花粉中转座元件的表观遗传重编程和小RNA沉默
Epigenetic reprogramming and small RNA silencing of transposable elements in pollen.
作者信息
Slotkin R Keith, Vaughn Matthew, Borges Filipe, Tanurdzić Milos, Becker Jörg D, Feijó José A, Martienssen Robert A
机构信息
Cold Spring Harbor Laboratory, 1 Bungtown Road, Cold Spring Harbor, NY 11724, USA.
出版信息
Cell. 2009 Feb 6;136(3):461-72. doi: 10.1016/j.cell.2008.12.038.
The mutagenic activity of transposable elements (TEs) is suppressed by epigenetic silencing and small interfering RNAs (siRNAs), especially in gametes that could transmit transposed elements to the next generation. In pollen from the model plant Arabidopsis, we show that TEs are unexpectedly reactivated and transpose, but only in the pollen vegetative nucleus, which accompanies the sperm cells but does not provide DNA to the fertilized zygote. TE expression coincides with downregulation of the heterochromatin remodeler decrease in DNA methylation 1 and of many TE siRNAs. However, 21 nucleotide siRNAs from Athila retrotransposons are generated and accumulate in pollen and sperm, suggesting that siRNA from TEs activated in the vegetative nucleus can target silencing in gametes. We propose a conserved role for reprogramming in germline companion cells, such as nurse cells in insects and vegetative nuclei in plants, to reveal intact TEs in the genome and regulate their activity in gametes.
转座元件（TEs）的诱变活性通过表观遗传沉默和小干扰RNA（siRNAs）得以抑制，尤其是在可能将转座元件传递给下一代的配子中。在模式植物拟南芥的花粉中，我们发现TEs意外地重新激活并发生转座，但仅发生在花粉营养核中，营养核伴随精细胞，但不向受精卵提供DNA。TEs的表达与异染色质重塑因子DNA甲基化减少1以及许多TE siRNAs的下调相一致。然而，来自Athila逆转座子的21个核苷酸的siRNAs在花粉和精子中产生并积累，这表明在营养核中激活的TEs产生的siRNAs可以靶向配子中的沉默作用。我们提出，在种系伴细胞（如昆虫中的滋养细胞和植物中的营养核）中重编程具有保守作用，以揭示基因组中完整的TEs并调节它们在配子中的活性。
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