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International audience; The prostate-specific antigen (PSA) is the main diagnostic biomarker for prostate cancer in clinical use, but it lacks specificity and sensitivity, particularly in low dosage values 1. 'How to use PSA' remains a current issue, either for diagnosis as a gray zone corresponding to a concentration in serum of 2.5-10 ng/ml which does not allow a clear differentiation to be made between cancer and noncancer 2 or for patient follow-up as analysis of post-operative PSA kinetic parameters can pose considerable challenges for their practical application 3,4. Alternatively, noncoding RNAs (ncRNAs) are emerging as key molecules in human cancer, with the potential to serve as novel markers of disease, e.g. PCA3 in prostate cancer 5,6 and to reveal uncharacterized aspects of tumor biology. Moreover, data from the ENCODE project published in 2012 showed that different RNA types cover about 62% of the genome. It also appears that the amount of transcriptional regulatory motifs is at least 4.5x higher than the one corresponding to protein-coding exons. Thus, long terminal repeats (LTRs) of human endogenous retroviruses (HERVs) constitute a wide range of putative/candidate transcriptional regulatory sequences, as it is their primary function in infectious retroviruses. HERVs, which are spread throughout the human genome, originate from ancestral and independent infections within the germ line, followed by copy-paste propagation processes and leading to multicopy families occupying 8% of the human genome (note that exons span 2% of our genome). Some HERV loci still express proteins that have been associated with several pathologies including cancer 7-10. We have designed a high-density microarray, in Affymetrix format, aiming to optimally characterize individual HERV loci expression, in order to better understand whether they can be active, if they drive ncRNA transcription or modulate coding gene expression. This tool has been applied in the prostate cancer field (Figure 1).

Recent studies suggested a role for the human endogenous retrovirus (HERV) group HERV-K(HML-2) in melanoma because of upregulated transcription and expression of HERV-K(HML-2)-encoded proteins. Very little is known about which HML-2 loci are transcribed in melanoma. We assigned >1,400 HML-2 cDNA sequences generated from various melanoma and related samples to genomic HML-2 loci, identifying a total of 23 loci as transcribed. Transcription profiles of loci differed significantly between samples. One locus was found transcribed only in melanoma-derived samples but not in melanocytes and might represent a marker for melanoma. Several of the transcribed loci harbor ORFs for retroviral Gag and/or Env proteins. Env-encoding loci were transcribed only in melanoma. Specific investigation of rec and np9 transcripts indicated transcription of protein encoding loci in melanoma and melanocytes hinting at the relevance of Rec and Np9 in melanoma. UVB irradiation changed transcription profiles of loci and overall transcript levels decreased in melanoma and melanocytes. We further identified transcribed HML-2 loci formed by reverse transcription of spliced HML-2 transcripts by L1 machinery or in a retroviral fashion, with loci potentially encoding HML-2-like proteins. We reveal complex, sample-specific transcription of HML-2 loci in melanoma and related samples. Identified HML-2 loci and proteins encoded by those loci are particularly relevant for further studying the role of HML-2 in melanoma. Transcription of HERVs appears as a complex mechanism requiring specific studies to elucidate which HERV loci are transcribed and how transcribed HERVs may be involved in disease.

Myalgic encephalomyelitis (ME) is a debilitating illness of unknown etiology characterized by neurocognitive dysfunction, inflammation, immune abnormalities and gastrointestinal distress. An increasing body of evidence suggests that disruptions in the gut may contribute to the induction of neuroinflammation. Therefore, reports of human endogenous retroviral (HERV) expression in association with neuroinflammatory diseases prompted us to investigate the gut of individuals with ME for the presence of HERV proteins. In eight out of 12 individuals with ME, immunoreactivity to HERV proteins was observed in duodenal biopsies. In contrast, no immunoreactivity was detected in any of the eight controls. Immunoreactivity to HERV Gag and Env proteins was uniquely co-localized in hematopoietic cells expressing the C-type lectin receptor CLEC4C (CD303/BDCA2), the costimulatory marker CD86 and the class II major histocompatibility complex HLA-DR, consistent with plasmacytoid dendritic cells (pDCs). Although the significance of HERVs present in the pDCs of individuals with ME has yet to be determined, these data raise the possibility of an involvment of pDCs and HERVs in ME pathology. To our knowledge, this report describes the first direct association between pDCs and HERVs in human disease.

