期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2015
卷号：112
期号：5
页码：1368-1373
DOI：10.1073/pnas.1423009112
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：SignificanceWe show that the assembly/disassembly of the purinosome is cell cycle-dependent and correlates with cellular demands for purine biosynthesis encountered during the cell cycle. The number of purinosome-containing cells fluctuates: it peaks in G1 phase in HeLa cells cultured under purine-depleted conditions, but remains high across G1, S, and G2/M phases in fibroblasts incapable of purine salvage owing to a deficiency in hypoxanthine-guanine phosphoribosyltransferase. Thus, purinosome function is a cellular biomarker for increased metabolic flux through the de novo purine biosynthetic pathway in response to cellular purine requirements. The de novo purine biosynthetic pathway relies on six enzymes to catalyze the conversion of phosphoribosylpyrophosphate to inosine 5'-monophosphate. Under purine-depleted conditions, these enzymes form a multienzyme complex known as the purinosome. Previous studies have revealed the spatial organization and importance of the purinosome within mammalian cancer cells. In this study, time-lapse fluorescence microscopy was used to investigate the cell cycle dependency on purinosome formation in two cell models. Results in HeLa cells under purine-depleted conditions demonstrated a significantly higher number of cells with purinosomes in the G1 phase, which was further confirmed by cell synchronization. HGPRT-deficient fibroblast cells also exhibited the greatest purinosome formation in the G1 phase; however, elevated levels of purinosomes were also observed in the S and G2/M phases. The observed variation in cell cycle-dependent purinosome formation between the two cell models tested can be attributed to differences in purine biosynthetic mechanisms. Our results demonstrate that purinosome formation is closely related to the cell cycle.
关键词：purinosome ; de novo purine biosynthesis ; cell cycle ; metabolism ; fluorescence microscopy
