Complementary DNA sequences encoding the multimammate rat MHC class II DQαandβchains and cross-species sequence comparison in rodents

The constitutive coexpression of the major histocompatibility complex (MHC) class II genes in B lymphocytes requires positive, trans-acting transcriptional factors. The need for these trans-acting factors has been suggested by the reversion of the MHC class II-negative phenotype of rare B-lymphocyte mutants through somatic cell fusion with B cells or T-cell lines. The mechanism by which the trans-acting factors exert their effect on gene transcription is unknown. The possibility that two highly conserved DNA sequences, located 90 to 100 base pairs (bp) (the A sequence) and 60 to 70 bp (the B sequence) upstream of the transcription start site of the class II genes, are recognized by the trans-acting factors was investigated in this study. By using the gel electrophoresis retardation assay, a minimum of two proteins which specifically bound the conserved A or B sequence of a rabbit DP beta gene were identified in murine nuclear extracts of a B-lymphoma cell line, A20-2J. Fractionation of nuclear extract through a heparin-agarose column allowed the identification of one protein, designated NF-MHCIIB, which bound an oligonucleotide containing the B sequence and protected the entire B sequence in the DNase I protection analysis. Another protein, designated NF-MHCIIA, which bound an oligonucleotide containing the A sequence and partially protected the 3' half of this sequence, was also identified. NF-MHCIIB did not protect a CCAAT sequence located 17 bp downstream of the B sequence. The possible relationship between these DNA-binding factors and the trans-acting factors identified in the cell fusion experiments is discussed.

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Two DNA-binding proteins discriminate between the promoters of different members of the major histocompatibility complex class II multigene family

Molecular and Cellular Biology ◽

10.1128/mcb.10.3.965-971.1990 ◽

1990 ◽

Vol 10 (3) ◽

pp. 965-971

Author(s):

M Kobr ◽

W Reith ◽

C Herrero-Sanchez ◽

B Mach

Keyword(s):

Gene Expression ◽

Major Histocompatibility Complex ◽

Mhc Class Ii ◽

Dna Sequences ◽

Multigene Family ◽

Class Ii ◽

Major Histocompatibility ◽

Histocompatibility Complex ◽

Hla Dr ◽

Beta Chain Genes

The regulation of major histocompatibility complex (MHC) class II gene expression is a key feature of the control of normal and abnormal immune responses. In humans, class II alpha - and beta-chain genes are organized in a multigene family with three distinct subregions, HLA-DR, -DQ, and -DP. The regulation of these genes is generally coordinated, and their promoters contain highly conserved motifs, in particular the X and Y boxes. We have identified five distinct proteins that bind to specific DNA sequences within the first 145 base pairs of the HLA-DR promoter, a segment known to be functionally essential for class II gene regulation. Among these, RF-X is of special interest, since mutants affected in the regulation of MHC class II gene expression have a specific defect in RF-X binding. Unexpectedly, RF-X displays a characteristic gradient of binding affinities for the X boxes of three alpha-chain genes (DRA greater than DPA much greater than DQA). The same observation was made with recombinant RF-X. We also describe a novel factor, NF-S, which bound to the spacer region between the X and Y boxes of class II promoters. NF-S exhibited a reverse gradient of affinity compared with RF-X (DQA greater than DPA much greater than DRA). As expected, RF-X bound well to the mouse IE alpha promoter, while NF-S bound well to IA alpha. The drastic differences in the binding of RF-X and NF-S to different MHC class II promoters contrasts with the coordinate regulation of HLA-DR, -DQ, and -DP genes.

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Two DNA-binding proteins discriminate between the promoters of different members of the major histocompatibility complex class II multigene family.

Molecular and Cellular Biology ◽

10.1128/mcb.10.3.965 ◽

1990 ◽

Vol 10 (3) ◽

pp. 965-971 ◽

Cited By ~ 38

Author(s):

M Kobr ◽

W Reith ◽

C Herrero-Sanchez ◽

B Mach

Keyword(s):

Gene Expression ◽

Major Histocompatibility Complex ◽

Mhc Class Ii ◽

Dna Sequences ◽

Multigene Family ◽

Class Ii ◽

Major Histocompatibility ◽

Histocompatibility Complex ◽

Hla Dr ◽

Beta Chain Genes

The regulation of major histocompatibility complex (MHC) class II gene expression is a key feature of the control of normal and abnormal immune responses. In humans, class II alpha - and beta-chain genes are organized in a multigene family with three distinct subregions, HLA-DR, -DQ, and -DP. The regulation of these genes is generally coordinated, and their promoters contain highly conserved motifs, in particular the X and Y boxes. We have identified five distinct proteins that bind to specific DNA sequences within the first 145 base pairs of the HLA-DR promoter, a segment known to be functionally essential for class II gene regulation. Among these, RF-X is of special interest, since mutants affected in the regulation of MHC class II gene expression have a specific defect in RF-X binding. Unexpectedly, RF-X displays a characteristic gradient of binding affinities for the X boxes of three alpha-chain genes (DRA greater than DPA much greater than DQA). The same observation was made with recombinant RF-X. We also describe a novel factor, NF-S, which bound to the spacer region between the X and Y boxes of class II promoters. NF-S exhibited a reverse gradient of affinity compared with RF-X (DQA greater than DPA much greater than DRA). As expected, RF-X bound well to the mouse IE alpha promoter, while NF-S bound well to IA alpha. The drastic differences in the binding of RF-X and NF-S to different MHC class II promoters contrasts with the coordinate regulation of HLA-DR, -DQ, and -DP genes.

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Two distinct nuclear factors bind the conserved regulatory sequences of a rabbit major histocompatibility complex class II gene

Molecular and Cellular Biology ◽

10.1128/mcb.8.5.2034-2041.1988 ◽

1988 ◽

Vol 8 (5) ◽

pp. 2034-2041

Author(s):

N Sittisombut

Keyword(s):

Major Histocompatibility Complex ◽

Cell Fusion ◽

Mhc Class Ii ◽

Dna Sequences ◽

B Lymphocyte ◽

Nuclear Extract ◽

Class Ii ◽

Regulatory Sequences ◽

Major Histocompatibility ◽

Histocompatibility Complex

The constitutive coexpression of the major histocompatibility complex (MHC) class II genes in B lymphocytes requires positive, trans-acting transcriptional factors. The need for these trans-acting factors has been suggested by the reversion of the MHC class II-negative phenotype of rare B-lymphocyte mutants through somatic cell fusion with B cells or T-cell lines. The mechanism by which the trans-acting factors exert their effect on gene transcription is unknown. The possibility that two highly conserved DNA sequences, located 90 to 100 base pairs (bp) (the A sequence) and 60 to 70 bp (the B sequence) upstream of the transcription start site of the class II genes, are recognized by the trans-acting factors was investigated in this study. By using the gel electrophoresis retardation assay, a minimum of two proteins which specifically bound the conserved A or B sequence of a rabbit DP beta gene were identified in murine nuclear extracts of a B-lymphoma cell line, A20-2J. Fractionation of nuclear extract through a heparin-agarose column allowed the identification of one protein, designated NF-MHCIIB, which bound an oligonucleotide containing the B sequence and protected the entire B sequence in the DNase I protection analysis. Another protein, designated NF-MHCIIA, which bound an oligonucleotide containing the A sequence and partially protected the 3' half of this sequence, was also identified. NF-MHCIIB did not protect a CCAAT sequence located 17 bp downstream of the B sequence. The possible relationship between these DNA-binding factors and the trans-acting factors identified in the cell fusion experiments is discussed.

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