Background Emerging evidence suggests that human cytomegalovirus (HCMV) is highly prevalent in tumours of different origin. This virus is implied to have oncogenic and oncomodulatory functions, through its ability to control host gene expression. Human endogenous retroviruses (HERV) are also frequently active in tumours of different origin, and are supposed to contribute as cofactors to cancer development. Due to the high prevalence of HCMV in several different tumours, and its ability to control host cell gene expression, we sought to define whether HCMV may affect HERV transcription. Findings Infection of 3 established cancer cell lines, 2 primary glioblastoma cells, endothelial cells from 3 donors and monocytes from 4 donors with HCMV (strains VR 1814 or TB40/F) induced reverse transcriptase (RT) activity in all cells tested, but the response varied between donors. Both, gammaretrovirus-related class I elements HERV-T, HERV-W, HERV-F and ERV-9, and betaretrovirus-related class II elements HML-2 - 4 and HML-7 - 8, as well as spuma-virus related class III elements of the HERV-L group were up-regulated in response to HCMV infection in GliNS1 cells. Up-regulation of HERV activity was more pronounced in cells harbouring active HCMV infection, but was also induced by UV-inactivated virus. The effect was only slightly affected by ganciclovir treatment and was not controlled by the IE72 or IE86 HCMV genes. Conclusions Within this brief report we show that HCMV infection induces HERV transcriptional activity in different cell types.

The MSRV (Multiple Sclerosis Associated Retro Virus) belongs to the human endogenous retrovirus HERV-W family. An envelope protein originating from the MSRV was found in most patients with multiple sclerosis (MS). This protein (Env-ms) has pro-inflammatory properties on several immune cells and could therefore play a role in the MS pathogenesis by promoting the leukocyte diapedesis observed in the central nervous system of patients. Our study aims to analyze the effects of Env-ms on the blood-brain barrier (BBB) at a molecular and functional level. We have demonstrated that the recombinant MSRV envelope was able to strongly stimulate several inflammatory parameters on a human BBB in vitro model, the HCMEC/D3 cell line. Indeed, Env-ms induced overexpression of ICAM-1, a major mediator of leukocyte adhesion to endothelial cells, in a dose-dependent manner and a strong dose-dependent production of the pro-inflammatory cytokines IL-6 and IL-8. Furthermore, using a silencing approach with siRNAs, we have shown that Env-ms was recognized via the TLR4 receptor, a pattern recognition receptor of innate immunity present on endothelial cells. Indeed, the knock down of TLR4 abolishes the pro-inflammatory effects of Env-ms. We have also shown using functionnal assays, that the treatment of brain endothelial cells with Env-ms significantly stimulated the adhesion of activated immune cells to the monolayer of endothelial cells. We also assessed the effects of Env-ms on primary endothelial cells HUVECs and we observed that the pro-inflammatory properties of the envelope protein were similar to those observed on HCMEC/D3. These findings support the hypothesis that MSRV could be involved in the pathogenesis of MS disease or at least in maintenance of inflammatory conditions thus fueling the auto-immune disorder. The MSRV could also play a role in other chronic inflammatory diseases.; Le MSRV (Multiple Sclerosis Associated Retro Virus) fait partie de la famille de rétrovirus endogènes humains HERV-W. Une protéine d'enveloppe provenant du MSRV est retrouvée chez la plupart des patients atteints de sclérose en plaque (SEP). Cette protéine (Env-ms) a des propriétés pro-inflammatoires sur les cellules immunitaires et pourrait donc jouer un rôle dans la pathogenèse de la SEP en exacerbant la diapédèse leucocytaire observée dans le système nerveux central (SNC) des patients. Cette étude vise principalement à analyser les effets de Env-ms sur la barrière hémato-encéphalique (BHE) au niveau moléculaire et fonctionnel. Nous avons pu démontrer que l'enveloppe recombinante du MSRV était capable de stimuler plusieurs paramètres inflammatoires sur un modèle humain de BHE in vitro, la lignée HCMEC/D3. En effet, Env-ms induit une surexpression d'ICAM-1, une protéine impliquée dans l'adhésion des leucocytes aux cellules endothéliales, d'une manière dose dépendante ainsi qu'une production dose dépendante de cytokines pro-inflammatoires comme l'IL-6 et l'IL-8. De plus, par une approche utilisant des siRNAs, nous avons pu montrer que Env-ms était reconnue par le récepteur TLR4, un récepteur de l'immunité innée exprimé par les cellules endothéliales. Nous avons aussi montré par des essais fonctionnels que Env-ms stimulait de manière significative l'adhésion de cellules immunitaires activées à la monocouche de cellules endothéliales. Enfin, nous avons aussi mesuré les effets de Env-ms sur des cultures primaires de cellules endothéliales HUVEC et nous avons pu montrer que les propriétés pro-inflammatoires de la protéine d'enveloppe étaient similaires à celles observées sur le modèle HCMEC/D3 Ces résultats appuient l'hypothèse selon laquelle le MSRV pourrait être impliqué dans la pathogenèse de la SEP ou bien dans le maintien d'un niveau d'inflammation élevé favorisant le désordre immunitaire observé chez les patients. Le MSRV pourrait également jouer un rôle dans d'autres maladies inflammatoires chroniques.

