Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 83
Filtrar
1.
PLoS Genet ; 19(7): e1010795, 2023 07.
Artigo em Inglês | MEDLINE | ID: mdl-37405998

RESUMO

Retrotransposons have generated about half of the human genome and LINE-1s (L1s) are the only autonomously active retrotransposons. The cell has evolved an arsenal of defense mechanisms to protect against retrotransposition with factors we are only beginning to understand. In this study, we investigate Zinc Finger CCHC-Type Containing 3 (ZCCHC3), a gag-like zinc knuckle protein recently reported to function in the innate immune response to infecting viruses. We show that ZCCHC3 also severely restricts human retrotransposons and associates with the L1 ORF1p ribonucleoprotein particle. We identify ZCCHC3 as a bona fide stress granule protein, and its association with LINE-1 is further supported by colocalization with L1 ORF1 protein in stress granules, dense cytoplasmic aggregations of proteins and RNAs that contain stalled translation pre-initiation complexes and form when the cell is under stress. Our work also draws links between ZCCHC3 and the anti-viral and retrotransposon restriction factors Mov10 RISC Complex RNA Helicase (MOV10) and Zinc Finger CCCH-Type, Antiviral 1 (ZC3HAV1, also called ZAP). Furthermore, collective evidence from subcellular localization, co-immunoprecipitation, and velocity gradient centrifugation connects ZCCHC3 with the RNA exosome, a multi-subunit ribonuclease complex capable of degrading various species of RNA molecules and that has previously been linked with retrotransposon control.


Assuntos
Retroelementos , Grânulos de Estresse , Humanos , Retroelementos/genética , Proteínas de Choque Térmico/genética , Zinco , Elementos Nucleotídeos Longos e Dispersos/genética , RNA Helicases/genética , RNA Helicases/metabolismo
2.
Annu Rev Genomics Hum Genet ; 22: 27-53, 2021 08 31.
Artigo em Inglês | MEDLINE | ID: mdl-33945751

RESUMO

I have been fortunate and privileged to have participated in amazing breakthroughs in human genetics since the 1960s. I was lucky to have trained in medical school at Dartmouth and Johns Hopkins, in pediatrics at the University of Minnesota and Johns Hopkins, and in genetics and molecular biology with Dr. Barton Childs at Johns Hopkins and Dr. Harvey Itano at the National Institutes of Health. Later, the collaborative spirit at Johns Hopkins and the University of Pennsylvania were important to my career. Here, I describe the thrill of scientific discovery in two diverse areas of human genetics: DNA haplotypes and their role in solving the molecular basis of beta thalassemia and the role of retrotransposons (jumping genes) in human biology. I hope that this article may inspire others who love human genetics as much as I do.


Assuntos
Genética Humana , Criança , Humanos
3.
Cell ; 135(1): 23-35, 2008 Oct 03.
Artigo em Inglês | MEDLINE | ID: mdl-18854152

RESUMO

Retrotransposons, mainly LINEs, SINEs, and endogenous retroviruses, make up roughly 40% of the mammalian genome and have played an important role in genome evolution. Their prevalence in genomes reflects a delicate balance between their further expansion and the restraint imposed by the host. In any human genome only a small number of LINE1s (L1s) are active, moving their own and SINE sequences into new genomic locations and occasionally causing disease. Recent insights and new technologies promise answers to fundamental questions about the biology of transposable elements.


Assuntos
Genoma Humano , Retroelementos , Animais , Humanos , Elementos Nucleotídeos Longos e Dispersos , Elementos Nucleotídeos Curtos e Dispersos
4.
Proc Natl Acad Sci U S A ; 117(51): 32215-32222, 2020 12 22.
Artigo em Inglês | MEDLINE | ID: mdl-33277430

