Comprehensive nucleosome mapping of the human genome in cancer progression

The human genome is organized into topologically associating domains (TADs), which represent contiguous regions with a higher frequency of intra-interactions as opposed to inter-interactions. TADs contribute to gene expression regulation by restricting the interactions between their regulatory elements, and TAD disruption has been associated with cancer. Here, we provide a proof of principle that mutations within TADs can be used to predict the survival of cancer patients. Specifically, we constructed a set of 1467 consensus TADs representing the three-dimensional organization of the human genome and used Cox regression analysis to identify a total of 35 prognostic TADs in different cancer types. Interestingly, only 46% of the 35 prognostic TADs comprised genes with known clinical relevance. Moreover, in the vast majority of such cases, the prognostic value of the TAD was not directly related to the presence/absence of mutations in the gene(s), emphasizing the importance of regulatory mutations. In addition, we found that 34% of the prognostic TADs show strong structural perturbations in the cancer genome, consistent with the widespread, global epigenetic dysregulation often observed in cancer patients. In summary, this study elucidates the mechanisms through which non-coding variants may influence cancer progression and opens new avenues for personalized medicine.

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Comprehensive nucleosome mapping of the human genome in cancer progression

10.1101/021618 ◽

2015 ◽

Author(s):

Brooke Druliner ◽

Daniel Vera ◽

Ruth Johnson ◽

Xiaoyang Ruan ◽

Lynne Apone ◽

...

Keyword(s):

Cancer Progression ◽

Chromatin Structure ◽

Colon Adenocarcinoma ◽

Transcription Start ◽

Transcription Start Sites ◽

Genome Wide ◽

Early Adenocarcinoma ◽

Capture Method ◽

Nucleosome Mapping

Altered chromatin structure is a hallmark of cancer, and inappropriate regulation of chromatin structure may represent the origin of transformation. Important studies have mapped human nucleosome distributions genome wide, but the role of chromatin structure in cancer progression has not been addressed. We developed a MNase-Transcription Start Site Sequence Capture method (mTSS-seq) to map the nucleosome distribution at human transcription start sites genome-wide in primary human lung and colon adenocarcinoma tissue. Here, we confirm that nucleosome redistribution is an early, widespread event in lung (LAC) and colon (CRC) adenocarcinoma. These altered nucleosome architectures are consistent between LAC and CRC patient samples indicating that they may serve as important early adenocarcinoma markers. We demonstrate that the nucleosome alterations are driven by the underlying DNA sequence and potentiate transcription factor binding. We conclude that DNA-directed nucleosome redistributions are widespread early in cancer progression. We have proposed an entirely new hierarchical model for chromatin-mediated genome regulation.

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Two isoleucyl tRNAs that decode ‘synonymous’ codons divergently regulate breast cancer progression

10.1101/2021.04.22.440519 ◽

2021 ◽

Author(s):

Lisa B. Earnest-Noble ◽

Dennis Hsu ◽

Hosseinali Asgharian ◽

Mandayam Nandan ◽

Maria C. Passarelli ◽

...

Keyword(s):

Breast Cancer ◽

Cancer Cells ◽

Human Genome ◽

Cancer Progression ◽

Human Cancer ◽

Breast Cancer Progression ◽

Human Cancer Cells ◽

Functional Studies ◽

Synonymous Codons ◽

Growth Promoting

The human genome contains 61 codons that encode for the 20 amino acids. The synonymous codons of a given amino acid are decoded by a set of transfer RNAs (tRNAs) called isoacceptors. We report the surprising observation that two isoacceptor tRNAs that decode synonymous codons are modulated in opposing directions during breast cancer progression. Specifically, tRNAIleUAU is upregulated, whereas tRNAIleGAU is repressed as breast cancer cells attained enhanced metastatic capacity. Functional studies revealed that tRNAIleUAU promoted and tRNAIleGAU suppressed metastatic colonization. The expression of these tRNAs mediated opposing effects on codon-dependent translation of growth promoting genes. Consistent with this, multiple mitotic gene sets in the human genome are significantly enriched in the codon cognate to the growth-promoting tRNAIleUAU and significantly depleted of the codon cognate to the growth-suppressive tRNAIleGAU. Our findings uncover a specific isoacceptor tRNA pair that act in opposition—divergently regulating genes that contribute to growth and a disease phenotype. The degeneracy of the genetic code can thus be biologically exploited by human cancer cells via tRNA isoacceptor shifts that facilitate the transition towards a growth-promoting state.

