Function and factor interactions of a locus control region element in the mouse T cell receptor-alpha/Dad1 gene locus.
Locus control regions (LCRs) refer to cis-acting elements composed of several DNase I hypersensitive sites, which synergize to protect transgenes from integration-site dependent effects in a tissue-specific manner. LCRs have been identified in many immunologically important gene loci, including one between the TCRdelta/TCRalpha gene segments and the ubiquitously expressed Dad1 gene. Expression of a transgene under the control of all the LCR elements is T cell specific. However, a subfragment of this LCR is functional in a wide variety of tissues. How a ubiquitously active element can participate in tissue-restricted LCR activity is not clear. In this study, we localize the ubiquitously active sequences of the TCR-alpha LCR to an 800-bp region containing a prominent DNase hypersensitive site. In isolation, the activity in this region suppresses position effect transgene silencing in many tissues. A combination of in vivo footprint examination of this element in widely active transgene and EMSAs revealed tissue-unrestricted factor occupancy patterns and binding of several ubiquitously expressed transcription factors. In contrast, tissue-specific, differential protein occupancies at this element were observed in the endogenous locus or full-length LCR transgene. We identified tissue-restricted AML-1 and Elf-1 as proteins that potentially act via this element. These data demonstrate that a widely active LCR module can synergize with other LCR components to produce tissue-specific LCR activity through differential protein occupancy and function and provide evidence to support a role for this LCR module in the regulation of both TCR and Dad1 genes.
Ortiz
B D
BD
Department of Biological Sciences, City University of New York, Hunter College, New York, NY 10021, USA. ortiz@genectr.hunter.cuny.edu
Harrow
F
F
Cado
D
D
Santoso
B
B
Winoto
A
A
D000818:Animals; D051017:Apoptosis Regulatory Proteins; D001483:Base Sequence; D050676:Core Binding Factor Alpha 2 Subunit; D018983:DNA Footprinting; D004268:DNA-Binding Proteins / Q000378:metabolism*; D003850:Deoxyribonuclease I / Q000737:chemistry; D005803:Genes, Immunoglobulin; D019901:Locus Control Region; D046911:Macromolecular Substances; D008565:Membrane Proteins / Q000235:genetics*; D051379:Mice; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000235:genetics*; D017384:Sequence Deletion; D013950:Thymus Gland / Q000276:immunology; D014157:Transcription Factors / Q000378:metabolism
D051017:Apoptosis Regulatory Proteins; D050676:Core Binding Factor Alpha 2 Subunit; D004268:DNA-Binding Proteins; C489987:Dad1 protein, mouse; C512897:ELF1 protein, human; C512896:Elf1 protein, mouse; D046911:Macromolecular Substances; D008565:Membrane Proteins; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D016693:Receptors, Antigen, T-Cell, alpha-beta; C493726:Runx1 protein, mouse; D014157:Transcription Factors; D003850:Deoxyribonuclease I