转录后基因沉默

POST-TRANSCRIPTIONAL GENE SILENCING

转录后基因沉默 (PTGS)普遍存在于生物界 ,如植物的共抑制、源于病原的 RNA介导的病毒抗性、真菌的基因沉默和动物的 RNA干扰等。这类现象有许多共同特点 ,如都是以向细胞内引入核酸 (转基因、双链 RNA或病毒 RNA)为诱因 ,依赖 RNA的 RNA聚合酶 (Rd RP)活性与基因沉默密切相关 ,在发生基因沉默的细胞中大多存在特定长度的小分子 RNA(2 1～ 2 5 nt) ,PTGS导致细胞质内 m RNA的特异性降解 ,不同生物的 PTGS相关基因及产物具有很高的相似性 ,基因沉默能够在细胞间传播并能以表型遗传的方式传递给下一代等。这说明各种生物的转录后基因沉默可能有相似的遗传起源 ,是一种抵抗外来核酸 (如病毒和转座子 )

Post transcriptional gene silencing (PTGS) has been found to occur in plants, fungi and animals. There are some common characteristics for PTGS found so far across biological kingdoms. Genes encoding proteins with sequence similar to RNA dependent RNA polymerase (RdRP) are involved in PTGS; small RNA molecules of 21-25 nt in size have been found both in plant and animal cells showing PTGS or RNAi; PTGS results in the degradation of mRNA in cytoplasm; silencing can be systemically transducted. All these findings suggest that PTGS is a universal gene regulation system which is fundamental in biological process, and that PTGS is a mechanism of living organisms to fight against the invasion of foreign nucleic acids, such as virus and transposon.