scholarly journals Reduced Phosphorylation of p50 Is Responsible for Diminished NF-κB Binding to the Major Histocompatibility Complex Class I Enhancer in Adenovirus Type 12-Transformed Cells

1999 ◽  
Vol 19 (3) ◽  
pp. 2169-2179 ◽  
Author(s):  
David B. Kushner ◽  
Robert P. Ricciardi
Keyword(s):  
Major Histocompatibility Complex ◽  
Cell Surface ◽  
Major Histocompatibility Complex Class ◽  
Adenovirus Type ◽  
Class I ◽  
Transformed Cells ◽  
Complex Class ◽  
Transformed Cell ◽  
Histocompatibility Complex ◽  
Nuclear Extracts

ABSTRACT Reduced cell surface levels of major histocompatibility complex class I antigens enable adenovirus type 12 (Ad12)-transformed cells to escape immunosurveillance by cytotoxic T lymphocytes (CTL), contributing to their tumorigenic potential. In contrast, nontumorigenic Ad5-transformed cells harbor significant cell surface levels of class I antigens and are susceptible to CTL lysis. Ad12 E1A mediates down-regulation of class I transcription by increasing COUP-TF repressor binding and decreasing NF-κB activator binding to the class I enhancer. The mechanism underlying the decreased binding of nuclear NF-κB in Ad12-transformed cells was investigated. Electrophoretic mobility shift assay analysis of hybrid NF-κB dimers reconstituted from denatured and renatured p50 and p65 subunits from Ad12- and Ad5-transformed cell nuclear extracts demonstrated that p50, and not p65, is responsible for the decreased ability of NF-κB to bind to DNA in Ad12-transformed cells. Hypophosphorylation of p50 was found to correlate with restricted binding of NF-κB to DNA in Ad12-transformed cells. The importance of phosphorylation of p50 for NF-κB binding was further demonstrated by showing that an NF-κB dimer composed of p65 and alkaline phosphatase-treated p50 from Ad5-transformed cell nuclear extracts could not bind to DNA. These results suggest that phosphorylation of p50 is a key step in the nuclear regulation of NF-κB in adenovirus-transformed cells.

scholarly journals Evidence for the involvement of a nuclear NF-kappa B inhibitor in global down-regulation of the major histocompatibility complex class I enhancer in adenovirus type 12-transformed cells.

1996 ◽  
Vol 16 (1) ◽  
pp. 398-404 ◽  
Author(s):  
X Liu ◽  
R Ge ◽  
R P Ricciardi
Keyword(s):  
Major Histocompatibility Complex ◽  
Major Histocompatibility Complex Class ◽  
Adenovirus Type ◽  
Class I ◽  
Transformed Cells ◽  
Complex Class ◽  
Major Histocompatibility ◽  
Nf Kappa B ◽  
Down Regulation ◽  
Histocompatibility Complex

Diminished expression of major histocompatibility complex class I antigens on the surface of adenovirus type 12 (Ad12)-transformed cells contributes to their high tumorigenic potential by enabling them to escape immune recognition by cytotoxic T lymphocytes. This low class I antigen expression is due to a block in class I transcription, which is mediated by Ad12 E1A. Genetic analysis has shown that the class I enhancer is the target for transcriptional down-regulation. In this study, we show that the ability of the R1 element of the class I enhancer to stimulate transcription is greatly reduced in Ad12-transformed cells. The loss of functional activity by the R1 element was attributed to loss of binding by the NF-kappa B p50-p65 heterodimer. NF-kappa B binding appears to be blocked within the nucleus rather than at the level of nuclear translocation. Significantly, NF-kappa B binding activity could be recovered from the nuclear extracts of Ad12-transformed cells following detergent treatment, suggesting that the block is mediated through a nuclear inhibitor present in the Ad12-transformed cells. These results, taken together with the fact that the R2 element of the class I enhancer exhibits strong binding to the transcriptional repressor COUP-TF, suggest that the class I enhancer is globally down-regulated in Ad12-transformed cells.

scholarly journals In Adenovirus Type 12 Tumorigenic Cells, Major Histocompatibility Complex Class I Transcription Shutoff Is Overcome by Induction of NF-κB and Relief of COUP-TFII Repression

