Mitogen‐activated protein kinase 4 is involved in the regulation of mitotic and cytokinetic microtubule transitions in Arabidopsis thaliana

Abstract

Summary• A mitogen-activated protein kinase kinase kinase (MAPKKK) double mutant, Arabidopsis homologue of nucleus and phragmoplast associated kinase (anp) anp2anp3, and the mitogen-activated protein kinase (MAPK) 4 mutant mpk4 of Arabidopsis thaliana show prominent cytokinetic defects. This prompted the analysis of mitotic and cytokinetic progression as a function of MAPK signalling. Mutants were compared with wild types untreated or treated with the specific MAPKK inhibitor PD98059.• This study included phenotype analysis, expression analysis of the MPK4 promoter, immunofluorescent localization of MPK4, tubulin and MAP65-1, and time-lapse microscopic visualization of the mitotic microtubule (MT) transitions in control, mutant and inhibitor-treated cells.• Mutant and inhibitor-treated cells showed defects in mitosis and cytokinesis, including aberrant spindle and phragmoplast formation and drastically delayed or abortive mitosis and cytokinesis. As a result, bi-and multinucleate cells were formed, ultimately disturbing the vegetative tissue patterning. MPK4 was localized to all stages of the expanding phragmoplast, in a pattern similar to that of its putative substrate MAP65-1.• In this study, MPK4 is shown to be involved in the regulation of mitosis ⁄ cytokinesis through modulation of the cell division plane and cytokinetic progression.

The Arabidopsis NUCLEUS- AND PHRAGMOPLAST-LOCALIZED KINASE1-Related Protein Kinases Are Required for Elicitor-Induced Oxidative Burst and Immunity

“…In ANP mutants, cytokinetic defects and root defects are similar to those of loss-of-function mutants for MPK4, which, like NPK1, localizes to the phragmoplast and physically interacts with MAP65-1, a major microtubulecross-linking protein that regulates the stability and turnover of phragmoplast microtubules (Krysan et al, 2002;Beck et al, 2010Beck et al, , 2011. ANPs have been shown to functionally interact with proteins that are required for cytokinesis and thought to control stability and turnover of microtubules (Takahashi et al, 2010;Komis et al, 2011).…”

“…Triple mutants were constructed by down-regulating, in an inducible manner, the expression of the third gene family member in both the double mutants anp1 anp2 and anp2 anp3. Only the latter double mutant exhibits developmental defects (Krysan et al, 2002;Beck et al, 2010Beck et al, , 2011. Conditional silencing was obtained by individually expressing ANP3-and ANP1-specific artificial microRNAs (amiRNAs), respectively, under the control of a b-estradiol-inducible promoter.…”

A MAP Kinase Kinase Interacts with SymRK and Regulates Nodule Organogenesis in Lotus japonicus

“…The Arabidopsis MKK4/MKK5-MPK3/MPK6 cascades play important roles in the regulation of plant development and biotic stress (Asai et al, 2002;Wang et al, 2007). The Arabidopsis MKK6-MPK4/MPK11 cascades directly regulate cytokinesis and mitosis (Beck et al, 2010(Beck et al, , 2011Takahashi et al, 2010). MKK7 leads to activation of plant basal and systemicacquired resistance in Arabidopsis .…”

Soybean Homologs of MPK4 Negatively Regulate Defense Responses and Positively Regulate Growth and Development

“…While MPK3 and MPK6 act as positive regulators of defense responses (Asai et al, 2002;Menke et al, 2005;Takahashi et al, 2007;Ren et al, 2008;Mao et al, 2011), MPK4 negatively regulates defense responses (Petersen et al, 2000;Brodersen et al, 2006;Gao et al, 2008). Besides its role in defense, MPK4 also plays a role in cytokinesis (Kosetsu et al, 2010;Beck et al, 2011;Zeng et al, 2011).…”