Cytokinesis defect in BY-2 cells caused by ATP-competitive kinase inhibitors

Abstract

Cytokinesis is last but not least in cell division as it completes the formation of the two cells. The main role in cell plate orientation and expansion have been assigned to microtubules and kinesin proteins. However, recently we reported severe cytokinesis defect in BY-2 cells not accompanied by changes in microtubules dynamics. Here we also confirmed that distribution of kinesin NACK1 is not the cause of cytokinesis defect. We further explored inhibition of the cell plate expansion by ATP-competitive inhibitors. Two different inhibitors, 5-Iodotubercidin and ML-7 resulted in a very similar phenotype, which indicates that they target same protein cascade. Interestingly, in our previous study we showed that 5-Iodotubercidin treatment affects concentration of actin filaments on the cell plate, while ML-7 is inhibitor of myosin light chain kinase. Although not directly, it indicates importance of actomyosin complex in plant cytokinesis.Abbreviations: AFs, actin filaments; BY-2, Bright Yellow-2; DMSO, dimethylsulfoxide; GFP, green fluorescent protein; 5-ITu, 5-iodotubercidin; MTs, mictrotubules KEYWORDS 5-Iodotubercidin; actomyosin role in plant cytokinesis; cytokinesis defect; Haspin kinase; inhibition of the cell plate expansion; kinesin NACK1; Cytokinesis in plants is essentially a process of building a new cell wall that separates two daughter cells. It is achieved by phragmoplast-guided vesicle transport to the division plane and vesicle fusion that forms a precursor of the cell wall. Dynamic changes in the phragmoplast are essential for proper cell plate formation and expansion; however, our understanding of what triggers and controls those changes is far from complete.Phragmoplast consists from microtubules (MTs), actin filaments (AFs) and associated proteins. MTs act as a driving force for vesicle trafficking and cell plate expansion. Kinesin proteins interact with MTs, providing spatial information for cell plate guidance or affecting their stability. Kinesin POK1 (phragmoplast-orientating kinesin-12) together with TAN and RAN-GAP1 is a part of pre-prophase band and during mitosis is localized to the cortical division zone. Knockouts of any protein from POK1, TAN and RANGAP1 results in cytokinesis defects.