Abstract
Aurora kinases constitute a family of enzymes that play a key role during metazoan cells division, being involved in events like centrosome maturation and division, chromatin condensation, mitotic spindle assembly, control of kinetochore-microtubule attachments, and cytokinesis initiation. In this work, three Aurora kinase homologues were identified in Trypanosoma cruzi (TcAUK1, -2 and -3), a protozoan parasite of the Kinetoplastida Class. The genomic organization of these enzymes was fully analyzed, demonstrating that TcAUK1 is a single-copy gene, TcAUK2 coding sequence is present in two different forms (short and long) and TcAUK3 is a multi-copy gene. The three TcAUK genes are actively expressed in the different life cycle forms of T. cruzi (amastigotes, trypomastigotes and epimastigotes). TcAUK1 showed a changing localization along the cell cycle of the proliferating epimastigote form: at interphase it is located at the extremes of the kinetoplast while in mitosis it is detected at the cell nucleus, in close association with the mitotic spindle. Overexpression of TcAUK1 in epimastigotes leaded to a delay in the G2/M phases of the cell cycle due a retarded beginning of kinetoplast duplication. By immunofluorescence, we found that when it was overexpressed TcAUK1 lost its localization at the extremes of the kinetoplast during interphase, being observed inside the cell nucleus throughout the entire cell cycle. In summary, TcAUK1 appears to be a functional homologue of human Aurora B kinase, as it is related to mitotic spindle assembling and chromosome segregation. Moreover, TcAUK1 also seems to play a role during the initiation of kinetoplast duplication, a novel role described for this protein.
Highlights
Cell cycle in eukaryotic cells involves the sequential transition between G1, S, G2 and M phases and this progression is tightly regulated by protein kinases and phosphatases [1]
We identified three Aurora kinase genes (TcAUK1, -2 and -3) in T. cruzi, the agent of Chagas disease, and established that TcAUK1 has the typical behavior of a mammalian Aurora B kinase, localizing inside the nucleus and associating with the mitotic spindle during mitosis
In this work we report the initial characterization of three Aurora kinase proteins in T. cruzi (TcAUK1, TcAUK2 and TcAUK3)
Summary
Cell cycle in eukaryotic cells involves the sequential transition between G1, S, G2 and M phases and this progression is tightly regulated by protein kinases and phosphatases [1]. While yeasts present a single Aurora kinase gene [2,3], organisms like C. elegans and D. melanogaster have two genes [4,5,6,7], whereas in vertebrates three Aurora kinase proteins are present [8] In this last group, the three members of the Aurora kinase family are named Aurora-A, -B and -C and each protein plays specific functions during the cell cycle. Aurora-B is named Equatorial Aurora because it locates in the mid-plane of the cell during mitosis (metaphase) and, as nuclear division proceeds, it is tightly associated with segregating chromosomes. This Aurora forms the Chromosomal Passenger Complex (CPC) with other three proteins (INCENP, Survivin and Borealin). In cytokinesis the CPC settles in the cell midzone and participates in the formation of the contractile ring and the cleavage furrow [13]
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