Gene expression levels are determined by the balance between rates of mRNA transcription and decay, and genetic variation in either of these processes can result in heritable differences in transcript abundance. Although the genetics of gene expression has been the subject of intense interest, the contribution of heritable variation in mRNA decay rates to gene expression variation has received far less attention. To this end, we developed a novel statistical framework and measured allele-specific differences in mRNA decay rates in a diploid yeast hybrid created by mating two genetically diverse parental strains. In total, we estimate that 31% of genes exhibit allelic differences in mRNA decay rate, of which 350 can be identified at a false discovery rate of 10%. Genes with significant allele-specific differences in mRNA decay rate have higher levels of polymorphism compared to other genes, with all gene regions contributing to allelic differences in mRNA decay rate. Strikingly, we find widespread evidence for compensatory evolution, such that variants influencing transcriptional initiation and decay having opposite effects, suggesting steady-state gene expression levels are subject to pervasive stabilizing selection. Our results demonstrate that heritable differences in mRNA decay rates are widespread, and are an important target for natural selection to maintain or fine-tune steady-state gene expression levels. Overall design: We measured rates of allele-specific mRNA decay (ASD) in a diploid yeast produced by mating two genetically diverse haploid Saccharomyces cerevisiae strains: the laboratory strain BY4716 (BY), which is isogenic to the reference sequence strain S288C, and the wild Californian vineyard strain RM11-1a (RM). Briefly, we introduced rpb1-1, a temperature sensitive mutation in an RNA polymerase II subunit, to each of the haploid yeast strains, mated the strains, and grew the resulting hybrid diploid to mid-log phase at 24 °C, before rapidly shifting the culture to 37 °C to inhibit transcription. RNA-seq was performed on culture samples taken at 0, 6, 12, 18, 24, and 42 minutes subsequent to the temperature shift. To identify ASD, we used transcribed polymorphisms to distinguish between parental transcripts, and compared the relative levels of transcript abundance over the time course. Note, this experimental design internally controls for trans-acting regulatory variation as well as environmental factors. Under the null hypothesis of no ASD, the proportion of reads from the BY transcript (p_BY = N_BY / (N_BY + N_RM)) observed over the time course remains unchanged. However, genes with ASD will exhibit an increasing or decreasing proportion of BY reads as a function of time. In total, we measured ASD from three independent biological replicates.
Heritable variation of mRNA decay rates in yeast.
Disease, Cell line, Subject
View SamplesEpithelial-mesenchymal transition (EMT) is a pivotal process in development and disease. In carcinogenesis, various signaling pathways are known to trigger EMT by inducing the expression of EMT transcription factors (EMT-TFs) like SNAIL1, ultimately promoting invasion, metastasis and chemoresistance. However, how EMT is executed downstream of EMT-TFs is incompletely understood. Here, using human colorectal cancer (CRC) and mammary cell line models of EMT, we demonstrate that SNAIL1 critically relies on bone morphogenetic protein (BMP) signaling for EMT execution. This activity requires the transcription factor SMAD4 common to BMP/TGFβ pathways, but is TGFβ signaling-independent. Further, we define a signature of BMP-dependent genes in the EMT-transcriptome which orchestrate EMT-induced invasiveness, and are found to be regulated in human CRC transcriptomes and during EMT in vivo. Collectively, our findings substantially augment the knowledge of mechanistic routes whereby EMT can be effectuated, which is relevant for the conceptual understanding and therapeutic targeting of EMT processes.
Canonical BMP Signaling Executes Epithelial-Mesenchymal Transition Downstream of SNAIL1.
Specimen part
View SamplesMaternal obesity during the pre-implantation period leads to a pro-inflammatory milieu in the ovaries. We conducted a global transcriptomic profiling in ovaries from TEN fed rats during the pre-implantation period. Microarray analysis revealed that obesity lead to increased expression of genes related to inflammation, decreased glucose transporters, and dysregulation of ovarian function-related genes in the ovaries. Our results suggest maternal obesity led to an up-regulation of inflammatory genes and Egr-1 protien expression in peri-implantation ovarian tissue, and a concurrent down-regulation of glucose transporters mRNA and AKT and PI3K protein levels.
Maternal obesity is associated with ovarian inflammation and upregulation of early growth response factor 1.
