Messier H, Fuller T, Mangal S, Brickner H, Igarashi S, Gaikwad J, Fotedar R, Fotedar A
Division of Molecular Biology, La Jolla Institute for Allergy and Immunology, CA 92037.
Proc Natl Acad Sci U S A. 1993 Apr 1;90(7):2685-9. doi: 10.1073/pnas.90.7.2685.
The p70 (Ku) autoantigen has been described as a nonhistone nuclear protein recognized by antibodies from lupus patients. In our studies on the regulation of T-cell receptor (TCR) beta-chain gene expression we have identified the p70 lupus autoantigen as a DNA-binding protein that binds the enhancer of the TCR beta-chain gene. This enhancer is essential for expression of the TCR beta gene. The core TCR beta enhancer contains the E3 motif, which we show here is essential for enhancer activity. The protection of the E3 motif in T cells and the marked reduction in enhancer activity when the E3 motif is mutated underline its physiological importance in regulating beta enhancer activity. The p70 lupus autoantigen gene was identified by screening T-cell lambda gt11 libraries with an E3 probe. The gene encodes a protein which binds the E3 motif in a sequence-specific manner. The identification of a 70-kDa protein as a major E3-binding protein by UV crosslinking is consistent with the conclusion that the p70 lupus autoantigen binds the beta enhancer. Finally, we have shown that T-cell nuclear proteins which bind the E3 motif bear p70 (Ku) lupus autoantigenic determinants. Together these data suggest that the p70 autoantigen binds a critical motif in the beta enhancer and probably regulates TCR beta gene expression.
p70（Ku）自身抗原被描述为一种非组蛋白核蛋白，可被狼疮患者的抗体识别。在我们对T细胞受体（TCR）β链基因表达调控的研究中，我们已确定p70狼疮自身抗原是一种与TCRβ链基因增强子结合的DNA结合蛋白。该增强子对TCRβ基因的表达至关重要。核心TCRβ增强子包含E3基序，我们在此表明它对增强子活性至关重要。T细胞中E3基序的保护以及E3基序突变时增强子活性的显著降低突显了其在调节β增强子活性中的生理重要性。通过用E3探针筛选T细胞λgt11文库鉴定了p70狼疮自身抗原基因。该基因编码一种以序列特异性方式结合E3基序的蛋白质。通过紫外线交联鉴定出一种70 kDa的蛋白质作为主要的E3结合蛋白，这与p70狼疮自身抗原结合β增强子的结论一致。最后，我们已表明与E3基序结合的T细胞核蛋白带有p70（Ku）狼疮自身抗原决定簇。这些数据共同表明，p70自身抗原结合β增强子中的一个关键基序，并可能调节TCRβ基因的表达。
