轉(zhuǎn)座子的插入和DNA重復(fù)序列的甲基化修飾通常會導(dǎo)致基因沉默,。AtMORC1和AtMORC6是保守的Microrchidia (MORC)三磷酸腺苷酶家族成員,，之前有分析預(yù)測其功能是催化染色質(zhì)超級結(jié)構(gòu)的改變,。
本文中，研究者在植物擬南芥中突變了AtMORC1和AtMORC6,。發(fā)現(xiàn)這兩個基因的作用是能夠去除細(xì)胞對于DNA甲基化和轉(zhuǎn)座子的阻遏,，但是不會影響DNA或組蛋白的甲基化修飾本身。
突變了AtMORC1和AtMORC6之后,，著絲粒周圍的異染色質(zhì)區(qū)域表現(xiàn)出去凝集,，同時該區(qū)域與基因組上其他區(qū)域的相互作用增強(qiáng)。這說明AtMORC1和AtMORC6對基因沉默有重要作用,。此外，研究人員在線蟲中敲減了MORC的同系物,，也出現(xiàn)了基因沉默效應(yīng)減弱的表型,。
綜上所述，研究者認(rèn)為MORC三磷酸腺苷酶家族的成員在真核生物中是保守的,，在調(diào)控基因沉默中扮演著重要角色,。（生物谷 Bioon.com ）
doi:10.1126/science.1221472
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MORC Family ATPases Required for Heterochromatin Condensation and Gene Silencing
Guillaume Moissiard, Shawn J. Cokus, Joshua Cary, Suhua Feng, Allison C. Billi, Hume Stroud, Dylan Husmann, Ye Zhan, Bryan R. Lajoie, Rachel Patton McCord, Christopher J. Hale, Wei Feng, Scott D. Michaels, Alison R. Frand, Matteo Pellegrini, Job Dekker, John K. Kim, Steven E. Jacobsen
Transposable elements (TEs) and DNA repeats are commonly targeted by DNA and histone methylation to achieve epigenetic gene silencing. We isolated mutations in two Arabidopsis genes, AtMORC1 and AtMORC6, which cause derepression of DNA-methylated genes and TEs but no losses of DNA or histone methylation. AtMORC1 and AtMORC6 are members of the conserved Microrchidia (MORC) adenosine triphosphatase (ATPase) family, which are predicted to catalyze alterations in chromosome superstructure. The atmorc1 and atmorc6 mutants show decondensation of pericentromeric heterochromatin, increased interaction of pericentromeric regions with the rest of the genome, and transcriptional defects that are largely restricted to loci residing in pericentromeric regions. Knockdown of the single MORC homolog in Caenorhabditis elegans also impairs transgene silencing. We propose that the MORC ATPases are conserved regulators of gene silencing in eukaryotes.
