The Experts below are selected from a list of 15147 Experts worldwide ranked by ideXlab platform
Masao Matsuoka - One of the best experts on this subject based on the ideXlab platform.
-
APOBEC3G Generates Nonsense Mutations in HTLV-1 Proviral Genomes In Vivo.
Journal of Virology, 2010Co-Authors: Jun Fan, Simon Wain-hobson, Kisato Nosaka, Junko Tanabe, Yorifumi Satou, Atsushi Koito, Jean-pierre Vartanian, Masao MatsuokaAbstract:Human T-cell leukemia virus type 1 (HTLV-1) induces cell proliferation after infection, leading to efficient transmission by cell-to-cell contact. After a long latent period, a fraction of carriers develop adult T-cell leukemia (ATL). In ATL cells, genetic changes in the tax gene were reported in about 10% of ATL cases. To determine genetic changes that may occur throughout the Provirus, we determined the whole sequences of HTLV-1 Provirus in 60 ATL cases. Abortive genetic changes including deletion, insertion and nonsense mutations were frequent in all viral genes except in the HBZ gene, which is transcribed from the minus strand of the virus. G-to-A base substitutions were the most frequent mutations in ATL cells. Sequence context of G-to-A mutations was in accordance with the preferred target sequence of human APOBEC3G (hA3G). Target sequences of hA3G were less frequent in the plus strand of the HBZ coding region than in other coding regions of HTLV-1 Provirus. Nonsense mutations in viral genes including tax were also observed in Proviruses from asymptomatic carriers, indicating that these mutations were generated during reverse transcription and prior to oncogenesis. That hA3G targets the minus strand during reverse transcription explains why the HBZ gene, which is encoded by the plus strand of Provirus, is not susceptible to such nonsense mutations. HTLV-1 infected cells likely take advantage of hA3G to escape from the host immune system by losing expression of viral proteins.
-
preferential selection of human t cell leukemia virus type 1 Provirus lacking the 5 long terminal repeat during oncogenesis
Journal of Virology, 2007Co-Authors: Maki Miyazaki, Jun-ichirou Yasunaga, Yuko Taniguchi, Sadahiro Tamiya, Tatsutoshi Nakahata, Masao MatsuokaAbstract:In adult T-cell leukemia (ATL) cells, a defective human T-cell leukemia virus type 1 (HTLV-1) Provirus lacking the 5′ long terminal repeat (LTR), designated type 2 defective Provirus, is frequently observed. To investigate the mechanism underlying the generation of the defective Provirus, we sequenced HTLV-1 Provirus integration sites from cases of ATL. In HTLV-1 Proviruses retaining both LTRs, 6-bp repeat sequences were adjacent to the 5′ and 3′ LTRs. In 8 of 12 cases with type 2 defective Provirus, 6-bp repeats were identified at both ends. In five of these cases, a short repeat was bound to CA dinucleotides of the pol and env genes at the 5′ end, suggesting that these type 2 defective Proviruses were formed before integration. In four cases lacking the 6-bp repeat, short (6- to 26-bp) deletions in the host genome were identified, indicating that these defective Proviruses were generated after integration. Quantification indicated frequencies of type 2 defective Provirus of less than 3.9% for two carriers, which are much lower than those seen for ATL cases (27.8%). In type 2 defective Proviruses, the second exons of the tax, rex, and p30 genes were frequently deleted, leaving Tax unable to activate NF-κB and CREB pathways. The HTLV-1 bZIP factor gene, located on the minus strand, is expressed in ATL cells with this defective Provirus, and its coding sequences are intact, suggesting its significance in oncogenesis.