The MSRV (Multiple Sclerosis Associated Retro Virus) belongs to the human endogenous retrovirus HERV-W family. An envelope protein originating from the MSRV was found in most patients with multiple sclerosis (MS). This protein (Env-ms) has pro-inflammatory properties on several immune cells and could therefore play a role in the MS pathogenesis by promoting the leukocyte diapedesis observed in the central nervous system of patients. Our study aims to analyze the effects of Env-ms on the blood-brain barrier (BBB) at a molecular and functional level. We have demonstrated that the recombinant MSRV envelope was able to strongly stimulate several inflammatory parameters on a human BBB in vitro model, the HCMEC/D3 cell line. Indeed, Env-ms induced overexpression of ICAM-1, a major mediator of leukocyte adhesion to endothelial cells, in a dose-dependent manner and a strong dose-dependent production of the pro-inflammatory cytokines IL-6 and IL-8. Furthermore, using a silencing approach with siRNAs, we have shown that Env-ms was recognized via the TLR4 receptor, a pattern recognition receptor of innate immunity present on endothelial cells. Indeed, the knock down of TLR4 abolishes the pro-inflammatory effects of Env-ms. We have also shown using functionnal assays, that the treatment of brain endothelial cells with Env-ms significantly stimulated the adhesion of activated immune cells to the monolayer of endothelial cells. We also assessed the effects of Env-ms on primary endothelial cells HUVECs and we observed that the pro-inflammatory properties of the envelope protein were similar to those observed on HCMEC/D3. These findings support the hypothesis that MSRV could be involved in the pathogenesis of MS disease or at least in maintenance of inflammatory conditions thus fueling the auto-immune disorder. The MSRV could also play a role in other chronic inflammatory diseases., Le MSRV (Multiple Sclerosis Associated Retro Virus) fait partie de la famille de rétrovirus endogènes humains HERV-W. Une protéine d'enveloppe provenant du MSRV est retrouvée chez la plupart des patients atteints de sclérose en plaque (SEP). Cette protéine (Env-ms) a des propriétés pro-inflammatoires sur les cellules immunitaires et pourrait donc jouer un rôle dans la pathogenèse de la SEP en exacerbant la diapédèse leucocytaire observée dans le système nerveux central (SNC) des patients. Cette étude vise principalement à analyser les effets de Env-ms sur la barrière hémato-encéphalique (BHE) au niveau moléculaire et fonctionnel. Nous avons pu démontrer que l'enveloppe recombinante du MSRV était capable de stimuler plusieurs paramètres inflammatoires sur un modèle humain de BHE in vitro, la lignée HCMEC/D3. En effet, Env-ms induit une surexpression d'ICAM-1, une protéine impliquée dans l'adhésion des leucocytes aux cellules endothéliales, d'une manière dose dépendante ainsi qu'une production dose dépendante de cytokines pro-inflammatoires comme l'IL-6 et l'IL-8. De plus, par une approche utilisant des siRNAs, nous avons pu montrer que Env-ms était reconnue par le récepteur TLR4, un récepteur de l'immunité innée exprimé par les cellules endothéliales. Nous avons aussi montré par des essais fonctionnels que Env-ms stimulait de manière significative l'adhésion de cellules immunitaires activées à la monocouche de cellules endothéliales. Enfin, nous avons aussi mesuré les effets de Env-ms sur des cultures primaires de cellules endothéliales HUVEC et nous avons pu montrer que les propriétés pro-inflammatoires de la protéine d'enveloppe étaient similaires à celles observées sur le modèle HCMEC/D3 Ces résultats appuient l'hypothèse selon laquelle le MSRV pourrait être impliqué dans la pathogenèse de la SEP ou bien dans le maintien d'un niveau d'inflammation élevé favorisant le désordre immunitaire observé chez les patients. Le MSRV pourrait également jouer un rôle dans d'autres maladies inflammatoires chroniques.