RESUMO

Somatic LINE-1 (L1) retrotransposition has been detected in early embryos, adult brains, and the gastrointestinal (GI) tract, and many cancers, including epithelial GI tumors. We previously found numerous somatic L1 insertions in paired normal and GI cancerous tissues. Here, using a modified method of single-cell analysis for somatic L1 insertions, we studied adenocarcinomas of colon, pancreas, and stomach, and found a variable number of somatic L1 insertions in tumors of the same type from patient to patient. We detected no somatic L1 insertions in single cells of 5 of 10 tumors studied. In three tumors, aneuploid cells were detected by FACS. In one pancreatic tumor, there were many more L1 insertions in aneuploid than in euploid tumor cells. In one gastric cancer, both aneuploid and euploid cells contained large numbers of likely clonal insertions. However, in a second gastric cancer with aneuploid cells, no somatic L1 insertions were found. We suggest that when the cellular environment is favorable to retrotransposition, aneuploidy predisposes tumor cells to L1 insertions, and retrotransposition may occur at the transition from euploidy to aneuploidy. Seventeen percent of insertions were also present in normal cells, similar to findings in genomic DNA from normal tissues of GI tumor patients. We provide evidence that: 1) The number of L1 insertions in tumors of the same type is highly variable, 2) most somatic L1 insertions in GI cancer tissues are absent from normal tissues, and 3) under certain conditions, somatic L1 retrotransposition exhibits a propensity for occurring in aneuploid cells.


Assuntos
Adenocarcinoma/genética , Neoplasias Gastrointestinais/genética , Elementos Nucleotídeos Longos e Dispersos/genética , Adenocarcinoma/patologia , Artefatos , Neoplasias Gastrointestinais/patologia , Humanos , Análise de Célula Única
5.
Am J Med Genet A ; 185(11): 3224-3229, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-33955173

RESUMO

Two members of the faculty-who witnessed the birth of Genetic Medicine and remained to see it evolve-present their reflections about the history of genetic medicine at the Johns Hopkins Medical Institutions. They tell how the genetic units in Pediatrics and Medicine that were initiated by Barton Childs and Victor McKusick, respectively, became the McKusick Nathans Department of Genetic Medicine in 2020.


Assuntos
Genética Médica/história , História do Século XX , História do Século XXI , Humanos , Universidades
6.
Genome Res ; 27(8): 1395-1405, 2017 08.
Artigo em Inglês | MEDLINE | ID: mdl-28483779

RESUMO

LINE-1 (L1) retrotransposons are a noted source of genetic diversity and disease in mammals. To expand its genomic footprint, L1 must mobilize in cells that will contribute their genetic material to subsequent generations. Heritable L1 insertions may therefore arise in germ cells and in pluripotent embryonic cells, prior to germline specification, yet the frequency and predominant developmental timing of such events remain unclear. Here, we applied mouse retrotransposon capture sequencing (mRC-seq) and whole-genome sequencing (WGS) to pedigrees of C57BL/6J animals, and uncovered an L1 insertion rate of ≥1 event per eight births. We traced heritable L1 insertions to pluripotent embryonic cells and, strikingly, to early primordial germ cells (PGCs). New L1 insertions bore structural hallmarks of target-site primed reverse transcription (TPRT) and mobilized efficiently in a cultured cell retrotransposition assay. Together, our results highlight the rate and evolutionary impact of heritable L1 retrotransposition and reveal retrotransposition-mediated genomic diversification as a fundamental property of pluripotent embryonic cells in vivo.


Assuntos
Embrião de Mamíferos/metabolismo , Elementos Nucleotídeos Longos e Dispersos , Animais , Embrião de Mamíferos/citologia , Feminino , Genômica/métodos , Células Germinativas , Células HeLa , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Mosaicismo , Sequenciamento Completo do Genoma/métodos
7.
Nucleic Acids Res ; 45(8): 4619-4631, 2017 05 05.
Artigo em Inglês | MEDLINE | ID: mdl-28334850

