Overexpression of the human <it>MNB/DYRK1A </it>gene induces formation of multinucleate cells through overduplication of the centrosome

• Main Authors: Hiraoka Yasushi, Haraguchi Tokuko, Hori Takamitsu, Funakoshi Eishi, Kudoh Jun, Shimizu Nobuyoshi, Ito Fumiaki
• Format: Article
• Language: English
• Published: BMC 2003-09-01
• Series: BMC Cell Biology
• Subjects: Down syndrome critical region; Dual-specificity protein kinase; Centrosome; Cell cycle; MNB/DYRK1A.
• Online Access: http://www.biomedcentral.com/1471-2121/4/12

<p>Abstract</p> <p>Background</p> <p>Previously we cloned the human <it>MNB/DYRK1A </it>gene from the "Down syndrome critical region" on chromosome 21. This gene encodes a dual specificity protein kinase that catalyzes its autophosphorylation on serine/threonine and tyrosine residues. But, the functions of the <it>MNB/DYRK1A </it>gene in cellular processes are unknown.</p> <p>Results</p> <p>In this study, we examined HeLa cells transfected with cDNA encoding a green fluorescent protein (GFP)-MNB/DYRK1A fusion protein and found 2 patterns of expression: In one group of transfected cells, GFP-MNB/DYRK1A was localized as dots within the nucleus; and in the other group, it was overexpressed and had accumulated all over the nucleus. In the cells overexpressing GFP-MNB/DYRK1A, multinucleation was clearly observed; whereas in those with the nuclear dots, such aberrant nuclei were not found. Furthermore, in the latter cells, essential processes such as mitosis and cytokinesis occurred normally. Multinucleation was dependent on the kinase activity of MNB/DYRK1A, because it was not observed in cells overexpressing kinase activity-negative mutants, GFP-MNB/DYRK1A (K179R) and GFP-MNB/DYRK1A (Y310F/Y312F). Immunostaining of GFP-MNB/DYRK1A-overexpressing cells with specific antibodies against α- and γ-tubulin revealed that multiple copies of centrosomes and aberrant multipolar spindles were generated in these cells.</p> <p>Conclusions</p> <p>These results indicate that overexpression of MNB/DYRK1A induces multinucleation in HeLa cells through overduplication of the centrosome during interphase and production of aberrant spindles and missegregation of chromosomes during mitosis.</p>