-
Preferential Selection of Human T-Cell Leukemia Virus Type 1 Provirus Lacking the 5′ Long Terminal Repeat during Oncogenesis
Journal of Virology, 2007Co-Authors: Maki Miyazaki, Jun-ichirou Yasunaga, Yuko Taniguchi, Sadahiro Tamiya, Tatsutoshi Nakahata, Masao MatsuokaAbstract:In adult T-cell leukemia (ATL) cells, a defective human T-cell leukemia virus type 1 (HTLV-1) Provirus lacking the 5′ long terminal repeat (LTR), designated type 2 defective Provirus, is frequently observed. To investigate the mechanism underlying the generation of the defective Provirus, we sequenced HTLV-1 Provirus integration sites from cases of ATL. In HTLV-1 Proviruses retaining both LTRs, 6-bp repeat sequences were adjacent to the 5′ and 3′ LTRs. In 8 of 12 cases with type 2 defective Provirus, 6-bp repeats were identified at both ends. In five of these cases, a short repeat was bound to CA dinucleotides of the pol and env genes at the 5′ end, suggesting that these type 2 defective Proviruses were formed before integration. In four cases lacking the 6-bp repeat, short (6- to 26-bp) deletions in the host genome were identified, indicating that these defective Proviruses were generated after integration. Quantification indicated frequencies of type 2 defective Provirus of less than 3.9% for two carriers, which are much lower than those seen for ATL cases (27.8%). In type 2 defective Proviruses, the second exons of the tax, rex, and p30 genes were frequently deleted, leaving Tax unable to activate NF-κB and CREB pathways. The HTLV-1 bZIP factor gene, located on the minus strand, is expressed in ATL cells with this defective Provirus, and its coding sequences are intact, suggesting its significance in oncogenesis.
-
Rapid quantification of HTLV-I Provirus load: Detection of monoclonal proliferation of HTLV-I-infected cells among blood donors
International Journal of Cancer, 1999Co-Authors: Ken Ichiro Etoh, Sherri Stuver, Nancy Mueller, Kiyoshi Takatsuki, Toshiki Watanabe, Kazunari Yamaguchi, Akihiko Okayama, Shinkan Tokudome, Masao MatsuokaAbstract:In this report, we quantified HTLV-I Provirus load using the AmpliSensor system, which utilizes fluorescence to measure PCR products. With this method, Provirus loads could be measured within 6 hr, and the results obtained correlated well with those obtained by other methods. Samples from 256 blood donors, who were positive for antibodies against HTLV-I, were analyzed, showing that Provirus load ranged from less than 0.1% to 56% among carriers. We analyzed the association between Provirus load and the biomarkers age and sex and found that it was not influenced by either. Provirus load was better correlated with soluble interleukin-2 receptor (sIL-2R) levels than with antibody titer against the virus. Among 18 blood donors with high Provirus load (more than 10%), Southern blotting detected monoclonal integration of HTLV-I in infected cells in 2 cases, both of them showing high sIL-2R levels (more than 900 U/ml). Sequential analyses of Provirus load showed stable levels of Provirus in the same carriers, suggesting that some factors other than age or sex determined Provirus load in infected individuals. Thus, this rapid method is a useful tool for the early detection of adult T-cell leukemia and other HTLV-I-associated diseases.
-
two types of defective human t lymphotropic virus type i Provirus in adult t cell leukemia
Blood, 1996Co-Authors: Sadahiro Tamiya, Ken Ichiro Etoh, Toshiki Watanabe, Kazunari Yamaguchi, Masao Matsuoka, Shimeru Kamihira, Kiyoshi TakatsukiAbstract:Adult T-cell leukemia (ATL), an aggressive neoplasm of mature helper T cells, is etiologically linked with human T lymphotropic virus type I (HTLV-1). After infection, HTLV-I randomly integrates its Provirus into chromosomal DNA. Since ATL is the clonal proliferation of HTLV-I-infected T lymphocytes, molecular methods facilitate the detection of clonal integration of HTLV-I Provirus in ATL cells. Using Southern blot analyses and long polymerase chain reaction (PCR) we examined HTLV-I Provirus in 72 cases of ATL, of various clinical subtypes. Southern blot analyses revealed that ATL cells in 18 cases had only one long terminal repeat (LTR). Long PCR with LTR primers showed bands shorter than for the complete virus (7.7 kb) or no bands in ATL cells with defective virus. Thus, defective virus was evident in 40 of 72 cases (56%). Two types of defective virus were identified: the first type (type 1) defective virus retained both LTRs and lacked internal sequences, which were mainly the 5' region of Provirus, such as gag and pol. Type 1 defective virus was found in 43% of all defective viruses. The second form (type 2) of defective virus had only one LTR, and 5'-LTR was preferentially deleted. This type of defective virus was more frequently detected in cases of acute and lymphoma-type ATL (21/54 cases) than in the chronic type (1/18 cases). The high frequency of this defective virus in the aggressive form of ATL suggests that it may be caused by the genetic instability of HTLV-I Provirus, and cells with this defective virus are selected because they escape from immune surveillance systems.