RESUMO

Maintaining genome integrity is important for cells and damaged DNA triggers autoimmunity. Previous studies have reported that Three-prime repair exonuclease 1(TREX1), an endogenous DNA exonuclease, prevents immune activation by depleting damaged DNA, thus preventing the development of certain autoimmune diseases. Consistently, mutations in TREX1 are linked with autoimmune diseases such as systemic lupus erythematosus, Aicardi-Goutières syndrome (AGS) and familial chilblain lupus. However, TREX1 mutants competent for DNA exonuclease activity are also linked to AGS. Here, we report a nuclease-independent involvement of TREX1 in preventing the L1 retrotransposon-induced DNA damage response. TREX1 interacted with ORF1p and altered its intracellular localization. Furthermore, TREX1 triggered ORF1p depletion and reduced the L1-mediated nicking of genomic DNA. TREX1 mutants related to AGS were deficient in inducing ORF1p depletion and could not prevent L1-mediated DNA damage. Therefore, our findings not only reveal a new mechanism for TREX1-mediated L1 suppression and uncover a new function for TREX1 in protein destabilization, but they also suggest a novel mechanism for TREX1-mediated suppression of innate immune activation through maintaining genome integrity.


Assuntos
DNA/genética , Exodesoxirribonucleases/genética , Genoma Humano , Fosfoproteínas/genética , Proteínas/genética , Retroelementos , Doenças Autoimunes do Sistema Nervoso/genética , Doenças Autoimunes do Sistema Nervoso/imunologia , Doenças Autoimunes do Sistema Nervoso/patologia , Autoimunidade , DNA/imunologia , Quebras de DNA de Cadeia Dupla , Exodesoxirribonucleases/antagonistas & inibidores , Exodesoxirribonucleases/imunologia , Regulação da Expressão Gênica , Instabilidade Genômica , Células HEK293 , Células HeLa , Humanos , Mutação , Malformações do Sistema Nervoso/genética , Malformações do Sistema Nervoso/imunologia , Malformações do Sistema Nervoso/patologia , Fosfoproteínas/antagonistas & inibidores , Fosfoproteínas/imunologia , Fosforilação , Plasmídeos/química , Plasmídeos/metabolismo , Proteínas/imunologia , RNA Interferente Pequeno/genética , RNA Interferente Pequeno/metabolismo , Proteínas Recombinantes/genética , Proteínas Recombinantes/imunologia , Transfecção
8.
Genome Res ; 25(10): 1536-45, 2015 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-26260970

RESUMO

Somatic L1 retrotransposition events have been shown to occur in epithelial cancers. Here, we attempted to determine how early somatic L1 insertions occurred during the development of gastrointestinal (GI) cancers. Using L1-targeted resequencing (L1-seq), we studied different stages of four colorectal cancers arising from colonic polyps, seven pancreatic carcinomas, as well as seven gastric cancers. Surprisingly, we found somatic L1 insertions not only in all cancer types and metastases but also in colonic adenomas, well-known cancer precursors. Some insertions were also present in low quantities in normal GI tissues, occasionally caught in the act of being clonally fixed in the adjacent tumors. Insertions in adenomas and cancers numbered in the hundreds, and many were present in multiple tumor sections, implying clonal distribution. Our results demonstrate that extensive somatic insertional mutagenesis occurs very early during the development of GI tumors, probably before dysplastic growth.


Assuntos
Neoplasias Gastrointestinais/genética , Elementos Nucleotídeos Longos e Dispersos , Mutagênese Insercional , Progressão da Doença , Perfilação da Expressão Gênica , Regulação Neoplásica da Expressão Gênica , Humanos , Proteínas de Neoplasias/biossíntese , Proteínas de Neoplasias/genética , Análise de Sequência com Séries de Oligonucleotídeos , Fatores de Tempo
9.
Cell ; 135(1): 192-192.e1, 2008 Oct 03.
Artigo em Inglês | MEDLINE | ID: mdl-18854165
10.
PLoS Genet ; 11(5): e1005252, 2015 May.
Artigo em Inglês | MEDLINE | ID: mdl-26001115

