标题：RNAi screen for telomerase reverse transcriptase transcriptional regulators identifies HIF1α as critical for telomerase function in murine embryonic stem cells
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：2010
卷号：107
期号：31
页码：13842-13847
DOI：10.1073/pnas.0913834107
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：In various types of stem cells, including embryonic stem (ES) cells and hematopoietic stem cells, telomerase functions to ensure long-term self-renewal capacity via maintenance of telomere reserve. Expression of the catalytic component of telomerase, telomerase reverse transcriptase (Tert), which is essential for telomerase activity, is limiting in many types of cells and therefore plays an important role in establishing telomerase activity levels. However, the mechanisms regulating expression of Tert in cells, including stem cells, are presently poorly understood. In the present study, we sought to identify genes involved in the regulation of Tert expression in stem cells by performing a screen in murine ES (mES) cells using a shRNA expression library targeting murine transcriptional regulators. Of 18 candidate transcriptional regulators of Tert expression identified in this screen, only one candidate, hypoxia inducible factor 1 alpha (Hif1{alpha}), did not have a significant effect on mES cell morphology, survival, or growth rate. Direct shRNA-mediated knockdown of Hif1{alpha} expression confirmed that suppression of Hif1{alpha} levels was accompanied by a reduction in both Tert mRNA and telomerase activity levels. Furthermore, gradual telomere attrition was observed during extensive proliferation of Hif1{alpha}-targeted mES cells. Switching Hif1{alpha}-targeted mES cells to a hypoxic environment largely restored Hif1{alpha} levels, as well as Tert expression, telomerase activity levels, and telomere length. Together, these findings suggest a direct effect of Hif1{alpha} on telomerase regulation in mES cells, and imply that Hif1{alpha} may have a physiologically relevant role in maintenance of functional levels of telomerase in stem cells.
