title: 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.
abstract: 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.
authors: 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.
authors: Binglian
authors: B
authors: Zheng
authors: Xuemei
authors: X
authors: Chen
authors: Sheila
authors: S
authors: McCormick
mesh_terms: D000595:Amino Acid Sequence; D064173:Anaphase-Promoting Complex-Cyclosome; D017360:Arabidopsis / Q000166:cytology / Q000235:genetics* / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D019926:Cyclin B / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D058685:Genetic Pleiotropy; D035683:MicroRNAs / Q000378:metabolism*; D008938:Mitosis; D008969:Molecular Sequence Data; D010641:Phenotype; D018515:Plant Leaves / Q000235:genetics / Q000254:growth & development; D030821:Plants, Genetically Modified / Q000235:genetics; D017354:Point Mutation; D011058:Pollen / Q000166:cytology / Q000254:growth & development* / Q000378:metabolism; D012319:RNA Polymerase II / Q000378:metabolism; D018749:RNA, Plant / Q000378:metabolism; D050436:Regulatory Elements, Transcriptional; D012440:Saccharomyces / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D043743:Ubiquitin-Protein Ligase Complexes / Q000235:genetics* / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; C462528:CycB1 protein, Arabidopsis; D019926:Cyclin B; C499555:DUO1 protein, Arabidopsis; D035683:MicroRNAs; D018749:RNA, Plant; D014157:Transcription Factors; D043743:Ubiquitin-Protein Ligase Complexes; D064173:Anaphase-Promoting Complex-Cyclosome; D012319:RNA Polymerase II