RESUMO

Intrinsic immunity describes the set of recently discovered but poorly understood cellular mechanisms that specifically target viral pathogens. Their discovery derives in large part from intensive studies of HIV and SIV that revealed restriction factors acting at various stages of the retroviral life cycle. Recent studies indicate that some factors restrict both retroviruses and retrotransposons but surprisingly in ways that may differ. We screened known interferon-stimulated antiviral proteins previously untested for their effects on cell culture retrotransposition. Several factors, including BST2, ISG20, MAVS, MX2, and ZAP, showed strong L1 inhibition. We focused on ZAP (PARP13/ZC3HAV1), a zinc-finger protein that targets viruses of several families, including Retroviridae, Tiloviridae, and Togaviridae, and show that ZAP expression also strongly restricts retrotransposition in cell culture through loss of L1 RNA and ribonucleoprotein particle integrity. Association of ZAP with the L1 ribonucleoprotein particle is supported by co-immunoprecipitation and co-localization with ORF1p in cytoplasmic stress granules. We also used mass spectrometry to determine the protein components of the ZAP interactome, and identified many proteins that directly interact and colocalize with ZAP, including MOV10, an RNA helicase previously shown to suppress retrotransposons. The detection of a chaperonin complex, RNA degradation proteins, helicases, post-translational modifiers, and components of chromatin modifying complexes suggest mechanisms of ZAP anti-retroelement activity that function in the cytoplasm and perhaps also in the nucleus. The association of the ZAP ribonucleoprotein particle with many interferon-stimulated gene products indicates it may be a key player in the interferon response.


Assuntos
Proteínas de Ligação a RNA/metabolismo , Retroelementos , Clonagem Molecular , Vírus de DNA/genética , Evolução Molecular , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Células HEK293 , Células HeLa , Humanos , Imunoprecipitação , Fatores Reguladores de Interferon/genética , Fatores Reguladores de Interferon/metabolismo , RNA Helicases/genética , RNA Helicases/metabolismo , Estabilidade de RNA , Proteínas de Ligação a RNA/genética
11.
Proc Natl Acad Sci U S A ; 112(35): E4894-900, 2015 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-26283398

RESUMO

Barrett's esophagus (BE) is a common disease in which the lining of the esophagus transitions from stratified squamous epithelium to metaplastic columnar epithelium that predisposes individuals to developing esophageal adenocarcinoma (EAC). We hypothesized that BE provides a unique environment for increased long-interspersed element 1 (LINE-1 or L1) retrotransposition. To this end, we evaluated 5 patients with benign BE, 5 patients with BE and concomitant EAC, and 10 additional patients with EAC to determine L1 activity in this progressive disease. After L1-seq, we confirmed 118 somatic insertions by PCR in 10 of 20 individuals. We observed clonal amplification of several insertions which appeared to originate in normal esophagus (NE) or BE and were later clonally expanded in BE or in EAC. Additionally, we observed evidence of clonality within the EAC cases; specifically, 22 of 25 EAC-only insertions were present identically in distinct regions available from the same tumor, suggesting that these insertions occurred in the founding tumor cell of these lesions. L1 proteins must be expressed for retrotransposition to occur; therefore, we evaluated the expression of open reading frame 1 protein (ORF1p), a protein encoded by L1, in eight of the EAC cases for which formalin-fixed paraffin embedded tissue was available. With immunohistochemistry, we detected ORF1p in all tumors evaluated. Interestingly, we also observed dim ORF1p immunoreactivity in histologically NE of all patients. In summary, our data show that somatic retrotransposition occurs early in many patients with BE and EAC and indicate that early events occurring even in histologically NE cells may be clonally expanded in esophageal adenocarcinogenesis.


Assuntos
Adenocarcinoma/genética , Esôfago de Barrett/genética , Neoplasias Esofágicas/genética , Elementos Nucleotídeos Longos e Dispersos/genética , Retroelementos , Sequência de Bases , DNA , Humanos , Dados de Sequência Molecular
12.
Genes Dev ; 23(11): 1303-12, 2009 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-19487571

RESUMO

Long Interspersed Element 1 (L1) is a retrotransposon that comprises approximately 17% of the human genome. Despite its abundance in mammalian genomes, relatively little is understood about L1 retrotransposition in vivo. To study the timing and tissue specificity of retrotransposition, we created transgenic mouse and rat models containing human or mouse L1 elements controlled by their endogenous promoters. Here, we demonstrate abundant L1 RNA in both germ cells and embryos. However, the integration events usually occur in embryogenesis rather than in germ cells and are not heritable. We further demonstrate L1 RNA in preimplantation embryos lacking the L1 transgene and L1 somatic retrotransposition events in blastocysts and adults lacking the transgene. Together, these data indicate that L1 RNA transcribed in male or female germ cells can be carried over through fertilization and integrate during embryogenesis, an interesting example of heritability of RNA independent of its encoding DNA. Thus, L1 creates somatic mosaicism during mammalian development, suggesting a role for L1 in carcinogenesis and other disease.