Sadahiro Tamiya - One of the best experts on this subject based on the ideXlab platform.
-
preferential selection of human t cell leukemia virus type 1 Provirus lacking the 5 long terminal repeat during oncogenesis
Journal of Virology, 2007Co-Authors: Maki Miyazaki, Jun-ichirou Yasunaga, Yuko Taniguchi, Sadahiro Tamiya, Tatsutoshi Nakahata, Masao MatsuokaAbstract:In adult T-cell leukemia (ATL) cells, a defective human T-cell leukemia virus type 1 (HTLV-1) Provirus lacking the 5′ long terminal repeat (LTR), designated type 2 defective Provirus, is frequently observed. To investigate the mechanism underlying the generation of the defective Provirus, we sequenced HTLV-1 Provirus integration sites from cases of ATL. In HTLV-1 Proviruses retaining both LTRs, 6-bp repeat sequences were adjacent to the 5′ and 3′ LTRs. In 8 of 12 cases with type 2 defective Provirus, 6-bp repeats were identified at both ends. In five of these cases, a short repeat was bound to CA dinucleotides of the pol and env genes at the 5′ end, suggesting that these type 2 defective Proviruses were formed before integration. In four cases lacking the 6-bp repeat, short (6- to 26-bp) deletions in the host genome were identified, indicating that these defective Proviruses were generated after integration. Quantification indicated frequencies of type 2 defective Provirus of less than 3.9% for two carriers, which are much lower than those seen for ATL cases (27.8%). In type 2 defective Proviruses, the second exons of the tax, rex, and p30 genes were frequently deleted, leaving Tax unable to activate NF-κB and CREB pathways. The HTLV-1 bZIP factor gene, located on the minus strand, is expressed in ATL cells with this defective Provirus, and its coding sequences are intact, suggesting its significance in oncogenesis.
-
Preferential Selection of Human T-Cell Leukemia Virus Type 1 Provirus Lacking the 5′ Long Terminal Repeat during Oncogenesis
Journal of Virology, 2007Co-Authors: Maki Miyazaki, Jun-ichirou Yasunaga, Yuko Taniguchi, Sadahiro Tamiya, Tatsutoshi Nakahata, Masao MatsuokaAbstract:In adult T-cell leukemia (ATL) cells, a defective human T-cell leukemia virus type 1 (HTLV-1) Provirus lacking the 5′ long terminal repeat (LTR), designated type 2 defective Provirus, is frequently observed. To investigate the mechanism underlying the generation of the defective Provirus, we sequenced HTLV-1 Provirus integration sites from cases of ATL. In HTLV-1 Proviruses retaining both LTRs, 6-bp repeat sequences were adjacent to the 5′ and 3′ LTRs. In 8 of 12 cases with type 2 defective Provirus, 6-bp repeats were identified at both ends. In five of these cases, a short repeat was bound to CA dinucleotides of the pol and env genes at the 5′ end, suggesting that these type 2 defective Proviruses were formed before integration. In four cases lacking the 6-bp repeat, short (6- to 26-bp) deletions in the host genome were identified, indicating that these defective Proviruses were generated after integration. Quantification indicated frequencies of type 2 defective Provirus of less than 3.9% for two carriers, which are much lower than those seen for ATL cases (27.8%). In type 2 defective Proviruses, the second exons of the tax, rex, and p30 genes were frequently deleted, leaving Tax unable to activate NF-κB and CREB pathways. The HTLV-1 bZIP factor gene, located on the minus strand, is expressed in ATL cells with this defective Provirus, and its coding sequences are intact, suggesting its significance in oncogenesis.
