An upstream Oct-1- and Oct-2-binding silencer governs B29 (Ig beta) gene expression.
The B cell-specific B29 (Igbeta) gene is activated in the earliest B cell precursors and is expressed throughout B cell development. Tissue-specific expression of the murine B29 gene is controlled by a B cell-specific promoter whose activity is governed by a cassette of upstream transcriptional silencers. This study describes a potent new silencer that is located 5' of the previously identified B29 silencer elements, FROG and TOAD. Like these known elements, the new B29 silencer is not restricted to the B29 promoter. Nuclear proteins from all cell lines tested interacted with this A+T-rich sequence, which closely resembled a noncanonical octamer binding motif and also conformed to the consensus sequence for nuclear matrix attachment regions. Interaction of Oct-1 and Oct-2 with the B29 A+T-rich sequence was confirmed using octamer-specific Abs. Oct-1/Oct-2 binding was required for the inhibitory activity of this sequence because mutations that blocked Oct-1/Oct-2 binding also eliminated inhibition of the B29 promoter. This B29 A+T-rich sequence specifically interacted with isolated nuclear matrix proteins in vitro, suggesting that it may also function as a matrix attachment region element. Maintenance of the level of B29 gene expression through the interaction of the minimal promoter and the upstream silencer elements FROG, TOAD, and the A+T-rich Oct-1/Oct-2 binding motif may be essential for normal B cell development and/or function.
Malone
C S
CS
Department of Microbiology and Immunology, and Molecular Biology Institute, University of California, School of Medicine, Los Angeles, CA 90095, USA.
Patrone
L
L
Buchanan
K L
KL
Webb
C F
CF
Wall
R
R
D020121:5' Untranslated Regions / Q000235:genetics* / Q000378:metabolism; D000225:Adenine / Q000378:metabolism; D020816:Amino Acid Motifs / Q000235:genetics; D000818:Animals; D015703:Antigens, CD / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism; D001402:B-Lymphocytes / Q000378:metabolism*; D051925:CD79 Antigens; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000276:immunology*; D051379:Mice; D016297:Mutagenesis, Site-Directed; D015530:Nuclear Matrix / Q000235:genetics / Q000378:metabolism; D050813:Octamer Transcription Factor-2; D011401:Promoter Regions, Genetic / Q000276:immunology; D012097:Repressor Proteins / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D013941:Thymine / Q000378:metabolism; D015534:Trans-Activators / Q000037:antagonists & inhibitors / Q000378:metabolism*; D014157:Transcription Factors / Q000037:antagonists & inhibitors / Q000378:metabolism*
D020121:5' Untranslated Regions; D015703:Antigens, CD; D051925:CD79 Antigens; C497884:Cd79b protein, mouse; D004268:DNA-Binding Proteins; D050813:Octamer Transcription Factor-2; C490424:Pou2af1 protein, mouse; C489206:Pou2f2 protein, mouse; D012097:Repressor Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D000225:Adenine; D013941:Thymine