Based on the octadecahedron of eleven-vertex closo-borane, the eleven-vertex closo-heteroborane was suggested with nonmetallic atoms instead of the different nonequivalent boron, and the stabilities were predicted at ...Based on the octadecahedron of eleven-vertex closo-borane, the eleven-vertex closo-heteroborane was suggested with nonmetallic atoms instead of the different nonequivalent boron, and the stabilities were predicted at G96PW91/6-31+G(3d,2p) level. The small heteroatoms, C, N, O, preferentially occupy vertex 2 with the absolutely lowest relative energy to form the high stabilization closo-heteroboranes. They cap four-membered rings to satisfy the geometrical demand of short B--Z bonds. The electron attractions from the vicinal boron atoms make the frameworks shrink. Differently, Si and Ge preferentially substitute for boron at vertex 1 with six tight B--Z bonds and form stabilized molecules. P, As, S, and Se tend to occupy vertex 4 and the optimized structures belong to the nido configura- tions. In contrast to high electronegative heteroatoms, S and Se transfer less negative charges to framework and the electropositive heteroatoms, Si and Ge transfer more negative charges to framework to form the delocalization structures. The HOMO-LUMO gaps show that most of predicted clusters possess chemical stabilities. The substitutions of heteroatoms for boron atoms in eleven-vertex closo-heteroboranes are consistent with the topological charge stabilization rule proposed by Gimarc.展开更多
Objective: Aberrant expression of ten-eleven translocation 1 (TET1) plays a critical role in tumor development and progression. We systematically summarized the latest research progress on the role and mechanisms o...Objective: Aberrant expression of ten-eleven translocation 1 (TET1) plays a critical role in tumor development and progression. We systematically summarized the latest research progress on the role and mechanisms of TET1 in cancer biology. Data Sources: Relevant articles published in English from 1980 to April 2016 were selected from the PubMed database. Tile terms "'ten-eleven translocation 1," "'SmC," '5hmC," 'microRNA,'" "hypoxia," and "'embryonic stem cell'" were used tbr the search. Study Selection: Articles focusing on the role and mechanism ofTETI in tumor were reviewed, including clinical and basic research articles. Results: TET proteins, the key enzymes converting 5-methylcytosine to 5-hydroxymethylcytosine, play vital roles in DNA demethylation regulation. Recent studies have shown that loss of TETI is associated with tumorigenesis and can be used as a potential biomarker for cancer therapy, which indicates that TETI serves as tumor suppressor gene. Moreover, besides its dioxygenase activity, TET1 could induce epithelial-mesenchymal transition and act as a coactivator to regulate gene transcription, such as developmental regulator in embryonic stem cells (ESCs) and hypoxia-responsive gene in cancer. The regulation of TETl is also correlated with microRNA in a posttranscriptional modification process. Hence, it is complex but critical to coaprehend the mechanisms of TETI in the biology of ESCs and cancer. Conclusions: TET I not only serves as a demethylation enzyme but also plays multiple roles during tumorigenesis and progression. More studies should be carried out to elucidate the exact mechanisms of TETI and its associations with cancer betbre considering it as a therapeutic tool.展开更多
Background: DNA hydroxymethylation refers to a chemical modification process in which 5-methylcytosine (5mC) is catalyzed to 5-hydroxymethylcytosine (5hmC) by ten-eleven translocation (TET) family proteins. Rec...Background: DNA hydroxymethylation refers to a chemical modification process in which 5-methylcytosine (5mC) is catalyzed to 5-hydroxymethylcytosine (5hmC) by ten-eleven translocation (TET) family proteins. Recent studies have revealed that aberrant TETs expression or 5hmC level may play important roles in the occurrence and development of various pathological and physiological processes including cancer and aging. This study aimed to explore the relation between aberrant DNA hydroxymethylation with skin photoaging and to investigate the levels of TETs, 5mC, and 5hmC expression 24 h after 40 mJ/cm^2 and 80 mJ/cm^2 doses of ultraviolet B (UVB) irradiation to HaCaT cells. Methods: To explore whether aberrant DNA hydroxymethylation is also related to skin photoaging, 40 mJ/cm^2 and 80 mJ/cm^2 doses of UVB were chosen to treat keratinocytes (HaCaT cells). After 24 h of UVB irradiation, 5mC and 5hmC levels were determined by immunohistochemistry (IHC) and immunofluorescence (IF), and at the same time, the expression levels of matrix metalloproteinase 1 (MMP-1) and TETs were assessed by reverse transcription-polymerase chain reaction or Western blot analysis. Results: After 40 mJ/cm^2 and 80 mJ/cm^2 doses of UVB exposure, both IHC and IF results showed that 5hmC levels increased significantly, while the 5mC levels did not exhibit significant changes in HaCaT cells, compared with HaCat cells without UVB exposure. Moreover, compared with HaCat cells without UVB exposure, the levels ofTET1, TET2, and TET3 mRNA and protein expression were significantly upregulated (mRNA: P = 0.0022 and 0.0043 for TET1; all P 〈 0.0001 for TET2; all P = 0.0006 for TET3; protein: P = 0.0012 and 0.0006 tbr TET 1 ; all P = 0.0022 for TET2; and all P = 0.0002 for TET3), and the levels of MMP- 1 mRNA expression increased dose dependently in 40 mJ/cm^2 and 80 mJ/cm^2 UVB-irradiated groups. Conclusion: UVB radiation could cause increased 5hmC and TET expression, which might become a novel biomarker in UVB-related skin aging.展开更多
文摘Based on the octadecahedron of eleven-vertex closo-borane, the eleven-vertex closo-heteroborane was suggested with nonmetallic atoms instead of the different nonequivalent boron, and the stabilities were predicted at G96PW91/6-31+G(3d,2p) level. The small heteroatoms, C, N, O, preferentially occupy vertex 2 with the absolutely lowest relative energy to form the high stabilization closo-heteroboranes. They cap four-membered rings to satisfy the geometrical demand of short B--Z bonds. The electron attractions from the vicinal boron atoms make the frameworks shrink. Differently, Si and Ge preferentially substitute for boron at vertex 1 with six tight B--Z bonds and form stabilized molecules. P, As, S, and Se tend to occupy vertex 4 and the optimized structures belong to the nido configura- tions. In contrast to high electronegative heteroatoms, S and Se transfer less negative charges to framework and the electropositive heteroatoms, Si and Ge transfer more negative charges to framework to form the delocalization structures. The HOMO-LUMO gaps show that most of predicted clusters possess chemical stabilities. The substitutions of heteroatoms for boron atoms in eleven-vertex closo-heteroboranes are consistent with the topological charge stabilization rule proposed by Gimarc.
