Remnant proviral sequences in the genome resulting from the ancient germline infection of exogeno... more Remnant proviral sequences in the genome resulting from the ancient germline infection of exogenous retroviruses are called endogenous retroviruses (ERVs). The transcriptional activation of human ERVs (HERVs) in the brain of patients with some neurologic diseases suggests that ERVs may participate in certain disease processes in the central nervous system. In this study, we identified putative murine ERVs (MuERVs) which are transcriptionally active in the brain and characterized their biological properties to better understand the ERVs’ roles in the brain pathophysiology. The brain and selective non-nervous tissues (heart, muscle, adrenal gland, and salivary gland) of female C57BL/6J mice were subjected to RT-PCR analyses of MuERV expression by amplifying the 3′-end U3 regions and full-length/subgenomic transcripts. The expression patterns of the U3 regions and subgenomic transcripts in the brain were unique compared to the other tissues as well as the genomic MuERV profile. Two putative MuERVs (8,027 and 5,668 bp) were mapped on the mouse genome (chromosome 10, and chromosomes 4 and 8, respectively) using the MuERV U3 sequences, which were evidently expressed in the brain, as probes. Biological properties of these putative MuERVs, such as transcription potential, primer binding site, coding potential, integration age, recombination, and flanking host genes, were characterized. In particular, one of the two putative MuERV isolates had coding potentials for intact group specific antigen (gag), and truncated polymerase (pol) and envelope (env) polypeptides, while the other was defective for all three polypeptides. The findings from this study suggest that a specific group of MuERVs are constitutively expressed in the brain and they may participate in normal and pathogenic events pertaining to the brain through their replication gene products (e.g., gag and env polypeptides) as well as interactions with flanking host genes.
Viral transcripts from endogenous retroviruses (ERVs) have been detected from patients with multi... more Viral transcripts from endogenous retroviruses (ERVs) have been detected from patients with multiple sclerosis, breast cancer, leukemia, and schizophrenia (Karlsson et al. 2001; Depil et al. 2002; Portis 2002; Wang-Johanning et al. 2003). While it is unknown whether the presence of the viral transcripts implicates ERVs in the pathological response, ERVs contain the necessary elements for regulating expression of host genes surrounding proviral integration sites (Majors 1990). With approximately 10% of the mouse genome and 8% of the human genome containing retrovirus-like elements, it is likely that some of these elements may participate in controlling gene expression in normal and stress conditions (Lander et al. 2001; Waterston et al. 2002).While ERVs within the human genome are inactive, there are transcription regulatory elements and coding sequences of viral genes within the retroviral sequences that are still intact (Schon et al. 2001). ERVs can affect gene expression in three way ...
Remnant proviral sequences in the genome resulting from the ancient germline infection of exogeno... more Remnant proviral sequences in the genome resulting from the ancient germline infection of exogenous retroviruses are called endogenous retroviruses (ERVs). The transcriptional activation of human ERVs (HERVs) in the brain of patients with some neurologic diseases suggests that ERVs may participate in certain disease processes in the central nervous system. In this study, we identified putative murine ERVs (MuERVs) which are transcriptionally active in the brain and characterized their biological properties to better understand the ERVs’ roles in the brain pathophysiology. The brain and selective non-nervous tissues (heart, muscle, adrenal gland, and salivary gland) of female C57BL/6J mice were subjected to RT-PCR analyses of MuERV expression by amplifying the 3′-end U3 regions and full-length/subgenomic transcripts. The expression patterns of the U3 regions and subgenomic transcripts in the brain were unique compared to the other tissues as well as the genomic MuERV profile. Two putative MuERVs (8,027 and 5,668 bp) were mapped on the mouse genome (chromosome 10, and chromosomes 4 and 8, respectively) using the MuERV U3 sequences, which were evidently expressed in the brain, as probes. Biological properties of these putative MuERVs, such as transcription potential, primer binding site, coding potential, integration age, recombination, and flanking host genes, were characterized. In particular, one of the two putative MuERV isolates had coding potentials for intact group specific antigen (gag), and truncated polymerase (pol) and envelope (env) polypeptides, while the other was defective for all three polypeptides. The findings from this study suggest that a specific group of MuERVs are constitutively expressed in the brain and they may participate in normal and pathogenic events pertaining to the brain through their replication gene products (e.g., gag and env polypeptides) as well as interactions with flanking host genes.
Viral transcripts from endogenous retroviruses (ERVs) have been detected from patients with multi... more Viral transcripts from endogenous retroviruses (ERVs) have been detected from patients with multiple sclerosis, breast cancer, leukemia, and schizophrenia (Karlsson et al. 2001; Depil et al. 2002; Portis 2002; Wang-Johanning et al. 2003). While it is unknown whether the presence of the viral transcripts implicates ERVs in the pathological response, ERVs contain the necessary elements for regulating expression of host genes surrounding proviral integration sites (Majors 1990). With approximately 10% of the mouse genome and 8% of the human genome containing retrovirus-like elements, it is likely that some of these elements may participate in controlling gene expression in normal and stress conditions (Lander et al. 2001; Waterston et al. 2002).While ERVs within the human genome are inactive, there are transcription regulatory elements and coding sequences of viral genes within the retroviral sequences that are still intact (Schon et al. 2001). ERVs can affect gene expression in three way ...
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