Rearrangement of T cell receptor genes Tcra and Tcrd and its regulatory mechanism / 中华微生物学和免疫学杂志

The high diversity of T cell receptors (TCRs) is the basis for recognizing antigens, playing an essential role in adaptive immunity. TCR diversity is generated from V(D)J rearrangement during the thymocyte development in the thymus. Standing out from the four TCR genes, Tcra and Tcrd genes are characterized by locating at the same locus and sharing specific V genes. Hence, their rearrangement and regulation have a certain particularity. Previous studies mainly focused on cis-regulatory elements and trans-acting factors regulating the Tcra/ Tcrd rearrangement. However, recent progress has shown that chromatin spatial organization plays an essential role in antigen receptor gene rearrangement. Chromatin organization proteins, such as CTCF-Cohesin, are involved in regulating rearrangement and enhancing the diversity of TCR repertoire by loop extrusion. Recombinase RAG also scans chromatin of antigen receptor genes for rearrangement. This review described the progress in the rearrangement of Tcra and Tcrd genes and the possible regulatory mechanism, especially the influence of the chromatin spatial organization.

DNA recognition patterns of the multi-zinc-finger protein CTCF: a mutagenesis study

CCCTC-binding factor (CTCF) is a zinc-finger protein, serving an important part in the genome architecture as well as some biochemical processes. Over 70,000 CTCF binding DNA sites have been detected genome-wide, and most anchors of chromatin loops are demarcated with the CTCF binding. Various protein or RNA molecules interact with DNA-bound CTCF to conduct different biological functions, and potentially the interfaces between CTCF and its cofactors can be targets for drug development. Here we identify the effective region of CTCF in DNA recognition, which defines the exposed CTCF surface feature for the interaction of cofactors. While the zinc-finger region contributes the most in DNA association, its binding affinity varies based on different DNA sequences. To investigate the effectiveness of individual zinc-fingers, the key residues are mutated to inactivate the DNA binding ability, while the finger configuration and the spacing between fingers are preserved. The strategy is proved to be successful, while clear differences are observed in the DNA binding affinities among the 11 finger mutants and the result is consistent to previous studies in general. With the help of inactivated finger mutants, we identify the ineffective fingers and the dominant effective fingers, which form distinctive patterns on different DNA targets.

CTCF, Cohesin, and Chromatin in Human Cancer

It is becoming increasingly clear that eukaryotic genomes are subjected to higher-order chromatin organization by the CCCTC-binding factor/cohesin complex. Their dynamic interactions in three dimensions within the nucleus regulate gene transcription by changing the chromatin architecture. Such spatial genomic organization is functionally important for the spatial disposition of chromosomes to control cell fate during development and differentiation. Thus, the dysregulation of proper long-range chromatin interactions may influence the development of tumorigenesis and cancer progression.

Effects of overexpression of CTCF on apoptosis factors Bax and Bcl-2 in breast cancer cells / 天津医药