Sex, Specimen part
View SamplesPI3K/AKT pathway plays one of pivotal roles in breast cancer development and maintenance. PIK3CA, coding PIK3 catalytic subunit, is the oncogene which shows the high frequency of gain-of-function mutations leading to the PI3K/AKT pathway activation in breast cancer. In particular in the ER-positive breast tumors PIK3CA mutations have been observed in 30% to 40%. However, genes expressed in connection to the pathway activation in breast tumorigenesis remain largely unknown.
Gene expression profiling reveals new aspects of PIK3CA mutation in ERalpha-positive breast cancer: major implication of the Wnt signaling pathway.
Sex, Age, Specimen part
View SamplesTime-series analysis of response to ribosome 28s damage at gene expression level
Early Response to the Plant Toxin Stenodactylin in Acute Myeloid Leukemia Cells Involves Inflammatory and Apoptotic Signaling.
Cell line, Treatment
View SamplesCUGBP1 and MBNL1 are developmentally regulated RNA-binding proteins that are causally associated with myotonic dystrophy type 1. Using HITS-CLIP anlysis, we found CUGBP1 and MBNL1 preferentially bind to alternatively spliced introns and exons, as well as to the 3' UTRs.
CUGBP1 and MBNL1 preferentially bind to 3' UTRs and facilitate mRNA decay.
Specimen part, Cell line
View SamplesMaternal obesity during pregnancy leads to a pro-inflammatory milieu in the placenta. We conducted a global transcriptomic profiling in BeWo cells following palmitic acid (PA, 500 uM) and/or TNF-alpha (10 ng/ml) treatment for 24 h. Microarray analysis revealed that placental cytotrophoblasts increased expression of genes related to inflammation, stress response and immediate-early factors in response to plamitic acid, TNF-alpha or a combination of both. Our results suggest that fatty acids and inflammatory cytokines induce inflammation in placental cells via activation of JNK-Egr-1 signaling.
Early growth response protein-1 mediates lipotoxicity-associated placental inflammation: role in maternal obesity.
Specimen part, Cell line
View SamplesTranscriptomic response of mouse mixed neuron-glial cell cultures to 1,25-dihydroxyvitamin D3
The transcriptomic response of mixed neuron-glial cell cultures to 1,25-dihydroxyvitamin d3 includes genes limiting the progression of neurodegenerative diseases.
Specimen part, Treatment
View SamplesTo determine the impact of ?Np63a knockdown on steady-state mRNA levels, we performed poly(A)-enriched RNA-seq analysis of lung squamous cell carcinoma line H226 (inducible shControl and shp63) in the presence of 1µg/mL doxycycline to induce shRNA expression. Overall design: Poly(A)+ RNA for two independent biological replicates was purified from H226 cells (inducible shControl and shp63) incubated treated for six days with 1 µg/mL doxycycline. a TruSeq Stranded mRNA Library Prep Kit (Illumina). Libraries were sequenced on an Illumina HiSeq 2000 system at the University of Colorado Cancer Center Genomics and Microarray Core facility. Reads were aligned (TopHat2) to the Human reference genome (GRCh37/hg19) and gene-level counts (HTseq-count) were used for differential expression analysis (DESeq2).
ΔNp63α Suppresses TGFB2 Expression and RHOA Activity to Drive Cell Proliferation in Squamous Cell Carcinomas.
Specimen part, Cell line, Treatment, Subject
View SamplesThe yeast PMR1 (ATP2C1) gene codes for the eukaryotic prototype of a high affinity P-type ATPase required for Ca2+/Mn2+ transport into the Golgi. Cells lacking PMR1 exhibit multiple genetic interactions with genes involved in DNA recombination and replication, a fact that is not yet understood. We find that deletion of PMR1 causes a delay in DNA replication initiation, progression and G2/M transition and induces the transcriptional up-regulation of genes involved in cell cycle regulation, including CLB5 and SWE1. Interestingly, pmr1 clb5 double mutants exhibit a dramatic delay in DNA replication and increased DNA breakage, while endoreplication and the formation of multi-nucleated, giant yeast is observed in pmr1 swe1 cells. Because these phenotypes can be attributed to impeded Mn2+-pump function, we provide a model in which Mn2+ interferes with Mg2+ in the nucleus, and vice versa, Mg2+ interferes with Mn2+ in the Golgi. Consequently, cell cycle progression is challenged by aberrant catalytic activities of enzymes involved in replication and protein glycosylation.
Impaired manganese metabolism causes mitotic misregulation.
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