Perhaps as much as two-thirds of the mammalian genome is composed of mobile genetic elements ('jumping genes'), a fraction of which is still active or can be reactivated. By their sheer number and mobility, retrotransposons, DNA transposons and endogenous retroviruses have shaped our genotype and phenotype both on an evolutionary scale and on an individual level. Notably, at least the non-long terminal repeat retrotransposons are still able to cause disease by insertional mutagenesis, recombination, providing enzymatic activities for other mobile DNA, and perhaps by transcriptional overactivation and epigenetic effects. Currently, there are nearly 100 examples of known retroelement insertions that cause disease. In this review, we highlight those genome-scale technologies that have expanded our knowledge of the diseases that these mobile elements can elicit, and we discuss the potential impact of these findings for medicine. It is now likely that at least some types of cancer and neurological disorders arise as a result of retrotransposon mutagenesis.

Objectives: Human Endogenous Retroviruses (HERVs) were originally derived from germ cell infection by exogenous retroviruses and comprise around eight per cent of the human genome. HERVs are highly expressed in the placenta, where HERV-W (syncytin 1) has been demonstrated to perform a fusogenic function. Due to their retroviral origin, placental syncytin 1 has been suggested to also be involved in modulating the maternal immune system. The placenta constantly sheds microvesicles (MV) into the maternal circulation, demonstrated to cause innate immune cell activation associated with normal pregnancy. In pre-eclampsia, there is both increased placental MV shedding and a heightened pro-inflammatory immune response. It was therefore hypothesised that HERVs shed via placental MV play a role in feto-maternal immune interactions and thus may be an important factor in the pathogenesis of preeclampsia (PE). More specifically, it was hypothesised that syncytin 1-positive MV activate monocytes through toll-like receptor 4 (TLR-4). The aim of this study was to determine if syncytin 1 is released from the placenta via MV and exerts an immunological effect.Methods: HERV mRNA and protein expression was measured in placenta and the BeWo choriocarcinoma cell line by qPCR, western blotting (WB) and immunostaining. Glycosylation of syncytin 1 protein was determined by PNGase F treatment followed by WB. MV shed by first trimester, term normal and PE placental explants as well as BeWo cells were isolated by ultracentrifugation. Morphology of these microvesicles was examined by electron microscopy. Syncytin 1 protein and RNA was detected in microvesicles by WB and PCR. Activation and priming of PBMCs to respond to lipopolysaccharide (LPS) by syncytin 1-positive MV and recombinant syncytin 1 was examined through cytokine production by ELISA and multiplex. Antagonism of TLR-4 by LPS-RS was used to determine involvement of the receptor. The role of syncytin 1 in MV activation was examined by siRNA knockdown.Results: HERVs are highly expressed in placental tissue. Syncytin 1 is a glycosylated protein and its expression is altered in PE. MV shed from the BeWo choriocarcinoma cell line and from first trimester and term placental explants, express HERV protein and RNA. Syncytin 1 positive MV and recombinant syncytin protein cause activation of PBMCs. Greatest activation is stimulated by PE MV. Normal MV exhibit a neutral or suppressive effect on subsequent LPS challenge to PBMCs. PE MV exacerbate the response to LPS. Antagonism of TLR-4 on PBMCs and knockdown of syncytin 1 content in MV reduces activation by placental MV.Conclusions: The findings of this thesis suggest that syncytin 1 protein expressed by the placenta is shed into the maternal circulation via MV, and can activate immune cells through TLR-4. Syncytin 1-positive microvesicles may play a role in endotoxin tolerance of innate immune cells in pregnancy. The increased activation by PE MV implies that in addition to the increased microvesicle load in this pathology, a factor intrinsic to PE MV is responsible for increased inflammation. These studies implicate microvesicle-bound syncytin 1 in the regulation of immunotolerance during pregnancy.

