Martins T J, Sugimoto Y, Erikson R L
Department of Cellular and Developmental Biology, Harvard University, Cambridge, Massachusetts 02138.
J Cell Biol. 1989 Feb;108(2):683-91. doi: 10.1083/jcb.108.2.683.
The metabolism of phosphatidylinositol (PI) and related intermediates was studied in uninfected and Rous sarcoma virus-(RSV) infected chicken embryo fibroblasts (CEFs). Cells infected with wild-type RSV exhibited twofold increases in steady-state concentrations of inositol trisphosphate (IP3) and inositol bisphosphate (IP2) as compared to uninfected CEFs. In addition, increased concentrations of IP3 and IP2 were observed in CEFs infected with the RSV temperature-sensitive transformation mutant NY72-4 when maintained at the permissive temperature (35 degrees C) for greater than 24 h. Slight increases were observed in the amounts of inositol lipids in RSV-transformed cells. Phosphoinositol metabolic changes were related to transformation and not to viral infection since CEFs infected with NY72-4, maintained at the nonpermissive temperature (41.5 degrees C), revealed amounts of phosphoinositols similar to that of uninfected cells. CEFs infected with a transformation-defective virus exhibited PI metabolic changes intermediate between those of transformed and nontransformed cells. NY72-4 CEF exhibited no increase in phosphoinositol concentrations before 8 h incubation at 35 degrees C, indicating that the transformation-specific changes in inositol metabolism were a delayed event. Furthermore, inositol turnover was not activated during this time. In contrast to the case of inositol metabolism, significant increases in diacylglycerol (DAG) concentrations were observed within 15-30 min after shift of NY72-4 CEFs to 35 degrees C. These findings suggest that (a) the major changes in inositol metabolism are specific for RSV-transformed cells; (b) transformation-specific changes in phosphoinositol content in RSV-infected CEFs are not an early effect of the expression of pp60v-src; and (c) increases in the DAG content of transformed cells occur before changes in inositol metabolism, indicating that DAG may be derived from other lipid sources.
在未感染和感染劳氏肉瘤病毒（RSV）的鸡胚成纤维细胞（CEF）中研究了磷脂酰肌醇（PI）及其相关中间体的代谢。与未感染的CEF相比，感染野生型RSV的细胞中肌醇三磷酸（IP3）和肌醇二磷酸（IP2）的稳态浓度增加了两倍。此外，当RSV温度敏感转化突变体NY72-4感染的CEF在允许温度（35℃）下维持超过24小时时，观察到IP3和IP2浓度增加。在RSV转化的细胞中观察到肌醇脂质的量略有增加。磷酸肌醇代谢变化与转化有关，而与病毒感染无关，因为在非允许温度（41.5℃）下维持的感染NY72-4的CEF显示出与未感染细胞相似的磷酸肌醇量。感染转化缺陷病毒的CEF表现出介于转化细胞和未转化细胞之间的PI代谢变化。NY72-4 CEF在35℃孵育8小时之前，磷酸肌醇浓度没有增加，这表明肌醇代谢中转化特异性变化是一个延迟事件。此外，在此期间肌醇周转率未被激活。与肌醇代谢的情况相反，在NY72-4 CEF转移到35℃后15 - 30分钟内观察到二酰基甘油（DAG）浓度显著增加。这些发现表明：（a）肌醇代谢的主要变化是RSV转化细胞特有的；（b）RSV感染的CEF中磷酸肌醇含量的转化特异性变化不是pp60v-src表达的早期效应；（c）转化细胞中DAG含量的增加发生在肌醇代谢变化之前，表明DAG可能来自其他脂质来源。
