| 1. |
- Barré, Benjamin P., et al.
(författare)
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Intragenic repeat expansion in the cell wall protein gene HPF1 controls yeast chronological aging
- 2020
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Ingår i: Genome Research. - : Cold Spring Harbor Laboratory. - 1088-9051 .- 1549-5469. ; 30:5, s. 697-710
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Tidskriftsartikel (refereegranskat)abstract
- Aging varies among individuals due to both genetics and environment, but the underlying molecular mechanisms remain largely unknown. Using a highly recombined Saccharomyces cerevisiae population, we found 30 distinct quantitative trait loci (QTLs) that control chronological life span (CLS) in calorie-rich and calorie-restricted environments and under rapamycin exposure. Calorie restriction and rapamycin extended life span in virtually all genotypes but through different genetic variants. We tracked the two major QTLs to the cell wall glycoprotein genes FLO11 and HPF1. We found that massive expansion of intragenic tandem repeats within the N-terminal domain of HPF1 was sufficient to cause pronounced life span shortening. Life span impairment by HPF1 was buffered by rapamycin but not by calorie restriction. The HPF1 repeat expansion shifted yeast cells from a sedentary to a buoyant state, thereby increasing their exposure to surrounding oxygen. The higher oxygenation altered methionine, lipid, and purine metabolism, and inhibited quiescence, which explains the life span shortening. We conclude that fast-evolving intragenic repeat expansions can fundamentally change the relationship between cells and their environment with profound effects on cellular lifestyle and longevity.
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| 2. |
- Belfield, Eric J., et al.
(författare)
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Thermal stress accelerates Arabidopsis thaliana mutation rate
- 2021
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Ingår i: Genome Research. - : COLD SPRING HARBOR LAB PRESS, PUBLICATIONS DEPT. - 1088-9051 .- 1549-5469. ; 31:1, s. 40-50
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Tidskriftsartikel (refereegranskat)abstract
- Mutations are the source of both genetic diversity and mutational load. However, the effects of increasing environmental temperature on plant mutation rates and relative impact on specific mutational classes (e.g., insertion /deletion [indel] vs. single nucleotide variant [SNV]) are unknown. This topic is important because of the poorly defined effects of anthropogen ic global temperature rise on biological systems. Here, we show the impact of temperature increase on Arabidopsis thaliana mutation, studying whole genome profiles of mutation accumulation (MA) lineages grown for 11 successive generations at 29 degrees C. Whereas growth of A. thaliana at standard temperature (ST; 23 degrees C) is associated with a mutation rate of 7 x10(-9) base substitutions per site per generation, growth at stressful high temperature (HT; 29 degrees C) is highly mutagenic, increasing the mutation rate to 12 x 10(-9). SNV frequency is approximately two- to threefold higher at HT than at ST, and HT-growth causes an similar to 19- to 23-fold increase in indel frequency, resulting in a disproportionate increase in indels (vs. SNVs). Most HT-induced indels are 1-2 bp in size and particularly affect homopolymeric or dinucleotide A or T stretch regions of the genome. HT-induced indels occur disproportionately in nucleosome-free regions, suggesting that much HT-induced mutational damage occurs during cell-cycle phases when genomic DNA is packaged into nucleosomes. We conclude that stressful experimental temperature increases accelerate plant mutation rates and particularly accelerate the rate of indel mutation. Increasing environmental temperatures are thus likely to have significant mutagenic consequences for plants growing in the wild and may, in particular, add detrimentally to mutational load.
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| 3. |
- de Hoon, M, et al.