Humane Endogene Retroviren (HERVs) sind Sequenzen ehemals exogener Retroviren, die vor Millionen von Jahren Keimbahnzellen menschlicher Vorfahren infizierten und ein Bestandteil des Genoms wurden. Nach ihrer Integration entstanden bei allen heute bekannten Elementen inaktivierende Mutationen. Die am besten erhaltenen und exprimierten Proviren mit zum Teil noch vollständig offenen Leserahmen für alle viralen Proteine gehören zur Familie HERV-K(HML-2). Die postinsertionalen Mutationen verhindern oder erschweren generelle Aussagen zu funktionellen Eigenschaften dieser Proteine. Aus diesem Grund wurde für die Untersuchungen ein Hüllprotein des Elements HERV-K113 verwendet, dessen postinsertionale Mutationen identifiziert und revertiert wurden. Die Sequenz des so rekonstituierten Hüllproteins eines prototypischen HERV-K(HML-2) Provirus vom Zeitpunkt der Integration und die Sequenz des heutigen Hüllproteins wurden zudem codonoptimiert. Dadurch wurde die Expression um den Faktor 50 gesteigert. Dies ermöglichte die in dieser Arbeit erfolgte weitreichende Charakterisierung des Proteins. Das rekonstituierte Hüllprotein ist im Vergleich zu dem heutigen stark glykosyliert und wird in virale Partikel eingebaut. Es ist in der Lage Infektionen zu vermitteln. Sowohl die Glykosylierung des Hüllproteins als auch das C-terminale Ende sind kritisch für den Partikeleinbau und deren Infektiosität. Beides kann durch Deletion des nahezu kompletten zytoplasmatischen Endes signifikant gesteigert werden. Mit dem rekonstituierten funktionellen Hüllprotein und pseudotypisierten Viren wurde eine umfangreiche Tropismusstudie durchgeführt. Dabei wurde deutlich, dass HERV-K(HML-2) eine sehr breite Wirtsspezifität aufweist und Zellen der meisten Spezies infiziert. Die Ergebnisse deuten darauf hin, dass die Verbreitung des noch unbekannten Rezeptors für HERV-K(HML-2) nicht gewebespezifisch ist, denn sowohl Leber-, Prostata-, Muskel-, Nieren-, Lungen-, Dickdarm-, Thymus-, Embryo-, Ovariums-, Bindegewebs-, Gehirn-, Harnblasen-, Keim- oder Hautzellen werden infiziert. HERV-K(HML-2) besitzt somit einen amphotropen Zelltropismus, wobei feline und canine Zelllinien besonders permissiv für Infektionen sind. Mit Hilfe von HERV-K113 Env-IgG- Immunoadhäsinen wurde der Tropismus für einige der Zellen bestätigt. In ersten Rezeptorstudien konnte gezeigt werden, dass der Transferrin Rezeptor 1 und die Hyaluronidase 2, die spezifischen Rezeptormoleküle der nahe verwandten Betaretroviren Mouse Mammary Tumor Virus und Jaagsiekte Sheep Retrovirus, den Eintritt von HERV-K113 in die Wirtzelle nicht vermitteln., Human endogenous retroviruses (HERVs) are sequences of ancient exogenous retroviruses that millions of years ago infected the germ cell line of human ancestors, becoming thereby part of the genome. Subsequent to integration, all HERVs known today suffered inactivating mutations. The best preserved and expressed proviruses, some of which have maintained open reading frames for all viral proteins, belong to the HERV-K(HML-2) family. However, postinsertional mutations make it difficult to draw general conclusions concerning the functional characteristics of these proteins and for this reason we used in these studies a HERV-K113 envelope protein (Env) for which postinsertional mutations had been identified and reversed. Furthermore this sequence, representing the reconstituted prototypical HERV-K(HML-2) provirus existing at the time of integration, together with the sequence of the present-day Env, was codon optimized. This resulted in a 50-fold or more increase in expression, allowing the protein to be characterized in detail. Compared to the modern envelope protein, the reconstituted ancient Env is heavily glycosylated, moderately incorporated into retroviral particles and able to mediate entry. The carbohydrates of the envelope protein as well as the cytoplasmic tail are critical for particle incorporation and infectivity, functions that can both be dramatically enhanced by deletion of virtually the complete cytoplasmic tail. Protein tropism was extensively studied using the reconstituted functional Env and pseudotyped viral particles. HERV-K(HML-2) was shown to have a broad host range and to be able to infect cell lines of most species studied. The results suggest that the distribution of the still unknown receptor is not tissue specific as many tissues including liver, prostate, muscle, kidney, lung, colon, thymus, embryo, ovary, fibroblast, brain, urinary bladder, germ cell and skin are permissive to HERV-K(HML-2) infection. HERV-K(HML-2) therefore has an amphotropic cell tropism, with feline and canine cell lines being particularly susceptible. The tropism of some of these cell lines was confirmed using HERV-K113 Env immunoadhesins. Initial receptor studies demonstrated that Transferrin Receptor 1 and Hyaluronidase 2, the specific receptor proteins used by the closely related βretroviruses, Mouse Mammary Tumor Virus and Jaagsiekte Sheep Retrovirus, do not facilitate the entry of HERV-K113 into host cells.

