Ki-67 protein is associated with ribosomal RNA transcription in quiescent and proliferating cells
Article first published online: 4 OCT 2005
Copyright © 2005 Wiley-Liss, Inc.
Journal of Cellular Physiology
Volume 206, Issue 3, pages 624–635, March 2006
How to Cite
Bullwinkel, J., Baron-Lühr, B., Lüdemann, A., Wohlenberg, C., Gerdes, J. and Scholzen, T. (2006), Ki-67 protein is associated with ribosomal RNA transcription in quiescent and proliferating cells. J. Cell. Physiol., 206: 624–635. doi: 10.1002/jcp.20494
- Issue published online: 16 DEC 2005
- Article first published online: 4 OCT 2005
- Manuscript Accepted: 24 JUL 2005
- Manuscript Received: 28 APR 2005
The nuclear Ki-67 protein (pKi-67) has previously been shown to be exclusively expressed in proliferating cells. As a result, antibodies against this protein are widely used as prognostic tools in cancer diagnostics. Here we show, that despite the strong downregulation of pKi-67 expression in non-proliferating cells, the protein can nevertheless be detected at sites linked to ribosomal RNA (rRNA) synthesis. Although this finding does not argue against the use of pKi-67 as a proliferation marker, it has wide ranging implications for the elucidation of pKi-67 function. Employing the novel antibody TuBB-9, we could further demonstrate that also in proliferating cells, a fraction of pKi-67 is found at sites linked to the rRNA transcription machinery during interphase and mitosis. Moreover, chromatin immunoprecipitation (ChIP) assays provided evidence for a physical association of pKi-67 with chromatin of the promoter and transcribed region of the rRNA gene cluster. These data strongly suggest a role for pKi-67 in the early steps of rRNA synthesis. © 2005 Wiley-Liss, Inc.