Original Paper

Male Germ Cell Expression of the PAS Domain Kinase PASKIN and its Novel Target Eukaryotic Translation Elongation Factor eEF1A1
Katrin Eckhardt^{1, ,*}, Juliane Tröger^1, , Jana Reissmann², Dörthe M. Katschinski^2,3, Klaus F. Wagner^4,5, Petra Stengel⁴, Uwe Paasch⁶, Peter Hunziker⁷, Emanuela Borter¹, Sandra Barth¹, Philipp Schläfli¹, Patrick Spielmann¹, Daniel P. Stiehl¹, Gieri Camenisch¹, Roland H. Wenger<sup>1

1</sup>Institute of Physiology and Zürich Center for Integrative Human Physiology (ZIHP), University of Zürich
²Cell Physiology Group, Medical Faculty, Martin-Luther-University Halle
³Heart and Circulatory Physiology, Georg August University Göttingen
⁴Institute of Physiology and
⁵Clinic of Anaesthesiology, University of Lübeck
⁶European Training Center of Andrology, University of Leipzig, and
⁷Functional Genomics Center Zürich, University of Zürich
The first two authors contributed equally to this publication
^*Present address: Institute of Cell Biology, ETH Zürich

Address of Corresponding Author

Cell Physiol Biochem 2007;20:227-240 (DOI: 10.1159/000104169)

  Key Words

• Energy homeostasis
• Glycogen synthesis
• Nitrogen fixation
• Protein phosphorylation
• Protein translation
• Testis

  Abstract

PASKIN links energy flux and protein synthesis in yeast, regulates glycogen synthesis in mammals, and has been implicated in glucose-stimulated insulin production in pancreatic -cells. Using newly generated monoclonal antibodies, PASKIN was localized in the nuclei of human testis germ cells and in the midpiece of human sperm tails. A speckle-like nuclear pattern was observed for endogenous PASKIN in HeLa cells in addition to its cytoplasmic localization. By yeast two-hybrid screening, we identified the multifunctional eukaryotic translation elongation factor eEF1A1 as a novel interaction partner of PASKIN. This interaction was mapped to the PAS A and kinase domains of PASKIN and to the C-terminus of eEF1A1 using mammalian two-hybrid and GST pull-down assays. Kinase assays, mass spectrometry and site-directed mutagenesis revealed PASKIN auto-phosphorylation as well as eEF1A1 target phosphorylation mainly but not exclusively at Thr432. Wild-type but not kinase-inactive PASKIN increased the in vitro translation of a reporter cRNA. Whereas eEF1A1 did not localize to the nucleus, it co-localizes with PASKIN to the cytoplasm of HeLa cells. The two proteins also showed a remarkably similar localization in the midpiece of the sperm tail. These data suggest regulation of eEF1A1 by PASKIN-dependent phosphorylation in somatic as well as in sperm cells.

Copyright © 2007 S. Karger AG, Basel

  Author Contacts

R. H. Wenger
Institute of Physiology, University of Zürich
Winterthurerstrasse 190, CH-8057 Zürich, (Switzerland)
Tel. +41 44 6355065, Fax: +41 44 6356814
E-Mail roland.wenger@access.uzh.ch

  Article Information

Accepted: February 02, 2007
Number of Print Pages : 14