Assuntos
Desenvolvimento Embrionário/fisiologia , Elementos Nucleotídeos Longos e Dispersos/fisiologia , Mosaicismo , Animais , Embrião de Mamíferos/embriologia , Embrião de Mamíferos/metabolismo , Desenvolvimento Embrionário/genética , Feminino , Genoma/genética , Genótipo , Células Germinativas/metabolismo , Elementos Nucleotídeos Longos e Dispersos/genética , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , RNA/metabolismo , Ratos , Ratos Sprague-Dawley , Ratos Transgênicos
13.
Hum Mutat ; 37(9): 942-54, 2016 09.
Artigo em Inglês | MEDLINE | ID: mdl-27319353

RESUMO

Squamous cell carcinoma of the esophagus (SCC) is the most common form of esophageal cancer in the world and is typically diagnosed at an advanced stage when successful treatment is challenging. Understanding the mutational profile of this cancer may identify new treatment strategies. Because somatic retrotransposition has been shown in tumors of the gastrointestinal system, we focused on LINE-1 (L1) mobilization as a source of genetic instability in this cancer. We hypothesized that retrotransposition is ongoing in SCC patients. The expression of L1 encoded proteins is necessary for retrotransposition to occur; therefore, we evaluated the expression of L1 open reading frame 1 protein (ORF1p). Using immunohistochemistry, we detected ORF1p expression in all four SCC cases evaluated. Using L1-seq, we identified and validated 74 somatic insertions in eight tumors of the nine evaluated. Of these, 12 insertions appeared to be somatic, not genetically inherited, and sub-clonal (i.e., present in less than one copy per genome equivalent) in the adjacent normal esophagus (NE), while clonal in the tumor. Our results indicate that L1 retrotransposition is active in SCC of the esophagus and that insertion events are present in histologically NE that expands clonally in the subsequent tumor.


Assuntos
Carcinoma de Células Escamosas/genética , Neoplasias Esofágicas/genética , Mutagênese Insercional , Proteínas/genética , Proteínas/metabolismo , Idoso , Carcinoma de Células Escamosas/metabolismo , Neoplasias Esofágicas/metabolismo , Carcinoma de Células Escamosas do Esôfago , Esôfago/metabolismo , Feminino , Humanos , Elementos Nucleotídeos Longos e Dispersos , Masculino , Pessoa de Meia-Idade , Análise de Sequência de DNA
14.
Hum Mol Genet ; 22(18): 3730-48, 2013 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-23696454

RESUMO

Long INterspersed Elements (LINE-1s, L1s) are responsible for over one million retrotransposon insertions and 8000 processed pseudogenes (PPs) in the human genome. An active L1 encodes two proteins (ORF1p and ORF2p) that bind with L1 RNA and form L1-ribonucleoprotein particles (RNPs). Although it is believed that the RNA-binding property of ORF1p is critical to recruit other mobile RNAs to the RNP, the identity of recruited RNAs is largely unknown. Here, we used crosslinking and immunoprecipitation followed by deep sequencing to identify RNA components of L1-RNPs. Our results show that in addition to retrotransposed RNAs [L1, Alu and SINE-VNTR-Alu (SVA)], L1-RNPs are enriched with cellular mRNAs, which have PPs in the human genome. Using purified L1-RNPs, we show that PP-source RNAs preferentially serve as ORF2p templates in a reverse transcriptase assay. In addition, we find that exogenous ORF2p binds endogenous ORF1p, allowing reverse transcription of the same PP-source RNAs. These data demonstrate that interaction of a cellular RNA with the L1-RNP is an inside track to PP formation.


