Expression of the mnb (dyrk) protein in adult and embryonic mouse tissues

Mnb is a human homologue of the Drosophila minibrain gene which encodes a serine/threonine protein kinase that is required in distinct neuroblast proliferation centers during postembryonic neurogenesis. The high degree of homology of the human gene to the murine gene (dyrk) allowed us to use a human polyclonal anti-mnb antibody to study the expression pattern of the protein in adult and embryonic mouse tissues. Western blot analysis and immunohistochemical methods were used to define the detailed distribution of mnb in adult brain and 17 days mouse embryos. The results show a high expression in the cerebral cortex, the cerebellum, the hippocampus which is in accordance with previous reports of in situ hybridization studies using mRNA probes but also a very strong expression in the epithelial layers of the skin, the retina, the tongue, the intestine and the kidney which has not been described before. Since epithelial cells are highly mitotic cells and since mnb shares sequence similarities with the cdk kinases involved in the regulation of cell division, this result may indicate a important role of mnb in the cell cycle control.