(författare)
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Deep sequencing of short capped RNAs reveals novel families of noncoding RNAs
- 2022
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Ingår i: Genome research. - : Cold Spring Harbor Laboratory. - 1549-5469 .- 1088-9051. ; 32:9, s. 1727-1735
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Tidskriftsartikel (refereegranskat)abstract
- In eukaryotes, capped RNAs include long transcripts such as messenger RNAs and long noncoding RNAs, as well as shorter transcripts such as spliceosomal RNAs, small nucleolar RNAs, and enhancer RNAs. Long capped transcripts can be profiled using cap analysis gene expression (CAGE) sequencing and other methods. Here, we describe a sequencing library preparation protocol for short capped RNAs, apply it to a differentiation time course of the human cell line THP-1, and systematically compare the landscape of short capped RNAs to that of long capped RNAs. Transcription initiation peaks associated with genes in the sense direction have a strong preference to produce either long or short capped RNAs, with one out of six peaks detected in the short capped RNA libraries only. Gene-associated short capped RNAs have highly specific 3′ ends, typically overlapping splice sites. Enhancers also preferentially generate either short or long capped RNAs, with 10% of enhancers observed in the short capped RNA libraries only. Enhancers producing either short or long capped RNAs show enrichment for GWAS-associated disease SNPs. We conclude that deep sequencing of short capped RNAs reveals new families of noncoding RNAs and elucidates the diversity of transcripts generated at known and novel promoters and enhancers.
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| 4. |
- Ekim, Baris, et al.
(författare)
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Efficient mapping of accurate long reads in minimizer space with mapquik
- 2023
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Ingår i: Genome Research. - 1088-9051 .- 1549-5469. ; 33:7, s. 1188-1197
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Tidskriftsartikel (refereegranskat)abstract
- DNA sequencing data continue to progress toward longer reads with increasingly lower sequencing error rates. We focus on the critical problem of mapping, or aligning, low-divergence sequences from long reads (e.g., Pacific Biosciences [PacBio] HiFi) to a reference genome, which poses challenges in terms of accuracy and computational resources when using cutting-edge read mapping approaches that are designed for all types of alignments. A natural idea would be to optimize efficiency with longer seeds to reduce the probability of extraneous matches; however, contiguous exact seeds quickly reach a sensitivity limit. We introduce mapquik, a novel strategy that creates accurate longer seeds by anchoring alignments through matches of k consecutively sampled minimizers (k-min-mers) and only indexing k-min-mers that occur once in the reference genome, thereby unlocking ultrafast mapping while retaining high sensitivity. We show that mapquik significantly accelerates the seeding and chaining steps-fundamental bottlenecks to read mapping-for both the human and maize genomes with >96% sensitivity and near-perfect specificity. On the human genome, for both real and simulated reads, mapquik achieves a 37x speedup over the state-of-the-art tool minimap2, and on the maize genome, mapquik achieves a 410x speedup over minimap2, making mapquik the fastest mapper to date. These accelerations are enabled from not only minimizer-space seeding but also a novel heuristic O(n) pseudochaining algorithm, which improves upon the long-standing O(nlogn) bound. Minimizer-space computation builds the foundation for achieving real-time analysis of long-read sequencing data.
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| 5. |
- Gao, W, et al.
(författare)
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Cell type-specific analysis by single-cell profiling identifies a stable mammalian tRNA-mRNA interface and increased translation efficiency in neurons
- 2022
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Ingår i: Genome research. - : Cold Spring Harbor Laboratory. - 1549-5469 .- 1088-9051. ; 32:1, s. 97-110
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Tidskriftsartikel (refereegranskat)abstract
- The correlation between codon and anticodon pools influences the efficiency of translation, but whether differences exist in these pools across individual cells is unknown. We determined that codon usage and amino acid demand are highly stable across different cell types using available mouse and human single-cell RNA-sequencing atlases. After showing the robustness of ATAC-sequencing measurements for the analysis of tRNA gene usage, we quantified anticodon usage and amino acid supply in both mouse and human single-cell ATAC-seq atlases. We found that tRNA gene usage is overall coordinated across cell types, except in neurons, which clustered separately from other cell types. Integration of these data sets revealed a strong and statistically significant correlation between amino acid supply and demand across almost all cell types. Neurons have an enhanced translation efficiency over other cell types, driven by an increased supply of tRNAAla (AGC) anticodons. This results in faster decoding of the Ala-GCC codon, as determined by cell type–specific ribosome profiling, suggesting that the reduction of tRNAAla (AGC) anticodon pools may be implicated in neurological pathologies. This study, the first such examination of codon usage, anticodon usage, and translation efficiency resolved at the cell-type level with single-cell information, identifies a conserved landscape of translation elongation across mammalian cellular diversity and evolution.
