The non-classical HLA class Ⅰ antigen HLA-G is an immune modulator which inhibits the functions of T cells, NK cells, and the Dendritic cells （DC）. As a result, HLA-G expression in malignant cells may provide them ...The non-classical HLA class Ⅰ antigen HLA-G is an immune modulator which inhibits the functions of T cells, NK cells, and the Dendritic cells （DC）. As a result, HLA-G expression in malignant cells may provide them with a mechanism to escape the immune surveillance. In melanoma, HLA-G antigen expression has been found in 30% of surgically removed lesions but in less than 1% of established cell lines. One possible mechanism underlying the differential HLA-G expression in vivo and in vitro is that the HLA-G gene is epigenetically repressed in melanoma cells in vitro. To test this hypothesis, we treated the HLA-G negative melanoma cell line OCM-1A with the DNA methyltransferase inhibitor 5-aza-2＇-deoxycytidine （5-AC） and analyzed whether HLA-G expression can be restored. Our data strongly suggest that HLA-G is silenced as a result of CpG hypermethylation within a 5＇ regulatory region encompassing 220 bp upstream of the start codon. After treatment, HLA-G mRNA expression was dramatically increased. Western blot and flow cytometry showed that HLA-G protein was induced. Interestingly, HLA-G cell surface expression on the 5-AC treated OCM-1A cells is much less than that on the HLA-G positive JEG-3 cells while a similar amount of total HLA-G was observed. Possible mechanisms for the difference were analyzed in the study such as cell cold-treatment, peptide loading and antigen processing machinery components （APM） as well as β2 microglobulin （β2-m） expression. Data revealed that the APM component calreticulin might be involved in the lower HLA-G surface expression on OCM-1A cells. Taken together, our results indicated that DNA methylation is an important epigenetic mechanism by which HLA-G antigen expression is modulated in melanoma cells in vitro. Furthermore, to the first time, we hypothesized that the deficiency of calreticulin might be involved in the low HLA-G surface expression on the 5-AC treated OCM-1A cells.展开更多
Early pregnancy factor (EPF) was purified from the pooled sera of 21 0 pregnant women at 3- 8 weeks of gestation. Sera from healthy nonpregnant women were used as control. The samples (G-Ⅱ . G-Ⅲ and G-Ⅳ) obtained f...Early pregnancy factor (EPF) was purified from the pooled sera of 21 0 pregnant women at 3- 8 weeks of gestation. Sera from healthy nonpregnant women were used as control. The samples (G-Ⅱ . G-Ⅲ and G-Ⅳ) obtained from pregnant women had EPF activity but no HCG activity. Polyacrylamide gel electrophoresis showed that the major bands in pregnant G-Ⅲ and G-Ⅳ were at similar positions in tube gels. The results of SDS-PAGE showed 3 bands in pregnant G-Ⅳ: 57. 0 kD. 38. 0 kD and 19. 0 kD. The basic active form of EPF may be a small peptide of 1 9. 0 kD. The isoelectric points of pregnant G-Ⅳ were 6. 45 and 8. 20.展开更多
Let d be the smallest generator number of a finite p-group P and let Md(P) = {P1,...,Pd} be a set of maximal subgroups of P such that ∩di=1 Pi = Φ(P). In this paper, we study the structure of a finite group G under ...Let d be the smallest generator number of a finite p-group P and let Md(P) = {P1,...,Pd} be a set of maximal subgroups of P such that ∩di=1 Pi = Φ(P). In this paper, we study the structure of a finite group G under the assumption that every member in Md(Gp) is S-semipermutable in G for each prime divisor p of |G| and a Sylow p-subgroup Gp of G.展开更多
文摘The non-classical HLA class Ⅰ antigen HLA-G is an immune modulator which inhibits the functions of T cells, NK cells, and the Dendritic cells （DC）. As a result, HLA-G expression in malignant cells may provide them with a mechanism to escape the immune surveillance. In melanoma, HLA-G antigen expression has been found in 30% of surgically removed lesions but in less than 1% of established cell lines. One possible mechanism underlying the differential HLA-G expression in vivo and in vitro is that the HLA-G gene is epigenetically repressed in melanoma cells in vitro. To test this hypothesis, we treated the HLA-G negative melanoma cell line OCM-1A with the DNA methyltransferase inhibitor 5-aza-2＇-deoxycytidine （5-AC） and analyzed whether HLA-G expression can be restored. Our data strongly suggest that HLA-G is silenced as a result of CpG hypermethylation within a 5＇ regulatory region encompassing 220 bp upstream of the start codon. After treatment, HLA-G mRNA expression was dramatically increased. Western blot and flow cytometry showed that HLA-G protein was induced. Interestingly, HLA-G cell surface expression on the 5-AC treated OCM-1A cells is much less than that on the HLA-G positive JEG-3 cells while a similar amount of total HLA-G was observed. Possible mechanisms for the difference were analyzed in the study such as cell cold-treatment, peptide loading and antigen processing machinery components （APM） as well as β2 microglobulin （β2-m） expression. Data revealed that the APM component calreticulin might be involved in the lower HLA-G surface expression on OCM-1A cells. Taken together, our results indicated that DNA methylation is an important epigenetic mechanism by which HLA-G antigen expression is modulated in melanoma cells in vitro. Furthermore, to the first time, we hypothesized that the deficiency of calreticulin might be involved in the low HLA-G surface expression on the 5-AC treated OCM-1A cells.
文摘Early pregnancy factor (EPF) was purified from the pooled sera of 21 0 pregnant women at 3- 8 weeks of gestation. Sera from healthy nonpregnant women were used as control. The samples (G-Ⅱ . G-Ⅲ and G-Ⅳ) obtained from pregnant women had EPF activity but no HCG activity. Polyacrylamide gel electrophoresis showed that the major bands in pregnant G-Ⅲ and G-Ⅳ were at similar positions in tube gels. The results of SDS-PAGE showed 3 bands in pregnant G-Ⅳ: 57. 0 kD. 38. 0 kD and 19. 0 kD. The basic active form of EPF may be a small peptide of 1 9. 0 kD. The isoelectric points of pregnant G-Ⅳ were 6. 45 and 8. 20.
基金the National Natural Science Foundation of China (No.10161001)the Natural Science Foundation of Guangxi Autonomous Region (No.0249001)a Research Grant of Shanghai University(No.SHUCX091043)
文摘Let d be the smallest generator number of a finite p-group P and let Md(P) = {P1,...,Pd} be a set of maximal subgroups of P such that ∩di=1 Pi = Φ(P). In this paper, we study the structure of a finite group G under the assumption that every member in Md(Gp) is S-semipermutable in G for each prime divisor p of |G| and a Sylow p-subgroup Gp of G.