文摘Objective: Aberrant expression of ten-eleven translocation 1 (TET1) plays a critical role in tumor development and progression. We systematically summarized the latest research progress on the role and mechanisms of TET1 in cancer biology. Data Sources: Relevant articles published in English from 1980 to April 2016 were selected from the PubMed database. Tile terms "'ten-eleven translocation 1," "'SmC," '5hmC," 'microRNA,'" "hypoxia," and "'embryonic stem cell'" were used tbr the search. Study Selection: Articles focusing on the role and mechanism ofTETI in tumor were reviewed, including clinical and basic research articles. Results: TET proteins, the key enzymes converting 5-methylcytosine to 5-hydroxymethylcytosine, play vital roles in DNA demethylation regulation. Recent studies have shown that loss of TETI is associated with tumorigenesis and can be used as a potential biomarker for cancer therapy, which indicates that TETI serves as tumor suppressor gene. Moreover, besides its dioxygenase activity, TET1 could induce epithelial-mesenchymal transition and act as a coactivator to regulate gene transcription, such as developmental regulator in embryonic stem cells (ESCs) and hypoxia-responsive gene in cancer. The regulation of TETl is also correlated with microRNA in a posttranscriptional modification process. Hence, it is complex but critical to coaprehend the mechanisms of TETI in the biology of ESCs and cancer. Conclusions: TET I not only serves as a demethylation enzyme but also plays multiple roles during tumorigenesis and progression. More studies should be carried out to elucidate the exact mechanisms of TETI and its associations with cancer betbre considering it as a therapeutic tool.
文摘Background: DNA hydroxymethylation refers to a chemical modification process in which 5-methylcytosine (5mC) is catalyzed to 5-hydroxymethylcytosine (5hmC) by ten-eleven translocation (TET) family proteins. Recent studies have revealed that aberrant TETs expression or 5hmC level may play important roles in the occurrence and development of various pathological and physiological processes including cancer and aging. This study aimed to explore the relation between aberrant DNA hydroxymethylation with skin photoaging and to investigate the levels of TETs, 5mC, and 5hmC expression 24 h after 40 mJ/cm^2 and 80 mJ/cm^2 doses of ultraviolet B (UVB) irradiation to HaCaT cells. Methods: To explore whether aberrant DNA hydroxymethylation is also related to skin photoaging, 40 mJ/cm^2 and 80 mJ/cm^2 doses of UVB were chosen to treat keratinocytes (HaCaT cells). After 24 h of UVB irradiation, 5mC and 5hmC levels were determined by immunohistochemistry (IHC) and immunofluorescence (IF), and at the same time, the expression levels of matrix metalloproteinase 1 (MMP-1) and TETs were assessed by reverse transcription-polymerase chain reaction or Western blot analysis. Results: After 40 mJ/cm^2 and 80 mJ/cm^2 doses of UVB exposure, both IHC and IF results showed that 5hmC levels increased significantly, while the 5mC levels did not exhibit significant changes in HaCaT cells, compared with HaCat cells without UVB exposure. Moreover, compared with HaCat cells without UVB exposure, the levels ofTET1, TET2, and TET3 mRNA and protein expression were significantly upregulated (mRNA: P = 0.0022 and 0.0043 for TET1; all P 〈 0.0001 for TET2; all P = 0.0006 for TET3; protein: P = 0.0012 and 0.0006 tbr TET 1 ; all P = 0.0022 for TET2; and all P = 0.0002 for TET3), and the levels of MMP- 1 mRNA expression increased dose dependently in 40 mJ/cm^2 and 80 mJ/cm^2 UVB-irradiated groups. Conclusion: UVB radiation could cause increased 5hmC and TET expression, which might become a novel biomarker in UVB-related skin aging.