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Science:MORC家族三磷酸腺苷酶调控基因沉默

来源:生物谷 2012-06-20 12:10

转座子的插入和DNA重复序列的甲基化修饰通常会导致基因沉默。AtMORC1和AtMORC6是保守的Microrchidia (MORC)三磷酸腺苷酶家族成员,之前有分析预测其功能是催化染色质超级结构的改变。

本文中,研究者在植物拟南芥中突变了AtMORC1和AtMORC6。发现这两个基因的作用是能够去除细胞对于DNA甲基化和转座子的阻遏,但是不会影响DNA或组蛋白的甲基化修饰本身。

突变了AtMORC1和AtMORC6之后,着丝粒周围的异染色质区域表现出去凝集,同时该区域与基因组上其他区域的相互作用增强。这说明AtMORC1和AtMORC6对基因沉默有重要作用。此外,研究人员在线虫中敲减了MORC的同系物,也出现了基因沉默效应减弱的表型。

综上所述,研究者认为MORC三磷酸腺苷酶家族的成员在真核生物中是保守的,在调控基因沉默中扮演着重要角色。(生物谷 Bioon.com  )

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.

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