Landberg G, Tan E M
W. M. Keck Autoimmune Disease Center, Department of Molecular and Experimental Medicine, Scripps Research Institute, La Jolla, California 92037.
Exp Cell Res. 1994 Jun;212(2):255-61. doi: 10.1006/excr.1994.1141.
During analysis of autoimmune sera showing reactivity to nuclear antigens a serum producing a previously undescribed cell cycle-specific nuclear immunofluorescence pattern was observed. By indirect immunofluorescence the serum generated a densely speckled nucleoplasmic staining pattern of varying intensity with relative sparing of the nucleoli. The staining pattern could be abolished by treating cells with DNase but was not affected by RNase treatment. By flow cytometric dual parameter analysis the antigen expression was shown to increase during S phase with a maximum in G2 cells, whereas G1 and M cells expressed low levels. The cell cycle-specific expression of the target antigen was similar in some aspects to the expression of cyclin A but clearly not identical. The serum recognized a 68/60 kDa doublet in immunoblotting of soluble MOLT-4 cell extract. Antibodies eluted separately from either of the two bands produced the cell cycle-specific staining pattern as well as the doublet in immunoblotting. DNA-cellulose was used for analysis of DNA-binding property and the higher band was found to be DNA-binding, whereas the lower band was not. In summary, this serum reacts with a DNA-binding and cell cycle-specific nuclear antigen which might be a novel protein involved in cell cycle progression.
在分析对核抗原有反应性的自身免疫血清时，观察到一种血清产生了一种先前未描述的细胞周期特异性核免疫荧光模式。通过间接免疫荧光，该血清产生了一种强度不同的密集斑点状核质染色模式，核仁相对较少着色。用DNA酶处理细胞可消除这种染色模式，但RNA酶处理对其无影响。通过流式细胞术双参数分析表明，抗原表达在S期增加，在G2期细胞中达到最大值，而G1期和M期细胞表达水平较低。靶抗原的细胞周期特异性表达在某些方面与细胞周期蛋白A的表达相似，但明显不同。该血清在可溶性MOLT-4细胞提取物的免疫印迹中识别出一条68/60 kDa的双条带。从两条带中分别洗脱的抗体在免疫印迹中产生了细胞周期特异性染色模式以及双条带。使用DNA纤维素分析DNA结合特性，发现较高的条带具有DNA结合能力，而较低的条带则没有。总之，该血清与一种DNA结合且细胞周期特异性的核抗原发生反应，该抗原可能是一种参与细胞周期进程的新型蛋白质。
