Cogoni C, Macino G
Istituto Pasteur Fondazione Cenci Bolognetti, Dipartimento di Biotecnologie Cellulari ed Ematologia, Sezione di Genetica Molecolare, Policlinico Umberto I, Universita' di Roma La Sapienza, Viale Regina Elena, 324, 00161 Rome, Italy.
Proc Natl Acad Sci U S A. 1997 Sep 16;94(19):10233-8. doi: 10.1073/pnas.94.19.10233.
We report the isolation of 15 Neurospora crassa mutants defective in "quelling" or transgene-induced gene silencing. These quelling-defective mutants (qde) belonging to three complementation groups have provided insights into the mechanism of posttranscriptional gene silencing in N. crassa. The recessive nature of the qde mutations indicates that the encoded gene products act in trans. We show that when qde genes are mutated in a transgenic-induced silenced strain containing many copies of the transgene, the expression of the endogenous gene is maintained despite the presence of transgene sense RNA, the molecule proposed to trigger quelling. Moreover, the qde mutants failed to show quelling when tested with another gene, suggesting that they may be universally defective in transgene-induced gene silencing. As such, qde genes may be involved in sensing aberrant sense RNA and/or targeting/degrading the native mRNA. The qde mutations may be used to isolate the genes encoding the first components of the quelling mechanism. Moreover, these quelling mutants may be important in applied and basic research for the creation of strains able to overexpress a transgene.
我们报道了15株在“基因压制”或转基因诱导的基因沉默方面存在缺陷的粗糙脉孢菌突变体的分离情况。这些属于三个互补群的基因压制缺陷型突变体（qde）为深入了解粗糙脉孢菌转录后基因沉默机制提供了线索。qde突变的隐性性质表明所编码的基因产物起反式作用。我们发现，在含有多个转基因拷贝的转基因诱导沉默菌株中，当qde基因发生突变时，尽管存在被认为可触发基因压制的转基因正义RNA，但内源基因的表达仍得以维持。此外，用另一个基因进行测试时，qde突变体未能表现出基因压制现象，这表明它们在转基因诱导的基因沉默方面可能普遍存在缺陷。因此，qde基因可能参与检测异常的正义RNA和/或靶向/降解天然mRNA。qde突变可用于分离编码基因压制机制首个组分的基因。此外，这些基因压制突变体对于创建能够过表达转基因的菌株的应用研究和基础研究可能具有重要意义。