Human endogenous retroviruses (HERVs) are globally silent in somatic cells. However, some HERVs display high transcription in physiological conditions. In particular, ERVWE1, ERVFRDE1 and ERV3, three proviruses of distinct families, are highly transcribed in placenta and produce envelope proteins associated with placenta development. As silencing of repeated elements is thought to occur mainly by DNA methylation, we compared the methylation of ERVWE1 and related HERVs to appreciate whether HERV methylation relies upon the family, the integration site, the tissue, the long terminal repeat (LTR) function or the associated gene function. CpG methylation of HERV-W LTRs in placenta-associated tissues was heterogeneous but a joint epigenetic control was found for ERVWE1 5'LTR and its juxtaposed enhancer, a mammalian apparent LTR retrotransposon. Additionally, ERVWE1, ERVFRDE1 and ERV3 5'LTRs were all essentially hypomethylated in cytotrophoblasts during pregnancy, but showed distinct and stage-dependent methylation profiles. In non-cytotrophoblastic cells, they also exhibited different methylation profiles, compatible with their respective transcriptional activities. Comparative analyses of transcriptional activity and LTR methylation in cell lines further sustained a role for methylation in the control of functional LTRs. These results suggest that HERV methylation might not be family related but copy-specific, and related to the LTR function and the tissue. In particular, ERVWE1 and ERV3 could be developmentally epigenetically regulated HERVs.

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.

