Chromosome 13 transfer provides evidence for regulation of RB1 protein expression.
Chromosome 13 transfer provides evidence for regulation of RB1 protein expression.
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13 号染色体转移为 RB1 蛋白表达的调节提供了证据。
DOI：
10.1002/gcc.2870090405
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发表时间：
1994
期刊：
影响因子：
--
通讯作者：
Stanbridge,EJ
中科院分区：
文献类型：
--
作者：
Anderson,MJ;Fasching,CL;Xu,HJ;Benedict,WF;Stanbridge,EJ
位于13号染色体上的人视网膜母细胞瘤易感基因（RBI）已被证明在大量人类癌症中起生长/肿瘤抑制基因的作用。虽然在大多数培养细胞和正常组织中观察到组成型表达，但RBI蛋白的过表达尚未得到充分证实。也许调节正常RBI蛋白表达水平是控制其功能的几种方法之一。为了验证这一假设，我们通过微细胞融合将13号染色体的正常拷贝转移到人纤维肉瘤细胞系HT 1080中。产生微细胞杂交体，其含有转移的成纤维细胞染色体13的一个、两个或三个额外拷贝。与亲本细胞系相比，杂交体在体外和体内的几个性质方面完全不变，包括形态学、生长速率和肿瘤形成。北方印迹分析显示RBImRNA表达逐步增加，其增加与每个细胞系中存在的等位基因数量成比例。尽管RBI蛋白在杂交体中表现出正确的核定位并以正常的细胞周期依赖性方式磷酸化，但每个杂交体中蛋白表达的增加水平几乎相同，并且没有增加超过阈值量，尽管mRNA表达继续增加。这些结果表明，HT 1080细胞可以耐受增加水平的RBI蛋白，但是超过一定水平的表达可能被下调。这些转移研究为RBI蛋白表达的调节提供了证据，并可能提出监测和控制正常RBI功能的替代形式.Genes Chrom Cancer 9：251 - 260（1994）.© 1994 Wiley利斯公司
The human retinoblastoma susceptibility gene (RBI) located on chromosome 13 has been shown to function as a growth/tumor suppressor gene in a large number of human cancers. Although constitutive expression has been observed in most cultured cells and normal tissues, overexpression of RBI protein has not been well documented. Perhaps regulating the level of normal RBI protein expression is one of several ways of controlling its function. To test this hypothesis we transferred normal copies of chromosome 13 via microcell fusion into the human fibrosarcoma cell line HT1080. Microcell hybrids were generated that contained one, two, or three extra copies of the transferred fibroblast chromosome 13. Compared to the parental cell line, the hybrids were completely unaltered with respect to several properties in vitro and in vivo, including morphology, growth rate, and tumor formation. Northern blot analysis revealed a stepwise increase inRBImRNA expression which increased in proportion to the number of alleles present in each cell line. Although RBI protein exhibited correct nuclear localization and was phosphorylated in a normal cell cycle‐dependent manner in the hybrids, the increased level of protein expression in each hybrid was nearly identical and did not increase beyond a threshold amount, although mRNA expression continued to increase. These results demonstrate that HT1080 cells can tolerate an increased level of RBI protein, but that expression beyond a certain level may be down‐regulated. These transfer studies provide evidence for regulation of RBI protein expression and may suggest an alternative form of monitoring and controlling normalRBIfunctioning.Genes Chrom Cancer9:251‐260 (1994). © 1994 Wiley‐Liss, Inc.