2002 ◽  
Vol 76 (7) ◽  
pp. 3212-3220 ◽  
Author(s):  
Shihe Hou ◽  
Hancheng Guan ◽  
Robert P. Ricciardi
Keyword(s):  
Major Histocompatibility Complex ◽  
Major Histocompatibility Complex Class ◽  
Nuclear Translocation ◽  
Adenovirus Type ◽  
Class I ◽  
Transformed Cells ◽  
Complex Class ◽  
Major Histocompatibility ◽  
Histocompatibility Complex ◽  
Tnf Α

ABSTRACT The surface levels of major histocompatibility complex class I antigens are diminished on tumorigenic adenovirus type 12 (Ad12)-transformed cells, enabling them to escape from immunosurveillant cytotoxic T lymphocytes (CTLs). This is due to the down-regulation of the class I transcriptional enhancer, in which there is strong binding of the repressor COUP-TFII and lack of binding of the activator NF-κB. Even though NF-κB (p65/p50) translocates to the nuclei of Ad12-transformed cells, it fails to bind to DNA efficiently due to the hypophosphorylation of the p50 subunit. In this study, tumor necrosis factor alpha (TNF-α) and interleukin 1β (IL-1β) were shown to promote degradation of the NF-κB cytoplasmic inhibitor IκBα and permit the nuclear translocation of a phosphorylated form of NF-κB that is capable of binding DNA. Interestingly, when Ad12-transformed cells were treated with TNF-α or IL-1β, class I gene transcription substantially increased when transcriptional repression by COUP-TFII was blocked. This indicates that in cytokine-treated Ad12-transformed cells, COUP-TFII is able to repress activation of class I transcription by newly nucleus-localized NF-κB. Our results suggest that Ad12 likely employs a “fail-safe” mechanism to ensure that the transcription of class I genes remains tightly repressed under various physiological conditions, thus providing tumorigenic Ad12-transformed cells with a means of escaping CTL recognition and lysis.

Major histocompatibility complex class I genes in murine fibrosarcoma IC9 are down regulated at the level of the chromatin structure

1989 ◽  
Vol 9 (7) ◽  
pp. 3136-3142
Author(s):  
U Maschek ◽  
W Pülm ◽  
S Segal ◽  
G J Hämmerling
Keyword(s):  
Major Histocompatibility Complex ◽  
Major Histocompatibility Complex Class ◽  
Chromatin Structure ◽  
Dnase I ◽  
Class I ◽  
Micrococcal Nuclease ◽  
Complex Class ◽  
Major Histocompatibility ◽  
Histocompatibility Complex ◽  
Nuclear Extracts

The fibrosarcoma IC9 is deficient in the expression of the major histocompatibility complex class I genes Kb, Kk, and Dk and expresses only the Db molecule. Because class I deficiency may enable tumor cells to escape the immune response by cytotoxic T lymphocytes, we investigated why the class I genes are not expressed. Expression of the silent class I genes could not be induced, but all known DNA-binding factors specific for class I genes could be detected in nuclear extracts of IC9 cells. After cloning of the silent Kb gene from the IC9 cells and subsequent transfection of this cloned Kb gene into LTK- and IC9 cells, normal Kb antigens were expressed on the cell surface of both cell lines. Digestion of the chromatin of IC9 cells with micrococcal nuclease and DNase I showed a decreased nuclease sensitivity of the silent class I genes in comparison with active genes and the absence of DNase I hypersensitive sites in the promoter region of the silent Dk gene. These findings demonstrate that class I expression is turned off by a cis-acting regulatory mechanism at the level of the chromatin structure.

Major histocompatibility complex class I-binding peptides are recycled to the cell surface after internalization

1993 ◽  
Vol 23 (12) ◽  
pp. 3224-3229 ◽  
Author(s):  
Ussama M. Abdel Motal ◽  
Xianzheng Zhou ◽  
Annalena Joki ◽  
Abdur Rehman Siddiqi ◽  
B. R. Srinivasa ◽  
...  
Keyword(s):  
Major Histocompatibility Complex ◽  
Cell Surface ◽  
Major Histocompatibility Complex Class ◽  
Class I ◽  
Complex Class ◽  
Major Histocompatibility ◽  
Histocompatibility Complex ◽  
Binding Peptides
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