OD in mid-logarithmic phase. Cells were pelleted, lysed, and total RNA was isolated for analysis by RNA-seq. Steady-state transcript levels in each synthetic resucue strain were compared to the correspoding slow-growing primary (single gene deletion) mutant strains. zwf.txt: Rockhoppper analysis; tab delimited text of gene expression (zwf deletion mutant versus synthetic rescue suppressors; sup) dgk.txt: Rockhoppper analysis; tab delimited text of gene expression (dgk deletion mutant versus synthetic rescue suppressors; sup) ppk.txt: Rockhoppper analysis; tab delimited text of gene expression (ppk deletion mutant versus synthetic rescue suppressors; sup) dapF.txt: Rockhoppper analysis; tab delimited text of gene expression (dapF deletion mutant versus synthetic rescue suppressors; sup) entC.txt: Rockhoppper analysis; tab delimited text of gene expression (entC deletion mutant versus synthetic rescue suppressors; sup)
Project description:Bacillus subtilis mutants lacking the SMC-ScpAB complex are severely impaired for chromosome condensation and partitioning, DNA repair, and cells are not viable under standard laboratory conditions. We isolated suppressor mutations that restored the capacity of a smc deletion mutant (Δsmc) to grow under standard conditions. These suppressor mutations reduced chromosome segregation defects and abrogated hypersensitivity to gyrase inhibitors of Δsmc. Three suppressor mutations were mapped in genes involved in tRNA aminoacylation and maturation pathways. A transcriptomic survey of isolated suppressor mutations pointed to a potential link between suppression of Δsmc and induction of the stringent response. This link was confirmed by (p)ppGpp quantification which indicated a constitutive induction of the stringent response in multiple suppressor strains. Furthermore, sublethal concentrations of arginine hydroxamate (RHX), a potent inducer of stringent response, restored growth of Δsmc under non permissive conditions. We showed that production of (p)ppGpp alone was sufficient to suppress the thermosensitivity exhibited by the Δsmc mutant. Our findings shed new light on the coordination between chromosome dynamics mediated by SMC-ScpAB and other cellular processes during rapid bacterial growth. A 7 array study of the transcriptome profiles of B. subtilis strain 168, CB167 and CB169: ylbM and ywlC mutant strains. Compared to the wild-type strain the mutant strains were used to characterize the effect of the mutation on transcript profiles in order to understand the suppression of the SMC deletion.