Objective To investigate the effect of the over-expressed CTCF on apoptosis factors Bax and Bcl-2 in human breast cancer cell line MDA-MB-231. Methods Reverse transcription-polymerase chain reaction (RT-PCR) were used to detect the expressions of CTCF,Bax and Bcl-2 in MDA-MB-231. The overexpression vector of CTCF/pEGFP-N1 was constructed. The overexpression plasmid CTCF/pEGFP-N1 and the empty vector plasmid pEGFP-N1 were transfected into breast cancer cell line MDA-MB-231 by lentivirus transfection, and the MDA-MB-231 cells were divided into CTCF group and control group. After successfully transfection of MDA-MB-231 identified by RT-PCR, real time quantitative PCR (Q-PCR) was used to detect the mRNA levels of Bax and Bcl-2 in MDA-MB-231 of the CTCF group and the control group. The protein levels of Bax and Bcl-2 were detected by Western blot assay and enzyme-linked immunosorbent assay (ELISA). Results The expression of CTCF was not found in MDA-MB-231, and expressions of Bax and Bcl-2 were found in MDA-MB-231. Results of Q-PCR showed that the mRNA levels of Bax were 4.63±1.08 and 2.27±0.16 in CTCF group and control group, respectively, and they were statistically significant (t=27.50, P<0.05). The mRNA levels of Bcl-2 were 1.39±0.14 and 3.56 ± 0.97 in CTCF group and control group, and there was significant difference between two groups(t=39.00, P<0.05). Results of Western blot assay showed that the protein level of Bax was higher in CTCF group compared with that of control group. The protein level of Bcl-2 was lower in CTCF group compared with that of control group. Results of ELISA showed that the protein levels of Bax were 15.25±2.17 and 6.24±1.78 in CTCF group and control group, respectively, and there was significant difference between the two groups (t=26.84, P<0.05). The protein levels of Bcl-2 were 4.59 ± 0.97 and 10.68 ± 1.93, and there was significant difference between the two groups (t=21.72, P<0.05). Conclusion The over-expressed CTCF can promote the expression of apoptotic factors and inhibit the expression of anti-apoptotic factors in breast cancer cells.

Effects of overexpression of CTCF on apoptosis factors Bax and Bcl-2 in breast cancer cells / 天津医药

Objective To investigate the effect of the over-expressed CTCF on apoptosis factors Bax and Bcl-2 in human breast cancer cell line MDA-MB-231. Methods Reverse transcription-polymerase chain reaction (RT-PCR) were used to detect the expressions of CTCF,Bax and Bcl-2 in MDA-MB-231. The overexpression vector of CTCF/pEGFP-N1 was constructed. The overexpression plasmid CTCF/pEGFP-N1 and the empty vector plasmid pEGFP-N1 were transfected into breast cancer cell line MDA-MB-231 by lentivirus transfection, and the MDA-MB-231 cells were divided into CTCF group and control group. After successfully transfection of MDA-MB-231 identified by RT-PCR, real time quantitative PCR (Q-PCR) was used to detect the mRNA levels of Bax and Bcl-2 in MDA-MB-231 of the CTCF group and the control group. The protein levels of Bax and Bcl-2 were detected by Western blot assay and enzyme-linked immunosorbent assay (ELISA). Results The expression of CTCF was not found in MDA-MB-231, and expressions of Bax and Bcl-2 were found in MDA-MB-231. Results of Q-PCR showed that the mRNA levels of Bax were 4.63±1.08 and 2.27±0.16 in CTCF group and control group, respectively, and they were statistically significant (t=27.50, P<0.05). The mRNA levels of Bcl-2 were 1.39±0.14 and 3.56 ± 0.97 in CTCF group and control group, and there was significant difference between two groups(t=39.00, P<0.05). Results of Western blot assay showed that the protein level of Bax was higher in CTCF group compared with that of control group. The protein level of Bcl-2 was lower in CTCF group compared with that of control group. Results of ELISA showed that the protein levels of Bax were 15.25±2.17 and 6.24±1.78 in CTCF group and control group, respectively, and there was significant difference between the two groups (t=26.84, P<0.05). The protein levels of Bcl-2 were 4.59 ± 0.97 and 10.68 ± 1.93, and there was significant difference between the two groups (t=21.72, P<0.05). Conclusion The over-expressed CTCF can promote the expression of apoptotic factors and inhibit the expression of anti-apoptotic factors in breast cancer cells.

