PASKIN der eukaryotische Verwandte des Sauerstoffsensors FixL der Stickstoff-fixierenden Knöllchenbakterien
Final Report Abstract
PASKIN has been identified by our group as the mammalian homolog of the oxygen sensing PAS protein FixL, which is responsible for oxygen-dependent gene expression in nitrogenfixing Rhizobium bacteria. In the funded project key findings regarding expression, function and activation of PASKIN were made. Knock out of PASKIN in mice did not have an obvious phenotype under resting conditions. Based on ß-galactosidase staining, which was used as reportergene, PASKIN is highly expressed in testis especially in male germ cells. To verify this expression pattern for the endogenous protein we established a monoclonal anti- PASKIN antibody. Immunohistochemistry and immunofluorescence labelling verified the expression of PASKIN in testis. Subcellular localization revealed a mostly cytoplasmic localization in HeLa cells. However, in addition nuclear speckles were found to stain positive for PASKIN. In post-meiotic sperm cells PASKIN localized mostly to the midpiece as analyzed by confocal immunofluorescence microscopy. Regarding PASKIN function, in a yeast to hybrid-screen the elongation factor eFIAl has been identified as PASKIN protein interaction partner. The protein interaction was verified in pull down experiments. In subsequent studies an influence of PASKIN on protein translation efficiency was identified. Finally, regarding PASKIN activation we identified a stimulation of PASKIN phosphorylation activity by phosphatidylserine and diacylglycerine, opening the possibility that PASKIN is a critical mediator of phospholipid signalling and protein translation.
Publications
- Eckardt, K., Tröger, J., Reissmann, J., Katschinski, D.M., Wagner K.F., Stengel, P., Paasch, U-, Hunziker, P., Borter, E., Barth, S., Schläfli, P., Spielmann, P., Stiehl, DP., Camenisch G., Wenger, R.H. Male germ cell expression of the PAS domain kinase PASKIN and ist target eukaryotic translation elongation factor eEFlAl. Cell Physiol Biochem: 227-240, 2007.
- Wenger, R.H., Katschinski, DM. The hypoxic testis and post-meiotic expression of PAS domain proteins. Sem Cell Dev Biol: 547-553 (2005).
