Interaction of the nuclear matrix-associated region (MAR)-binding proteins, SATB1 and CDP/Cux, with a MAR element (L2a) in an upstream regulatory region of the mouse CD8a gene.
Matrix-associated regions (MARs), AT-rich DNA segments that have an affinity for the nuclear matrix, have been shown to play a role in transcriptional regulation of eukaryotic genes. The present study demonstrates that a DNA element, called L2a, which has been implicated in the transcriptional regulation of the mouse CD8a gene encoding an important T cell coreceptor, is a MAR. Moreover, the identities of two nuclear proteins, L2a-P1 and L2a-P2, previously shown to bind to the L2a element, have been determined. The L2a-P1 protein found to be present in all CD8-positive T cell lines tested is SATB1, a known MAR-binding protein. The widely expressed L2a-P2 protein is CDP/Cux, a MAR-binding protein that has been associated with repression of gene transcription. Interaction of both proteins with the L2a element was studied using the missing nucleoside approach, DNase I footprinting, and electrophoretic mobility shift assays with wild type and mutant L2a elements. The data suggest that CDP/Cux bound to the L2a element is displaced by binding of SATB1 and the accompanying conformational change in the DNA lying between the primary binding sites of SATB1 and CDP/Cux. We suggest that displacement of CDP/Cux by SATB1 favors transcription of the CD8a gene, possibly by enhancing or altering its association with the nuclear matrix.
Banan
M
M
Department of Microbiology and Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, Texas 78712, USA.
Rojas
I C
IC
Lee
W H
WH
King
H L
HL
Harriss
J V
JV
Kobayashi
R
R
Webb
C F
CF
Gottlieb
P D
PD
D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D016827:CD8 Antigens / Q000096:biosynthesis* / Q000235:genetics*; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000378:metabolism*; D018398:Homeodomain Proteins / Q000378:metabolism; D036961:Matrix Attachment Region Binding Proteins; D051379:Mice; D008961:Models, Structural; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D015530:Nuclear Matrix / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D012045:Regulatory Sequences, Nucleic Acid; D012097:Repressor Proteins / Q000378:metabolism*; D013601:T-Lymphocytes; D014158:Transcription, Genetic; D014162:Transfection
D016827:CD8 Antigens; C000624101:Cux1 protein, mouse; D004268:DNA-Binding Proteins; D018398:Homeodomain Proteins; D036961:Matrix Attachment Region Binding Proteins; D009687:Nuclear Proteins; D011994:Recombinant Proteins; D012097:Repressor Proteins; C076189:SATB1 protein, human