Cai Q Q, Plet A, Imbert J, Lafage-Pochitaloff M, Cerdan C, Blanchard J M
Institut de Génétique Moléculaire de Montpellier, UMR9942, France.
Cytogenet Cell Genet. 1994;65(4):221-7. doi: 10.1159/000133635.
Ku protein is a relatively abundant DNA-binding nuclear protein complex composed of two polypeptide subunits, p70 and p80. Ku has been recently identified as the regulatory component of the DNA-dependent protein kinase that phosphorylates RNA polymerase II. To further characterize in vivo regulation of Ku protein, we studied the expression of the transcripts coding for the Ku p70 and p80 subunits in different human cell lines and normal tissues by Northern blot hybridization, using specific cDNA probes. The expression level of both genes was approximately 10-fold higher in established cell lines than in normal tissues. However, mRNA expression levels in permanent cell lines correlated more strongly with their proliferative state than with their level of malignant transformation. In purified T lymphocytes induced to proliferate by the combined action of monoclonal antibodies directed against the CD2 and CD28 adhesion molecules, Ku p70 and p80 mRNA steady-state levels increased as soon as 6 h after activation and lasted at least 72 h. The human genes coding for the Ku p70 and p80 subunits were localized by cytogenetic mapping, using fluorescence in situ hybridization, to 22q13 and 2q33-->q35, respectively.
Ku蛋白是一种相对丰富的DNA结合核蛋白复合物，由两个多肽亚基p70和p80组成。Ku最近被确定为DNA依赖性蛋白激酶的调节成分，该激酶可使RNA聚合酶II磷酸化。为了进一步表征Ku蛋白的体内调节，我们使用特异性cDNA探针，通过Northern印迹杂交研究了不同人类细胞系和正常组织中编码Ku p70和p80亚基的转录本的表达。在已建立的细胞系中，这两个基因的表达水平比正常组织中高约10倍。然而，永久细胞系中的mRNA表达水平与其增殖状态的相关性比与恶性转化水平的相关性更强。在通过针对CD2和CD28粘附分子的单克隆抗体的联合作用诱导增殖的纯化T淋巴细胞中，Ku p70和p80 mRNA稳态水平在激活后6小时就开始增加，并持续至少72小时。使用荧光原位杂交通过细胞遗传学定位，编码Ku p70和p80亚基的人类基因分别定位于22q13和2q33→q35。