-
two types of defective human t lymphotropic virus type i Provirus in adult t cell leukemia
Blood, 1996Co-Authors: Sadahiro Tamiya, Ken Ichiro Etoh, Toshiki Watanabe, Kazunari Yamaguchi, Masao Matsuoka, Shimeru Kamihira, Kiyoshi TakatsukiAbstract:Adult T-cell leukemia (ATL), an aggressive neoplasm of mature helper T cells, is etiologically linked with human T lymphotropic virus type I (HTLV-1). After infection, HTLV-I randomly integrates its Provirus into chromosomal DNA. Since ATL is the clonal proliferation of HTLV-I-infected T lymphocytes, molecular methods facilitate the detection of clonal integration of HTLV-I Provirus in ATL cells. Using Southern blot analyses and long polymerase chain reaction (PCR) we examined HTLV-I Provirus in 72 cases of ATL, of various clinical subtypes. Southern blot analyses revealed that ATL cells in 18 cases had only one long terminal repeat (LTR). Long PCR with LTR primers showed bands shorter than for the complete virus (7.7 kb) or no bands in ATL cells with defective virus. Thus, defective virus was evident in 40 of 72 cases (56%). Two types of defective virus were identified: the first type (type 1) defective virus retained both LTRs and lacked internal sequences, which were mainly the 5' region of Provirus, such as gag and pol. Type 1 defective virus was found in 43% of all defective viruses. The second form (type 2) of defective virus had only one LTR, and 5'-LTR was preferentially deleted. This type of defective virus was more frequently detected in cases of acute and lymphoma-type ATL (21/54 cases) than in the chronic type (1/18 cases). The high frequency of this defective virus in the aggressive form of ATL suggests that it may be caused by the genetic instability of HTLV-I Provirus, and cells with this defective virus are selected because they escape from immune surveillance systems.
Maki Miyazaki - One of the best experts on this subject based on the ideXlab platform.
-
preferential selection of human t cell leukemia virus type 1 Provirus lacking the 5 long terminal repeat during oncogenesis
Journal of Virology, 2007Co-Authors: Maki Miyazaki, Jun-ichirou Yasunaga, Yuko Taniguchi, Sadahiro Tamiya, Tatsutoshi Nakahata, Masao MatsuokaAbstract:In adult T-cell leukemia (ATL) cells, a defective human T-cell leukemia virus type 1 (HTLV-1) Provirus lacking the 5′ long terminal repeat (LTR), designated type 2 defective Provirus, is frequently observed. To investigate the mechanism underlying the generation of the defective Provirus, we sequenced HTLV-1 Provirus integration sites from cases of ATL. In HTLV-1 Proviruses retaining both LTRs, 6-bp repeat sequences were adjacent to the 5′ and 3′ LTRs. In 8 of 12 cases with type 2 defective Provirus, 6-bp repeats were identified at both ends. In five of these cases, a short repeat was bound to CA dinucleotides of the pol and env genes at the 5′ end, suggesting that these type 2 defective Proviruses were formed before integration. In four cases lacking the 6-bp repeat, short (6- to 26-bp) deletions in the host genome were identified, indicating that these defective Proviruses were generated after integration. Quantification indicated frequencies of type 2 defective Provirus of less than 3.9% for two carriers, which are much lower than those seen for ATL cases (27.8%). In type 2 defective Proviruses, the second exons of the tax, rex, and p30 genes were frequently deleted, leaving Tax unable to activate NF-κB and CREB pathways. The HTLV-1 bZIP factor gene, located on the minus strand, is expressed in ATL cells with this defective Provirus, and its coding sequences are intact, suggesting its significance in oncogenesis.
