Riehs Nina, Akimcheva Svetlana, Puizina Jasna, Bulankova Petra, Idol Rachel A, Siroky Jiri, Schleiffer Alexander, Schweizer Dieter, Shippen Dorothy E, Riha Karel
Gregor Mendel Institute of Molecular Plant Biology, Austrian Academy of Sciences, Dr Bohr-Gasse 3, 1030 Vienna, Austria.
J Cell Sci. 2008 Jul 1;121(Pt 13):2208-16. doi: 10.1242/jcs.027862. Epub 2008 Jun 10.
Meiosis consists of two nuclear divisions that are separated by a short interkinesis. Here we show that the SMG7 protein, which plays an evolutionarily conserved role in nonsense-mediated RNA decay (NMD) in animals and yeast, is essential for the progression from anaphase to telophase in the second meiotic division in Arabidopsis. Arabidopsis SMG7 is an essential gene, the disruption of which causes embryonic lethality. Plants carrying a hypomorphic smg7 mutation exhibit an elevated level of transcripts containing premature stop codons. This suggests that the role of SMG7 in NMD is conserved in plants. Furthermore, hypomorphic smg7 alleles render mutant plants sterile by causing an unusual cell-cycle arrest in anaphase II that is characterized by delayed chromosome decondensation and aberrant rearrangement of the meiotic spindle. The smg7 phenotype was mimicked by exposing meiocytes to the proteasome inhibitor MG115. Together, these data indicate that SMG7 counteracts cyclin-dependent kinase (CDK) activity at the end of meiosis, and reveal a novel link between SMG7 and regulation of the meiotic cell cycle.
减数分裂由两次核分裂组成，两次分裂之间有一段短暂的分裂间期。我们在此表明，SMG7蛋白在动物和酵母的无义介导的RNA降解（NMD）中发挥着进化上保守的作用，它对于拟南芥第二次减数分裂中从后期到末期的进程至关重要。拟南芥SMG7是一个必需基因，其破坏会导致胚胎致死。携带亚效等位基因smg7的植物中，含有过早终止密码子的转录本水平升高。这表明SMG7在NMD中的作用在植物中是保守的。此外，亚效smg7等位基因通过在后期II导致异常的细胞周期停滞，使突变植物不育，其特征是染色体解聚延迟和减数分裂纺锤体的异常重排。通过将减数分裂细胞暴露于蛋白酶体抑制剂MG115，模拟了smg7的表型。这些数据共同表明，SMG7在减数分裂末期抵消细胞周期蛋白依赖性激酶（CDK）的活性，并揭示了SMG7与减数分裂细胞周期调控之间的新联系。
