The Anaphase-Promoting Complex Is a Dual Integrator That Regulates Both MicroRNA-Mediated Transcriptional Regulation of Cyclin B1 and Degradation of Cyclin B1 during Arabidopsis Male Gametophyte Development

Plant Gene Expression Center, U.S. Department of Agriculture/Agricultural Research Service and Department of Plant and Microbial Biology, University of California-Berkeley, Albany, California 94710, USA.
The Plant Cell (Impact Factor: 9.34). 03/2011; 23(3):1033-46. DOI: 10.1105/tpc.111.083980
Source: PubMed


The anaphase-promoting complex/cyclosome (APC/C), an essential ubiquitin protein ligase, regulates mitotic progression and exit by enhancing degradation of cell cycle regulatory proteins, such as CYCB1;1, whose transcripts are upregulated by DUO POLLEN1 (DUO1). DUO1 is required for cell division in male gametophytes and is a target of microRNA 159 (miR159) in Arabidopsis thaliana. Whether APC/C is required for DUO1-dependent CYCB1;1 regulation is unknown. Mutants in both APC8 and APC13 had pleiotrophic phenotypes resembling those of mutants affecting microRNA biogenesis. We show that these apc/c mutants had reduced miR159 levels and increased DUO1 and CYCB1;1 transcript levels and that APC/C is required to recruit RNA polymerase II to MIR159 promoters. Thus, in addition to its role in degrading CYCB1;1, APC/C stimulates production of miR159, which downregulates DUO1 expression, leading to reduced CYCB1;1 transcription. Both MIR159 and APC8-yellow fluorescent protein accumulated in unicellular microspores and bicellular pollen but decreased in tricellular pollen, suggesting that spatial and temporal regulation of miR159 by APC/C ensures mitotic progression. Consistent with this, the percentage of mature pollen with no or single sperm-like cells increased in apc/c mutants and plants overexpressing APC8 partially mimicked the duo1 phenotype. Thus, APC/C is an integrator that regulates both microRNA-mediated transcriptional regulation of CYCB1;1 and degradation of CYCB1;1.

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Available from: Sheila McCormick, Oct 13, 2015
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    • "Histochemical staining showed that the GUS activity was dramatically higher in prl1-9 root meristem compared to WT (Figure 2(e)), suggesting that the cell cycle in prl1-9 RAM was slowed down at the G2 to M phase transition. It is known that CycB1;1 transcription is activated in G2 phase, and CycB1;1 is degraded by the anaphase-promoting complex/cyclosome activator (APC/C) complex at metaphase (Zheng et al., 2011), APC/C complex contains at least 11 different subunits (APC1–APC11), including the catalytic core subunits APC2 and APC11, and among them, activation and substrate specificity of APC2 and APC11 are regulated by the Fizzy-related (FZR) proteins. In Arabidopsis, there are three FZR homolog genes (FZR1, FZR2, FZR3) (Bao et al., 2012). "
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    • "The PCR products were cloned into pENTR™/D-TOPO (Invitrogen). The resulting promoter fragments were subsequently transferred into a Gateway-compatible version (Zheng et al., 2011) of the pGreenII-based vector NLS:3GFP:NOSt (Takada and Jürgens, 2007), termed pGII_GW:NLS:3GFP:NOSt. For AGP1, AGP15, and AGP23 β-glucuronidase (GUS) constructs, the respective promoter fragments were cloned into the binary vector pBG- WFS7 (Karimi et al., 2002). "
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