Project description:Human Cytomegalovirus (HCMV) causes severe morbidity and mortality in an immune-compromised or immune-naïve host. Among DNA viruses, the genetic diversity of HCMV is unexpectedly high and comparable to those of RNA viruses, which hinders the development of effective vaccines and causes the emergence of antiviral resistance. However, little is known about how HCMV acquires genetic variation. Here, we propose an evolution strategy of HCMV, that exploits host “jumping DNA” L1 retrotransposon as a mutagen. We found that HCMV infection switches on L1 expression by upregulating transcription factors YY1 and RUNX3. Furthermore, HCMV DNA processivity factor, UL44 recruits L1 ribonucleoproteins to viral replication compartments and induces DNA damage to its genome. Deep-sequencing analysis of cultured HCMV genome revealed that L1 retrotransposon facilitates mutation burden on the viral genome. Indeed, laboratory adaptation of HCMV to fibroblasts is only observed upon active L1 expression. These findings demonstrate the evolution mechanism and molecular insights of how HCMV acquires genetic fitness by the hijacking of host L1 retrotransposon.
Project description:LINE-1/L1 retrotransposon sequences compose 17% of the human genome. Among the many classes of mobile genetic elements, L1 is the only autonomous retrotransposon that still drives human genomic plasticity today. Through its co-evolution with the human genome, L1 has intertwined itself with host cell biology to aid its proliferation.
Project description:Human Cytomegalovirus (HCMV) is a ubiquitous pathogen that has co-evolved with its host and in doing so, is highly efficient in undermining antiviral responses that limit successful infections. As a result, HCMV infections are highly problematic in individuals with weakened or underdeveloped immune systems including transplant recipients and newborns. Understanding how HCMV controls the microenvironment of an infected cell so as to favor productive replication is of critical importance. To this end, we took an unbiased proteomics approach to identify the highly reversible, stress induced, post-translational modification (PTM), protein S-nitrosylation, on viral proteins to determine the biological impact on viral replication. We identified protein S-nitrosylation of 13 viral proteins during infection of highly permissive fibroblasts. One of these proteins, pp71, is critical for efficient viral replication, as it undermines host antiviral responses, including STING activation. By exploiting site-directed mutagenesis of the specific amino acids we identified in pp71 as protein S-nitrosylated, we found this pp71 PTM diminishes its ability to undermine antiviral responses induced by the STING pathway. Our results suggest a model in which protein S-nitrosylation may function as a host response to viral infection that limits viral spread.
Project description:Genome-wide profiling establishes that human cytomegalovirus (HCMV) exerts an extensive, unforeseen level of specific control over which cellular mRNAs are recruited to or excluded from polyribosomes. The landscape of translationally-regulated host mRNAs regulates HCMV replication. The HCMV imposed translational signature shares similarities with cancer cells
Project description:The long interspersed nuclear element-1 (LINE-1 or L1) retrotransposon is the only active autonomously replicating retrotransposon in the human genome. L1 harms the cell by inserting new copies, generating DNA damage, and triggering inflammation. Therefore, L1 inhibition could be used to treat many diseases associated with these processes. Previous research has focused on inhibition of the L1 reverse transcriptase due to the prevalence of well-characterized inhibitors of related viral enzymes. Here we present the L1 endonuclease as another target for reducing L1 activity. We have characterized structurally diverse small molecule endonuclease inhibitors using computational, biochemical, and biophysical methods. We also show that these inhibitors reduce L1 retrotransposition, L1-induced DNA damage, and inflammation reinforced by L1 in senescent cells. These inhibitors could be further used to better understand the life cycle of this element and its impact on human health.
Project description:<p>Insertions of the human-specific subfamily of LINE-1 (L1) retrotransposon are highly polymorphic across individuals and can critically influence the human transcriptome. We hypothesized that L1 insertions could represent genetic variants determining important human phenotypic traits, and performed an integrated analysis of L1 elements and single nucleotide polymorphisms (SNPs) in several human populations. We found that a large fraction of L1s were in high linkage disequilibrium (LD) with their surrounding genomic regions and that they were well-tagged by SNPs. However, L1 variants were only partially captured by SNPs on standard SNP arrays, so that their potential phenotypic impact would be frequently missed by SNP array-based genome-wide association studies. We next identified potential phenotypic effects of L1s by looking for signatures of natural selection linked to L1 insertions; significant extended haplotype homozygosity (EHH) was detected around several L1 insertions. This suggests that some of these L1 insertions may have been the target of recent positive selection.</p>
Project description:Using Next-generation sequencing of total RNA isolated from human cytomegalovirus virions we have identified host (human) tRNA molecules.
Project description:Using Next-generation sequencing of total RNA isolated from human cytomegalovirus virions we have analyzed host (human) snoRNA molecules.
Project description:piRNA-deficient Maelstrom (Mael) null mice are characterized by a strong upregulation of retrotransposon LINE-1 (L1) in meiotic spermatocytes. This defect turns out in the accumulation of L1 RNA and ORF1p in their cytoplasm and the formation of prominent ribonucleoprotein aggregates. We used 3-months-old Mael-/- male mice to characterize the protein composition of those ORF1p aggregates.