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(Arteriosclerosis, Thrombosis, and Vascular Biology. 2003;23:e54.)
© 2003 American Heart Association, Inc.

Letters to the Editor

Research Letter

Role of Telomerase in Human Endothelial Cell Proliferation

David J. Kurz

Cardiovascular Research, Institute of Physiology, University of Zurich, and Cardiology, University Hospital, Zurich, Switzerland

Jorge D. Erusalimsky

The Cell Biology Group at the British Heart Foundation Laboratories, Department of Medicine, University College London, London, UK

An extract of the first 250 words of the full text is provided, because this article has no abstract.

To the Editor:

Conflicting views exist as to whether human endothelial cells express telomerase^1–4 and, if they do, to what extent telomerase fulfills a physiological function. This may be due to the fact that activity levels in endothelial cells are low compared with tumor cells,⁴ and that during serial passage, endothelial cell telomeres continually shorten, in apparent defiance of the established function of telomerase, namely telomere length maintenance. In our own study published recently in this Journal,⁴ we demonstrated that telomerase activity is reversibly upregulated in proliferating endothelial cells but is not detectable during quiescence. We further showed that telomerase was upregulated by fibroblast growth factor-2 (FGF-2) but not by vascular endothelial growth factor A (VEGF), an effect that was associated with an extended replicative life span during serial passage of endothelial cells in the presence of FGF-2 compared with VEGF. It was noteworthy that this could not be attributed to a decrease in the rate of telomere shortening. To explain this phenomenon, we proposed that in human endothelial cells telomerase plays an active role in promoting extended cell growth by a mechanism that preserves telomere function independently of telomere length maintenance.

Substantial evidence has now been published to support this model of telomerase function in somatic human cells. In a study investigating the relationship between telomerase and telomere structure and function in normal human fibroblasts, Masutomi et al⁵ demonstrated the presence of telomerase in these cells. They further showed that although levels of expression were extremely low, they prevented . . . [Full Text of this Article]

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