Assuntos
Elementos Nucleotídeos Longos e Dispersos/genética , Fases de Leitura Aberta , Pseudogenes , Proteínas de Ligação a RNA/genética , Proteínas de Ligação a RNA/metabolismo , RNA/metabolismo , Ribonucleoproteínas/metabolismo , Expressão Gênica , Células HEK293 , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , RNA/genética , DNA Polimerase Dirigida por RNA/genética , DNA Polimerase Dirigida por RNA/metabolismo , Retroelementos , Ribonucleoproteínas/genética
16.
Genome Res ; 22(12): 2328-38, 2012 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-22968929

RESUMO

L1 retrotransposons comprise 17% of the human genome and are its only autonomous mobile elements. Although L1-induced insertional mutagenesis causes Mendelian disease, their mutagenic load in cancer has been elusive. Using L1-targeted resequencing of 16 colorectal tumor and matched normal DNAs, we found that certain cancers were excessively mutagenized by human-specific L1s, while no verifiable insertions were present in normal tissues. We confirmed de novo L1 insertions in malignancy by both validating and sequencing 69/107 tumor-specific insertions and retrieving both 5' and 3' junctions for 35. In contrast to germline polymorphic L1s, all insertions were severely 5' truncated. Validated insertion numbers varied from up to 17 in some tumors to none in three others, and correlated with the age of the patients. Numerous genes with a role in tumorigenesis were targeted, including ODZ3, ROBO2, PTPRM, PCM1, and CDH11. Thus, somatic retrotransposition may play an etiologic role in colorectal cancer.


Assuntos
Neoplasias Colorretais/genética , Elementos Nucleotídeos Longos e Dispersos/genética , Retroelementos/genética , Genoma Humano , Sequenciamento de Nucleotídeos em Larga Escala/métodos , Humanos , Masculino , Metilação , Instabilidade de Microssatélites , Mutagênese Insercional , Fenótipo , Reação em Cadeia da Polimerase , Reprodutibilidade dos Testes , Análise de Sequência de DNA
17.
Nucleic Acids Res ; 41(15): 7401-19, 2013 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-23749060

RESUMO

LINE1s occupy 17% of the human genome and are its only active autonomous mobile DNA. L1s are also responsible for genomic insertion of processed pseudogenes and >1 million non-autonomous retrotransposons (Alus and SVAs). These elements have significant effects on gene organization and expression. Despite the importance of retrotransposons for genome evolution, much about their biology remains unknown, including cellular factors involved in the complex processes of retrotransposition and forming and transporting L1 ribonucleoprotein particles. By co-immunoprecipitation of tagged L1 constructs and mass spectrometry, we identified proteins associated with the L1 ORF1 protein and its ribonucleoprotein. These include RNA transport proteins, gene expression regulators, post-translational modifiers, helicases and splicing factors. Many cellular proteins co-localize with L1 ORF1 protein in cytoplasmic granules. We also assayed the effects of these proteins on cell culture retrotransposition and found strong inhibiting proteins, including some that control HIV and other retroviruses. These data suggest candidate cofactors that interact with the L1 to modulate its activity and increase our understanding of the means by which the cell coexists with these genomic 'parasites'.


Assuntos
Mapeamento de Interação de Proteínas/métodos , Proteínas/metabolismo , Retroelementos , Sobrevivência Celular , Grânulos Citoplasmáticos/metabolismo , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Células HEK293 , HIV-1 , Células HeLa , Humanos , Complexos Multiproteicos/genética , Complexos Multiproteicos/metabolismo , Proteínas/genética , Pseudogenes , RNA Helicases/genética , RNA Helicases/metabolismo , Transporte de RNA , Ribonucleoproteínas/genética , Ribonucleoproteínas/metabolismo , Transcrição Gênica
18.
PLoS Genet ; 8(10): e1002941, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-23093941