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| 6. |
- Gao, W, et al.
(författare)
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Cell type-specific analysis by single-cell profiling identifies a stable mammalian tRNA-mRNA interface and increased translation efficiency in neurons
- 2022
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Ingår i: Genome research. - : Cold Spring Harbor Laboratory. - 1549-5469 .- 1088-9051. ; 32:1, s. 97-110
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Tidskriftsartikel (refereegranskat)abstract
- The correlation between codon and anticodon pools influences the efficiency of translation, but whether differences exist in these pools across individual cells is unknown. We determined that codon usage and amino acid demand are highly stable across different cell types using available mouse and human single-cell RNA-sequencing atlases. After showing the robustness of ATAC-sequencing measurements for the analysis of tRNA gene usage, we quantified anticodon usage and amino acid supply in both mouse and human single-cell ATAC-seq atlases. We found that tRNA gene usage is overall coordinated across cell types, except in neurons, which clustered separately from other cell types. Integration of these data sets revealed a strong and statistically significant correlation between amino acid supply and demand across almost all cell types. Neurons have an enhanced translation efficiency over other cell types, driven by an increased supply of tRNAAla (AGC) anticodons. This results in faster decoding of the Ala-GCC codon, as determined by cell type–specific ribosome profiling, suggesting that the reduction of tRNAAla (AGC) anticodon pools may be implicated in neurological pathologies. This study, the first such examination of codon usage, anticodon usage, and translation efficiency resolved at the cell-type level with single-cell information, identifies a conserved landscape of translation elongation across mammalian cellular diversity and evolution.
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| 7. |
- Geng, KY, et al.
(författare)
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Target-enriched nanopore sequencing and de novo assembly reveals co-occurrences of complex on-target genomic rearrangements induced by CRISPR-Cas9 in human cells
- 2022
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Ingår i: Genome research. - : Cold Spring Harbor Laboratory. - 1549-5469 .- 1088-9051. ; 32:10, s. 1876-1891
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Tidskriftsartikel (refereegranskat)abstract
- The CRISPR-Cas9 system is widely used to permanently delete genomic regions via dual guide RNAs. Genomic rearrangements induced by CRISPR-Cas9 can occur, but continuous technical developments make it possible to characterize complex on-target effects. We combined an innovative droplet-based target enrichment approach with long-read sequencing and coupled it to a customized de novo sequence assembly. This approach enabled us to dissect the sequence content at kilobase scale within an on-target genomic locus. We here describe extensive genomic disruptions by Cas9, involving the allelic co-occurrence of a genomic duplication and inversion of the target region, as well as integrations of exogenous DNA and clustered interchromosomal DNA fragment rearrangements. Furthermore, we found that these genomic alterations led to functional aberrant DNA fragments and can alter cell proliferation. Our findings broaden the consequential spectrum of the Cas9 deletion system, reinforce the necessity of meticulous genomic validations, and introduce a data-driven workflow enabling detailed dissection of the on-target sequence content with superior resolution.
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| 8. |
- Hashimoto, K, et al.
(författare)
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Embryonic LTR retrotransposons supply promoter modules to somatic tissues
- 2021
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Ingår i: Genome research. - : Cold Spring Harbor Laboratory. - 1549-5469 .- 1088-9051. ; 31:11, s. 1983-1993
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Tidskriftsartikel (refereegranskat)abstract
- Long terminal repeat (LTR) retrotransposons are widely distributed across the human genome. They have accumulated through retroviral integration into germline DNA and are latent genetic modules. Active LTR promoters are observed in germline cells; however, little is known about the mechanisms underlying their active transcription in somatic tissues. Here, by integrating our previous transcriptome data set with publicly available data sets, we show that the LTR families MLT2A1 and MLT2A2 are primarily expressed in human four-cell and eight-cell embryos and are also activated in some adult somatic tissues, particularly pineal gland. Three MLT2A elements function as the promoters and first exons of the protein-coding genes ABCE1, COL5A1, and GALNT13 specifically in the pineal gland of humans but not in that of macaques, suggesting that the exaptation of these LTRs as promoters occurred during recent primate evolution. This analysis provides insight into the possible transition from germline insertion to somatic expression of LTR retrotransposons.
