A computational framework to assess genome-wide distribution of polymorphic human endogenous retrovirus-K In human populations

Interspersed repetitive sequences (IRSs) are a major contributor to genome size and may contribute to cellular functions. IRSs are subdivided according to size and functionally related structures into short interspersed elements, long interspersed elements (LINEs), DNA transposons, and LTR-retrotransposons. Many IRSs may produce RNA and regulate genes by a variety of mechanisms. The majority of DNA methylation occurs in IRSs and is believed to suppress IRS activities. Global hypomethylation, or the loss of genome-wide methylation, is a common epigenetic event not only in senescent cells but also in cancer cells. Loss of LINE-1 methylation has been characterized in many cancers. Here, we evaluated the methylation levels of peripheral blood mononuclear cells of LINE-1, Alu, and human endogenous retrovirus K (HERV-K) in 177 samples obtained from volunteers between 20 and 88 yr of age. Age was negatively associated with methylation levels of Alu (r = −0.452, P < 10−3) and HERV-K (r = −0.326, P < 10−3) but not LINE-1 (r = 0.145, P = 0.055). Loss of methylation of Alu occurred during ages 34–68 yr, and loss of methylation of HERV-K occurred during ages 40–63 yr and again during ages 64–83 yr. Interestingly, methylation of Alu and LINE-1 are directly associated, particularly at ages 49 yr and older (r = 0.49, P < 10−3). Therefore, only some types of IRSs lose methylation at certain ages. Moreover, Alu and HERV-K become hypomethylated differently. Finally, there may be several mechanisms of global methylation. However, not all of these mechanisms are age-dependent. This finding may lead to a better understanding of not only the biological causes and consequences of genome-wide hypomethylation but also the role of IRSs in the aging process.

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A computational framework to assess genome-wide distribution of polymorphic human endogenous retrovirus-K in human populations

10.1101/444034 ◽

2018 ◽

Cited By ~ 1

Author(s):

Weiling Li ◽

Lin Lin ◽

Raunaq Malhotra ◽

Lei Yang ◽

Raj Acharya ◽

...

Keyword(s):

Disease Risk ◽

Sequence Data ◽

Endogenous Retrovirus ◽

Genomic Diversity ◽

Human Endogenous Retrovirus ◽

Human Populations ◽

Whole Genome ◽

Short Read ◽

Reference Set ◽

Type K

AbstractHuman Endogenous Retrovirus type K (HERV-K) is the only HERV known to be insertionally polymorphic. It is possible that HERV-Ks contribute to human disease because people differ in both number and genomic location of these retroviruses. Indeed viral transcripts, proteins, and antibody against HERV-K are detected in cancers, auto-immune, and neurodegenerative diseases. However, attempts to link a polymorphic HERV-K with any disease have been frustrated in part because population frequency of HERV-K provirus at each site is lacking and it is challenging to identify closely related elements such as HERV-K from short read sequence data. We present an integrated and computationally robust approach that uses whole genome short read data to determine the occupation status at all sites reported to contain a HERV-K provirus. Our method estimates the proportion of fixed length genomic sequence (k-mers) from whole genome sequence data matching a reference set ofk-mersunique to each HERV-K loci and applies mixture model-based clustering to account for low depth sequence data. Our analysis of 1000 Genomes Project Data (KGP) reveals numerous differences among the five KGP super-populations in the frequency of individual and co-occurring HERV-K proviruses; we provide a visualization tool to easily depict the prevalence of any combination of HERV-K among KGP populations. Further, the genome burden of polymorphic HERV-K is variable in humans, with East Asian (EAS) individuals having the fewest integration sites. Our study identifies population-specific sequence variation for several HERV-K proviruses. We expect these resources will advance research on HERV-K contributions to human diseases.Author summaryHuman Endogenous Retrovirus type K (HERV-K) is the youngest of retrovirus families in the human genome and is the only group that is polymorphic; a HERV-K can be present in one individual but absent from others. HERV-Ks could contribute to disease risk but establishing a link of a polymorphic HERV-K to a specific disease has been difficult. We develop an easy to use method that reveals the considerable variation existing among global populations in the frequency of individual and co-occurring polymorphic HERV-K, and in the total number of HERV-K that any individual has in their genome. Our study provides a global reference set of HERV-K genomic diversity and tools needed to determine the genomic landscape of HERV-K in any patient population.

