• Journal of Life Science
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• v.25 no.4
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• pp.481-485
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• 2015

Retroviruses genes have been inserted into the human genome for millions of years. These retroviruses are now inactive due to mutations such as deletions or nonsense mutations. After mutation, retroviruses eventually became fixed in the genome in their endogenous forms and existed as traces of ancient viruses. These retroviruses are called endogenous retroviruses (ERVs), with the human form known as human endogenous retrovirus. HERV cannot become a fully active virus, but a number of viral proteins or even virus particles are expressed under various conditions. Compared to endogenous retroviruses, some exogenous retroviruses are still infectious and can threaten human life. Among these, human immunodeficiency virus (HIV) is one of the most well-known and best-studied. Recent studies have shown some elements of HERV were activated by HIV infection and interact with HIV-derived proteins. In addition, many studies have attempted to use HERV as vaccination against HIV infection. This review will describe the regulation and interaction between HERV and HIV infection and mention the development of vaccines and therapeutic agents against HIV infection by using HERV elements.

• BMB Reports
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• v.54 no.7
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• pp.368-373
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• 2021

The vertebrate genome contains an endogenous retrovirus that has been inherited from the past millions of years. Although approximately 8% of human chromosomal DNA consists of sequences derived from human endogenous retrovirus (HERV) fragments, most of the HERVs are currently inactive and noninfectious due to recombination, deletions, and mutations after insertion into the host genome. Several studies suggested that Human endogenous retroviruses (HERVs) factors are significantly related to certain cancers. However, only limited studies have been conducted to analyze the expression of HERV derived elements at protein levels in certain cancers. Herein, we analyzed the expression profiles of HERV-K envelope (Env) and HERV-R Env proteins in eleven different kinds of cancer tissues. Furthermore, the expression patterns of both protein and correlation with various clinical data in each tissue were analyzed. The expressions of both HERV-K Env and HERV-R Env protein were identified to be significantly high in most of the tumors compared with normal surrounding tissues. Correlations between HERV Env expressions and clinical investigations varied depending on the HERV types and cancers. Overall expression patterns of HERV-K Env and HERV-R Env proteins were different in every individual but a similar pattern of expressions was observed in the same individual. These results demonstrate the expression profiles of HERV-K and HERV-R Env proteins in various cancer tissues and provide a good reference for the association of endogenous retroviral Env proteins in the progression of various cancers. Furthermore, the results elucidate the relationship between HERV-Env expression and the clinical significance of certain cancers.

• Journal of Life Science
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• v.31 no.8
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• pp.771-777
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• 2021

Human endogenous retroviruses (HERVs) were inserted into the human genome millions of years ago but they are currently inactive and non-infectious due to recombinations, deletions, and mutations after insertion into the host genome. Nonetheless, recent studies have shown that HERV-derived elements are actually involved in physiological phenomena and certain diseases including cancers. Among the various physiological phenomena related to HERV-derived elements, it is necessary to focus on inflammatory response. HERV-derived elements have been reported to be directly involved in various inflammatory diseases, including autoimmune diseases such as rheumatoid arthritis, multiple sclerosis, amyotrophic lateral sclerosis, and Sjogren's syndrome. As a mechanism for regulating inflammation through HERV-derived elements, the possibility that HERV-derived elements may cause nonspecific innate immune processes and that HERV-derived RNA or proteins may cause selective signaling mechanisms through specific receptors can be considered. However, the mechanism through which HERV-derived elements regulate inflammatory response, such as how silent HERV elements are activated in inflammatory response and what factors and signaling mechanisms are involved in HERV-derived elements, have not been identified to date, making it difficult to study the onset of HERV-related inflammatory disease. In this review, we introduce HERV-related autoimmune diseases and propose the mechanisms of HERV-derived elements at the molecular level of HERV in inflammatory response.

• Animal cells and systems
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• v.5 no.2
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• pp.133-137
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• 2001

Long terminal repeats (LTRs) of the human endogenous retrovirus K family (HERV-K) have been found to be coexpressed with sequences of genes closely located nearby. We examined transcribed HERV-K LTR elements in human brain tissue. Using cDNA synthesized from mRNA of the human brain, we performed PCR amplification and identified ten HERV-K LTR elements. These LTR elements showed a high degree of sequence similarity (92.4-99.7%) with the human-specific LTR elements. A phylogenetic tree obtained by the neighbor-joining method revealed that HERV-K LTR elements could be divided into two groups through evolutionary divergence. Some HERV-K LTR elements (HKL-B7, HKL-B8, HKL-B10) belonging to the group II from human brain cDNA were closely related to the human-specific HERV-K LTR elements. Our data suggest that HERV-K LTR element are active in the human brain; they could conceivably play a pathogenic role in human diseases such as psychosis.

• Journal of Life Science
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• v.10 no.2
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• pp.45-49
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• 2000

Long terminal repeat (LTR) of human endogenous retrovirus K family (HERV-K) has been found to be coexpressed with sequences of closely located genes. We examined the transcribed HERV-K LTR elements in human liver and kidney tissues. Using the cDNA synthesized from mRNA of human liver and kidney, we performed PCR amplification and identified six HERV-K LTR elements. Those LTR elements showed a high degree of sequence similarity (93.3∼96.6%) with human-specific LTR. A phylogenetic tree obtained by the neighbor-joining method revealed that HERV-K LTR elements (Liv-1, 2, 3 and Kid-1, 2, 3) were belonged to group I. Our data suggests that HERV-K LTR elements are active on human liver and kidney tissues and may represent a source of genetic variation connected to human disease.

