Newman J D, Campbell I L, Maher F, Harrison L C
Burnet Clinical Research Unit, Walter and Eliza Hall Institute of Medical Research, Royal Melbourne Hospital, Parkville, Australia.
Mol Endocrinol. 1989 Mar;3(3):597-602. doi: 10.1210/mend-3-3-597.
The specific binding of insulin to either intact or Triton-solubilized Daudi cells (a Burkitt lymphoma cell line) was reduced by over 95% compared to that to control IM-9 lymphocytes due to a decrease in receptor number without a change in affinity. Analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography revealed that 125I-labeled Daudi cells had reduced amounts (approximately 1/20th) of immunoprecipitable binding (alpha) subunit [mol wt (Mr), 130,000] of the receptor and a relatively abundant 210,000 Mr form not seen in IM-9 cells. The transmembranous (beta) subunit (Mr, 90,000) of the receptor, although not detected by 125I surface labeling, could be phosphorylated and, together with the 210,000 Mr form, exhibited the same 2-fold stimulation of phosphorylation by insulin as that in IM-9 cells. Northern blot hybridization revealed a decrease in Daudi cells of all four major species of insulin receptor mRNA. The Raji cell, another Burkitt lymphoma cell line, also exhibited reduced protein and genetic expression of the insulin receptor, indicating that reduced insulin receptor expression may be representative of other Burkitt lymphoma cell lines.
与对照IM-9淋巴细胞相比，胰岛素与完整的或经曲拉通增溶的Daudi细胞（一种伯基特淋巴瘤细胞系）的特异性结合减少了95%以上，这是由于受体数量减少而亲和力未改变所致。通过十二烷基硫酸钠-聚丙烯酰胺凝胶电泳和放射自显影分析发现，125I标记的Daudi细胞中可免疫沉淀的受体结合（α）亚基[分子量（Mr），130,000]含量减少（约为1/20），且有相对丰富的210,000 Mr形式，这在IM-9细胞中未见。受体的跨膜（β）亚基（Mr，90,000）虽然不能通过125I表面标记检测到，但可被磷酸化，并且与210,000 Mr形式一起，表现出与IM-9细胞中相同的2倍胰岛素刺激磷酸化作用。Northern印迹杂交显示Daudi细胞中所有四种主要的胰岛素受体mRNA种类均减少。另一种伯基特淋巴瘤细胞系Raji细胞也表现出胰岛素受体蛋白和基因表达减少，这表明胰岛素受体表达减少可能是其他伯基特淋巴瘤细胞系的特征。
