Depletion of the yeast nuclear exosome subunit Rrp6 results in accumulation of polyadenylated RNAs in a discrete domain within the nucleolus
Depletion of the yeast nuclear exosome subunit Rrp6 results in accumulation of polyadenylated RNAs in a discrete domain within the nucleolus
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DOI：
10.1128/mcb.00120-07
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发表时间：
2007-06-01
影响因子：
5.3
通讯作者：
Carmo-Fonseca, Maria
中科院分区：
文献类型：
--
作者：
Carneiro, Tiago;Carvalho, Celia;Carmo-Fonseca, Maria
最近的数据表明，RNA聚合酶I，II和III产生的转录物的相当大的一部分在细胞核中迅速降解的外泌体和非典型的聚（A）聚合酶活性的联合作用。这项工作确定了在核外泌体RNase Rrp 6或外泌体辅因子Mtr 4不存在的情况下富含多腺苷酸化RNA的酵母核仁内的结构域。在正常酵母细胞中，在核仁中检测不到poly（A）（+）RNA，但Rrp 6或Mtr 4的缺失导致多聚腺苷酸化RNA在离散的亚核仁区域中积累。该核仁poly（A）结构域富含U14 snoRNA和snoRNP蛋白Nop 1，但与在snoRNA成熟中起作用的核仁体不同。在缺乏Rrp 6和多聚腺苷酸聚合酶Trf 4的菌株中，多聚腺苷酸（+）RNA的积累受到抑制，表明Trf 4-Air 1/2-Mtr 4多聚腺苷酸化（TRAMP）复合物的参与。聚腺苷酸化snoRNA在离散核仁结构域中的积累可以促进它们作为外泌体底物的识别。
Recent data reveal that a substantial fraction of transcripts generated by RNA polymerases I, II, and III are rapidly degraded in the nucleus by the combined action of the exosome and a noncanonical poly(A) polymer-ase activity. This work identifies a domain within the yeast nucleolus that is enriched in polyadenylated RNAs in the absence of the nuclear exosome RNase Rrp6 or th exosome cofactor Mtr4. In normal yeast cells, poly(A) (+) RNA was undetectable in the nucleolus but the depletion of either Rrp6 or Mtr4 led to the accumulation of polyadenylated RNAs in a discrete subnucleolar region. This nucleolar poly(A) domain is enriched for the U14 snoRNA and the snoRNP protein Nop1 but is distinct from the nucleolar body that functions in snoRNA maturation. In strains lacking both Rrp6 and the poly(A) polymerase Trf4, the accumulation of poly(A) (+) RNA was suppressed, suggesting the involvement of the Trf4-Air1/2-Mtr4 polyadenylation (TRAMP) complex. The accumulation of polyadenylated snoRNAs in a discrete nucleolar domain may promote their recognition as substrates for the exosome.