The psoriasis susceptibility locus 1 (PSORS1) mutation is assumed to reside within a region around human leukocyte antigen-C spanning 250 kb, termed risk haplotype (RH) 1/2. By re-analyzing a published data set with a previously developed method, the haplotype sharing statistic, we confirm localization of PSORS1 to the RH1 region and refine its location to marker M6S168. We replicate this result in an independent patient sample. The target region harbors fragments of a human endogenous retrovirus K (HERV-K) endogenous retrovirus. Two single-nucleotide polymorphisms with alleles differing between high- and low-risk haplotypes are located within the HERV-K dUTPase. One of these encodes a predicted non-conserved Glu-Arg exchange. The HERV-K dUTPase is expressed in peripheral blood and in normal as well as lesional psoriatic skin. Our results indicate that an endogenous retroviral dUTPase constitutes a candidate gene for the PSORS1 mutation.

Few human endogenous retroviruses (HERVs) have been extensively studied in non-human primates. Such investigations have demonstrated that several element classes are primate unique, contain members with important biological function, are conserved in specific primate lineages, and have in some cases expanded in copy number. We have examined multiple sub-families of all major groups of HERVs using a DNA microarray based on the reverse transcriptase (RT) domain of the viral polymerase gene (pol). The microarray was used to investigate the distribution of HERVs in non-human primates with particular focus on the differences between New World monkeys (NWMs) and other anthropoids. This is the first study examining most HERV families in multiple non-human primate DNAs using a uniform and sensitive method and suggests that major differences exist between primate groups. The results indicate that a major invasion and expansion of pol containing HERVs occurred after the platyrrhine (NWM) lineage separated from the catarrhines (Old World Monkeys and apes).

For several decades the incidence of cutaneous malignant melanoma (CMM) steadily increased in fair-skinned, indoor-working people around the world. Scientists think poor tanning ability resulting in sunburns initiate CMM, but they do not understand why the incidence continues to increase despite the increased use of sunscreens and formulations offering more protection. This paradox, along with lower incidences of CMM in outdoor workers, although they have significantly higher annual UV doses than indoor workers have, perplexes scientists. We found a temporal exponential increase in the CMM incidence indicating second-order reaction kinetics revealing the existence of 2 major risk factors. From epidemiology studies, we know one major risk factor for getting CMM is poor tanning ability and we now propose the other major risk factor may be the Human Papilloma Virus (HPV) because clinicians find β HPVs in over half the biopsies. Moreover, we uncovered yet another paradox; the increasing CMM incidences significantly correlate with decreasing personal annual UV dose, a proxy for low vitamin D3 levels. We also discovered the incidence of CMM significantly increased with decreasing personal annual UV dose from 1960, when it was almost insignificant, to 2000. UV and other DNA-damaging agents can activate viruses, and UV-induced cytokines can hide HPV from immune surveillance, which may explain why CMM also occurs in anatomical locations where the sun does not shine. Thus, we propose the 2 major risk factors for getting CMM are intermittent UV exposures that result in low cutaneous levels of vitamin D3 and possibly viral infection.

Human endogenous retroviruses (HERVs) represent approximately 7% of the human genome. This investigation was focused on one particular HERV, ERV3, with the main purpose of characterising its gene expression patterns and genomic distribution of ERV3-like sequences. Furthermore, this careful expression study should provide insights into the biological role of HERVs. The impact of HERVs in health and disease is not yet clarified. ERV3 is expressed as three envelope (env) transcripts, of which two also contain a cellular gene, H-plk (human proviral linked Krüppel). ERV3 env expression was mainly investigated at the RNA level. The gene expression of two other HERVs, HERV-K and HERV-E was analysed and compared with ERV3 activity. Real-time PCRs were developed and in combination with in situ hybridisation, it was found that ERV3 is expressed in a tissue- and cell-specific way. High levels of ERV3 mRNA (up to six times over Histone3.3) were demonstrated in placenta, sebaceous glands, foetal and adult adrenal glands, brown adipose tissue, corpus luteum, pituitary gland, thymus and testis. In monocytic cells including both normal monocytes and malignant U-937 cells, elevated mRNA levels were observed after retinoic acid (RA)-induced differentiation. ERV3-encoded Env protein was detected in selected cases, one following RA-treatment. In addition, several new ERV3-like sequences were discovered in the human genome. ERV3 was found to have conserved open reading frames in contrast to other ERV3-like sequences in the human genome. This suggests that ERV3 may be involved in important cellular processes such as differentiation, cell fusion, immunomodulation and protection against infectious retroviruses. The developed techniques and obtained results will allow further studies of HERV expression to better correlate HERV activity to both normal development and disease.

