The Experts below are selected from a list of 51 Experts worldwide ranked by ideXlab platform
Daniel R. Schoenberg - One of the best experts on this subject based on the ideXlab platform.
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Identification of Fhit as a post-transcriptional effector of Thymidine Kinase 1 expression.
2017Co-Authors: Daniel L. Kiss, Teresa Druck, Catherine E. Waters, Iman M. Ouda, Joshua C. Saldivar, Jenna R. Karras, Zaynab A. Amin, Seham Mahrous, Ralf Bundschuh, Daniel R. SchoenbergAbstract:FHIT is a genome Caretaker Gene that is silenced in >50% of cancers. Loss of Fhit protein expression promotes accumulation of DNA damage, affects apoptosis and epithelial-mesenchymal transition, though molecular mechanisms underlying these alterations have not been fully elucidated. Initiation of genome instability directly follows Fhit loss and the associated reduced Thymidine Kinase 1 (TK1) protein expression. The effects on TK1 of Fhit knockdown and Fhit induction in the current study confirmed the role of Fhit in regulating TK1 expression. Changes in Fhit expression did not impact TK1 protein turnover or transcription from the TK1 promoter, nor steady-state levels of TK1 mRNA or turnover. Polysome profile analysis showed that up-regulated Fhit expression resulted in decreased TK1 RNA in non-translating messenger ribonucleoproteins and increased ribosome density on TK1 mRNA. Fhit does not bind RNA but its expression increased luciferase expression from a transGene bearing the TK1 5'-UTR. Fhit has been reported to act as a scavenger decapping enzyme, and a similar result with a mutant (H96) that binds but does not cleave nucleoside 5',5'-triphosphates suggests the impact on TK1 translation is due to its ability to modulate the intracellular level of cap-like molecules. Consistent with this, cells expressing Fhit mutants with reduced activity toward cap-like dinucleotides exhibit DNA damage resulting from TK1 deficiency, whereas cells expressing wild-type Fhit or the H96N mutant do not. The results have implications for the mechanism by which Fhit regulates TK1 mRNA, and more broadly, for its modulation of multiple functions as tumor suppressor/genome Caretaker.
Joshua C. Saldivar - One of the best experts on this subject based on the ideXlab platform.
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Identification of Fhit as a post-transcriptional effector of Thymidine Kinase 1 expression.
2017Co-Authors: Daniel L. Kiss, Teresa Druck, Catherine E. Waters, Iman M. Ouda, Joshua C. Saldivar, Jenna R. Karras, Zaynab A. Amin, Seham Mahrous, Ralf Bundschuh, Daniel R. SchoenbergAbstract:FHIT is a genome Caretaker Gene that is silenced in >50% of cancers. Loss of Fhit protein expression promotes accumulation of DNA damage, affects apoptosis and epithelial-mesenchymal transition, though molecular mechanisms underlying these alterations have not been fully elucidated. Initiation of genome instability directly follows Fhit loss and the associated reduced Thymidine Kinase 1 (TK1) protein expression. The effects on TK1 of Fhit knockdown and Fhit induction in the current study confirmed the role of Fhit in regulating TK1 expression. Changes in Fhit expression did not impact TK1 protein turnover or transcription from the TK1 promoter, nor steady-state levels of TK1 mRNA or turnover. Polysome profile analysis showed that up-regulated Fhit expression resulted in decreased TK1 RNA in non-translating messenger ribonucleoproteins and increased ribosome density on TK1 mRNA. Fhit does not bind RNA but its expression increased luciferase expression from a transGene bearing the TK1 5'-UTR. Fhit has been reported to act as a scavenger decapping enzyme, and a similar result with a mutant (H96) that binds but does not cleave nucleoside 5',5'-triphosphates suggests the impact on TK1 translation is due to its ability to modulate the intracellular level of cap-like molecules. Consistent with this, cells expressing Fhit mutants with reduced activity toward cap-like dinucleotides exhibit DNA damage resulting from TK1 deficiency, whereas cells expressing wild-type Fhit or the H96N mutant do not. The results have implications for the mechanism by which Fhit regulates TK1 mRNA, and more broadly, for its modulation of multiple functions as tumor suppressor/genome Caretaker.
