CArG box-binding factor-A interacts with multiple motifs in immunoglobulin promoters and has a regulated subcellular distribution.
CArG box-binding factor-A (CBF-A) is a protein involved in transcriptional control and interacts specifically with the penta-decameric (pd) element in kappa promoters. We show here that CBF-A will also bind specifically to a second region in the kappa promoter that overlaps with an early B cell factor binding site. Furthermore, the same region is present in multiple Ig promoters and we show that CBF-A can bind to several of these. Mitogenic stimulation of untransformed B lymphocytes promoted nuclear localisation of CBF-A. Using enhanced GFP (EGFP)-tagged constructs and transfection into COS7 cells, a nuclear localisation signal was defined in the C terminus of CBF-A. Deletion of only 13 amino acids from the C terminus of CBF-A led to the accumulation of the protein in bright speckles at the nuclear/cytoplasmic border. We also identified the heterogeneous ribonucleoprotein H as a specific interaction partner of CBF-A, but this interaction could be detected in the cytoplasm only. Thus, CBF-A has the potential to regulate the expression of multiple Ig V genes and has a complex, mitogen-responsive regulation of its intracellular localisation.
Aranburu
Alaitz
A
Immunology Group, Lund University, Lund, Sweden.
Liberg
David
D
Honoré
Bent
B
Leanderson
Tomas
T
D021581:Active Transport, Cell Nucleus; D000818:Animals; D001483:Base Sequence; D002454:Cell Differentiation; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D003593:Cytoplasm / Q000378:metabolism; D004247:DNA / Q000235:genetics / Q000378:metabolism; D034481:Heterogeneous-Nuclear Ribonucleoprotein Group A-B / Q000235:genetics / Q000378:metabolism*; D007136:Immunoglobulins / Q000235:genetics* / Q000378:metabolism*; D008540:Meiosis; D051379:Mice; D008969:Molecular Sequence Data; D019913:Nuclear Localization Signals; D011401:Promoter Regions, Genetic / Q000235:genetics*; D011485:Protein Binding
D034481:Heterogeneous-Nuclear Ribonucleoprotein Group A-B; D007136:Immunoglobulins; D019913:Nuclear Localization Signals; D004247:DNA