Caracterização funcional da interação entre as proteínas CTSP-1 e CTCF / Functional characterization of the interaction between the proteins CTSP-1 and CTCF

Os antígenos cancer-testis (CT) são proteínas imunogênicas expressas em tecido gametogênico e em diferentes tipos de tumor, sendo considerados candidatos promissores para a imunoterapia do câncer. Entretanto, pouco se sabe sobre a função desses antígenos na tumorigênese. Em 2006, identificamos CTSP-1 como um novo antígeno CT, frequentemente expresso em vários tumores. Nesse trabalho, investigamos a função de CTSP-1 por meio da identificação de proteínas expressas em tumores de próstata e que são capazes de interagir fisicamente com esse antígeno. Demonstramos que CTSP-1 interage com a proteína CTCF em ensaios de duplo-híbrido em leveduras, pulldown e de co-localização e, em seguida, analisamos o impacto da superexpressão de CTSP-1 no controle da expressão de genes CT mediada por CTCF e na progressão do ciclo celular. Utilizando o CT NY-ESO-1 como modelo, demonstramos que a superexpressão de CTSP-1 não altera os níveis endógenos de NY-ESO-1 na linhagem celular tumoral H1299. Por outro lado, observamos que a superexpressão de CTSP-1 48h após as transfecções em H1299 induz um bloqueio do ciclo em G0/G1, reduzindo a capacidade clonogênica dessas células por um mecanismo dependente dos níveis de expressão de CTSP-1. Resultados semelhantes não foram observados em ensaios com clones superexpressando CTSP-1 estavelmente, o que sugere que eles tenham se originado de células que conseguiram escapar do bloqueio em G0/G1. Resultados preliminares sugerem que a redução da capacidade clonogênica das células H1299 que superexpressam CTSP-1 48h após as tansfecções não está associada à ocorrência de morte por apoptose.

Cancer-testis (CT) antigens are immunogenic proteins expressed in gametogenic tissues and in different histological types of tumors, being considered promising candidates for cancer immunotherapy. However, little is known about their role in tumorigenesis. In 2006, we identified CTSP-1 as a novel CT antigen, frequently expressed in different types of tumors. In this work, we investigated the functional role of CTSP-1 through the identification of proteins expressed in prostate tumors and that physically interact with this tumor antigen. We demonstrate that CTSP-1 interacts with the CTCF protein using the yeast two-hybrid system, pulldown and co-localization assays and have further analyzed the impact of CTSP-1 overexpression on the expression of CT genes mediated by CTCF and on the cell cycle progression. Using the CT antigen NY-ESO-1 as a model, we showed that the CTSP-1 overexpression does not alter the endogenous levels of NY-ESO-1 in the tumor cell line H1299. On the other hand, we observed that the overexpression of CTSP-1 in H1299 cells 48h after the transfections induces a cell cycle arrest in G0/G1 and reduces the clonogenic capacity of these cells by a mechanism dependent on the CTSP-1 expression levels. Similar results were not observed for cell clones stably overexpressing CTSP-1, suggesting that these clones have arisen from cells that managed to escape cell cycle arrest in G0/G1. Preliminary results suggest that the reduced clonogenic capacity of H1299 cells expressing CTSP-1 and analyzed 48h after the transfections is not associated with cell death by apoptosis.

Caracterização funcional da interação entre as proteínas CTSP-1 e CTCF / Functional characterization of the interaction between the proteins CTSP-1 and CTCF

Os antígenos cancer-testis (CT) são proteínas imunogênicas expressas em tecido gametogênico e em diferentes tipos de tumor, sendo considerados candidatos promissores para a imunoterapia do câncer. Entretanto, pouco se sabe sobre a função desses antígenos na tumorigênese. Em 2006, identificamos CTSP-1 como um novo antígeno CT, frequentemente expresso em vários tumores. Nesse trabalho, investigamos a função de CTSP-1 por meio da identificação de proteínas expressas em tumores de próstata e que são capazes de interagir fisicamente com esse antígeno. Demonstramos que CTSP-1 interage com a proteína CTCF em ensaios de duplo-híbrido em leveduras, pulldown e de co-localização e, em seguida, analisamos o impacto da superexpressão de CTSP-1 no controle da expressão de genes CT mediada por CTCF e na progressão do ciclo celular. Utilizando o CT NY-ESO-1 como modelo, demonstramos que a superexpressão de CTSP-1 não altera os níveis endógenos de NY-ESO-1 na linhagem celular tumoral H1299. Por outro lado, observamos que a superexpressão de CTSP-1 48h após as transfecções em H1299 induz um bloqueio do ciclo em G0/G1, reduzindo a capacidade clonogênica dessas células por um mecanismo dependente dos níveis de expressão de CTSP-1. Resultados semelhantes não foram observados em ensaios com clones superexpressando CTSP-1 estavelmente, o que sugere que eles tenham se originado de células que conseguiram escapar do bloqueio em G0/G1. Resultados preliminares sugerem que a redução da capacidade clonogênica das células H1299 que superexpressam CTSP-1 48h após as tansfecções não está associada à ocorrência de morte por apoptose