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Nanopore sequencing and assembly of a human genome with ultra-long reads

10.1101/128835 ◽

2017 ◽

Cited By ~ 51

Author(s):

Miten Jain ◽

S Koren ◽

J Quick ◽

AC Rand ◽

TA Sasani ◽

...

Keyword(s):

Human Genome ◽

Cancer Progression ◽

De Novo ◽

Sequence Data ◽

Point Of Care ◽

Genetic Diseases ◽

Nanopore Sequencing ◽

Repeat Structure ◽

Long Reads ◽

Amazon Web Services

AbstractNanopore sequencing is a promising technique for genome sequencing due to its portability, ability to sequence long reads from single molecules, and to simultaneously assay DNA methylation. However until recently nanopore sequencing has been mainly applied to small genomes, due to the limited output attainable. We present nanopore sequencing and assembly of the GM12878 Utah/Ceph human reference genome generated using the Oxford Nanopore MinION and R9.4 version chemistry. We generated 91.2 Gb of sequence data (∼30× theoretical coverage) from 39 flowcells. De novo assembly yielded a highly complete and contiguous assembly (NG50 ∼3Mb). We observed considerable variability in homopolymeric tract resolution between different basecallers. The data permitted sensitive detection of both large structural variants and epigenetic modifications. Further we developed a new approach exploiting the long-read capability of this system and found that adding an additional 5×-coverage of ‘ultra-long’ reads (read N50 of 99.7kb) more than doubled the assembly contiguity. Modelling the repeat structure of the human genome predicts extraordinarily contiguous assemblies may be possible using nanopore reads alone. Portable de novo sequencing of human genomes may be important for rapid point-of-care diagnosis of rare genetic diseases and cancer, and monitoring of cancer progression. The complete dataset including raw signal is available as an Amazon Web Services Open Dataset at: https://github.com/nanopore-wgs-consortium/NA12878.

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DNA methylation in satellite repeats disorders

Essays in Biochemistry ◽

10.1042/ebc20190028 ◽

2019 ◽

Vol 63 (6) ◽

pp. 757-771 ◽

Cited By ~ 4

Author(s):

Claire Francastel ◽

Frédérique Magdinier

Keyword(s):

Dna Methylation ◽

Human Genome ◽

Repetitive Dna ◽

Dna Sequences ◽

Satellite Repeats ◽

Tremendous Progress ◽

Genes Encoding ◽

Dna Elements ◽

Near Future

Abstract Despite the tremendous progress made in recent years in assembling the human genome, tandemly repeated DNA elements remain poorly characterized. These sequences account for the vast majority of methylated sites in the human genome and their methylated state is necessary for this repetitive DNA to function properly and to maintain genome integrity. Furthermore, recent advances highlight the emerging role of these sequences in regulating the functions of the human genome and its variability during evolution, among individuals, or in disease susceptibility. In addition, a number of inherited rare diseases are directly linked to the alteration of some of these repetitive DNA sequences, either through changes in the organization or size of the tandem repeat arrays or through mutations in genes encoding chromatin modifiers involved in the epigenetic regulation of these elements. Although largely overlooked so far in the functional annotation of the human genome, satellite elements play key roles in its architectural and topological organization. This includes functions as boundary elements delimitating functional domains or assembly of repressive nuclear compartments, with local or distal impact on gene expression. Thus, the consideration of satellite repeats organization and their associated epigenetic landmarks, including DNA methylation (DNAme), will become unavoidable in the near future to fully decipher human phenotypes and associated diseases.

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