Adhesion induced expression of the serine/threonine kinase Fnk in human macrophages

• Published in: Oncogene Vol. 19; no. 42; pp. 4832 - 4839
• Main Authors: HOLTRICH, Uwe, WOLF, Georg, KUHL, Dietmar, STREBHARDT, Klaus, JUPING YUAN, BEREITER-HAHN, Jürgen, KARN, Thomas, WEILER, Markus, KAUSELMANN, Gunther, REHLI, Michael, ANDREESEN, Reinhard, KAUFMANN, Manfred
• Format: Journal Article
• Language: English
• Published: Basingstoke Nature Publishing 05.10.2000; Nature Publishing Group
• Subjects: Actin; Actins - metabolism; Adult; Animals; Biological and medical sciences; Blood cells; Blood Cells - cytology; Blood Cells - drug effects; Blood Cells - enzymology; Calcineurin; Calcineurin - chemistry; Calcium - physiology; Calcium-binding protein; Calcium-Binding Proteins; Calmodulin; Calmodulin - chemistry; Carrier Proteins - chemistry; Carrier Proteins - metabolism; Cell adhesion; Cell Adhesion - drug effects; Cell Adhesion - genetics; Cell culture; Cell Cycle Proteins; Cell Differentiation; Cell growth; Cell Membrane - enzymology; Cell membranes; Cell proliferation; Chlorocebus aethiops; Cib protein; COS Cells; Culture Media - pharmacology; Culture Media, Serum-Free - pharmacology; Cytoskeleton - metabolism; Cytoskeleton - ultrastructure; DNA, Complementary - genetics; Fnk gene; Fnk protein; Fundamental and applied biological sciences. Psychology; Fusion protein; Gene expression; Gene Expression Regulation, Developmental; Genes. Genome; HL-60 Cells; Homology; Humans; Immunoprecipitation; Kinases; Macrophages; Macrophages - drug effects; Macrophages - enzymology; Mammalian cells; Molecular and cellular biology; Molecular genetics; Monocytes; Monocytes - cytology; Monocytes - drug effects; Monocytes - enzymology; Multigene Family; Peripheral blood; Polo-like kinase; Polo-Like Kinase 1; Polymerase Chain Reaction; Protein Kinases - classification; Protein Kinases - genetics; Protein Serine-Threonine Kinases - biosynthesis; Protein Serine-Threonine Kinases - genetics; Protein-serine/threonine kinase; Proteins; Proto-Oncogene Proteins; Recombinant Fusion Proteins - physiology; RNA, Messenger - biosynthesis; Signal Transduction; Transcription; Transcription, Genetic; Transfection; Tumor Suppressor Proteins; Two-Hybrid System Techniques; U937 Cells; Human; Nucleotide sequence; Enzyme; Induction; Transferases; Hematopoietic cell; Homology; Molecular interaction; Gene expression; Adhesion; Protein kinase; Plasma membrane; Localization; Macrophage
• ISSN: 0950-9232; 1476-5594
• DOI: 10.1038/sj.onc.1203845

Members of the polo subfamily of protein kinases play crucial roles in cell proliferation. To study the function of this family in more detail, we isolated the cDNA of human Fnk (FGF-inducible kinase) which codes for a serine/threonine kinase of 646 aa. Despite the homology to the proliferation-associated polo-like kinase (Plk), tissue distribution of Fnk transcripts and expression kinetics differed clearly. In contrast to Plk no correlation between cell proliferation and Fnk gene expression was found. Instead high levels of Fnk mRNA were detectable in blood cells undergoing adhesion. The transition of monocytes from peripheral blood to matrix bound macrophages was accompanied by increasing levels of Fnk with time in culture. Neither treatment of monocytes with inducers of differentiation nor withdrawal of serum did influence Fnk mRNA levels significantly, suggesting that cell attachment triggers the onset of Fnk gene transcription. The idea that Fnk is part of the signalling network controlling cellular adhesion was supported by the analysis of the cytoplasmic distribution of the Fnk protein and the influence of its overexpression on the cellular architecture. Fnk as fusion protein with GFP localized at the cellular membrane in COS cells. Dysregulated Fnk gene expression disrupted the cellular f-actin network and induced a spherical morphology. Furthermore, Fnk binds to the Ca2+/integrin-binding protein Cib in two-hybrid-analyses and co-immunoprecipitation in assays. Moreover, both proteins were shown to co-localize in mammalian cells. The homology of Cib with calmodulin and with calcineurin B suggests that Cib might be a regulatory subunit of polo-like kinases.