RESUMO

MOV10 protein, a putative RNA helicase and component of the RNA-induced silencing complex (RISC), inhibits retrovirus replication. We show that MOV10 also severely restricts human LINE1 (L1), Alu, and SVA retrotransposons. MOV10 associates with the L1 ribonucleoprotein particle, along with other RNA helicases including DDX5, DHX9, DDX17, DDX21, and DDX39A. However, unlike MOV10, these other helicases do not strongly inhibit retrotransposition, an activity dependent upon intact helicase domains. MOV10 association with retrotransposons is further supported by its colocalization with L1 ORF1 protein in stress granules, by cytoplasmic structures associated with RNA silencing, and by the ability of MOV10 to reduce endogenous and ectopic L1 expression. The majority of the human genome is repetitive DNA, most of which is the detritus of millions of years of accumulated retrotransposition. Retrotransposons remain active mutagens, and their insertion can disrupt gene function. Therefore, the host has evolved defense mechanisms to protect against retrotransposition, an arsenal we are only beginning to understand. With homologs in other vertebrates, insects, and plants, MOV10 may represent an ancient and innate form of immunity against both infective viruses and endogenous retroelements.


Assuntos
RNA Helicases/metabolismo , Retroelementos , Trifosfato de Adenosina/metabolismo , Motivos de Aminoácidos , Animais , Linhagem Celular , Grânulos Citoplasmáticos/metabolismo , Expressão Gênica , Humanos , Mutagênese Insercional , Ligação Proteica , Transporte Proteico , RNA Helicases/química , Ribonucleoproteínas/genética , Ribonucleoproteínas/metabolismo
19.
Genome Res ; 21(6): 985-90, 2011 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-20980553

RESUMO

High-throughput sequencing has recently begun to revolutionize the study of structural variants in the genomes of humans and other species. More recently, this technology and others have been applied to the study of human retrotransposon insertion polymorphisms (RIPs), yielding an unprecedented catalog of common and rare variants due to insertional mutagenesis. At the same time, the 1000 Genomes Project has released an enormous amount of whole-genome sequence data. In this article, we present evidence for 1016 L1 insertions across all studies to date that are not represented in the reference human genome assembly, many of which appear to be specific to populations or groups of populations, particularly Africans. Additionally, a cross-comparison of several studies shows that, on average, 27% of surveyed nonreference insertions is present in only one study, indicating the low frequency of many RIPs.


Assuntos
Genoma Humano/genética , Sequenciamento de Nucleotídeos em Larga Escala/métodos , Elementos Nucleotídeos Longos e Dispersos/genética , Análise de Sequência de DNA/métodos , Biologia Computacional/métodos , Mineração de Dados/métodos , Bases de Dados Genéticas , Frequência do Gene , Humanos , Grupos Raciais/genética
20.
Hum Mol Genet ; 20(17): 3386-400, 2011 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-21636526

RESUMO

Human retrotransposons generate structural variation and genomic diversity through ongoing retrotransposition and non-allelic homologous recombination. Cell culture retrotransposition assays have provided great insight into the genomic impact of retrotransposons, in particular, LINE-1(L1) and Alu elements; however, no such assay exists for the youngest active human retrotransposon, SINE-VNTR-Alu (SVA). Here we report the development of an SVA cell culture retrotransposition assay. We marked several SVAs with either neomycin or EGFP retrotransposition indicator cassettes. Engineered SVAs retrotranspose using L1 proteins supplemented in trans in multiple cell lines, including U2OS osteosarcoma cells where SVA retrotransposition is equal to that of an engineered L1. Engineered SVAs retrotranspose at 1-54 times the frequency of a marked pseudogene in HeLa HA cells. Furthermore, our data suggest a variable requirement for L1 ORF1p for SVA retrotransposition. Recovered engineered SVA insertions display all the hallmarks of LINE-1 retrotransposition and some contain 5' and 3' transductions, which are common for genomic SVAs. Of particular interest is the fact that four out of five insertions recovered from one SVA are full-length, with the 5' end of these insertions beginning within 5 nt of the CMV promoter transcriptional start site. This assay demonstrates that SVA elements are indeed mobilized in trans by L1. Previously intractable questions regarding SVA biology can now be addressed.


Assuntos
Retroelementos/genética , Elementos Alu/genética , Northern Blotting , Linhagem Celular , Linhagem Celular Tumoral , Células HeLa , Humanos , Repetições Minissatélites/genética , Reação em Cadeia da Polimerase , Elementos Nucleotídeos Curtos e Dispersos/genética , Sítio de Iniciação de Transcrição
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA