Nucleic Acids Res:厦门大学陶懿教授课题组等揭示拟南芥FEN1突变体的
2015年12月31日，国际知名期刊杂志《Nucleic Acids Research》在线发表厦门大学陶懿课题组与美国希望之城(City of Hope)医学中心Beckman研究中心沈炳辉课题组合作完成的一篇研究论文，该研究首次报导了植物FEN1突变体的表型，对植物发育和抗逆性的影响，及其产生的分子机制，揭示拟南芥FEN1突变体的表型特征以及导致这种突变体表型的分子机制。研究题为“Shade avoidance 6 encodes an Arabidopsis flap endonuclease required for maintenance of genome integrity and development” 。
FEN1(Flap endonuclease I)是RAD2家族的一种通过特异性识别底物结构进行核酸剪切的核酶，在DNA复制、损伤修复以及维持端粒稳定性等方面发挥着重要作用。该基因的突变在哺乳动物中会引起基因组不稳定，肿瘤的发生，甚至胚胎的死亡。尽管人们对FEN1在哺乳动物、酵母中的功能已经有了一定的了解，但是在植物中尚无相关研究。
陶懿教授课题组通过正向遗传学筛选获得避荫反应相关的sav6突变体。通过图位克隆，他们发现SAV6编码拟南芥FEN1同源基因。sav6突变体对紫外线和导致双链DNA损伤的诱变剂表现出超敏的表型;其根尖细胞中与DNA损伤修复相关基因的表达量升高，说明SAV6参于DNA损伤修复以及基因组完整性的维持。
SAV6的突变还影响了根尖分生组织的发育。他们发现sav6突变体中的DNA 损伤导致一方面通过影响细胞周期调控蛋白SMR7的表达而影响根尖分生组织细胞的分裂;另一方面，通过持续激活ERF115-PSK5信号通路，促进根尖干细胞组织中心细胞的分裂，使其丧失干细胞组织中心的特征，从而影响根尖分生组织的发育。
原文链接：
Shade avoidance 6 encodes an Arabidopsis flap endonuclease required for maintenance of genome integrity and development.
原文摘要：
Flap endonuclease-1 (FEN1) belongs to the Rad2 family of structure-specific nucleases. It is required for several DNA metabolic pathways, including DNA replication and DNA damage repair. Here, we have identified a shade avoidance mutant, sav6, which reduces the mRNA splicing efficiency of SAV6. We have demonstrated that SAV6 is an FEN1 homologue that shows double-flap endonuclease and gap-dependent endonuclease activity, but lacks exonuclease activity. sav6 mutants are hypersensitive to DNA damage induced by ultraviolet (UV)-C radiation and reagents that induce double-stranded DNA breaks, but exhibit normal responses to chemicals that block DNA replication. Signalling components that respond to DNA damage are constitutively activated in sav6 mutants. These data indicate that SAV6 is required for DNA damage repair and the maintenance of genome integrity. Mutant sav6 plants also show reduced root apical meristem (RAM) size and defective quiescent centre (QC) development. The expression of SMR7, a cell cycle regulatory gene, and ERF115 and PSK5, regulators of QC division, is increased in sav6 mutants. Their constitutive induction is likely due to the elevated DNA damage responses in sav6 and may lead to defects in the development of the RAM and QC. Therefore, SAV6 assures proper root development through maintenance of genome integrity.
作者：陶懿
