Affiliations: Department of Pathology, Institute of Surgical Pathology, University Hospital Zurich, Zurich, Switzerland | Laboratory of Pathology, NCI, Center for Cancer Research, Bethesda, MD, USA | Institute of Pathology, Johannes Gutenberg-University, Mainz, Germany | Institute of Physiology, University of Regensburg, Regensburg, Germany | Clinic and Policlinic for Internal Medicine, University of Münster, Münster, Germany
Note: [] Corresponding author: Achim Weber, Department of Pathology, Institute of Surgical Pathology, University Hospital Zurich, Schmelzbergstr. 12, 8091 Zurich, Switzerland. Tel.: +41 44 255 2781; Fax: +41 44 255 4416; E-mail: achim.weber@usz.ch.
Abstract: Background: The general transcription factor II H (TFIIH), comprised of a core complex and an associated CAK-complex, functions in transcription, DNA repair and cell cycle control. Mutations of the two largest subunits, p89 (XPB) and p80 (XPD), cause the hereditary cancer-prone syndrome xeroderma pigmentosum. Methods: The TFIIH subunit p89 was monitored during interphase and cell division by immunofluorescence staining, GFP-fusion constructs including deletions, live cell imaging and immuno-precipitations. Results: Here we demonstrate that during cell division, from prophase until telophase, the TFIIH core subunit p89, but not other subunits of TFIIH, associates with the centrosomes and the adjacent parts of the mitotic spindle. With overall constant levels throughout mitosis, p89 re-localizes to the newly formed nuclei by the end of mitosis. Furthermore, p89 interacts with the centrosomal protein γ-tubulin. Truncations of p89 result in an abnormal subcellular distribution during interphase and abolished centrosomal association during mitosis. Conclusions: Our observations suggest a so far unappreciated role for p89 in cell cycle regulation, and may be the structural basis for a long known, but hitherto unexplained interaction between p89 and tubulin.
