科研之友
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摘要
The chicken B-cell line DT40 has two isoforms of phosphatidylinositol 5-phosphate 4-kinase (PI5P4K), alpha and beta, which are likely to exist as a mixture of obligate homo- and hetero-dimers. Previous work has led us to speculate that an important role of the beta isoform may be to target the more active PI5P4K alpha isoform to the nucleus. In the present study we expand upon that work by genomically tagging the PI5P4Ks with fluorochromes in the presence or absence of stable or acute depletions of PI5P4K beta. Consistent with our original hypothesis we find that PI5P4K alpha is predominantly (possible entirely) cytoplasmic when PI5P4K beta is stably deleted from cells. In contrast, when PI5P4K beta is inducibly removed within 1 h PI5P4K alpha retains its wild-type distribution of approximately 50: 50 between cytoplasm and nucleus even through a number of cell divisions. This leads us to speculate that PI5P4K alpha is chromatin-associated. We also find that when cells are in the exponential phase of growth PI5P4K beta is primarily cytoplasmic but translocates to the nucleus upon growth into the stationary phase or upon serum starvation. Once again this is not accompanied by a change in PI5P4K alpha localization and we show, using an in vitro model, that this is possible because the dimerization between the two isoforms is dynamic. Given this shift in PI5P4K beta upon nutrient deprivation we explore the phenotype of PI5P4K B-null cells exposed to this stress and find that they can sustain a greater degree of nutrient deprivation than their wild-type counterparts possibly as a result of up-regulation of autophagy.
- 出版日期2016-7
- 单位河北医科大学
