Visit our Expo - Redox and Inflammation signaling 2012

Session III : Protein kinase cascades as therapeutic targets Poster III, 35
Dlk/ZIP Kinase is involved in Mitosis and Cytokinesis
Steve Manderscheid, Gerd Landsberg, Dominik Brinckmann and Karl Heinz
Scheidtmann
Institute of Genetics, University of Bonn, Roemerstr. 164 D-53117 Bonn, Germany. Email:
stevemander@web.de
Dlk/ZIP Kinase is a Serin /Threonin specific Kinase of the proapoptotic DAP Kinase family.
Dlk/ZIP Kinase does not induce apoptosis per se, rather it seems to be involved in regulation
of transcription, contractile processes and mitosis, particularly cytokinesis. During mitosis
Dlk/ZIP Kinase associates with centrosomes, centromeres and the contractile ring. In order to
elucidate the biological role of these interactions and to map the interaction domains of
Dlk/ZIP Kinase with these structures we established cell lines stably expressing N- and Cterminal
truncation mutants at a low level. Mutant &N1 consisting of the extracatalytic
domain colocalized with centrosomes and the contractile ring but not with
centromere/kinetochore structures. Constitutive expression of this mutant did not reveal any
phenotype indicating that it did not act in a dominant negative manner, at least not at the low
expression level.
On the other hand, &C2NLS lacking the C-terminal 110 amino acid residues including the
leucine zipper, but containing a heterologous NLS did not associate with centrosomes or the
contractile ring, though it was found associated with chromatin. In contrast to &N1-expressing
cells, the cell line expressing &C2NLS exhibited a multinucleation phenotype. Interestingly,
the &C2NLS cell line appeared heterogeneous. The majority of cells expressed the GFP
fusion construct at a low level whereas about a quarter of the cells exhibited strong
overexpression, mainly in the nucleus. Overexpression strongly correlated with generation of
large round or deformed nuclei. Multinucleated cells were observed too.
Cells were additionally analysed for phosphorylation of histone H3, expression and
localization of chromosomal passenger proteins (aurora B, INCENP, and survivin). H3
phosphorylation of Serin 10 and Threonin 11 was normal, the chromosomal passenger
showed the known distribution pattern. Our data show for the first time that Dlk might be
involved in mitotic processes, prior to cytokinesis.
Acknowledgement : This work is supported by DFGGrant Sche 246/16 and “bourse de
formation-recherche” BFR 03/021
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