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| 9. |
- Jolma, A, et al.
(författare)
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Binding specificities of human RNA-binding proteins toward structured and linear RNA sequences
- 2020
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Ingår i: Genome research. - : Cold Spring Harbor Laboratory. - 1549-5469 .- 1088-9051. ; 30:7, s. 962-973
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Tidskriftsartikel (refereegranskat)abstract
- RNA-binding proteins (RBPs) regulate RNA metabolism at multiple levels by affecting splicing of nascent transcripts, RNA folding, base modification, transport, localization, translation, and stability. Despite their central role in RNA function, the RNA-binding specificities of most RBPs remain unknown or incompletely defined. To address this, we have assembled a genome-scale collection of RBPs and their RNA-binding domains (RBDs) and assessed their specificities using high-throughput RNA-SELEX (HTR-SELEX). Approximately 70% of RBPs for which we obtained a motif bound to short linear sequences, whereas ∼30% preferred structured motifs folding into stem–loops. We also found that many RBPs can bind to multiple distinctly different motifs. Analysis of the matches of the motifs in human genomic sequences suggested novel roles for many RBPs. We found that three cytoplasmic proteins—ZC3H12A, ZC3H12B, and ZC3H12C—bound to motifs resembling the splice donor sequence, suggesting that these proteins are involved in degradation of cytoplasmic viral and/or unspliced transcripts. Structural analysis revealed that the RNA motif was not bound by the conventional C3H1 RNA-binding domain of ZC3H12B. Instead, the RNA motif was bound by the ZC3H12B's PilT N terminus (PIN) RNase domain, revealing a potential mechanism by which unconventional RBDs containing active sites or molecule-binding pockets could interact with short, structured RNA molecules. Our collection containing 145 high-resolution binding specificity models for 86 RBPs is the largest systematic resource for the analysis of human RBPs and will greatly facilitate future analysis of the various biological roles of this important class of proteins.
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| 10. |
- Kjellin, Jonas, et al.
(författare)
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Abundantly expressed class of noncoding RNAs conserved through the multicellular evolution of dictyostelid social amoebas
- 2021
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Ingår i: Genome Research. - : Cold Spring Harbor Laboratory Press (CSHL). - 1088-9051 .- 1549-5469. ; 31:3, s. 436-447
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Tidskriftsartikel (refereegranskat)abstract
- Aggregative multicellularity has evolved multiple times in diverse groups of eukaryotes, exemplified by the well-studied development of dictyostelid social amoebas, for example, Dictyostelium discoideum. However, it is still poorly understood why multicellularity emerged in these amoebas while the majority of other members of Amoebozoa are unicellular. Previously, a novel type of noncoding RNA, Class I RNAs, was identified in D. discoideum and shown to be important for normal multicellular development. Here, we investigated Class I RNA evolution and its connection to multicellular development. We identified a large number of new Class I RNA genes by constructing a covariance model combined with a scoring system based on conserved upstream sequences. Multiple genes were predicted in representatives of each major group of Dictyostelia and expression analysis confirmed that our search approach identifies expressed Class I RNA genes with high accuracy and sensitivity and that the RNAs are developmentally regulated. Further studies showed that Class I RNAs are ubiquitous in Dictyostelia and share highly conserved structure and sequence motifs. In addition, Class I RNA genes appear to be unique to dictyostelid social amoebas because they could not be identified in outgroup genomes, including their closest known relatives. Our results show that Class I RNA is an ancient class of ncRNAs, likely to have been present in the last common ancestor of Dictyostelia dating back at least 600 million years. Based on previous functional analyses and the presented evolutionary investigation, we hypothesize that Class I RNAs were involved in evolution of multicellularity in Dictyostelia.
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