网织红细胞与骨髓瘤缺陷株细胞杂交前后HGPRT酶基因产物的测定

本研究建立了HGPRT酶的测定方法,对自然去核的哺乳类网织红细胞与小鼠骨髓瘤及人肿瘤突变型细胞杂交前后的HGPRT基因产物进行测定结果表明:①自然去核后的兔和小鼠网织红细胞质中含有高活性的HGPRT酶,其活性浓度与有细胞核的人早幼粒白血病细胞HL-60及人胃癌823细胞相当;②无核和缺失HGPRT酶基因定位的X染色体的上述网织红细胞分别与HGPRT阴性的小鼠骨髓瘤Bw及人早幼粒白血病的HL-AR突变株细胞杂交后,获得HGPRT阳性的胞质体杂交细胞。这些杂交细胞及其子代均出现中等阳性的HGPRT酶活性。提示用无细胞核而含基因产物的胞质体可能激活或诱导宿主细胞相应基因进行表达。

Detection of HGPRT Gene Product before and after Hybridazation of Reticulocytes with Myeloma Cells

In order to investigate the possible regulatory effect of cytoplasmic factors on gene expression of tumor cell nucleus, the present study was designed to detect HGPRT gene products before and after hybridazation of mouse myeloma cell line (Bw) or human cancer mutauts(HL-AR)with mammalian reticu-locyte cytoplasts. The results indicated: 1) both mouse (R) and rabbit (RR) reticulocytes, showed strong HGPRT activities after natural denucleation even as high as that of human promyelocytic leukemia cells HL-60 and human stomach cancer cell line HS-823; 2) the cybrids derived from the fusion of HGPRT positive reticulocytes and HGPRT negative mouse myeloma cells or human promyelocytic leukemia cells could grow in HAT selective media and main-tain HGPRT positive during passage (8th passage of cybrid Bw-RR, 14th and 17th passages of Bw-R and 3rd, 5th passages of HL-R). They were analyzed by showing moderate enzyme activity in their final generations. These results together with our previous experiments with globin gene expression in cybrid subcultures provided evidences suggesting that gene products present in the reticulocyte cyoplasts could activate or induce the expression of correspontiug gene in host cells during cellular hybridization.