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common chromosome fragile sites in human and murine epithelial cells and fhit fra3b loss induced global genome instability
2013Co-Authors: Seyed Ali Hosseini, Joshua C. Saldivar, Susan Horton, Satoshi Miuma, Martha R Stampfer, Nyla A Heerema, Kay HuebnerAbstract:Chromosomal positions of common fragile sites differ in lymphoblasts and fibroblasts, with positions dependent on the epiGenetically determined density of replication origins at these loci. Because rearrangement of fragile loci and associated loss of fragile Gene products are hallmarks of cancers, we aimed to map common fragile sites in epithelial cells, from which most cancers derive. Among the five most frequently activated sites in human epithelial cells were chromosome bands 2q33 and Xq22.1, which are not among top fragile sites identified in lymphoblasts or fibroblasts. FRA16D at 16q23 was among the top three fragile sites in the human epithelial cells examined, as it is in lymphoblasts and fibroblasts, while FRA3B at 3p14.2, the top fragile locus in lymphoblasts, was not fragile in most epithelial cell lines tested. Epithelial cells exhibited varying hierarchies of fragile sites; some frequent epithelial cell fragile sites are apparently not frequently altered in epithelial cancers and sites that are frequently deleted in epithelial cancers are not necessarily among the most fragile. Since we have reported that loss of expression of the FRA3B-encoded FHIT protein causes increased replication stress-induced DNA damage, we also examined the effect of FHIT-deficiency on markers of genome instability in epithelial cells. FHIT-deficient cells exhibited increases in fragile breaks and in γH2AX and 53BP1 foci in G1 phase cells, confirming in epithelial cells that the FHIT Gene and encompassing FRA3B, is a “Caretaker Gene” necessary for maintenance of genome stability.
Daniel L. Kiss - One of the best experts on this subject based on the ideXlab platform.
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Identification of Fhit as a post-transcriptional effector of Thymidine Kinase 1 expression.
2017Co-Authors: Daniel L. Kiss, Teresa Druck, Catherine E. Waters, Iman M. Ouda, Joshua C. Saldivar, Jenna R. Karras, Zaynab A. Amin, Seham Mahrous, Ralf Bundschuh, Daniel R. SchoenbergAbstract:FHIT is a genome Caretaker Gene that is silenced in >50% of cancers. Loss of Fhit protein expression promotes accumulation of DNA damage, affects apoptosis and epithelial-mesenchymal transition, though molecular mechanisms underlying these alterations have not been fully elucidated. Initiation of genome instability directly follows Fhit loss and the associated reduced Thymidine Kinase 1 (TK1) protein expression. The effects on TK1 of Fhit knockdown and Fhit induction in the current study confirmed the role of Fhit in regulating TK1 expression. Changes in Fhit expression did not impact TK1 protein turnover or transcription from the TK1 promoter, nor steady-state levels of TK1 mRNA or turnover. Polysome profile analysis showed that up-regulated Fhit expression resulted in decreased TK1 RNA in non-translating messenger ribonucleoproteins and increased ribosome density on TK1 mRNA. Fhit does not bind RNA but its expression increased luciferase expression from a transGene bearing the TK1 5'-UTR. Fhit has been reported to act as a scavenger decapping enzyme, and a similar result with a mutant (H96) that binds but does not cleave nucleoside 5',5'-triphosphates suggests the impact on TK1 translation is due to its ability to modulate the intracellular level of cap-like molecules. Consistent with this, cells expressing Fhit mutants with reduced activity toward cap-like dinucleotides exhibit DNA damage resulting from TK1 deficiency, whereas cells expressing wild-type Fhit or the H96N mutant do not. The results have implications for the mechanism by which Fhit regulates TK1 mRNA, and more broadly, for its modulation of multiple functions as tumor suppressor/genome Caretaker.
Sabina Pucci - One of the best experts on this subject based on the ideXlab platform.
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the expression and the nuclear activity of the Caretaker Gene ku86 are modulated by somatostatin
2009Co-Authors: Sabina Pucci, Elena Bonanno, Flavia Pichiorri, Paola Mazzarelli, L G SpagnoliAbstract:Somatostatin is a peptide hormone that exerts antisecretory and antiproliferative activities on some human tumors. The Ku70/86 heterodimer acts as regulatory subunit of the DNA dependent protein kinase and its DNA binding activity mediates DNA double strands breaks repair that is crucial to maintain the Genetic integrity of the genome. The activation of the heterodimer regulates cell cycle progression and the activity of nuclear transcription factors involved in DNA replication and cell proliferation. Moreover Ku86 behaves as a receptor for the growth inhibitory tetradecapeptide, somatostatin. Herein we report that somatostatin treatment to a colon carcinoma cell line (Caco-2) inhibits cell growth and, at same time, strongly modulates the activation of Ku70/86 heterodimer and the levels of Ku86 in the nucleus by increasing its specific mRNA level. Our findings are consistent with the hypothesis that somatostatin controls cell cycle progression and DNA repair through a new signalling pathway that involves the regulation of Ku86 level and modulates the Ku70/86 activity in the nucleus.