• Journal of Life Science
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• v.11 no.2
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• pp.83-86
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• 2001

The long terminal repeat (LTR) elements of human endogenous retrovirus (HERV) have been found to be coexpressed with genes located nearby. It has been suggested that the LTR elements have contributed to the genetic variation of human genome connected to various diseases. Recently, HERV-W family was identified in the cerebrospinal fluids and brains of individuals with schizophrenia. Using genomic DNAs derived from schizophrenia, we performed PCR amplification and identified six HERV-W LTR elements. Those LTR elements showed a high degree of sequence similarity (87.7-99.5%) with HERV-W LTR (AF072500). Sequence analysis of the HERV-W LTR elements revealed that clone W-sch1 showed identical sequence with the AC003014 (PAC clone RP1-290B4) derived from human Xq23. Clone W-sch2 was closely related to the AC0072442 derived from human Y chromosome by phylogenetic analysis. Our data suggest that new HERV-W LTR elements in schizophrenia may be very useful for further studies to understand neuropsychiatric diseases.

• Animal cells and systems
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• v.6 no.1
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• pp.81-84
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• 2002

SINE-R retroposons have been derived from human endogenous retrovirus HERV-K family and found to be hominoid specific. Both SINE-R retroposons and HERV_K family are potentially capable of affecting the expression of closely located genes. Using the genomic DNA from patients with schizophrenia, we identified 26 SINE-R retroposons and analyzed them with the sequences derived from the hominoid primates. The SINE-R retroposons from schizophrenia showed 89.7-96.6％ sequence similarities with the sequence of the schizo-cDNA clone that derived from postmortem tissue from the frontal cortex of an individual suffering from schizophrenial. Phylogenetic analysis using the neighbor-joining method revealed that the new SINE-R retroposons in schizophrenia have proliferated independently during hominid evolution. Such retroposons have great relevance to genomic change connected to human diseases. The data suggest that new SINE-R retroposons identified in schizophrenia deserve further investigation as potential leads on the understanding of neuropsychiatric diseases.

• Animal cells and systems
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• v.6 no.2
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• pp.167-170
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• 2002

The long terminal repeats (LTRs) of human endogenous retrovirus (HERV) have been found to be coexpressed with sequences of closely located genes. It has been suggested that the LTR elements have contributed to the structural change or genetic variation of human genome connected to various diseases and evolution. We examined the HERV-W LTR elements in various cancer cells (2F7, A43l , A549, HepG2, MIA-PaCa-2, PC-3, RT4, SiHa, U-937, and UO-31). Using genomic DNA from the cancer cells, we performed PCR amplification and identified twelve new HERV-W LTR elements. Those LTR elements showed a high degree of sequence similarity (88-99％) with HERV-W LTR (AF072500). A phylogenetic tree obtained by the neighbor-joining method revealed that HERV-W LTR elements could be mainly divided into two groups through evolutionary divergence. Three HERV-W LTR elements (RT4-2, A43l-1, and UO3l-2) belonged to Group 1, whereas nine LTR elements (2F7-2, A549-1, A549-3, HepG2-3, MP2-2, PC3-1, SiHa-8, SiHa-10, and U937-1) belonged to Group 11. Taken together, our new sequence data of the HERV-W LTR elements may contribute to an understanding of tissue-specific cancer by genomic instability of LTR integration.

• Journal of Life Science
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• v.11 no.4
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• pp.379-384
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• 2001

Long terminal repeats(LTRs) of the human endogenous retrovirus(HERV) heve been found to be coexpresed with genes located nearby. It has been suggested that the LTR elements have contributed to the genetic variation of human genome connected to various diseases. Recently, HERV-W family was identified in the cerebrospinal fluids and brains of individuals with schizophrenia. Using cHNA library derived from human fetal brain, we performed PCR amplification and identified seven new HERV-W LTR elements. Those LTR elements showed a high degree of sequence similarity(98∼99%) with HERV-W (AF072500). A phylogentic tree obtained by the neighbor-joining method revealed that seven new HERV-W LTR elements(FB-1, 2, 4, 8, 9, 10, 12) were closely related to the AX000960, AF072504, and AF072506 from Gen Bank database. Our data suggest that several copy numbers of the HERV-W LTR elements are expressed in human feta brain and may contribute to an understanding of biological function connected to neuropsychiatric diseases.

• Journal of Life Science
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• v.11 no.5
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• pp.400-404
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• 2001

A new human endogenous retroviral family (HERV-S) has recently been identified from human X chromosome. It is 6.7 kb in length and has a typical retroviral structure with LTR-gag-pol-env-LTR. Using the PCR and sequencing approach, we investigated LTR elements of the HERV-S family from a human genomic DNA. Four LTR elements (HSL-1, HSL-5, HSL-10, HSL-11) were identified and have a high degree of sequence similarity(96-99%) with that of the HERV-S. Phylogenetic analysis from the HERV-S family indicated that the LTR elements were mainly divided into 2- groups through evolutionary divergence in the primate evolution. Further investigation of the HERV-S LTR elements in primates may cast light on the integration timing into the primate genome and understanding of human evolution.