-
Preferential Selection of Human T-Cell Leukemia Virus Type 1 Provirus Lacking the 5′ Long Terminal Repeat during Oncogenesis
Journal of Virology, 2007Co-Authors: Maki Miyazaki, Jun-ichirou Yasunaga, Yuko Taniguchi, Sadahiro Tamiya, Tatsutoshi Nakahata, Masao MatsuokaAbstract:In adult T-cell leukemia (ATL) cells, a defective human T-cell leukemia virus type 1 (HTLV-1) Provirus lacking the 5′ long terminal repeat (LTR), designated type 2 defective Provirus, is frequently observed. To investigate the mechanism underlying the generation of the defective Provirus, we sequenced HTLV-1 Provirus integration sites from cases of ATL. In HTLV-1 Proviruses retaining both LTRs, 6-bp repeat sequences were adjacent to the 5′ and 3′ LTRs. In 8 of 12 cases with type 2 defective Provirus, 6-bp repeats were identified at both ends. In five of these cases, a short repeat was bound to CA dinucleotides of the pol and env genes at the 5′ end, suggesting that these type 2 defective Proviruses were formed before integration. In four cases lacking the 6-bp repeat, short (6- to 26-bp) deletions in the host genome were identified, indicating that these defective Proviruses were generated after integration. Quantification indicated frequencies of type 2 defective Provirus of less than 3.9% for two carriers, which are much lower than those seen for ATL cases (27.8%). In type 2 defective Proviruses, the second exons of the tax, rex, and p30 genes were frequently deleted, leaving Tax unable to activate NF-κB and CREB pathways. The HTLV-1 bZIP factor gene, located on the minus strand, is expressed in ATL cells with this defective Provirus, and its coding sequences are intact, suggesting its significance in oncogenesis.
Madahavan Nair - One of the best experts on this subject based on the ideXlab platform.
-
A CRISPR/Cas9 guidance RNA screen platform for HIV Provirus disruption and HIV/AIDS gene therapy in astrocytes
Scientific Reports, 2017Co-Authors: Zaohua Huang, Madahavan NairAbstract:HIV/AIDS remains a major health threat despite significant advances in the prevention and treatment of HIV infection. The major reason is the inability of existing treatments to eradicate the multiple HIV reservoirs in the human body, including astrocytes in the human brain. CRISPR/Cas9 system is an emerging gene-editing technique with the potential to eliminate or disrupt HIV Provirus in HIV reservoir cells, which may lead to a complete cure of HIV/AIDS. The key components of CRISPR/Cas9 are guide RNAs (gRNAs) which determine specific sequence targeting of DNAs. This study established a novel, simple and quick screening method to identify gRNA candidates for targeting HIV Provirus in astrocytes. Briefly, stable astrocytes clones with an integrated fluorescent HIV reporter and Cas9 expression gene were generated. Various gRNAs were screened for their efficiencies against HIV Provirus in these cells. Moreover, these gRNAs and Cas9 protein were successfully tested on HIV latent astrocytes without Cas9 expression to mimic clinical conditions. HIV Provirus gene-editing were confirmed by cell genomic DNA PCR and fluorescent marker expression analysis. In the future, the established transgenic cells can be used for other gene-editing studies and is well-suited for high-throughput screen application.
-
a crispr cas9 guidance rna screen platform for hiv Provirus disruption and hiv aids gene therapy in astrocytes
Scientific Reports, 2017Co-Authors: Zaohua Huang, Madahavan NairAbstract:HIV/AIDS remains a major health threat despite significant advances in the prevention and treatment of HIV infection. The major reason is the inability of existing treatments to eradicate the multiple HIV reservoirs in the human body, including astrocytes in the human brain. CRISPR/Cas9 system is an emerging gene-editing technique with the potential to eliminate or disrupt HIV Provirus in HIV reservoir cells, which may lead to a complete cure of HIV/AIDS. The key components of CRISPR/Cas9 are guide RNAs (gRNAs) which determine specific sequence targeting of DNAs. This study established a novel, simple and quick screening method to identify gRNA candidates for targeting HIV Provirus in astrocytes. Briefly, stable astrocytes clones with an integrated fluorescent HIV reporter and Cas9 expression gene were generated. Various gRNAs were screened for their efficiencies against HIV Provirus in these cells. Moreover, these gRNAs and Cas9 protein were successfully tested on HIV latent astrocytes without Cas9 expression to mimic clinical conditions. HIV Provirus gene-editing were confirmed by cell genomic DNA PCR and fluorescent marker expression analysis. In the future, the established transgenic cells can be used for other gene-editing studies and is well-suited for high-throughput screen application.
Toshiki Watanabe - One of the best experts on this subject based on the ideXlab platform.