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tumor specific modulation of ku70 80 dna binding activity in breast and bladder human tumor biopsies
2001Co-Authors: Sabina Pucci, Paola Mazzarelli, Carla Rabitti, M Giai, M Gallucci, Gerardo Flammia, Antonio Alcini, Vittorio Altomare, Vito Michele FazioAbstract:The Ku70/80 heterodimer is the regulatory subunit of the DNA-dependent protein kinase (DNA-PK) and its DNA-binding activity mediates DNA double-strand breaks repair. Although Ku80 was recently proposed as a Caretaker Gene involved in the control of genome integrity, no data are available on Ku70/80 DNA-binding activity in human tumors. Heterodimer DNA-binding activity and protein expression were assayed by electrophoretic-mobility-shift-assay (EMSA) and Western blot analysis, in nuclear and cytoplasmic extracts from eight breast, seven bladder primary tumors and three metastatic nodes from breast cancers. Corresponding normal tissues of the same patients were used as controls. Ten out of 15 tumors showed nuclear Ku-binding activity 3-10 times higher than in the normal tissues, irrespective of bladder or breast origin. Conversely, in 5/15 primary tumors and in all the metastatic nodes analysed, nuclear Ku-activity was 1.5-4.5-fold lower than in the corresponding normal tissues. Cytoplasmic heterodimer activity significantly differed between tumor and normal tissues, displaying a 2-10-fold increase in neoplastic tissues. Three different patterns combining both Ku expression and activity with tumor characteristics were identified. In low aggressive breast tumors p70/p80 proteins were expressed in tumor but not in normal tissues. The heterodimer binding-activity matched the protein levels. In non-invasive bladder carcinomas no significant differences in protein expression between tumor and the corresponding normal tissues were found, however heterodimer binding-activity was increased in tumor samples. In breast and bladder tumors, at the advanced stage and in node metastases, the binding activity was strongly reduced in tumor biopsies, however no differences were demonstrated between normal and tumor protein levels. Our results suggest a different modulation of Ku70/80 DNA-binding activity in human neoplastic tissues, possibly related to tumor progression. Findings provide further data on tissue-specific protein expression and post-translational regulation of heterodimer activity.
Paola Mazzarelli - One of the best experts on this subject based on the ideXlab platform.
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the expression and the nuclear activity of the Caretaker Gene ku86 are modulated by somatostatin
2009Co-Authors: Sabina Pucci, Elena Bonanno, Flavia Pichiorri, Paola Mazzarelli, L G SpagnoliAbstract:Somatostatin is a peptide hormone that exerts antisecretory and antiproliferative activities on some human tumors. The Ku70/86 heterodimer acts as regulatory subunit of the DNA dependent protein kinase and its DNA binding activity mediates DNA double strands breaks repair that is crucial to maintain the Genetic integrity of the genome. The activation of the heterodimer regulates cell cycle progression and the activity of nuclear transcription factors involved in DNA replication and cell proliferation. Moreover Ku86 behaves as a receptor for the growth inhibitory tetradecapeptide, somatostatin. Herein we report that somatostatin treatment to a colon carcinoma cell line (Caco-2) inhibits cell growth and, at same time, strongly modulates the activation of Ku70/86 heterodimer and the levels of Ku86 in the nucleus by increasing its specific mRNA level. Our findings are consistent with the hypothesis that somatostatin controls cell cycle progression and DNA repair through a new signalling pathway that involves the regulation of Ku86 level and modulates the Ku70/86 activity in the nucleus.
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tumor specific modulation of ku70 80 dna binding activity in breast and bladder human tumor biopsies
2001Co-Authors: Sabina Pucci, Paola Mazzarelli, Carla Rabitti, M Giai, M Gallucci, Gerardo Flammia, Antonio Alcini, Vittorio Altomare, Vito Michele FazioAbstract:The Ku70/80 heterodimer is the regulatory subunit of the DNA-dependent protein kinase (DNA-PK) and its DNA-binding activity mediates DNA double-strand breaks repair. Although Ku80 was recently proposed as a Caretaker Gene involved in the control of genome integrity, no data are available on Ku70/80 DNA-binding activity in human tumors. Heterodimer DNA-binding activity and protein expression were assayed by electrophoretic-mobility-shift-assay (EMSA) and Western blot analysis, in nuclear and cytoplasmic extracts from eight breast, seven bladder primary tumors and three metastatic nodes from breast cancers. Corresponding normal tissues of the same patients were used as controls. Ten out of 15 tumors showed nuclear Ku-binding activity 3-10 times higher than in the normal tissues, irrespective of bladder or breast origin. Conversely, in 5/15 primary tumors and in all the metastatic nodes analysed, nuclear Ku-activity was 1.5-4.5-fold lower than in the corresponding normal tissues. Cytoplasmic heterodimer activity significantly differed between tumor and normal tissues, displaying a 2-10-fold increase in neoplastic tissues. Three different patterns combining both Ku expression and activity with tumor characteristics were identified. In low aggressive breast tumors p70/p80 proteins were expressed in tumor but not in normal tissues. The heterodimer binding-activity matched the protein levels. In non-invasive bladder carcinomas no significant differences in protein expression between tumor and the corresponding normal tissues were found, however heterodimer binding-activity was increased in tumor samples. In breast and bladder tumors, at the advanced stage and in node metastases, the binding activity was strongly reduced in tumor biopsies, however no differences were demonstrated between normal and tumor protein levels. Our results suggest a different modulation of Ku70/80 DNA-binding activity in human neoplastic tissues, possibly related to tumor progression. Findings provide further data on tissue-specific protein expression and post-translational regulation of heterodimer activity.