反式作用干扰小RNA

反式作用干扰小RNA（Trans-acting siRNA，簡稱tasiRNA）是陸生植物的一類小干擾RNA（siRNA），可進行RNA干擾，抑制其他基因的表現^[1]^[2]^[3]。tasiRNA最早於2004年在模式生物阿拉伯芥中發現^[1]^[2]，植物有TAS1、TAS2、TAS3與TAS4四個基因家族的基因編碼tasiRNA，這些基因轉錄產生的RNA後會被多腺苷酸化，在miRNA介導之下TAS1、TAS2與TAS4轉錄的RNA5'端會被Ago1（英语：Ago1）切割，TAS3轉錄的RNA則是3'端被Ago7切割^{[註 1]}^[5]，接著此RNA由RNA複製酶RDR6轉為雙股RNA後，再被DCL4切割成長21nt且3'端有突出端的小雙股RNA^[6]^[7]，可與RNA誘導沉默複合體（RISC）結合以進行RNA干擾，將目標mRNA的切割移除^[1]。

陸生植物有數種tasiRNA可抑制生长素应答因子（auxin response factor，ARF）的mRNA表現，其突變會造成植株發育異常^[4]。

註腳[编辑]

^ 過去認為需TAS3轉錄的RNA在此步驟有兩個位點會與Ago7結合，但僅有3'端的位點被切割，後續研究認為僅有5'端的位點和Ago7結合並非必要，但可增進tasiRNA生成與調控的準確度^[4]。

參考文獻[编辑]

^ ^1.0 ^1.1 ^1.2 Vazquez F, Vaucheret H, Rajagopalan R, Lepers C, Gasciolli V, Mallory AC, Hilbert JL, Bartel DP, Crété P. Endogenous trans-acting siRNAs regulate the accumulation of Arabidopsis mRNAs. Mol. Cell. 2004, 16 (1): 69–79. PMID 15469823. doi:10.1016/j.molcel.2004.09.028.
^ ^2.0 ^2.1 Peragine A, Yoshikawa M, Wu G, Albrecht HL, Poethig RS. SGS3 and SGS2/SDE1/RDR6 are required for juvenile development and the production of trans-acting siRNAs in Arabidopsis. Genes Dev. 2004, 18 (19): 2368–79. PMC 522987 . PMID 15466488. doi:10.1101/gad.1231804.
^ Axtell MJ, Jan C, Rajagopalan R, Bartel DP. A two-hit trigger for siRNA biogenesis in plants. Cell. 2006, 127 (3): 565–77. PMID 17081978. doi:10.1016/j.cell.2006.09.032.
^ ^4.0 ^4.1 de Felippes FF, Marchais A, Sarazin A, Oberlin S, Voinnet O. A single miR390 targeting event is sufficient for triggering TAS3-tasiRNA biogenesis in Arabidopsis.. Nucleic Acids Res. 2017, 45 (9): 5539–5554. PMC 5435969 . PMID 28334969. doi:10.1093/nar/gkx119.
^ Allen E, Howell MD. miRNAs in the biogenesis of trans-acting siRNAs in higher plants.. Semin Cell Dev Biol. 2010, 21 (8): 798–804. PMID 20359543. doi:10.1016/j.semcdb.2010.03.008.
^ Talmor-Neiman M, Stav R, Klipcan L, Buxdorf K, Baulcombe DC, Arazi T. Identification of trans-acting siRNAs in moss and an RNA-dependent RNA polymerase required for their biogenesis. Plant J. 2006, 48 (4): 511–21. PMID 17076803. doi:10.1111/j.1365-313X.2006.02895.x.
^ Rajeswaran R, Aregger M, Zvereva AS, Borah BK, Gubaeva EG, Pooggin MM. Sequencing of RDR6-dependent double-stranded RNAs reveals novel features of plant siRNA biogenesis.. Nucleic Acids Res. 2012, 40 (13): 6241–54. PMC 3401431 . PMID 22434877. doi:10.1093/nar/gks242.

[5] 過去認為需TAS3轉錄的RNA在此步驟有兩個位點會與Ago7結合，但僅有3'端的位點被切割，後續研究認為僅有5'端的位點和Ago7結合並非必要，但可增進tasiRNA生成與調控的準確度^[4]。

[Vazquez_2004-1] 1.0 ^1.1 ^1.2 Vazquez F, Vaucheret H, Rajagopalan R, Lepers C, Gasciolli V, Mallory AC, Hilbert JL, Bartel DP, Crété P. Endogenous trans-acting siRNAs regulate the accumulation of Arabidopsis mRNAs. Mol. Cell. 2004, 16 (1): 69–79. PMID 15469823. doi:10.1016/j.molcel.2004.09.028.

[Peragine_2004-2] 2.0 ^2.1 Peragine A, Yoshikawa M, Wu G, Albrecht HL, Poethig RS. SGS3 and SGS2/SDE1/RDR6 are required for juvenile development and the production of trans-acting siRNAs in Arabidopsis. Genes Dev. 2004, 18 (19): 2368–79. PMC 522987 . PMID 15466488. doi:10.1101/gad.1231804.

[pmid17081978-3] Axtell MJ, Jan C, Rajagopalan R, Bartel DP. A two-hit trigger for siRNA biogenesis in plants. Cell. 2006, 127 (3): 565–77. PMID 17081978. doi:10.1016/j.cell.2006.09.032.

[pmid28334969-4] 4.0 ^4.1 de Felippes FF, Marchais A, Sarazin A, Oberlin S, Voinnet O. A single miR390 targeting event is sufficient for triggering TAS3-tasiRNA biogenesis in Arabidopsis.. Nucleic Acids Res. 2017, 45 (9): 5539–5554. PMC 5435969 . PMID 28334969. doi:10.1093/nar/gkx119.

[pmid20359543-6] Allen E, Howell MD. miRNAs in the biogenesis of trans-acting siRNAs in higher plants.. Semin Cell Dev Biol. 2010, 21 (8): 798–804. PMID 20359543. doi:10.1016/j.semcdb.2010.03.008.

[Talmor-Neiman_2006-7] Talmor-Neiman M, Stav R, Klipcan L, Buxdorf K, Baulcombe DC, Arazi T. Identification of trans-acting siRNAs in moss and an RNA-dependent RNA polymerase required for their biogenesis. Plant J. 2006, 48 (4): 511–21. PMID 17076803. doi:10.1111/j.1365-313X.2006.02895.x.

[pmid22434877-8] Rajeswaran R, Aregger M, Zvereva AS, Borah BK, Gubaeva EG, Pooggin MM. Sequencing of RDR6-dependent double-stranded RNAs reveals novel features of plant siRNA biogenesis.. Nucleic Acids Res. 2012, 40 (13): 6241–54. PMC 3401431 . PMID 22434877. doi:10.1093/nar/gks242.

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