Cancer-testis (CT) antigens are immunogenic proteins expressed in gametogenic tissues and in different histological types of tumors, being considered promising candidates for cancer immunotherapy. However, little is known about their role in tumorigenesis. In 2006, we identified CTSP-1 as a novel CT antigen, frequently expressed in different types of tumors. In this work, we investigated the functional role of CTSP-1 through the identification of proteins expressed in prostate tumors and that physically interact with this tumor antigen. We demonstrate that CTSP-1 interacts with the CTCF protein using the yeast two-hybrid system, pulldown and co-localization assays and have further analyzed the impact of CTSP-1 overexpression on the expression of CT genes mediated by CTCF and on the cell cycle progression. Using the CT antigen NY-ESO-1 as a model, we showed that the CTSP-1 overexpression does not alter the endogenous levels of NY-ESO-1 in the tumor cell line H1299. On the other hand, we observed that the overexpression of CTSP-1 in H1299 cells 48h after the transfections induces a cell cycle arrest in G0/G1 and reduces the clonogenic capacity of these cells by a mechanism dependent on the CTSP-1 expression levels. Similar results were not observed for cell clones stably overexpressing CTSP-1, suggesting that these clones have arisen from cells that managed to escape cell cycle arrest in G0/G1. Preliminary results suggest that the reduced clonogenic capacity of H1299 cells expressing CTSP-1 and analyzed 48h after the transfections is not associated with cell death by apoptosis

Expression of the CTCF gene in bovine oocytes and preimplantation embryos

The CCCTC - binding factor (CTCF) is a protein involved in repression, activation, hormone-inducible gene silencing, functional reading of imprinted genes and X-chromosome inactivation. We analyzed CTCF gene expression in bovine peripheral blood, oocytes and in different cellular stages (2-4 cells, 8-16 cells, 16-32 cells, morulae, and blastocysts) of in vitro fertilized embryos. This is the first report of CTCF expression in oocytes and preimplantation bovine embryos and has implications for the production of embryonic stem cells and the development of novel medical technologies for humans.

Single Nucleotide Polymorphisms of a 16 kb Region on Human Chromosome 11p15.5 that Includes the H19 Gene

The H19 gene, located at human chromosome 11p15.5, is imprinted in most normal human tissues. However, imprinting is often lost in tumors suggesting H19 is a putative tumor suppressor. We analyzed the single nucleotide polymorphisms (SNPs) of a 16 kb region that includes the H19 gene and its imprinting control region (ICR) in the Korean population. To identify SNPs, we directly sequenced this region in 18 Korean subjects. We identified 64 SNPs, of which 7 were in the exons of H19, 2 were in the introns, 14 were in the 3' intergenic region and 41 were in the 5' intergenic region. Of the 64 SNPs, 21 had not previously been reported and thus appear to be unique to the Korean population. The identified SNPs of H19 in the Korean population may eventually be useful as genetic markers associated with various diseases. In this study, 7 of the 64 identified SNPs were at CTCF binding sites in the ICR and may affect regulation of H19 gene imprinting. Thus, several genetic variations of the H19 gene may be important markers in human diseases that involve genomic imprinting, including cancer.