-
5' long terminal repeat (LTR)-selective methylation of latently infected HIV-1 Provirus that is demethylated by reactivation signals
Retrovirology, 2006Co-Authors: Takaomi Ishida, Akiko Hamano, Tsukasa Koiwa, Toshiki WatanabeAbstract:We previously described selective hypermethylation of the 5'-long terminal repeat (LTR) of HTLV-1 Provirus in vivo and in vitro. This prompted us to analyze CpG methylation of the two LTRs of the HIV Provirus in chronically infected cell lines. The results demonstrate selective hypermethylation of the 5' LTR of the HIV Provirus in ACH-2 cells. Moreover, induction of viral gene expression by TNF-α resulted in demethylation of the 5'-LTR. These results suggest that selective epigenetic modification of the 5'LTR of the HIV-1 Provirus may be an important mechanism by which proviral activity is suppressed.
-
Rapid quantification of HTLV-I Provirus load: Detection of monoclonal proliferation of HTLV-I-infected cells among blood donors
International Journal of Cancer, 1999Co-Authors: Ken Ichiro Etoh, Sherri Stuver, Nancy Mueller, Kiyoshi Takatsuki, Toshiki Watanabe, Kazunari Yamaguchi, Akihiko Okayama, Shinkan Tokudome, Masao MatsuokaAbstract:In this report, we quantified HTLV-I Provirus load using the AmpliSensor system, which utilizes fluorescence to measure PCR products. With this method, Provirus loads could be measured within 6 hr, and the results obtained correlated well with those obtained by other methods. Samples from 256 blood donors, who were positive for antibodies against HTLV-I, were analyzed, showing that Provirus load ranged from less than 0.1% to 56% among carriers. We analyzed the association between Provirus load and the biomarkers age and sex and found that it was not influenced by either. Provirus load was better correlated with soluble interleukin-2 receptor (sIL-2R) levels than with antibody titer against the virus. Among 18 blood donors with high Provirus load (more than 10%), Southern blotting detected monoclonal integration of HTLV-I in infected cells in 2 cases, both of them showing high sIL-2R levels (more than 900 U/ml). Sequential analyses of Provirus load showed stable levels of Provirus in the same carriers, suggesting that some factors other than age or sex determined Provirus load in infected individuals. Thus, this rapid method is a useful tool for the early detection of adult T-cell leukemia and other HTLV-I-associated diseases.
-
two types of defective human t lymphotropic virus type i Provirus in adult t cell leukemia
Blood, 1996Co-Authors: Sadahiro Tamiya, Ken Ichiro Etoh, Toshiki Watanabe, Kazunari Yamaguchi, Masao Matsuoka, Shimeru Kamihira, Kiyoshi TakatsukiAbstract:Adult T-cell leukemia (ATL), an aggressive neoplasm of mature helper T cells, is etiologically linked with human T lymphotropic virus type I (HTLV-1). After infection, HTLV-I randomly integrates its Provirus into chromosomal DNA. Since ATL is the clonal proliferation of HTLV-I-infected T lymphocytes, molecular methods facilitate the detection of clonal integration of HTLV-I Provirus in ATL cells. Using Southern blot analyses and long polymerase chain reaction (PCR) we examined HTLV-I Provirus in 72 cases of ATL, of various clinical subtypes. Southern blot analyses revealed that ATL cells in 18 cases had only one long terminal repeat (LTR). Long PCR with LTR primers showed bands shorter than for the complete virus (7.7 kb) or no bands in ATL cells with defective virus. Thus, defective virus was evident in 40 of 72 cases (56%). Two types of defective virus were identified: the first type (type 1) defective virus retained both LTRs and lacked internal sequences, which were mainly the 5' region of Provirus, such as gag and pol. Type 1 defective virus was found in 43% of all defective viruses. The second form (type 2) of defective virus had only one LTR, and 5'-LTR was preferentially deleted. This type of defective virus was more frequently detected in cases of acute and lymphoma-type ATL (21/54 cases) than in the chronic type (1/18 cases). The high frequency of this defective virus in the aggressive form of ATL suggests that it may be caused by the genetic instability of HTLV-I Provirus, and cells with this defective virus are selected because they escape from immune surveillance systems.