Previously, we found a retroviral sequence, HML-6.2BC1,to be expressed at high levels in a multifocal ductal breast cancer from a 41-year-old woman who also developed ovarian carcinoma. The sequence of a human genomic clone (HML-6.28) selected by high-stringency hybridization with HML-6.2BC1is reported here. It was 99% identical to HML-6.2BC1and gave the same restriction fragments as total DNA. HML-6.28 is a 4.7-kb provirus with a 5′LTR, truncated in RT. Data from two similar genomic clones and sequences found in GenBank are also reported. Overlaps between them gave a rather complete picture of the HML-6.2BC1-like human endogenous retroviral elements. Work with somatic cell hybrids and FISH localized HML-6.28 to chromosome 6, band p21, close to the MHC region. The causal role of HML-6.28 in breast cancer remains unclear. Nevertheless, the ca. 20 Myr old HML-6 sequences enabled the definition of common and unique features of type A, B, and D (ABD) retroviruses. In Gag, HML-6 has no intervening sequences between matrix and capsid proteins, unlike extant exogenous ABD viruses, possibly an ancestral feature. Alignment of the dUTPase showed it to be present in all ABD viruses, but gave a phylogenetic tree different from trees made from other ABD genes, indicating a distinct phylogeny of dUTPase. A conserved 24-mer sequence in the amino terminus of some ABD envelope genes suggested a conserved function.

Background Human Endogenous Retroviruses (HERVs) comprise about 8% of the human genome and have lost their ability to replicate or to produce infectious particles after having accumulated mutations over time. We assessed the kinetics of expression of HERV-K (HML-2) Envelope mRNA transcript and surface unit (SU) and transmembrane (TM) subunit proteins during HIV-1 infection. We also mapped the specificity of the humoral response to HERV-K (HML-2) Envelope protein in HIV-1 infected subjects at different stages of disease, and correlated the response with plasma viral load. Results We found that HIV-1 modified HERV-K (HML-2) Env mRNA expression, resulting in the expression of a fully N-glycosylated HERV-K (HML-2) envelope protein on the cell surface. Serological mapping of HERV-K (HML-2) envelope protein linear epitopes revealed two major immunogenic domains, one on SU and another on the ectodomain of TM. The titers of HERV-K (HML-2) TM antibodies were dramatically increased in HIV-1 infected subjects (p Conclusions These data collectively suggest that HIV-1 infection induces fully glycosylated HERV-K (HML-2) envelope TM protein to which antibodies are induced. These anti-HERV-K (HML-2) TM antibodies are a potential marker of HIV-1 infection, and are at higher titer in elite controllers. HERV-K (HML-2) envelope TM protein may be a new therapeutic target in HIV-1 infection.

International audience; Sjögren's syndrome (SS) is a chronic autoimmune epithelitis, and several lines of experiments indicate that multifactorial factors contribute to salivary gland epithelial cells (SGEC) dysfunctions including a combination of environmental factors, lymphocytic infiltrations, genetic predispositions as well as epigenetic defects. Such statement is reinforced by the observation that global DNA methylation (5MeCyt) is altered in minor salivary glands from pSS patients and that such defect is associated cytokeratin 19 (KRT19) overexpression. An epigenetic deregulation of the KRT19 gene was further tested by treating the human salivary gland (HSG) cell line with the DNA demethylating agent 5-azacytidin, and with the histone acetylase inhibitor trichostatin A. Blocking DNA methylation, but not histone acetylation, with 5-azacytidin was associated with KRT19 overexpression at both transcriptional and protein level. Next, analysis of the CpG genome-wide methylome array in the KTR19 locus from long term cultured SGEC obtained from 8 pSS patients revealed a more reduced DNA methylation level in those patients with defective global DNA methylation. Altogether, our data, therefore, suggest that alteration of DNA methylation in SGEC may contribute to pSS pathophysiology in part by controlling the expression of KRT19.