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Genome-wide transcriptome analysis of prostate cancer tissue identified overexpression of specific members of the human endogenous retrovirus-K family

Cancer Translational Medicine ◽

10.4103/2395-3977.200859 ◽

2017 ◽

Vol 3 (1) ◽

pp. 1 ◽

Cited By ~ 3

Author(s):

Behnam Sayanjali

Keyword(s):

Prostate Cancer ◽

Transcriptome Analysis ◽

Endogenous Retrovirus ◽

Human Endogenous Retrovirus ◽

Cancer Tissue ◽

Genome Wide ◽

Prostate Cancer Tissue

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Unbiased examination of genome-wide human endogenous retrovirus transcripts in MS brain lesions

Multiple Sclerosis Journal ◽

10.1177/1352458520987269 ◽

2021 ◽

pp. 135245852098726

Author(s):

Maria L Elkjaer ◽

Tobias Frisch ◽

Arianna Tonazzolli ◽

Richard Röttger ◽

Richard Reynolds ◽

...

Keyword(s):

Genetic Risk ◽

Potential Role ◽

Brain Lesion ◽

Endogenous Retrovirus ◽

Brain Lesions ◽

Human Endogenous Retrovirus ◽

High Quality ◽

Genome Wide ◽

And Control ◽

Herv Expression

Background: Human endogenous retrovirus (HERV) expression in multiple sclerosis (MS) brain lesions may contribute to chronic inflammation, but expression of genome-wide HERVs in different MS lesions is unknown. Objective: We examined the HERV expression landscape in different MS lesions compared to control brains. Methods: Transcripts from 71 MS brain samples and 25 control WM were obtained by next-generation RNA sequencing and mapped against HERV transcripts across the human genome. Differential expression of mapped HERV-W and HERV-H reads between MS lesion types and controls was analysed. Results: Out of 6.38 billion high-quality paired end reads, 174 million reads (2.73%) mapped to HERV transcripts. There was no difference in HERVs expression level between MS and control brains, but HERV-W transcripts were significantly reduced in chronic active lesions. Of the four HERV-W transcripts exclusively present in MS, ERV3633503 located on chromosome 7q21.13 close to the MS genetic risk locus had the highest number of reads. In the HERV-H family, 75% of transcripts located to nearby 7q21-22 were overrepresented in MS, and ERV3643914 was expressed more than 16 times in MS compared to control brains. Conclusion: Novel HERV-W and HERV-H transcripts located at chromosome 7 regions were uniquely expressed in MS lesions, indicating their potential role in brain lesion evolution.

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A unified computational framework for modeling genome-wide nucleosome landscape

10.1101/202580 ◽

2017 ◽

Author(s):

Hu Jin ◽

Alex I. Finnegan ◽

Jun S. Song

Keyword(s):

Dna Sequence ◽

Genomic Sequence ◽

Nucleosome Occupancy ◽

Building Blocks ◽

Wide Distribution ◽

Computational Framework ◽

Genome Wide ◽

Eukaryotic Chromatin

AbstractNucleosomes form the fundamental building blocks of eukaryotic chromatin, and previous attempts to understand the principles governing their genome-wide distribution have spurred much interest and debate in biology. In particular, the precise role of DNA sequence in shaping local chromatin structure has been controversial. This paper rigorously quantifies of the contribution of hitherto-debated sequence features – including G+C content, 10.5-bp periodicity, and poly(dA:dT) tracts – to three distinct aspects of genome-wide nucleosome landscape: occupancy, translational positioning and rotational positioning. Our computational framework simultaneously learns nucleosome number and nucleosome-positioning energy from genome-wide nucleosome maps. In contrast to other previous studies, our model can predict bothin-vitroandin-vivonucleosome maps inS. cerevisiae. We find that although G+C content is the primary determinant of MNase-derived nucleosome occupancy, MNase digestion biases may substantially influence this GC dependence. By contrast, poly(dA:dT) tracts are seen to deter nucleosome formation, regardless of the experimental method used. We further show that the 10.5-bp nucleotide periodicity facilitates rotational but not translational positioning. Applying our method toin-vivonucleosome maps demonstrates that, for a subset of genes, the regularly-spaced nucleosome arrays observed around transcription start sites can be partially recapitulated by DNA sequence alone. Finally,in-vivonucleosome occupancy derived from MNase-seq experiments around transcription termination sites can be mostly explained by the genomic sequence. Implications of these results and potential extensions of the proposed computational framework are discussed

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